[HN Gopher] Perseverance Rover lands on Mars [video]
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Perseverance Rover lands on Mars [video]
Author : malloreon
Score : 1487 points
Date : 2021-02-18 19:16 UTC (1 days ago)
(HTM) web link (www.youtube.com)
(TXT) w3m dump (www.youtube.com)
| adolph wrote:
| Clicking on the solar system icon at the top of this page
| provides a JavaScript version of NASA's Eyes solar system mapping
| application. You can look up the Perseverance mission as "Mars
| 2020" right now.
|
| https://solarsystem.nasa.gov/interactives/
| MisterBiggs wrote:
| NASA works.
| perryizgr8 wrote:
| I must say that this mission is highly disappointing. No risks,
| no major progress, no pushing the limits.
|
| What does NASA have to show for a decade of work, since Curiosity
| landed in 2012? A toy helicopter, a drill that poops pellets.
| Billions of dollars and millions of man-hours later, this is the
| only progress.
|
| The truth is NASA has become extremely conservative and slow.
| Compare this to the moon landing. NASA went from one man in Earth
| orbit in 1961 to people walking on the moon as a matter of
| routine in 1969. That is the pace needed for serious
| technological progress in space.
|
| We must let NASA die, and let others pursue these feats, people
| who have a real passion for space exploration. If NASA had only a
| bit of passion, they would have sent men on this mission, based
| on all the learnings from Curiosity.
|
| Defund NASA.
| justforfunhere wrote:
| They have put onboard, microphones for the first time, two of
| them. We should be able to get some recorded sounds of Martian
| surface soon.
|
| The EDL phase was quite complex this time. The cameras took
| pictures of the surface while landing and compared them to the
| maps it had from orbital missions. Using these two, it decided in
| realtime, which place would be the best of the its landing. This
| made it possible for it land in a more difficult terrain, like
| the crater where it landed.
| [deleted]
| davidw wrote:
| I love space science and engineering! It's such a beacon of hope
| and a demonstration of what we can do when we work hard and
| innovate. And it's pretty interesting in its own right.
| jaegerpicker wrote:
| Yes, especially during the Covid pandemic and the political
| unrest in the US. Space exploration has helped keep me sane and
| to have some hope for mankind.
| ssijak wrote:
| It is just mind boggling that something so far away is
| autonomously landing on a another planet in such a complicated
| manner and reporting back to us. Humans can be amazing, this kind
| of achievements always make me tear up from joy.
| Shivetya wrote:
| Also on https://www.twitch.tv/nasa
|
| They were showing off a model of the rover, I did not realize
| just how large this one is!
| [deleted]
| sethbannon wrote:
| These accomplishments are so damn inspiring. Reminds me of this
| West Wing clip: https://www.youtube.com/watch?v=R2HzHSeV9v8
| crubier wrote:
| Space exploration is unlike anything else. Perfect combination of
| exploring unknowns + badass robots + science.
| tectonic wrote:
| You can also watch an EDL visualization in your browser:
| https://eyes.nasa.gov/apps/mars2020/#/home
|
| And read about how it will use Terrain Relative Navigation to
| find a safe landing spot: https://www.jpl.nasa.gov/news/a-neil-
| armstrong-for-mars-land...
|
| Perseverance is phenomenally complex, its Sample Caching System
| alone contains 3,000+ parts and two robotic arms. So exited for
| all the sciencing this nuclear-powered, sample-drilling, laser-
| zapping behemoth can do when it joins its friends on the only
| planet (known) to be inhabited solely by robots.
|
| Edit: Percy is about to release its two 77 kg Cruise Mass Balance
| Devices (is this what NASA calls 'weights'?) to setup the right
| lift-to-drag ratio for entry. Mars InSight will be listening for
| the 14,000 km/hr impacts of these weights, providing useful
| calibration data. We wrote about this in this week's issue of our
| space-related newsletter, Orbital Index -
| https://orbitalindex.com/archive/2021-02-17-Issue-104/
| michaelwilson wrote:
| It turns out that they took 640lbs (!) of weight to mars to be
| tossed off at various points during EDL. The video is worth
| watching if you'd like some more of the nitty-gritty behind the
| process: https://www.youtube.com/watch?v=W0NakShgbHY
| rsj_hn wrote:
| Thanks for introducing me to the French Space Guy! I am
| hooked.
| jessriedel wrote:
| Great video! I am also surprised by the fact that they bring
| that much mass just to jettison. In theory they could mounted
| some of the useful mass on a slider/rail system to achieve
| the necessary adjustment to the mass distribution without
| dropping mass overall, but apparently it wasn't worth the
| complexity/volume cost.
|
| I'm sort of surprised we don't yet have ML powered "de-
| accent-ization". His french accent isn't hard to understand
| at normal speed, but when I set it to 1.5x or 2x speed it
| becomes hard to decipher in a way native speakers usually are
| not. If there was just a button (for him or me) to hit to
| tweak the sounds a bit to reduce the accent, I bet this
| problem would go away.
| nippoo wrote:
| No need to have a fancy all-new ML algorithm - stick a
| text-to-speech output on the auto-generated video subtitles
| and you can set it to whatever language you like.
|
| If the speech recognition / subtitling algorithm can't
| understand the nuances of the language, that's going to be
| a problem anyway... accented pronunciation is so
| multidimensional, you're pretty much going to have to
| transcribe syllables/phonemes first...
| stargazer-3 wrote:
| I, for one, would be uncomfortable with AI removing my
| accent. I understand it's for other people to understand me
| better - and I am fine with AI-generated subtitles - but
| altering the way I speak would reduce the amount of "me" in
| ways I'm not fully ok with.
| omni wrote:
| What's special about speech that makes this argument
| apply to speech alteration but not to subtitles? It's a
| tool to make you easier to understand, not to erase your
| person.
| throwaway316943 wrote:
| Interesting, are you uncomfortable with the current
| option to increase or decrease playback speed?
| jessriedel wrote:
| You wouldn't need to use it on videos you produce if you
| don't want.
| _-___________-_ wrote:
| I'm amazed that people still say things like "de-accent" as
| if there was such a thing as "no accent". You are asking
| for a button that makes his French accent more like your
| own. It's a separate thing from native vs. non-native
| speakers - there are plenty of native English speakers with
| accents that you would also find challenging.
| aardshark wrote:
| There is no such thing as "no accent". There is such a
| thing as a more neutral accent, or an accent more widely
| understood.
| jessriedel wrote:
| You are reading something into my comment that wasn't
| there in order to pick a boring fight. There is of course
| no such thing as no accent a priori, but there is such a
| thing as "accents understood by (vastly) more people" and
| "accents closer to the mean accent of native speakers".
| When I learn Russian, my English accent is not on the
| same footing as a Muscovite's; the intended notion of
| "de-accenting" the English accent on my Russian is
| obvious.
|
| Consider responding to the substance of the comment
| instead.
| [deleted]
| enriquto wrote:
| > accents closer to the mean accent of native speakers
|
| Notice that, for the case of English, most speakers are
| not native, by a huge margin! Native English speakers are
| a biased minority, and with a lot of variation within.
| Not sure that an "average native" accent is a useful
| concept at all. I, for one, tend to find most non-native
| English speakers vastly easier to understand than many
| native speakers.
| jychang wrote:
| This is a dumb fight to pick. Dude just wants some ML
| software to figure out how to change accents.
|
| Maybe he wants to change the accent to a Texas accent, or
| the Queen's english, who cares, it's the ML part that's
| interesting.
| jessriedel wrote:
| > Notice that, for the case of English, most speakers are
| not native, by a huge margin!
|
| I'm well aware, and this does not rebut any of my points.
|
| > I, for one, tend to find most non-native English
| speakers vastly easier to understand than many native
| speakers.
|
| That "many" native speakers in a language of hundreds of
| millions of speakers are hard to understand does not
| challenge the claim that a non-native accent brought
| closer to any native accent, much less the mean native
| accent, will for the large majority if listeners be
| easier rather than harder to understand.
| lopis wrote:
| Note: that's 290kg in NASA units
| thamer wrote:
| I was hoping someone would link this video, it describes the
| various phases with a ton of details that.
|
| Some of the other videos on this channel are just as in-
| depth: the ones about the plumes/exhaust of rocket engines as
| well as star occlusions are incredibly detailed.
| twic wrote:
| > Cruise Mass Balance Devices
|
| They put those in to make the probe seem higher-quality. They
| got the idea from Beats headphones.
| azernik wrote:
| We were doing that at Meraki back in the early 2010s (it
| turned out they were also useful as a heat sink and, because
| the metal was exposed to air, a radiator). Pretty sure Meraki
| got the idea from some Apple product or other.
| darkwater wrote:
| Speaking of Meraki, I had an awful experience with those
| devices. Basically we were in building with TONS of other
| wifi networks around and Meraki network just went crazy
| from time to time until we fine tune it down to the channel
| for each AP. I mean, for something you pay $$$ to buy the
| devices and $$$ each month for the subscription is a pretty
| poor experience.
| jamiek88 wrote:
| Just to set the record a bit straighter and ruin your joke,
| those pics of beats with weights were knockoff beats from the
| flea market not real.
| lathiat wrote:
| Reporting on that: https://gizmodo.com/are-beats-
| headphones-really-designed-to-...
| dmix wrote:
| > And read about how it will use Terrain Relative Navigation to
| find a safe landing spot:
|
| So basically TERCOM from cruise missles but used on space
| crafts? All you need is a radar countour map of the area and it
| can automate it's way to the endzone.
|
| https://en.wikipedia.org/wiki/TERCOM
| FredFS456 wrote:
| Perseverance's Terrain Relative Navigation uses a camera
| system and generates a full 3D position fix, but the idea is
| similar.
| spaetzleesser wrote:
| They should make km the default unit and not miles....
| mulmen wrote:
| Ever been on an airplane? Altitude was almost certainly
| measured in kilofeet.
|
| As noted in other comments, NASA (like the rest of the United
| States [1]) does use the metric system.
|
| But it doesn't matter. Nothing about the metric system makes
| it uniquely suitable to landing on Mars. Or space travel in
| general. What matters is a consistent standard.
|
| Internally NASA could use Armstrongs. Where 1 is the weight
| or height of Neil Armstrong at KSC on July 16, 1969 at
| 13:32:00 UTC. It doesn't matter. As long as it is consistent.
|
| [1]: https://en.m.wikipedia.org/wiki/Metrication_in_the_Unite
| d_St...
| dieortin wrote:
| It does matter. See the errors caused in the past by using
| the imperial system. The metric system has a number of
| advantages.
| mulmen wrote:
| The errors were not caused by the imperial system. The
| errors were caused by using the imperial system _and_ the
| metric system. Specifically in expecting one system and
| getting the other.
| zajio1am wrote:
| >The errors were caused by using the imperial system and
| the metric system
|
| Using one universally accepted system is core idea behind
| metric system. Now, it looks like it is competition
| between two equal systems, but historically it is
| competition between ideas 'we should have one universal
| system' and 'every country/area can stay on their local
| systems'. Just all other legacy local systems (outside
| u.s. customary) disappeared.
| bernulli wrote:
| The thing is, though, that you have these conversions
| even within the imperial system (https://en.m.wikipedia.o
| rg/wiki/Imperial_units#/media/File%3...) but not within
| the metric system.
|
| My experience with U.S. students is that they are having
| a much harder time making sense of the imperial system
| (that they are used to) than doing problems in metric,
| even though they don't use it in everyday life.
| mulmen wrote:
| Ok, so?
|
| First off, you linked to a list of english measures which
| are not used in the US. Nobody uses fathoms or
| barleycorns.
|
| Here is the list of actual US customary units: https://en
| .m.wikipedia.org/wiki/United_States_customary_unit...
|
| Second, none of that is relevant to landing on Mars.
|
| The only problem space where metric has an advantage is
| in converting between meters, kilometers and millimeters.
|
| That's great, and it's easy to learn. But it doesn't
| suddenly make all problems of distance easier to solve.
|
| If I am traveling toward Mars at 47 meters per second it
| doesn't help me to know that is also .047km per second.
| And converting to kilometers per hour involves using base
| 60 twice anyway because metric time is unwieldy.
|
| In reality none of your _measurements_ are going to be
| nice round numbers. Mentally converting from meters to km
| might be nice sometimes but it's essentially a party
| trick.
|
| It won't help the lander make decisions. The hardware
| doesn't inherently work in base 10.
|
| Does NASA mix meters and kilometers? Isn't that the same
| problem that destroyed the Mars Climate Orbiter?
|
| The fact is the units are irrelevant beyond just being
| defined and used consistently.
|
| Also, I can't think of a situation where I need to
| convert miles to feet. My bike ride is six miles, I'm
| never going to express that in feet. If I need to
| describe the size of a thing in a room I will probably
| use feet, maybe inches if it is small. Probably not feet
| and inches. I wouldn't use miles at all. Easy conversion
| between those units just isn't a problem that comes up.
| It's more important to me to have reasonably sized units
| and that the person I am communicating with understands
| them.
| bernulli wrote:
| Yes I understand. Imperial is awesome because you can
| divide a foot by exactly 2, 3, 4 , and 6, which of
| course, is the main problem everyone has every day.
| Metric on the other hand sucks because none of my
| measurements will ever be nice round numbers.
|
| The hardware doesn't think in base 10, but having more
| than that in imperial makes it better?
|
| Your document lists 12 mass units alone. I rest my case,
| what could possibly be more logical, convenient, and need
| less conversion.
|
| If communication was your major goal, then the system
| that is used by 7.3 billion people on this planet would
| be your choice.
| mulmen wrote:
| > Yes I understand. Imperial is awesome because you can
| divide a foot by exactly 2, 3, 4 , and 6, which of
| course, is the main problem everyone has every day.
|
| Great, we agree.
|
| > Metric on the other hand sucks because none of my
| measurements will ever be nice round numbers.
|
| Depends on the situation. Metric units can be useful.
|
| > The hardware doesn't think in base 10, but having more
| than that in imperial makes it better?
|
| No, it means neither system has an advantage so just pick
| one. Or invent a new one that allows better hardware
| utilization.
|
| > Your document lists 12 mass units alone. I rest my
| case, what could possibly be more logical, convenient,
| and need less conversion.
|
| I don't convert, I just pick the unit that fits the
| problem.
|
| > If communication was your major goal, then the system
| that is used by 7.3 billion people on this planet would
| be your choice.
|
| Yeah I use the metric system all the time. Just like
| NASA.
| bernulli wrote:
| >> The hardware doesn't think in base 10, but having more
| than that in imperial makes it better? >No, it means
| neither system has an advantage so just pick one. Or
| invent a new one that allows better hardware utilization.
|
| But one of the systems does have an advantage because it
| stays in base 10, whereas the other doesn't.
|
| >> Your document lists 12 mass units alone. I rest my
| case, what could possibly be more logical, convenient,
| and need less conversion. >I don't convert, I just pick
| the unit that fits the problem
|
| But you can't if you just use the `intuitive unit', and
| that's the whole problem. How would you measure the
| amount of liquid fuel in, say, the small tank for an
| attitude control thruster of some probe? How does that
| add to the overall mass of the whole probe? Or to the
| force you then need to accelerate it by a certain amount?
| And now compared to the whole launcher?
|
| In which units do you measure everything going on in a
| small wind tunnel model, and how do you compare that with
| the real thing?
|
| Under which conditions do you go from fluid ounces to
| ounces to cups to pints to quarts to gallons (also note
| that, again, you not only switch units but bases)?
|
| >Yeah I use the metric system all the time. Just like
| NASA.
|
| Good for you, it solves all the problems.
| mulmen wrote:
| > But one of the systems does have an advantage because
| it stays in base 10, whereas the other doesn't.
|
| That's a benefit to humans, not to hardware, which was
| the context in which I was speaking.
|
| > But you can't if you just use the `intuitive unit', and
| that's the whole problem. How would you measure the
| amount of liquid fuel in, say, the small tank for an
| attitude control thruster of some probe? How does that
| add to the overall mass of the whole probe? Or to the
| force you then need to accelerate it by a certain amount?
| And now compared to the whole launcher?
|
| Honestly? I'd probably _measure_ it in volts. That 's
| what the hardware is doing after all. That's my point, it
| doesn't help the computer to convert to base 10 and do
| calculations that way. Fuel level is measured in volts
| using binary. For a human something like grams probably
| makes more sense so sure, display it in those units. But
| that's a conversion.
|
| > In which units do you measure everything going on in a
| small wind tunnel model, and how do you compare that with
| the real thing?
|
| Again, volts on strain sensors. Maybe analog or maybe
| binary, in newtons. Again, the hardware doesn't think in
| units humans prefer. There has to be a conversion that
| doesn't use simple in-your-head math.
|
| > Under which conditions do you go from fluid ounces to
| ounces to cups to pints to quarts to gallons (also note
| that, again, you not only switch units but bases)?
|
| Cups, pints, quarts and gallons are all based on the
| ounce and powers of two. A gallon is 128oz, a half gallon
| is 64oz, a quart is 1/2 of a half gallon (or a quarter
| gallon) or 32oz (also, approximately a liter). A pint is
| half a quart or 1/8th of a gallon or 16oz, a cup is half
| a pint or 1/16th of a gallon or 8 oz. These fractional
| scales are really handy for converting between units in
| some situations. The unit fits the task at hand or you
| can trivially double or halve the size of the unit if
| needed. It's the same fractional scale and math used with
| the inch.
| jerven wrote:
| I just want to add. It's quite common in carpentry to
| work with 120cm base wood. Which devides just as nice.
| And even then it's easier to convert when moving into
| bigger or smaller units.
| cambalache wrote:
| Without looking could you tell me..
|
| How many pounds does a cubic feet of water have?
|
| How many BTUs do you need to heat 10x10x3 ft water pool
| 20 degrees F?
|
| How much work in ft-lb is done by gravity when a 10 oz
| mass drops from 19 yards?
|
| How many HP are needed to rais 2400 lbs 74 inches in 30
| sec?
|
| It is obvious you have 0 experience doing back-of-the-
| envelope calculations for scientific or engineering
| purposes. It is a no-contest between the metric and the
| imperial systems.
| mulmen wrote:
| I'd love to have a box of JPL envelopes so I can do
| calculations like a real engineer.
| lmm wrote:
| > If I am traveling toward Mars at 47 meters per second
| it doesn't help me to know that is also .047km per
| second.
|
| Yes it does. It means you can immediately sanity-check
| your numbers even if you don't have a good sense of what
| meters and kilometers are, because you have that
| base/kilo relationship.
|
| > My bike ride is six miles, I'm never going to express
| that in feet.
|
| You can eyeball how fast you're going in feet per second
| and have a rough idea of how long your ride is going to
| take. Or rather you could if you had any idea of how long
| your ride was in feet. There are lots of little everyday
| things that just become much easier.
| mulmen wrote:
| I'm not sure how that sanity check works, can you
| explain? Do you mean checking conversion between meters
| and kilometers? Because sure, that's easier but you could
| just do everything in meters instead and not run the risk
| of crashing a spacecraft because of unnecessary
| conversions or bad assumptions.
|
| I estimate my bike ride progress in landmarks and time.
| Not feet per second. Did I get to the boat ramp in
| 20minutes? Better speed up and get to the park by 30.
| lmm wrote:
| > Do you mean checking conversion between meters and
| kilometers? Because sure, that's easier but you could
| just do everything in meters instead and not run the risk
| of crashing a spacecraft because of unnecessary
| conversions or bad assumptions.
|
| But you'll have small distances and large distances and
| pieces from external sources who use measurements on a
| scale that makes sense to them. You can make your
| external sources do conversions themselves, but that's
| just moving the problem around. There will usually end up
| being a point, or probably several points, where you have
| to relate a small distance to a large distance, and
| wherever that happens, a human sanity check is a help.
|
| > I estimate my bike ride progress in landmarks and time.
| Not feet per second. Did I get to the boat ramp in
| 20minutes? Better speed up and get to the park by 30.
|
| Precisely - you have no sense of the relation between
| your speed and how far you can go, because you're using a
| terrible measurement system, and you don't even notice
| the how that's robbing you of the ability to develop
| useful intuitions.
| mulmen wrote:
| My bicycle doesn't even have a speedometer so I'm not
| sure how the metric system is supposed to expand my
| world. I'm happy looking around and glancing at my watch.
|
| Miles per hour is literally a measure of distance over
| time. If I wanted to use my GPS I could very easily
| determine how far I can go in a given amount of time. I
| can do this equally well in the metric or imperial
| systems, without converting to feet or meters.
| Cthulhu_ wrote:
| Quick, how many miles is 26357 feet?
|
| With metric it's a matter of shifting the decimal.
|
| How much is a sixteenth inch anyways.
| mulmen wrote:
| Yes, conversion between mm, cm, m and km is easy. What's
| your point? If something is miles away why do I care
| about it in terms of feet? How many meters is the sun
| from here? How many km is 1/3 of an AU? How many seconds
| does it take light to go a meter in vacuum?
|
| A 16th is half an 8th. Twice as much as a 32nd. AKA 2^4,
| 2^3 and 2^5, respectively.
| Melkman wrote:
| Consistency is not the only value of a system of units.
| Convenience is also of importance. And that is where the
| metric system shines. Having all measures of a unit in
| multiples 10 combines perfectly with our decimal
| calculations. Having as few as possible magical numbers to
| convert and combine between units makes making mistakes
| harder. How many calories in kinetic energy has a pound
| going 10 miles per hour ? I know a kilo going 10 meters per
| second has 50 joules of kinetic energy without looking up
| anything and doing the calculation in my head.
| killjoywashere wrote:
| Can't talk to the statute mile, but the nautical mile is
| sublime: one minute of latitude. The amount of math you
| can do in your head with a system with so many factors of
| 2, 3, and 5 is truly amazing.
| mulmen wrote:
| I'm not aware of any tricks to make mile calculations
| easier but the fractional scale common with the inch is
| very useful for real-world mental calculation and
| practical exchange. Effectively everything is powers of
| two. Got something between 1/4 and 1/2 inch? Great, use
| 1/8ths. It's three. Not close enough? How about five
| 16ths? It infinitely scales to provide another unit that
| is suited to the measurement at hand. In some contexts
| you might just say you pick the closest 1/8th. In others
| you might use 32nds. You can use the same measuring
| devices to agree on an ad-hoc standard that everyone
| understands.
|
| But with the metric system you only really get cm (too
| coarse) and mm (too fine) but you don't get something
| like 9/16 so you can't "work in 16ths" and have
| everything be whole units again.
|
| Adjusting HVAC in degrees-C is infuriating to my
| Fahrenheit sensibilities. 20C is cold, 22C is hot. 21C is
| probably ok but really I want something like 20.5C. The
| comfortable range for a room is 3-5 whole units of F, but
| requires a bunch of fractions in C that you may not even
| have available on your thermostat.
|
| Sure, converting between units is easy in the metric
| system. That doesn't make it the best thing to use all
| the time. Hell, the idea of thousandths of an inch is
| used commonly, so even the imperial system is base 1000
| in some cases. But I've never seen anyone utilize the
| fractional scale with metric units, probably because the
| units are the wrong size for that to be useful.
| onion2k wrote:
| _But with the metric system you only really get cm (too
| coarse) and mm (too fine) but you don 't get something
| like 9/16 so you can't "work in 16ths" and have
| everything be whole units again._
|
| People who use metric units are perfectly happy rounding
| to the nearest 0.5cm or 0.25cm if that's what's needed,
| exactly as people do with inches. Why on earth would you
| imagine people use mm if something doesn't call for them?
| mulmen wrote:
| But does anyone say 1/8th centimeter? Seems easier to
| just drop down to millimeters at that point. Which is
| fine, but it loses out on the convenience of fractions.
| onion2k wrote:
| People do say things like 1.25mm, which is 1/8th of 1 cm.
|
| Presumably someone who uses Imperial would say 5/128th
| inches if they wanted to describe something that's
| equivalent to 1mm?
| Evidlo wrote:
| Most likely they would use mils/thou.
|
| 25mils ~ 1mm
|
| Or 1/16in as others have said.
| danaliv wrote:
| Also the average of one minute of arc on a great circle
| route, which was the real handy thing about it at sea.
| killjoywashere wrote:
| Yes, meridians (on which latitude is measured) being a
| special case of great circle routes that happen to pass
| through the poles. That said, as a practical matter, you
| are more frequently contemplating a chart of smaller
| scale than "globe" so you're usually counting up distance
| between fixes, or distance to next turn in a harbor, or
| some such thing, where you have a compass in hand and
| just need to set the compass to the length of a mile. The
| nearest latitude tick marks are quite handy for that.
| sojournerc wrote:
| As an occasional woodworker and carpenter, I can tell you
| having evenly divisable (inch) measurements makes mental
| division a whole lot easier. It's just a case of using
| the right tool for the job.
| mulmen wrote:
| It's unfortunate that fractional measurements and the
| base size of units get conflated.
|
| Maybe metric users do use fractions and I just don't hear
| about it. Is that table one and a quarter meters high?
| spaetzleesser wrote:
| People often say something is 1 and a half meters long. I
| don't understand how people can work with inch
| measurements. How do you divide 7"3/8 by 5? This seems a
| major pain.
| chordalkeyboard wrote:
| You multiply 7* 8 then add 3 and put that number over 8*
| 5, resulting in 59/40, roughly 1.5".
| mulmen wrote:
| One and a half seems natural. What about something like a
| quarter meter? I guess that just becomes some number of
| centimeters?
|
| > How do you divide 7"3/8 by 5?
|
| Same way I divide 4.7625 cm by 5. With a calculator.
| flemhans wrote:
| > I guess that just becomes some number of centimeters?
|
| 25, yes. It's not too hard to do the math.
|
| > Same way I divide 4.7625 cm by 5. With a calculator.
|
| That's roughly 0.95 right by intuition, but (7"3/8) / 5
| doesn't come easy to me.
| sojournerc wrote:
| There's something just right about 1/16th of an inch.
| About the same as a millimeter, and easy to do math
| with... it is weird though 1/8th, centimeter is hard to
| conceive, for me anyway.
|
| When more precision is needed, so easy to go to the 32nd
| ascorbic wrote:
| All you're saying is that inches are what you're used to.
| Being in the UK I am familiar with both inches and mm,
| and mm are far easier to work with than 16ths of an inch.
| grecy wrote:
| We use millimetres. That table is 1250mm high.
|
| If you're cutting it yourself, a precision of 1mm is
| finer than your saw blade or pencil line anyway, so it's
| plenty enough.
|
| When I hear anything past about 1/8th of an inch my brain
| shuts down, and I give up.
| mulmen wrote:
| My argument is a mm is too fine in that situation. 1/8ths
| and 1/16ths are ideal when working at those scales.
|
| In reality I use both systems all the time. It's
| situational.
|
| > When I hear anything past about 1/8th of an inch my
| brain shuts down, and I give up.
|
| Realistically, same. 32nds don't get used outside of some
| specialty wrenches. 16ths are a practical limit where
| other scales start to make more sense. Probably
| millimeters.
| cambalache wrote:
| So 3 mm is a weird measure but 1/8 of an inch is just
| perfect? You are like those guys who say that Fahrenheit
| is better because it feels "more natural and obvious"
| mulmen wrote:
| I don't understand why it has to be one or the other?
| Working in fractions is nice sometimes. Inches are a
| useful size for some situations. I find it easier to say
| that's three eighths than 9mm because my ruler doesn't
| have different marks for the factors of each mm mark.
|
| I use both systems.
|
| I do prefer Fahrenheit for HVAC (and weather) because
| it's higher resolution and has reasonable values at human
| scales. Thermostats that lack half-degrees-c are never
| quite right IMO.
| cambalache wrote:
| > I do prefer Fahrenheit for HVAC (and weather) because
| it's higher resolution and has reasonable values at human
| scales.
|
| So you are one of those, lol. There is nothing "less
| human" about 25 C than say 72 F. Nothing, it just happen
| to be the scale you are used to.Both are arbitrary.
|
| > Fahrenheit for HVAC (and weather) because it's higher
| resolution
|
| 99.99% of thermostats and thermometer in C had at least 1
| decimal place. At usual "human temperatures" the
| difference in resolution between the scales is less than
| 2X, so even assuming only integer values, I am willing to
| bet against you in a double blind test that you cannot
| differentiate 68F vs 69F in an statistical significant
| way.
|
| > I find it easier to say that's three eighths than 9mm
|
| Just because you are used to. Fractions are more
| complicated than integers, every elementary school
| program knows it.
|
| So to summarize, the problem is not with the magnitude of
| the units which is arbitrary (a degree F and inches are
| not more human, logical or normal that a degree C or
| cm)the problem is with the convoluted way of the imperial
| system for multiples and submultiples of the base unit.
| mulmen wrote:
| "Human scales" meaning temperatures that won't burn my
| skin or give me frostbite. 70 is nice. 60 is cool. 50 is
| cold. 40 is really cold. 80 is hot. 90 is really hot. 100
| is potentially dangerously hot.
|
| I guess 20.5 is nice, 15.5 is cool, 10 is cold, 4.5 is
| really cold, 26.5 is hot, 32 is really hot and 37.7 is
| dangerously hot. It's fine if you are used to it but I
| don't really see a benefit.
|
| I was in a hotel room in Japan that only had whole unit
| adjustments for the A/C. To get 20.5C I had to switch to
| Fahrenheit. I guess I was unlucky.
|
| I find distances in metric and imperial perfectly usable
| and use both regularly.
|
| As outlined in detail elsewhere in the thread there are
| advantages to working in fractions in some situations.
| Specifically when using a ruler or tape measure with
| different markings for 1/2, 1/4, 1/8 and 1/16. There's no
| reason that has to be unique to inches, it just works out
| well in some cases.
| thiht wrote:
| > I guess 20.5 is nice, 15.5 is cool, 10 is cold, 4.5 is
| really cold, 26.5 is hot, 32 is really hot and 37.7 is
| dangerously hot.
|
| Or, you know, 20, 15, 5, 30 and 40 instead of the
| arbitrary decimals you chose to use to prove your point
| mulmen wrote:
| Sure, you can pick even numbers in either scale that are
| awkward decimals in the other. I just prefer the ten
| degree bands of the Fahrenheit scale for these ranges.
| thiht wrote:
| > I just prefer the ten degree bands of the Fahrenheit
| scale for these ranges.
|
| To the identical 5 degrees range of the Celsius scale ?
| mulmen wrote:
| It's not really identical though. Like I said, Fahrenheit
| is higher resolution at these scales so that is an
| advantage. It doesn't mean everyone should convert to F.
| Just that both systems have benefits. If I changed my
| perception of the world to C I wouldn't actually gain
| anything, personally, in the context of weather and HVAC.
|
| If I need to take measurements while boiling water or
| making ice then I would probably use C.
| [deleted]
| mulmen wrote:
| If working with simple units of ten is beneficial then
| every mission should redefine units in terms of expected
| velocities and vehicle size so they are optimized for the
| actual calculations at hand.
|
| That's not realistic, obviously, so we just pick one. The
| units in the system are arbitrary, really.
|
| In reality regardless of the system you choose every
| calculation is going to end up with fractions of
| something. You aren't just going to do it in your head.
| heisenzombie wrote:
| Physicists are quite fond of redefining units so that the
| constants they care about are all just 1.
| (https://en.wikipedia.org/wiki/Natural_units).
|
| For example, you could define mars units where the
| gravitational acceleration on mars is 1. Now your
| velocity in freefall is just equal to the time you've
| been freefalling! You don't even have to do a
| calculation!
|
| (note: Don't actually do this. Gravitational acceleration
| isn't a constant when you're doing orbital mechanics.)
| mulmen wrote:
| Honestly I would expect something _like_ that to be
| happening at a hardware level. The number of bits in a
| memory address for the ground sensing radar _is_ very
| interesting. Or the algorithm to determine vehicle
| acceleration given the voltage reading of a solid-state
| sensor vs the baseline. The metric system vs the imperial
| system is not an interesting distinction in these
| contexts.
| boilerupnc wrote:
| NASA has experience in unit foul-ups. Mars Climate Orbiter is
| the $125M poster project reminding everyone of the importance
| in having consistency in units.
|
| "At 09:00:46 UT Sept. 23, 1999, the orbiter began its Mars
| orbit insertion burn as planned. The spacecraft was scheduled
| to re-establish contact after passing behind Mars, but,
| unfortunately, no signals were received from the spacecraft.
|
| An investigation indicated that the failure resulted from a
| navigational error due to commands from Earth being sent in
| English units (in this case, pound-seconds) without being
| converted into the metric standard (Newton-seconds).
|
| The error caused the orbiter to miss its intended orbit (87
| to 93 miles or 140 to 50 kilometers) and to fall into the
| Martian atmosphere at approximately 35 miles (57 kilometers)
| in altitude and to disintegrate due to atmospheric
| stresses."[0]
|
| [0] https://solarsystem.nasa.gov/missions/mars-climate-
| orbiter/i...
| lmilcin wrote:
| Actually, NASA uses metric system internally. Imperial units
| are probably used for general public convenience.
| spaetzleesser wrote:
| Considering that one of NASA's roles is to inspire young
| people to enter STEM I think it would be important to
| promote metric as much as possible.
| lmilcin wrote:
| I don't see how the choice here can promote STEM.
|
| Do you think kids find it sexy to talk about meters,
| kilograms and degrees Celcius rather than feet, miles,
| pounds and Fahrenheit?
|
| I can't fault for choosing what is more understandable to
| the target audience.
| fckthisguy wrote:
| As another commenter said, NASA uses metric.
|
| During the stream, you can hear the various teams giving
| measurements in metric, whilst the media gave coverage in
| imperial.
|
| It's a pretty interesting video from that perspective, as you
| can hear the two "realities" being translated for the
| intended audience.
| tectonic wrote:
| Also, InSight's SEIS seismometer is a true marvel: "We have
| been able to detect, at about 10 hertz, displacement of the
| ground of the order of less than 5 picometers...which is a
| fraction of the size of an atom." --
| https://eos.org/features/a-modern-manual-for-marsquake-monit...
| peter303 wrote:
| LIGO puts this shame with 10^11 better sensitivity.
| koheripbal wrote:
| Any idea when they will start experimentation? I want to find
| microbial life!
| Nzen wrote:
| I don't know in general, but JPL published a video [0]
| yesterday of three interviews. One of the systems engineers
| for the MOXIE (atmospheric oxygen separation) unit will wait
| several weeks after landing before their first experiment.
| Actually, scientific american has published a timeline that
| seems to corroborate that [1].
|
| [0] https://youtu.be/TUd604rBR6I?t=643
|
| [1] https://www.scientificamerican.com/article/the-
| first-100-day...
| frabbit wrote:
| What is it about that that excites you so much?
|
| Is it the idea that life could originate elsewhere and that
| there might really be aliens?
|
| Or is it the idea that Mars could support some sort of
| colony?
|
| Or the hope of completely novel microbiology?
| yellowapple wrote:
| Yes.
|
| Any one of these things would be a massive boon to our
| understanding of life throughout the solar system and
| broader universe, right down even to here on Earth. All
| _three_ of them would arguably mark a new era in Earth 's
| history.
| cdelsolar wrote:
| we are very screwed if they find life on Mars. It means
| life is incredibly common and thus the Great Filter
| theory is true and we only have a few years left as a
| species most likely.
| DowsingSpoon wrote:
| Disagree. If there is a filter at all then it could
| easily be that we've already passed it. Maybe the filter
| is the formation of multicellular life, for example.
| Also, Earth and Mars have exchanged a lot of material. If
| we find Mars life, it would not at all be surprising to
| learn it is related to Earth life.
| yellowapple wrote:
| > and thus the Great Filter theory is true
|
| Or we're just ahead of the curve.
| JohnJamesRambo wrote:
| I find it extremely hard to believe you could kill every
| human being on earth at this point. We've reached
| critical mass, we aren't going anywhere. When we had that
| few thousand individuals population bottleneck in the
| past was when it was dicey. What sort of event could kill
| every human and end our species? I can only think of
| planet-wide extinction events like massive asteroid
| impacts that sterilized the whole earth. And we haven't
| ever had one of those in billions of years. Call me too
| optimistic but I think humans are too resourceful. Some
| of us would survive anything smaller.
| sjy wrote:
| There have been at least five mass extinction events in
| the last 500 million years. The most recent one wiped out
| all non-avian dinosaurs, after they had dominated the
| earth for 100 million years. Tool-using apes with
| language have been around for less than 5 million. I
| think it's far too early to say we'll survive the next
| extinction event, or even make it that far before
| diverging into new species.
| mongol wrote:
| I wonder what a huge Carrington solar storm would do to
| humanity. If electricity went out everywhere,
| transformers burned up all over, electronics fried. If
| this caused transport failures, mass starvation could
| follow. I really hope a severe solar storm would not be
| as bad as that and hopefully someone could enlighten me
| on this.
| saagarjha wrote:
| Killing literally every single human being is not easy.
| Sure, killing off half of humanity is pretty easy to
| conceive, but to kill all of humanity it takes a lot more
| work.
| xaqfox wrote:
| Luckily, we have great minds working on this problem:
| https://www.appliedeschatology.com/
| throwaway0a5e wrote:
| >I wonder what a huge Carrington solar storm would do to
| humanity
|
| Worst case it sets us back to 1870ish, maybe. Depends on
| how fast things go to crap vs how fast things can be
| rebuilt.
|
| Likely case you'd basically get a "purge" because society
| as we know it can't keep on rolling with the kind of
| economic breakdown something like that would cause so
| there's be a lot of dying in the interim but if you don't
| starve or get shot in the first 6mo you're probably good
| with the very old, very young and unproductive bearing
| the brunt of it (same as every other disaster) It would
| be like the black death, but global and all at once.
| Balance of power globally would definitely be altered in
| unforeseeable ways but the overall net result is things
| would bounce back hard.
| yellowapple wrote:
| > When we had that few thousand individuals population
| bottleneck in the past was when it was dicey.
|
| Yeah, but those individuals were presumably all in pretty
| close proximity to one another. If we were left with a
| few thousand individuals across the entire range of the
| human-inhabited Earth, we'd have one heck of a time
| continuing as a species.
|
| In any case, the risk of an extinction event on Earth is
| exactly why I believe space colonization needs to be
| Priority Zero for humanity, from two different angles:
|
| 1. Living beyond Earth means that we as a species are
| that much more resilient against a literal-Earth-
| shattering catastrophe (and if we can get the bulk of
| Earth's current/future population _off_ of Earth, then we
| might very well be able to avoid a couple different
| plausible extinction events).
|
| 2. If we can colonize entirely inhospitable worlds like
| Mars or the Moon (or my votes, Ceres, Venus, and
| Enceladus), then "colonizing" Earth is easy-peasy-lemon-
| squeezy even if it does become Venus 2: Greenhouse
| Boogaloo.
| russtrotter wrote:
| Some interesting reasons: the proverbial "2nd genesis",
| panspermia possibilities of our own planet, and answering
| lots of questions on formation of life on ours and any
| other planet we might encounter.
| WJW wrote:
| > is this what NASA calls 'weights'?
|
| Well no, the Cruise Mass Balance Devices are intended to
| Balance the Mass of the spaceship during Cruise conditions.
| That these Devices are single-part and constructed out of a
| single chunk of metal each should not be construed as merely
| being 'weights'. :)
| theelous3 wrote:
| What I'm getting from this, is that you can use weights to
| balance the mass of the spaceship during cruise conditions.
| numpad0 wrote:
| Actually more like that you can eject weights to
| intentionally un-balance the mass of a spaceship so it'll
| glide rather than falling straight down.
|
| Atmospheric drag force center of drag and center of gravity
| to line up on a same axis, which force the craft to fly
| slightly sideways if spacecraft isn't perfectly balanced.
| Done carefully, it leads to direction of flight being
| slightly sideways, which is awkward but basically same as
| having lift towards that direction. Add roll control
| thrusters into the mix, and you get a really crude glider,
| with fixed pitch force, zero yaw control and barely
| controllable roll. With JPL-class engineering, such a
| spacecraft will be capable of actively correcting landing
| location.
| jcims wrote:
| It's like hypersonic curling
| Aeolun wrote:
| Maybe they have both, and needed a name to distinguish the
| ejectable weights from the non-ejectable weights?
| xarope wrote:
| Ships do this all the time (ballast), and anybody who's
| ever flown on a light aircraft or helicopter also knows the
| importance a pilot places on weight distribution.
|
| I guess what's surprising is that they needed that much
| weight (140+kg seems like a lot?) and couldn't redistribute
| existing componentry; guess the knapsack algorithm wasn't
| good enough, or that they just couldn't break up enough
| pieces?
|
| And yes, Cruise Mass Balance Devices sounds like the type
| of name a tired engineer would come up with to convince
| upper management...lol
| FredFS456 wrote:
| They can't redistribute existing componentry because of
| competing requirements: during cruise, the spacecraft
| needs to be balanced around the rotational axis
| (perseverance rotates at 2RPM in cruise). During re-
| entry, an asymmetric weight distribution is needed to
| generate lift.
| xarope wrote:
| Surely you mean: "What I'm getting from this, is that you
| can use devices to balance the mass of the spaceship during
| cruise conditions"...j/k
| rkagerer wrote:
| Got it. Fancy weights.
| [deleted]
| nerfhammer wrote:
| from the author of that software
| https://twitter.com/mrdoob/status/1362508150507790343
| nelsonmandela wrote:
| Apparently the copter was made with off-the-shelf parts.
|
| I wonder if I can cop a replica somewhere, and how it would fly
| considering it is built for martian air
| kibwen wrote:
| Here's a really excellent video that answers all your
| questions: https://m.youtube.com/watch?v=GhsZUZmJvaM
|
| TL;DW: Martian atmosphere is so sparse that it's equivalent to
| flying at 100,000 feet on Earth. (The altitude record on Earth
| is 85,000 feet, set by the SR-71.) In order to fly at all the
| blades have to spin at nearly the (Martian) speed of sound. The
| drone wouldn't fly on Earth because the atmosphere is so dense
| that the blades would never make it up to speed.
| dralley wrote:
| > (The altitude record on Earth is 85,000 feet, set by the
| SR-71.)
|
| The A-12 Arkangel flew higher (95,000 feet) and faster, but
| was short-lived and so highly classified that it doesn't hold
| any "official" records.
|
| And a MiG pilot flew up to 123,000 feet, but only on a
| ballistic trajectory, it wasn't a sustainable altitude.
| ggreer wrote:
| If it was made with off-the-shelf parts then it's a testament
| to how wasteful NASA has become. Building that helicopter took
| them 6 years and $80 million.[1]
|
| 1. See page 20 of the launch press kit:
| https://www.jpl.nasa.gov/news/press_kits/mars_2020/download/...
| vietjtnguyen wrote:
| They can't exactly procure a bunch of parts and then call it
| a day. Lots of the cost is tied to the verification and
| validation. Then there's the system design, requirements
| engineering, trade studies, system integration, engineering
| models, simulation, software, environmental testing, launch
| costs, ground command and data systems, interfacing with the
| rover, etc. Paying engineers to do all that is what makes it
| so expensive.
| m4rtink wrote:
| Yeah, with launch windows every two and hal years only, 9
| months of travel time, still expensive launch costs and
| complicated landing requirements you really need to make
| sure stuff works.
|
| Sure, for stuff you can reasonably test in Earth gravity
| and atmosphere you can just weld stuff together in a field
| and then fly it until it stops crashing. Thats a case when
| you can iterate quickly and relatively easily with lots of
| COTS stuff.
| ggreer wrote:
| The $80M doesn't cover the launch costs. That would be part
| of the $2.4B for the overall rover project.
|
| For comparison: SpaceX's entire Falcon 1 program cost $90M
| over 6 years. That was to develop two new rocket engines
| (Merlin & Kestrel), build out the launch site on Omelek
| Island, and launch five times.
| vietjtnguyen wrote:
| Sure. I meant it more in the sense that there are some
| launch costs associated with the Mars Helicopter because
| it consumes mass budget.
|
| As to the SpaceX point. Yes, I think SpaceX is more
| efficient with their money than NASA, but this will boil
| down to a discussion of counterfactuals and degrees of
| "wastefulness". Was NASA wasteful? What does it mean to
| be wasteful? What's the threshold? What would it cost
| SpaceX to build the Mars Helicopter? Can we really
| compare a launch vehicle versus a tech demo of a
| rotorcraft operating on another planet? Would that $80M
| be better spent just funding SpaceX? I don't know. I just
| don't think it's fair to simply say "If it was made with
| off-the-shelf parts then it's a testament to how wasteful
| NASA has become". The engineering has to happen. Could
| NASA have been more efficient with it? Probably. Was it
| wasteful? I don't think so.
| tectonic wrote:
| A super exciting and well-executed landing with years of practice
| ahead of time to make it look easy. Things I'm looking forward
| to: - Sample collection and caching for pickup by a future sample
| return mission
|
| - Flying an experimental helicopter on Mars
|
| - Gauging the habitability of its landing region (Jezero Crater,
| a paleo-lakebed with preserved river delta and sediments) and
| hunting for ancient microbial biosignatures (with lasers!)
|
| - A drill (that can cut intact rock cores, rather than
| pulverizing them like Curiosity)
|
| - An ISRU experiment that makes oxygen from CO2
|
| - Way more advanced autonomous navigation
| pklausler wrote:
| I very much enjoyed learning a new acronym: SUFR ("straighten up
| & fly right", if I remember rightly).
| me_me_me wrote:
| Helicopters on Mars, what a time to be alive!
| rpiguyshy wrote:
| im really sad to say that NASAs website is an absolute dumpster
| fire... does anyone know of a simple repository of all the images
| and videos captured by each mission? i just want to flip through
| the pictures perseverance has taken so far without sifting
| through cancerous news sites.
|
| edit: the closest thing ive found is data.nasa.gov. how hard is
| it to just generate a fucking simple html website with
| chronologically ordered images? this is bullshit
|
| edit: ok, here is almost exactly what i wanted:
| https://mars.nasa.gov/mars2020/multimedia/raw-images/ the
| internet really sucks compared to what it might be... go to
| nasa.gov and click percy mission from the drop down and it takes
| you to a part of nasa.gov thats filled with eye-cancer tiles and
| javascript with sensor imaging mixed in with PR images and
| promotional material. but they tuck the (sort of) clean,
| organized data into some other website basically? maybe its a
| small gripe but this way of doing it is disorganized and
| infuriating.
|
| edit: wow, this website is fucking amazing! you can see the real-
| time position of all nasa mars vehicles 3D google earth style:
| https://mars.nasa.gov/explore/mars-now/ anyone who has not looked
| around in mars.nasa.gov should bookmark that right away
|
| curiosity shots:
|
| https://mars.nasa.gov/raw_images/895098/?site=msl
|
| https://mars.nasa.gov/raw_images/896437/?site=msl
|
| https://mars.nasa.gov/raw_images/895971/?site=msl
|
| https://mars.nasa.gov/raw_images/895971/?site=msl
|
| https://mars.nasa.gov/raw_images/895077/?site=msl
|
| https://mars.nasa.gov/raw_images/891625/?site=msl
|
| https://mars.nasa.gov/raw_images/888957/?site=msl
|
| https://mars.nasa.gov/raw_images/887028/?site=msl
|
| https://mars.nasa.gov/raw_images/886343/?site=msl
| drewblaisdell wrote:
| When can we expect any imagery from Perseverance? The Curiosity
| photos were incredible.
| ryankrage77 wrote:
| Probably around 20-30 minutes after it's landed. Perseverance
| needs to lock onto sattelites that are part of the Deep Space
| Network for the bandwidth required to send media. It also takes
| 22 minutes to send a command and get a response back.
| ceejayoz wrote:
| It was already communicating with DSN the whole way down, via
| one of the orbiters, and "send a pic" was apparently a pre-
| programmed command not requiring Earth initiation.
| comfydragon wrote:
| We actually got a picture like 3 minutes after landing.
| (Okay, a picture from shortly after landing.)
| someperson wrote:
| Probably routed through the Mars Reconnaissance Orbiter,
| Maven and possibly Europe's Mars Express satellites, rather
| than a direct connection to the Deep Space Network
|
| https://en.wikipedia.org/wiki/Mars_Reconnaissance_Orbiter
|
| https://en.wikipedia.org/wiki/MAVEN
| shadowgovt wrote:
| If I understood the livestream correctly, it's because they
| were able to (maintain|quickly establish) lock to the MRO
| after touch-down and zip a couple of images up through the
| "bent-pipe" UHF-to-high-power relay into the Deep Space
| Network.
| GeorgeTirebiter wrote:
| It would seem they had MRO in position to snap a few
| photos of the landing / descent as well as do the relay.
| jasonjayr wrote:
| First few low-res pictures posted here:
|
| https://twitter.com/NASAPersevere
|
| I'd bet they post the first high-res pictures once they arrive.
| The link from Mars to earth is sending a lot of information
| about what just happened, so understandably bandwidth is pretty
| saturated
| f154hfds wrote:
| Pictures already coming in to JPL apparently.
|
| https://www.youtube.com/watch?v=kPrbJ63qUc4
| ilrwbwrkhv wrote:
| It brings tears to my eyes. When the touchdown happens, these
| people experience a level of joy and satisfaction which I can
| only dream of while doing my job of optimizing ad clicks and
| profile photos.
| thisistheend123 wrote:
| This is so awesome. Go Nasa!
|
| I am amazed at what humans have been able to achieve in short
| time since the Industrial revolution.
|
| After all the negativity of last few months, this brings so much
| hope.
|
| Waiting for the first human foot touch down on Mars in my
| lifetime.
| koheripbal wrote:
| The pandemic has, in many ways, accelerated advancement and
| technological development.
| burrows wrote:
| All hail the shining twin gods, Advancement and Progress.
| wiz21c wrote:
| I'm a bit surprised that NASA doesn't communicate anymore since
| they landed the rover. I thought other pictures would come today
| in the morning...
| sixothree wrote:
| Shout out to the team member with the "This is fine" plush dog on
| their desk.
| arnaudsm wrote:
| Picture :
| https://twitter.com/PlanetDr/status/1362487492662996996
| Aperocky wrote:
| The dog is a fine addition to any meeting.
| thisistheend123 wrote:
| How much more time for EDL? Can't find that information anywhere!
| [deleted]
| devb wrote:
| I was wrong... estimated touchdown is 15:55 eastern time.
| whitehouse3 wrote:
| It's great to see NASA livestreaming in similar quality/fashion
| to spacex. It reminds me of watching the NASA feeds on public
| television in the 90's but much more nicely produced.
| criddell wrote:
| On space shuttle launch days, my parents would let me stay home
| from school to watch TV. At the time I was an ungrateful idiot
| but now I realize my parents understood me better than I
| understood them.
| hikerclimber wrote:
| hope it crashes.
| hedgehog wrote:
| I read that the design life of the helicopter is five flights.
| Does anyone know what the limiting factors are? The brutal cold
| and abrasive dust both seem like they could contribute but I am
| curious what the real answer is.
| bluescrn wrote:
| Dust on the solar panel seems likely to be a problem after the
| first landing, unless it's got a clever way to keep it clean.
|
| And its got to be tough conditions for the battery, low
| temperatures and probably deep discharges to make the most of
| it.
| joeyh wrote:
| It's powered by plutonium.
|
| Rovers with solar panels deal with the dust by waiting for a
| storm to blow it away.
| bluescrn wrote:
| Perseverance is powered by an RTG, but the Ingenuity, the
| helicopter, is powered by lithium-ion batteries recharged
| via a solar panel.
|
| I'd expect it to kick up a fair bit of dust on landing. But
| I suppose that's something else that'll behave a bit
| differently on Mars to what we'd expect in Earth's
| atmosphere.
| sephamorr wrote:
| The helicopter doesn't have enough power generation to stay
| warm through the Martian winter; the solar panel that feeds it
| is extremely small, so at the very least, it is unlikely to
| last beyond the summer. Here's the thermal design paper for the
| helicopter:
|
| https://ttu-ir.tdl.org/bitstream/handle/2346/74036/ICES_2018...
| dmurray wrote:
| The "design life" figure is something like the 5th percentile,
| if previous rovers are anything to go by. As in, they can
| estimate a 95% chance it makes it through 5 flights.
|
| I'd bet on it making 20+ at evens.
| m4rtink wrote:
| If we go by MER Opportunity standards (surviving 55x times
| its design timespan) we might go up to 275 flights! :D
| happy-go-lucky wrote:
| An exceptional feat of the human intellect. Bravo!
| jb1991 wrote:
| I can't find any articles that highlight what that component that
| "flies away" after the landing is going to do next. Does it just
| get dumped somewhere? Does it go back into orbit?
| solipsism wrote:
| It flies either forward (with respect to the rover) or backward
| -- whichever is closer to North -- and crash lands on the
| surface some distance away.
| Plutoberth wrote:
| It GTFO with its remaining fuel and then crash lands. Going
| back to orbit would require enormous amounts of fuel.
| ncmncm wrote:
| It's funny that they never say. (My mother-in-law asked if it
| would go back to orbit, too.) Saying "it flies far enough
| away to be sure it won't hit the lander when it crashes"
| would sound funny. They never seem to drive over to check it
| out, either, AFAIK.
|
| It started with ~800 lbs of hydrazine fuel on board that had
| to slow tons moving at 200 mph to a dead stop, and then hover
| for 10+ seconds while the lander spun down; and then boost
| away and crash. ("Crash-land" sounds like entirely more
| control than what really happened.)
| [deleted]
| ckosidows wrote:
| I can't find this information online... There were four cameras
| capturing video of the descent. Do we know when that footage will
| be available? Days? Weeks? Months?
| soheil wrote:
| So where are the images? (not the black and white fisheye)
| FredFS456 wrote:
| It will be a while before they get better images downlinked.
| The radio link is unbelievably slow by modern internet
| standards[0]. Note that the faster 2 Mbps link is only
| available when one of the orbiters is overhead (4-6
| times/martian day[1]). They also have a lot of work to do
| checking out the rover systems making sure everything is
| healthy, etc.
|
| [0]
| https://mars.nasa.gov/mars2020/spacecraft/rover/communicatio...
|
| [1] https://mars.nasa.gov/mars2020/mission/communications/
| garden_hermit wrote:
| Watching these is always a stressful experience, I can't imagine
| what it would be like sitting in that room, praying that the
| object you spend years of work on is able to land by itself 7
| light-minutes away.
|
| I'm looking forward to what Perseverance will teach us.
| sneak wrote:
| > _Watching these is always a stressful experience, I can 't
| imagine what it would be like sitting in that room_
|
| Sitting in any closed space like that one, with other people,
| masks or no, is stressful right now. It's a shame that NASA can
| communicate with a rover 125 million KM away but their staff
| have to all be crammed into one small enclosed space. You'd
| think we'd be able to communicate just as effectively over
| several kilometers.
|
| I imagine that people will look back on videos from this time
| period where ~3M people died (mostly unnecessarily) and wonder
| what on Earth people were thinking, carrying on like that.
| tester756 wrote:
| what if those people were tested for covid and there was no
| risk?
| DonHopkins wrote:
| That's how Trump got it, then spread it.
| jussij wrote:
| This morning on the radio and Australian scientist told the
| listeners he had spent 10 years working on his small part of
| the Perseverance mission.
|
| That would help to make the landing quite a nerve racking
| event.
| spullara wrote:
| Right now it is 11 minutes away!
| garden_hermit wrote:
| I was still under the assumption of Curiosity's 7 minutes!
| Thanks for letting me know
| SubiculumCode wrote:
| You know, in some ways its like any scientific endeavor.
| Hypothesis, funding, data collection can take years of effort.
| Then you look at your data and test hypotheses, and you have no
| control of the outcome. It can be terrifying, to be honest,
| which is why I support publishing of negative results. Of
| course crashing on Mars would be a terrible null result ;)
| ghoshbishakh wrote:
| Thank you for posting this. Let's witness what science and
| engineering is capable of achieve today.
|
| It is just amazing to think that a robot is roaming around in
| Mars, and a second one might be joining today.
| JebusAustralia wrote:
| Please donate ethereum to this address as I am being kept hostage
| by a psychopath called Satoshi Nakamoto. He has scattered all of
| my personal information and economical research all over youtube,
| cnbc, techcrunch, the local mainstream media in the netherlands.
| https://ibb.co/74qYknK
| aaron695 wrote:
| I don't get why they had to bring the children into this asking
| questions constantly. Do we really want to reinforce this is just
| for children?
|
| SpaceX doesn't do this. They are always top quality. Adults doing
| professional things in space, that to me is more inspiring to
| children and young adults.
|
| Can't they have an adult stream and one dumbed down for the
| children if they really think these things should be dumbed down.
|
| It was better than ESA I guess
| science4sail wrote:
| I wonder if it's a case of misaimed audience?
|
| Even though "children asking questions" may be less appealing
| to children than "adults asking questions", the former might
| get aired anyway because it's more appealing to the adults that
| make children's programs.
| abalaji wrote:
| I'm excited for the HD video of the landing that was promised.
| Nekhrimah wrote:
| And audio as well!
| aembleton wrote:
| How are they getting audio without an atmosphere?
| gillytech wrote:
| There is a thin atmosphere on Mars and sound does exist.
| It's also how this lander was able to land.
| Ne02ptzero wrote:
| NASA actually made a pretty informative page about it[1],
| with some simulation of sound on Mars, compared to Earth.
| Hopefully we won't need the simulation much longer!
|
| [1] https://mars.nasa.gov/mars2020/participate/sounds/
| vagrantJin wrote:
| Mars does have an atmos.
|
| Or are you reffering to something else?
| tcpekin wrote:
| Currently watching it using Streamlink [0] to watch in VLC. This
| is so exciting! Wishing them, and the rover, all the best in the
| landing!
|
| [0] https://streamlink.github.io/
| Koshkin wrote:
| A hacker on HN?
| inspector-g wrote:
| Watching the live feed was a blast. When they said they received
| the exact landing coordinates I was extremely curious to see it
| plotted vs their targeted landing zone, but unfortunately they
| haven't shown it yet. However, I could audibly hear an engineer
| in the background say "Oof, well, we'll take it!"
|
| Anyone seen anything about the precise location yet?
| dylan604 wrote:
| In one of the previous threads about Mars missions, one of the
| comments was how we have gotten to the ability of "land it
| close enough, and we'll drive the rest of the way". Seems
| pretty accurate for this mission.
| tectonic wrote:
| https://twitter.com/jccwrt/status/1362514739671298051
|
| > UNOFFICIAL but it looks like Percy landed right on the edge
| of the Mafic Floor Unit, with older (probably sedimentary)
| rocks that were buried by it only a short drive away.
| raphaelj wrote:
| NASA's ability of succeeding at landing things successfully on
| the first try on foreign bodies since 1969 is mind-blowing.
|
| Meanwhile, SpaceX takes half a dozen tries before managing to do
| the same on a fully known environment on Earth.
| dawnerd wrote:
| You had me until you started to bash SpaceX for no reason. NASA
| has had plenty of failures and you're framing it as if they
| haven't ever.
| TulliusCicero wrote:
| That snipe was really unnecessary.
|
| Not to mention weird, considering how successful SpaceX has
| been at dominating the commercial launch sector.
| Daho0n wrote:
| I'm not commenting on the rest of your post but the
| "dominating the commercial sector" just so you don't think
| I'm badmouthing SpaceX. Just wanted to add that if you sell X
| pounds of cargo to the commercial sector but sell the same
| capacity to the military for X times 3 then your are not
| dominating but are subsidized by the state and in a position
| to undercut the commercial competition. It's not just for PR
| that SpaceX competitors, both foreign and nationally, are
| saying SpaceX is propped up by the state.
| TulliusCicero wrote:
| Was SpaceX uncompetitive in its bids for the government
| launches or something? My understanding is that they were
| much cheaper than other bidders, not more expensive.
| gfodor wrote:
| Consider for a second that blowing up no prototypes or blowing
| up lots of prototypes are both well considered methodologies
| and what you state is by design and expected.
| emilecantin wrote:
| Perseverance is one of the largest objects that NASA landed
| (along with the Apollo lander), and it's about the size of an
| SUV.
|
| SpaceX is trying to land things the size of buildings.
|
| Let's just say it's a very different problem.
| Daho0n wrote:
| .
| m4rtink wrote:
| Actually, all the Starship flights are fully automated,
| possibly except a very nervous person somewhere with the
| self-destruct button and binoculars.
|
| If you though there is someone in Boca Chica flying
| Starship remotely with joystick and steady hand, I'm afraid
| I need to disappoint you.
| Daho0n wrote:
| That wasn't the point but this is Reddit level snarky
| commenting so I'll be on my way.
| PeterisP wrote:
| Neither Perseverence or SpaceX landings involve latency for
| control commands, they are automated/preprogrammed in the
| vehicle and do not rely on real-time commands from the
| ground.
| Daho0n wrote:
| No one have said otherwise. The point still stands that
| landing on earth is not in the same universe as landing
| on Mars. Comparing is stupid.
| jaegerpicker wrote:
| SpaceX has a very different set of risk tolerances and
| approaches. Nasa is a government funded entity and the
| tolerance for failure (rightly or wrongly) is very low
| according to every thing I've read.
|
| SpaceX being private has a much larger cushion for failure.
| Elon will keep funding it far longer than congress would Nasa
| is my guess. If SpaceX loses some rockets that's the cost of
| business, of course once those missions are manned it's a huge
| difference but until then I think it's not really comparable.
| mempko wrote:
| You have it exactly backwards. Risk tolerance is higher for
| the government. Fox example, SpaceX would never just send a
| rocket to mars just to do science which would bring it zero
| profits. It won't take risk funding something where the
| science may or may not bear any fruit.
|
| Also, SpaceX IS mostly funded by NASA anyway as a government
| contractor. SpaceX exists because the government wanted to
| create a private space market. Strangely thank George Bush
| for it. https://www.fool.com/investing/2017/02/05/how-
| profitable-is-...
|
| As you can see, SpaceX was so cash strapped in 2017 it
| obviously didn't go to mars in 2018 as they wanted. Also
| notice Elon didn't fund that trip (otherwise it would have
| happened). There is no way he would risk HIS own money on
| that.
| m4rtink wrote:
| Main reason for Red Dragon not happening was NASA
| requesting parachute landing into the ocean instead of the
| previously planned propulsive landing on land for Dragon 2.
|
| This would mean that SpaceX would need to develop and fund
| Dragon 2 propulsive landing on their own, with only real
| mission fully requiring it being Red Dragon.
|
| In the end it was much easier to just drop the whole thing,
| especially with the much more perspective Starship on the
| horizon.
| macintux wrote:
| I'm sure this will be downvoted to oblivion shortly, but it's
| mind-boggling that the company who's turned rocket landings so
| routine that it's notable when they fail is being singled out
| as a failure.
|
| (Update: sorry, by "this" I mean the parent comment.)
| [deleted]
| electriclove wrote:
| We really should take the SpaceX approach. There is too much at
| stake on a singular multi-billion dollar rover landing on Mars
| every now and then. We need more funding so that we can send
| these things to Mars much more frequently and get samples back
| before my kids have their own kids.
| FrojoS wrote:
| Rediciolous comparison.
|
| The size of the objects that SpaceX is landing is much larger.
| The approach that was used here for Perseverance (Skycrane)
| would not work for larger ships, like those required for a
| human mission. Just like the previous approaches, e.g.
| Lithobraking with Spirit and Opportunity, would not have worked
| for Perseverance.
|
| Larger objects are much more difficult to land. Simply put,
| while mass will increase by the power of three, surface area,
| which is used for aerobraking only scales by the power of two,
| relative to size.
|
| In order to land something large enough to carry and support
| humans (10-100t), you need hypersonic retropropulsion. Guess
| who was the first to achieve this? SpaceX. And they remain the
| only ones. When they light the three engines for the entry burn
| the earth atmosphere is very similar to the relevant section of
| the future Mars decent. By developing the first stage landing
| of Flacon 9, they solved one of the biggest development
| challenges for humans landing on Mars and it was not by
| accident. NASA was very happy to get that data and helped them
| collect it with their chase planes.
| m4rtink wrote:
| The Mars atmosphere is at a tricky spot where you can't
| ignore it like when landing on the Moon (also Mars gravity is
| higher than on the Moon) yet it's not thick enough for
| survivable landing with parachutes or wings (as envisioned in
| the earliest Mars mission plans) only.
|
| That's why you always see parachutes + something else for
| Mars EDL - parachutes + rockets, parachutes + airbags,
| parachutes + skycranes. And in Starship case, high speed
| glide and speed shedding with propulsive landing at the end.
| nitrogen wrote:
| _NASA 's ability of succeeding at landing things successfully
| on the first try on foreign bodies since 1969 is mind-blowing._
|
| https://en.wikipedia.org/wiki/Mars_Climate_Orbiter
|
| > The spacecraft encountered Mars on a trajectory that brought
| it too close to the planet, and it was either destroyed in the
| atmosphere or escaped the planet's vicinity and entered an
| orbit around the sun. An investigation attributed the failure
| to a measurement mismatch between two software systems: metric
| units by NASA and non-metric ("English") units by spacecraft
| builder Lockheed Martin.
|
| https://en.wikipedia.org/wiki/Mars_Polar_Lander#Landing_atte...
|
| > Communication was expected to be reestablished with the
| spacecraft at 20:39:00 UTC after having landed. However, no
| communication was possible with the spacecraft, and the lander
| was declared lost.
| m4rtink wrote:
| Mars Observer is mad that you forgot to mention it!
| https://en.m.wikipedia.org/wiki/Mars_Observer
|
| Actually it is not mad - becase it exploded into millions of
| pieces due to the leaky fuel system...
| macintux wrote:
| In fairness to the parent comment: those weren't the first
| try.
| user3939382 wrote:
| Yeah, c'mon Elon. It's not rocket science!
| joe_91 wrote:
| NASA also requires 10-100x more money & time to do so. Both
| just have very different ways of working. Both work and there
| are pro's and con's to either way!
| notum wrote:
| I'll just leave Thunderf00t's latest video here:
| https://www.youtube.com/watch?v=4TxkE_oYrjU
|
| Let's not diminish ether's breakthroughs, but financial isn't
| one of SpaceX's.
| shazmosushi wrote:
| That video was incorrect on so many levels that I have made
| a rebuttal: https://www.youtube.com/watch?v=36o4UrS9OS4
| raphaelj wrote:
| How could you know? SpaceX never landed or sent a craft on a
| foreign body.
| joe_91 wrote:
| Haha, good point - we'll have to come back in 4-5 years
| time when SpaceX have touched down on the moon and mars and
| check the cost. Considering their low cost & speed at
| getting things into orbit these days and the plans they
| have for starship I hope that the data will prove me right
| in a few years
| m4rtink wrote:
| While this timeline might be optimistic, this is what
| came to my mind when I heard about the current timeline
| for Mars sample return - samples returning back to Earth
| in _2031_.
|
| https://en.wikipedia.org/wiki/Mars_sample-
| return_mission#NAS...
|
| Like it's nice to finally have a firmer timeline for
| that, but damn, 10 years from now. A SpaceX employee
| gathering the sample tubes into his backpack in a couple
| years time to be returned on the next milk-run flight
| back to Earth is just so much cooler! :)
| joe_91 wrote:
| Yes, hopefully SpaceX can do it quicker than 10 years!
| Considering 15 years ago they started with their first
| rocket and how far they've come in that time I have high
| hopes.
|
| I think Elon was hoping for a manned mission to Mars in
| 2024 back in 2017 but his latest projection is 2026. He's
| certainly optimistic :)
| ALittleLight wrote:
| SpaceX hasn't been around as long as NASA. Also, remind me,
| did NASA develop reusable rockets?
| Rebelgecko wrote:
| NASA doesn't really build rockets in-house, all of their
| reusable rockets were built by contractors under NASA's
| supervision. Sometimes NASA collaborated with other
| organizations (e.g. DARPA/military funding paid for a lot
| of the DC-X reusable rocket)
| m4rtink wrote:
| Well, nssa worked on Delta Clipper and DC-X. Also Venture
| Star. And the integrated powered demonstrator/FastTrack &
| pointless injectors that formed the basis of the Merlin
| engine IIRC.
| thelean12 wrote:
| > Also, remind me, did NASA develop reusable rockets?
|
| I can't tell if this is sarcasm or not but... yes, of
| course NASA developed reusable rockets. The space shuttle
| missions reused the shuttles and the boosters.
| ALittleLight wrote:
| The space shuttle was partially reusable.
| marcinzm wrote:
| The Space Shuttle was reusable (with massive refurbishing
| after each flight) but given that'd it cost significantly
| more than a non-reusable rocket per pound I think the
| point stands. SpaceX managed to make a financially viable
| reusable rocket.
| Daho0n wrote:
| They really didn't. SpaceX is not cheaper than the
| shuttle no matter how many times it gets repeated. That
| SpaceX fudges the numbers so it is hard to compare
| doesn't make it true. In reality SpaceX is more expensive
| than not only the shuttle but also their own projections.
|
| Here's a breakdown: https://youtu.be/4TxkE_oYrjU
| tristanb wrote:
| you're wrong. That video is a bunch of crud
| Daho0n wrote:
| And I'm sure you believe that US and foreign competitors
| of SpaceX who says the same thing are just spewing PR,
| right? It was a random video. The message is not wrong.
| Being snippy doesn't change facts.
| Nekhrimah wrote:
| > Here's a breakdown: https://youtu.be/4TxkE_oYrjU
|
| I watched the first 90 seconds of this. On the cost of
| re-usability of a falcon 9 point, the figures are shown
| as from Wikipedia.
|
| So 1) not a primary source. 2) fails to calculate the
| percentage correctly between $62m and $50m as "around
| 10%". It's almost 20% on those figures. 3) and most
| importantly, those numbers are the cost to the customer,
| not SpaceX's internal cost. As they have no current
| competition in rocket re-usability, they are able to
| recoup the R&D cost for developing this technology.
|
| I don't think I'll bother watching the rest of the video.
| m4rtink wrote:
| Yeah, they are certainly not launching so many Starlinks
| at the same price they charge to the customers. A very
| big benefit having your own partially reusable rocket
| (especially as long as no one other has one yet).
| thelean12 wrote:
| > I think the point stands
|
| No it doesn't. The person was trying to say SpaceX >
| NASA. Many people here are trying to shit on the other
| side as if they have a real point.
|
| They're both doing cool and useful things and they're
| both really really good at what they do.
| ALittleLight wrote:
| I'm not trying to say that SpaceX is better than NASA. I
| am responding to the point that NASA has done things that
| SpaceX hasn't (e.g. landing on other celestial bodies) by
| pointing out that SpaceX has done things NASA hasn't
| (e.g. SpaceX rockets land and can be reused).
|
| I don't think it makes sense to talk about which is
| better unless there is some specific metric that can be
| measured so a conclusion could be reached. I am
| encouraged though that SpaceX has a trajectory that will
| allow greater access to space. By bringing the cost of
| space travel down, I expect we will get a lot more of it.
| NASA (and other governmental space programs) started the
| initiative, but I think SpaceX is continuing it
| marvelously.
| Daho0n wrote:
| I'm not saying SpaceX isn't doing good but the price has
| gone up per (re)launch, not down as projected, so at the
| moment of it were possible to buy a trip to space for a
| few tourists it would be cheaper on a shuttle.
| erulabs wrote:
| They did, you're not wrong at all, but just to add a
| little bit of clarity the space shuttle was never as
| reusable as was hoped - it wound up costing a huge amount
| of time and money to retrofit the shuttle again before
| each launch. Reusable and Re-usability are different
| things :P
|
| As far as I know no solid state boosters were ever re-
| used (how would that work?) - but then again SpaceX
| doesn't re-use solid state boosters either (because they
| do not use any)...
|
| Things can be more complex and nuanced than quippy
| internet back and forth suggest. That's not even touching
| on the ship-of-theseus problem that is many former NASA
| engineers working at SpaceX these days.
| Daho0n wrote:
| It doesn't really matter much because a look at the
| actual numbers shows that SpaceX charge more than the
| cost of launching the exact same payload would have cost
| using the shuttle. Besides the reusability point is
| disingenuous when talking cost since SpaceX's cost have
| actually gone up per (re)launch, not down. So yes, it is
| more complex than quippy internet back and forth
| suggests.
|
| Here is a video that explains it in decent details if you
| are interested, but the TL;DR is that SpaceX is more
| expensive than the shuttle and way more expensive than
| they said they would be: https://youtu.be/4TxkE_oYrjU
| m4rtink wrote:
| The SRB segments vere regularly reused, not sure about
| the parachutes and the nozzle stearing gear. Still
| reportedly it was more expensive to reuse the segments
| (basically big metal tubes) than to build new set if SRBs
| for each flight, possibly using better techniques
| (monolithic carbon fibre overwrapped solid motors, like
| on Ariane 5/6).
| erulabs wrote:
| Oh interesting! Very cool, thanks for the info :)
| retzkek wrote:
| > s far as I know no solid state boosters were ever re-
| used (how would that work?)
|
| Nitpicking of "reuse" vs "refurbish" aside the SRBs were
| significantly reused:
|
| > The RSRM was designed to make the most use of
| recoverable hardware. The majority of metal hardware was
| recycled through ATK's Clearfield refurbishment plant in
| Utah and returned to a flight-qualified conditioned.
|
| https://ntrs.nasa.gov/citations/20120001536
|
| The boosters used for the final mission, STS-135, even
| included parts from STS-1!
| https://spaceflightnow.com/shuttle/sts135/fdf/135srbs.pdf
| smilespray wrote:
| Didn't they reuse the solid rocket boosters for the
| shuttle? (Granted, they were delivered by Morton Thiokol
| and didn't function well in cold weather...)
| [deleted]
| redisman wrote:
| Lets just say both are doing very important work with very
| different incentives
| simonlang wrote:
| A few years ago I made a mars rover image viewer for a job
| interview question.
|
| Will have to update it if images from Perseverance become
| available through the NASA Open APIs.
|
| https://simon-lang.github.io/mars-rover-image-viewer/#/colle...
| iexplainbtc wrote:
| That live stream was epic! It was great to see them so happy :)
| 0_____0 wrote:
| Hard for me to imagine what it's like to spend years of your
| life working on a singular launch project. So much riding on
| what happens in a handful of moments, whether that's launch or
| EDL. Pretty sure I'd just start sobbing in the control room if
| that were me regardless of outcome.
| iexplainbtc wrote:
| These live streams are anxiety inducing for us, I can only
| imagine how they must feel!
| mrfusion wrote:
| I thought they looked anxious and overheated.
| ashton314 wrote:
| Part of me is sad that I'm too young to have seen the moon
| landings. But stuff like this gives me a taste of the thrill of
| those days. Congratulations to everybody at NASA. Thank you for
| this inspiring endeavor!
| throwaway542 wrote:
| Fun fact: The rover used software from Bellard's FFMPEG.
| chasd00 wrote:
| fricken awesome! i love being able to watch these things live.
| now i have to get back to work making pixels light up at the
| right time and the right color all day long.
| WJW wrote:
| IT LANDED!
| shadowgovt wrote:
| Upright and in one piece. :) No, but seriously: amazing
| engineering and amazing work. So great to see the images
| streaming in already.
| WJW wrote:
| The skycrane system is just SO COOL. It's also one of those
| things that is super easy to explain but incredibly difficult
| to actually construct, let alone have it work well after
| flying all the way to Mars.
| chasd00 wrote:
| i can't believe it works. Those thrusters making all that
| turbulence and racket. Then the cables have to unwind
| without getting tangled and at the same rate. Then,
| finally, at the end, they have to detach the cables and fly
| away. It's pretty nuts.
| tnorthcutt wrote:
| They're not _that_ hard to make and fly... in Kerbal Space
| Program ;)
|
| (I'm totally kidding; what they've accomplished is
| incredible!)
| pupdogg wrote:
| It took them approx. 4,881 hours from launch to land approx.
| 127,770,000 miles away. Is it safe to say that the average speed
| of the mission can be calculated as 436 miles/hour?
| mikeyouse wrote:
| I think you dropped a thousands somewhere.. 127.8M
| miles/4,881hrs = 26,000 mph.[1]
|
| But in reality, it obviously didn't fly in a straight line,
| Looks like it traveled closer to 292 million miles[2], so more
| like 60,000 mph.[3]
|
| [1] -
| https://www.wolframalpha.com/input/?i=127800000+miles%2F4881...
|
| [2] - https://mars.nasa.gov/mars2020/timeline/cruise/
|
| [3] -
| https://www.wolframalpha.com/input/?i=292526838+miles%2F4881...
| pupdogg wrote:
| You are correct, I did. Thank you. That's just amazing!
| andbberger wrote:
| no. hohmann transfer, not a straight line. also there are no
| absolute reference frames.
| alkonaut wrote:
| > also there are no absolute reference frames.
|
| "Well, officer, perhaps to _you_ it seemed like I was
| speeding there... "
| mr_toad wrote:
| Just, remember that you're standing on a planet that's
| evolving And revolving at nine hundred miles an hour That's
| orbiting at nineteen miles a second, so it's reckoned A sun
| that is the source of all our power The sun, and you and
| me, and all the stars that we can see Are moving at a
| million miles a day In an outer spiral arm at forty
| thousand miles an hour Of the galaxy we call the Milky Way
|
| - Monty Python.
| klohto wrote:
| Clean feed here - https://www.youtube.com/watch?v=kPrbJ63qUc4
|
| EDIT: Congrats to the team! Great success
| johnohara wrote:
| Reading you 5 by 5. Thank you.
| distortedsignal wrote:
| My personal preference is the JPL raw feed (here:
| https://www.youtube.com/watch?v=kPrbJ63qUc4) but I think that
| more people watching space here is better! Great link!
| blach wrote:
| From the JPL feed: "My computer was having trouble with Webex,
| I'll restart Webex and try the visualization again."
|
| Hope Percy isn't running Webex.
| yellowapple wrote:
| I mean, I'd be pretty impressed if NASA managed to get Webex
| to run on a 133MHz PowerPC CPU and 128MB of RAM.
| winrid wrote:
| Are those the hardware specs of this rover?
|
| EDIT: It's a 200mhz CPU alongside 256mb of ram.
| https://mars.nasa.gov/mars2020/spacecraft/rover/brains/
| rpiguyshy wrote:
| i wish they would stream the video and audio from the craft live
| as it descends to the martian surface
| ryankrage77 wrote:
| The bandwidth to stream video from mars simply isn't available.
| Once it's landed, perserverance must lock onto sattelites
| orbiting mars in order to send media back to earth.
| GeorgeTirebiter wrote:
| Actually, Percy has her own Mars-to-Earth radio. It's that
| the high bandwidth is UHF to MRO, MRO to Earth usually (as I
| understand it). My guess is they probably could manage a few
| FPS at low resolution directly from Percy - but probably
| wouldn't do that for power reasons. https://mars.nasa.gov/mar
| s2020/spacecraft/rover/communicatio...
| gillytech wrote:
| What an accomplishment for mankind. Congratulations to NASA, JPL
| and the whole team.
| m4rtink wrote:
| Congratulations!
| unanswered wrote:
| Something I don't understand: when they say "X is 1 minute from
| happening", does that mean it's really 1 minute from happening or
| does that mean "in 1 minute we'll receive the signal that X has
| happened"?
|
| Maybe my question makes more sense in the case of "X is happening
| right now", because then I should either understand "we infer
| that X should have happened right about now" or "we have
| confirmed via signal that X has happened", and that's a big big
| difference.
|
| I know in some cases they explicitly say the latter, so I guess
| my _real_ real question is, do they just keep the communication
| delay implied in all countdowns & references in discussion, to
| avoid confusion?
|
| (ETA: No need to let me know about simultaneity problems in
| relativity -- earth and mars are, relative to c and to
| macroscopic time scales, essentially not moving relative to each
| other AFAIK, so that simultaneity _is_ essentially well-defined.
| My question was about a much more boring classical-universe
| problem.)
| PeterisP wrote:
| It's the latter. The Earth-Mars latency at this time is
| something like 11 minutes, and the landing itself takes about 7
| minutes, so when we on Earth first saw the craft entering
| atmosphere on Mars, by that time all the landing was already
| over, one way or another.
| interestica wrote:
| NASA has a good breakdown of their expected miletones at
| 'earth receive time' - https://www.nasa.gov/feature/jpl/nasa-
| s-next-mars-rover-is-r...
|
| Apparently the latency time is currently 11 mins 22 seconds
| -- which is somewhere near the average. It goes from under 4
| mins to over 22mins depending on distance.
| DiogenesKynikos wrote:
| It depends on what coordinate system you're using. Simultaneity
| is ill defined in relativity. There's only future, past and
| "spacelike-separated" (neither past nor future). When they say,
| "X is 1 minute from happening," it's actually neither in the
| past nor the future. It's currently spacelike-separated, but in
| 1 minute, it will be in our past.
| unanswered wrote:
| Yes, yes, you have shown you know what relativity is. But the
| relative velocity of earth and mars -- which I can't convince
| Wolfram Alpha to tell me, but it's got to be on the order of
| their orbital velocity so let's say 5x10^4 mph -- is a tiny
| tiny fraction of c so their inertial reference frames are
| essentially identical. So sitting in our reference frame, we
| _can_ make inferences about what 's happening "now" on
| mars,such that these inferences are consistent (to within
| that tiny fraction of c) with all of our current and future
| observations in this reference frame; i.e., consistent with a
| classical(+ finite speed of light) model of the universe.
| Which is why I left this out of my question and only asked
| about the consequences of a finite speed of light.
|
| Put another way, simultaneity is perfectly well defined in a
| single inertial reference frame, and for purposes of my
| question, earth and mars can be considered to be relatively
| motionless.
| jtsiskin wrote:
| No, I don't think you're quiet understanding what they are
| saying. They aren't talking about the different speeds of
| earth or Mars.
|
| Simultaneity is not "perfectly well defined in a single
| intertidal reference frame". That is just a convention.
|
| If the RTT of earth to Mars is 20 minutes, then we can say
| that it takes us 20 minutes for our message to reach the
| rover, and the rover's message arrives instantly, and
| that's a consistent definition of simultaneity.
|
| https://www.pitt.edu/~jdnorton/teaching/HPS_0410/chapters/s
| i...
| unanswered wrote:
| Except that an observer located in the
| (hypothetical/approximate) common reference frame, but
| situated halfway to Mars, will _report_ observations
| _inconsistent_ with this definition (NB of course we
| receive their report at a time consistent with the
| definition, but the contents of the report are not
| consistent). So yes, you can play games with your
| definition of simultaneity, but you will win stupid
| prizes like observers in the same reference frame no
| longer agreeing about simultaneity when such a result is
| _worse_ than what relativity requires.
|
| Your link points this out. You _can_ play these games; I
| don 't dispute it. But it's a separate matter entirely
| from anything to do with relativity, _as your link points
| out_ , which is itself separate from the classical
| problem I originally posed. So we are now two steps
| removed from anything relevant to the Mars rover; I guess
| we get a sense of pride and accomplishment?
| DiogenesKynikos wrote:
| It doesn't depend on the relative velocity of Earth and
| Mars. It depends on your coordinate system. You can use
| Schwarzschild coordinates centered on the Sun and use the
| time coordinate to define simultaneity, but that's an
| arbitrary choice.
| johncolanduoni wrote:
| Now is the part where someone brings up even with the low
| relative velocity, you haven't accounted for the
| simultaneity issues we'd have if the earth collided with a
| black hole while the rover landing was happening.
| unanswered wrote:
| Or the fact that mars is not as deep in the gravity well
| of the Sun! I wonder if they have to account for that one
| when programming, like, antenna aiming or something.
| minitoar wrote:
| IIRC gps suffers about 1hz of blueshift due to descending
| into earths gravity. I think the velocity (Doppler) shift
| of the spacecraft is a way bigger factor than the
| gravitational shifting.
| colechristensen wrote:
| It looked like they were quoting time as it would appear for an
| earth-local observer (i.e. a million light-year away supernova
| that showed up five minutes ago happened "five minutes ago" not
| 1 million years and five minutes ago.
|
| With your personal light cone, it's fine to equate "now" with
| what you see in the moment. It just has to be clear what you
| mean for situations where communication might be ambiguous. If
| you have a person on mars, be sure to be precise what you mean
| when you tell them to do something in five minutes, when they
| receive the message they won't know if you mean five minutes
| after they receive the message or anywhere between 17 minutes
| before and 2 minutes after they receive the message.
|
| When you get into relativistic speeds (and especially very
| short time intervals), _nobody_ can even agree on when
| something "actually" happened, different observers have
| different opinions about what happens when even after you
| account for light travel time.
| extropy wrote:
| Relative time (in five minutes) without relativistic speeds
| is actually uniform. The is no observable difference to
| either participant.
|
| And there is no concept of now in a significantly distant
| location. Related video: https://youtu.be/pTn6Ewhb27k
| gfiorav wrote:
| Waiting for the physicist in the room to point out: there is no
| such thing as simultaneity!
|
| :)
| cambalache wrote:
| Oh but there is. Just not in the same frame of reference.
| cphajduk wrote:
| Depends what type of physicist you ask.
|
| According to the energy-time uncertainty principle we don't
| even know when exactly the RF waves that transmitted
| information hit the receiver on Earth either.
| whatshisface wrote:
| Simultaneity is at least as well defined as clock time. Both
| clock time and the velocity of your reference frame can have
| arbitrary constants added to them to yield equally valid
| coordinate systems. So "it's not really simultaneous" is
| analogous to "it's not really 6:30 PM."
| bregma wrote:
| Well, it's 6:30 PM _somewhere_.
|
| _lifts glass_
| UnpossibleJim wrote:
| From The Hitchhiker's Guide to the Galaxy: "Time is an
| illusion. Lunchtime doubly so."
| [deleted]
| avz wrote:
| In the absence of a physicist, I suppose that a software
| engineer in the room might do. After all, the
| counterintuitive consequences of relativity have their
| counterparts in counterintuitive effects in distributed
| systems and concurrent programming. In both cases, the core
| issue that misleads our intuition is the lack of a shared
| global clock that would impose a total ordering [1] on
| events/reads/writes/etc. Instead, events in both situations
| are only ordered partially [2]. In relativity the ordering is
| determined by the speed of light, in distributed systems the
| ordering is determined by what messages have been exchanged
| by two nodes and in concurrent programming reads and writes
| are ordered by synchronization actions such as lock
| acquisition and release, memory barriers etc (c.f. the
| happens-before relationship in JMM [3] and other memory
| models).
|
| See for example [4] and [5].
|
| [1]: https://en.wikipedia.org/wiki/Total_order
|
| [2]: https://en.wikipedia.org/wiki/Partially_ordered_set
|
| [3]: https://en.wikipedia.org/wiki/Java_memory_model
|
| [4]: https://www.youtube.com/watch?v=UYZIHP120go
|
| [5]: https://www.microsoft.com/en-
| us/research/publication/time-cl...
| Daho0n wrote:
| S/he already did. We just don't know yet.
| extropy wrote:
| She both did and did not until we observe :p.
|
| And even that is not correct. Events happening propagate
| with speed of light - the event horizon. We can predict we
| will receive information of something happening, bit that's
| just prediction about future events, regardless of the
| location.
| fckthisguy wrote:
| You can just say "they".
|
| (Not trying to be judgy. People just seem to forget about
| the gender neutral use of "they".)
| buzzerbetrayed wrote:
| There are like 500 other ways you could have said what
| you just said as well. Doesn't mean the way you said it
| is invalid.
| unanswered wrote:
| Why is it acceptable to use the wrong pronoun, such as
| "they", for someone who chooses the pronoun "she" or
| "he"?
| detaro wrote:
| They are not talking about a specific person, so how is
| "they" wrong?
| randomchars wrote:
| > used to refer to a person of unspecified gender.
|
| How is this offensive to anyone??
| unanswered wrote:
| For the same reason referring to _anyone_ with the wrong
| pronouns is, I would assume. Isn 't that offensive? I
| didn't realize this was up for debate in 2021.
| randomchars wrote:
| But you're not referring to someone with the wrong
| pronoun, but using a gender neutral one.
| unanswered wrote:
| I'm sorry, I honestly don't understand what distinction
| you're trying to point out. If someone's preferred
| pronoun is "she", for example, and I refer to her as a
| "they", then that's the wrong pronoun, isn't it? That's
| literally the definition of "wrong", at least the
| definition I understand. The right pronoun is "she" and
| other pronouns such as "he" and "they" and "it" are, by
| exclusion, wrong.
|
| But it seems like you're saying there's some kind of
| complex relation where sometimes people don't get to
| choose their own pronouns, but other people get to choose
| which one out of many to use based on convenience. Maybe
| it would help my understand if you could provide a chart
| relating the pronouns someone chooses with the pronouns
| other people are then allowed to use?
| randomchars wrote:
| > Maybe it would help my understand if you could provide
| a chart relating the pronouns someone chooses with the
| pronouns other people are then allowed to use?
|
| I think this is everything wrong with the world
| currently. Provide you with a chart, so I can justify
| using gender neutral pronoun?
|
| https://apastyle.apa.org/blog/singular-they
|
| This is barely more than a year old, is it already
| outdated? I am an asshole for daring to use "they"?
| unanswered wrote:
| > If a person uses "she" or "he," do not use "they"
| instead. Likewise, if a person uses "they," do not switch
| to "he" or "she." Use the pronouns the person uses.
|
| This matches my own understanding; I have no idea why you
| are referring to this article as if it supports your
| bizarre crusade to misgender people.
| randomchars wrote:
| You are aware that we are talking about the mars rover,
| right?
|
| The comment that you replied to:
|
| > You can just say "they".
|
| Was a reply to this:
|
| > S/he already did. We just don't know yet.
|
| Which was talking about the mars rover.
| jonathanstrange wrote:
| I'm not a native speaker but the problem I have with it
| is that it has the wrong numerus. Although I have done so
| in papers recently, because it seems to be a trend,
| sentences like _" If a person chose option B, they were
| categorized as a cautious assessor"_ seem ungrammatical
| to me. (In this case it's easy to reformulate the
| sentence in plural and simpler, but that's not always the
| case and I hope you get the point.)
| frosted-flakes wrote:
| If the person is hypothetical or not fleshed-out and
| without a gender, like your example, _they_ is fine and I
| don 't even notice. But if the person is known, the use
| of _they_ catches me off guard every time. I recently
| read a book by Brandon Sanderson that had aliens on
| another planet with a different gender system, so
| Sanderson just used _they_ to refer to those aliens even
| though the characters were obviously either feminine or
| masculine. It completely broke the illusion of the story
| and was a complete turn-off. I _always_ notice in such
| cases, but for some reason some people say it 's totally
| standard English.
| walrus01 wrote:
| > simultaneity
|
| not in the true accurate to the picosecond sense of the word,
| no, but the exact word simultaneity is used when discussing
| number and density of satellites about a given
| latitude/longitude in the starlink beta program. Since
| they're LEO and orbiting at only 550 km, the satellites above
| a given spot on the ground vary greatly in the not-yet-
| complete sparse network.
|
| Usually related to discussions of whether a beta test
| customer terminal will briefly hiccup and lose connection to
| its default gateway, or if somebody is at a sufficiently high
| latitude that they can have full coverage for all 86400
| seconds in a day.
|
| https://satellitemap.space/ has a good animated visualization
| of this.
| theNJR wrote:
| Came here to suggest The Order of Time by C Rovelli, which
| explains this in such a captivating way.
| amelius wrote:
| I think this video explains the issue quite well in only
| two minutes:
|
| https://www.youtube.com/watch?v=wteiuxyqtoM
| Dylan16807 wrote:
| But that only happens with sufficiently high relative
| velocities. Earth and Mars are effectively in the same
| reference frame.
| melenaboija wrote:
| Another one here, it is in Catalan but with subtitles in
| english. Minute 18 is where it is explained although I
| think is worth it to watch all of it
|
| https://www.ccma.cat/tv3/alacarta/quequicom/tempus-fugit-
| sub...
| Sharlin wrote:
| Yes, those are all Earth Receive Time, that is, when they were
| saying that eg. entry interface is two minutes away, in reality
| the rover was already sitting on the surface and we were just
| waiting for the radio signal to get here.
| unanswered wrote:
| > Earth Receive Time
|
| Ah great, that's a great phrase to make everything clear and
| provide a kind of "frame of reference" to think & communicate
| in. Always need these abstractions.
| m4rtink wrote:
| The local Czech stream (20k viewers!) I watched went over the
| events in real time and then commented how events were
| happening as signals were received on Earth - with the final
| confirmation of successful landing coming first via Twitter,
| no less! :)
|
| Still a very nice yet nerve wrecking idea to do it like this
| - you _know_ the lander is on Mars _now_. But is it safely on
| the ground or is there a third Shapirelli crater now ? You
| don 't know! A huge relief in the end. :)
| matt-attack wrote:
| But aren't those two events essentially simultaneous in the
| relativistic sense? That is by some definitions of
| "simultaneous"?
| zwkrt wrote:
| In one sense, light experiences no time during travel, so
| anytime you are hit by radiation (like from a star) there
| is frame of reference in which the event was instantaneous.
|
| On the other hand, if you were on Earth and I was in
| between Earth and Mars, I would receive the data more
| quickly than you, and I could even watch it whiz by me on
| its way to you. The thing about relativity is that it's...
| relative!
| OliverGilan wrote:
| Doesn't relativity tell us it doesn't matter?
| cjohnson318 wrote:
| There's a lag time in communication due to distance. I don't
| see what that has to do with relativity.
| runarberg wrote:
| PBS Space Time recently explained what the present time means
| within general relativity[1]. As I understand it... it
| matters in this context.
|
| [1]: https://www.youtube.com/watch?v=EagNUvNfsUI
| scotty79 wrote:
| True fun begins when you consider General Relativity (which
| takes into account gravity and acceleration). From what I
| heard there is no definition of simultaneity and you can
| define it in different ways.
| runningmike wrote:
| I never forget a great fosdem talk regarding living on mars.
| https://archive.fosdem.org/2015/schedule/event/living_on_mar...
| unfortunately it turned out to be a hoax.
| sidcool wrote:
| Touchdown confirmed!! Congrats NASA.
| mu_killnine wrote:
| The Nasa person they have helping narrate what's going on is so
| genuinely happy the landing went well. It made me kinda tear up.
| It's infectious just how excited all these people are about this
| project. Also, I was a bit worried he was going to pass out.
| 10/10, would watch again (and probably will with my kids)
| shadowgovt wrote:
| The audible _whew_ from one of the crew members after maximum
| deceleration when the telemetry re-established was heart-
| rending. Years of work, and there 's nothing anyone here can do
| eleven light-minutes away; it was either going to work or one
| of the thousands of things that had to happen correctly wasn't
| going to happen.
|
| Everything happened correctly. :)
| [deleted]
| electriclove wrote:
| This guy?
| https://www.youtube.com/watch?v=gm0b_ijaYMQ&t=1h41m36s
|
| That is Rob Manning, an absolute legend! Here is an interview
| with him from a few years back:
| https://solarsystem.nasa.gov/people/2280/rob-manning/
|
| He also wrote this great book: https://www.amazon.com/Mars-
| Rover-Curiosity-Curiositys-Engin...
| tomc1985 wrote:
| I love the fact that you could hear people saying things like
| "yes yes yes YES YES!" in the background as data came in. Like
| you say, very infectious
| Azrael3000 wrote:
| It's a great achievement with some really interesting work done
| on the landing algorithms with terrain recognition and it seemed
| to have worked exceptionally well.
|
| Looking forward for the next landing in May of the Chinese rover
| and all the science these robots will produce. Also, the test of
| Ingenuity, the helicopter, will be very interesting to watch,
| that could really pave the way for a different exploration style
| in the future.
|
| And finally, maybe the next transfer window will already see some
| Starships, that would really change everything.
| jaegerpicker wrote:
| Ingenuity is maybe the most interesting and coolest advance for
| space travel. The idea of a remote drone to explore Mars is
| just rad! I can totally nerd out about that!
| suyash wrote:
| More about Ingenuity
| https://spectrum.ieee.org/automaton/aerospace/robotic-
| explor... and it's source code https://github.com/nasa/fprime
| jvanderbot wrote:
| That is not Ingenuity's source code, that's the software
| framework used to link the various software modules. It's
| generic to any mission / instrument.
| suyash wrote:
| correct
| kibwen wrote:
| A great video where the host visits the drone, interviews its
| makers, and goes over the cool technical aspects of it and
| its mission: https://m.youtube.com/watch?v=GhsZUZmJvaM
| jvanderbot wrote:
| You may be interested in dragonfly then:
| https://www.nasa.gov/dragonfly
| jws wrote:
| Early starships got me thinking: given the high likelihood of a
| failed starship landing, and maybe having the ability to send
| one before fully engineering a payload...
|
| What would you ballast a starship with for the practice
| missions?
|
| Useful materials which might survive a RUD and aim for
| someplace near a likely landing zone? If you crash the parts of
| a milling machine, a lathe, some tooling, some assorted metals
| stock, and a bunch of assorted wire, well sure you just cleared
| out a machine shop auction, but maybe there comes a day when an
| early Mars colony would be thrilled to go clean up your
| "landing" site.
| gameswithgo wrote:
| we playing factorio here?
| L_226 wrote:
| Soil? Though not sure it is prudent to potentially spread
| active biological material all over a pristine (eco)system.
| danw1979 wrote:
| Water.
| blackrock wrote:
| Don't litter Mars Elon. Stick your landing. LOL.
| mikewarot wrote:
| Why not work on some very small machines that can mine and
| refine materials to make more of themselves?
| george3d6 wrote:
| Because "refine" really means "melt at temperatures ranging
| from 500 to 4000 degrees celsisu and then extract via
| various mechanical processes and/or using various reactants
| which often require gigantic plants to produce and are
| highly unstable".
|
| Basically all of the history of science until 200 years ago
| was figuring out "mine and extract" and the course of
| civilization is very much linked with the price & quality
| of metal structures they could produce. But it's gotten so
| good we take it for granted.
|
| However that is because of gigantic plants situated in
| specific areas where energy is cheap that do this thing at
| an amazing scale.
|
| Aluminum is cheap as chips, except that it used to be more
| expensive than platinum (and at a much higher impurity
| ratio than the stuff we use for baking or for making cheap
| cases).
|
| Heck, gold is "a thing" because we could purify and mold it
| without bringing it to a melting point and it was, for a
| very long time, the only metal available to us to do
| anything with, way before the bronze age.
|
| And the problem with the refinement process is that you
| can't really "be smart" about it, reaching very high
| temperatures is one of those things you can't really scale
| down in an efficient way. You'd have to propel 100,000 tons
| of factory to mars in order to efficiently refine anything
| remotely close to the metals we had access to 100 years
| ago.
|
| Which is not to touch on the mining bit, that is in itself
| very complicated (see how slowly and shallowly rovers are
| currently able to drill).
|
| Are there workarounds for this? Maybe, I don't think anyone
| knows them though, they are not the kind of thing that's
| within easy reach. Maybe if we happen to stumble upon large
| reserves of bismuth or lead or gallium or mercury close to
| the surface of Mars, and build a whole branch of
| engineering around using those to build machinery... ? But
| my limited knowledge of geophysics and geology tells me
| that finding those in large amounts is very unlikely.
|
| For reference, if you take an oven, that can reach, say,
| 450 degrees celsius (home) and up to 700 (industrial).
| Those aren't enough to refine any "useful" metal (e.g.
| iron) and building them requires materials that were
| produced at 1500+ degrees.
|
| IANAChemist/IANAMaterialScientist/IANABlacksmith though, so
| take with a spoon of salt.
| mikewarot wrote:
| We don't have to be efficient, just small and reliable,
| no matter how slow... if there were enough small machines
| to turn out enough materials to build new ones faster
| than the failure rate, then geometric growth wins, and
| you can build whatever you want, eventually.
| zo1 wrote:
| It could be something very low-tech even. Just a machine
| that turns solar-energy + some mechanical power into say
| mars-dust bricks, non-stop for use in future missions?
| Maybe something that just keeps digging a perpetually
| deeper and deeper trench in a straight line so that
| subsequent missions don't need big drills to find out
| below-surface samples?
|
| But thinking about it now, I can't envision that we here
| would be able to come up with something sublime/novel
| that a huge army of really-smart people haven't already
| after spending decades thinking about it. Then again, we
| have a lot of smart people concentrated in this forum, so
| who knows if a weird/silly conversation triggered by IT-
| minded people, acts as a catalyst for the engineer-
| lurkers that see it.
| george3d6 wrote:
| I don't think you're getting my point, consider reading
| again. There's a fundamental limit you will hit here, you
| can't just "make it slower" or "make it worst" to lower
| that limit.
| mikewarot wrote:
| There is a fundamental limit of power... I get that. The
| Perseverance Mars Rover has one experiment that requires
| 180 watts of power, (The Oxygen Generator experiment) and
| it has a 110 watt RTG powering everything. They charge up
| some lithium batteries during down time, and use them to
| make up the difference.
|
| In the limit, If something takes 5,000 watts, you could
| run it for a few minutes/day, with that same RTG,
| provided you had suitable energy storage.
|
| Perhaps they could gather grains of material, and just
| sort them, one at a time, only keeping the iron rich
| material, or use a permanent magnet to gather ferrous
| material. You could sinter the grains together using a
| microwave or laser pulse.
|
| The results don't need great quality, just enough tensile
| and compressive strength to be mechanically stable during
| additive or subtractive manufacture.
|
| Lots of minds have been thinking about refining metals
| for a very long time, but they haven't been thinking
| about doing it on Mars, with limited power, and very far
| outside the box of normal constraints, like cost.
|
| This is one time capitalism doesn't apply at all... and
| most solutions assume capitalist incentives and costs,
| instead of going back to first principles thinking.
| saberdancer wrote:
| Bunch of 2x4s and screws/nails :D.
| skapadia wrote:
| Great, humans are starting to accumulate trash on Mars before we
| even step foot. Descent stage, heat shield. Pile it up!
| chasd00 wrote:
| heh my 11 year old quipped "i bet the martians are like 'these
| guys!? again??'". it made me laugh pretty hard
| huhtenberg wrote:
| First surface photo is in too!
|
| https://i.imgur.com/C2s1job.jpg
| kaycebasques wrote:
| N00b question: why is it black & white?
| nwallin wrote:
| Other posters have pointed out that it's the hazard avoidance
| camera, but they haven't said why the hazard avoidance camera
| is black and white.
|
| When you do computer vision, the first step you do is convert
| your color image into a black and white image, and run your
| CV algorithms on the black and white image. This is because
| when you're looking at objects and shapes and stuff, it's
| contrast that tells you where the boundaries between things
| are. This is true even in a human world of human objects,
| which tend to be many colored. It's even more true on Mars
| where basically everything is varying shades of orange. So
| having color doesn't help a whole lot, and you also have to
| do the additional step of converting the color image to black
| and white, which takes CPU power and adds latency. Remember,
| the purpose is hazard avoidance- latency is bad.
|
| Additionally, color camera sensors aren't actually color
| sensors. They're black and white sensors. In front of every
| pixel on the black and white sensor is a filter that is
| either red, green, or blue. Pixels are grouped into sets of
| four, and there are two pixels with green filters, one pixel
| with a blue filter, and one filter with a red filter.
| (sometimes one of the green filters is omitted, giving red,
| green, blue, and b&w, or sometimes one of the green filters
| is a filter that allows IR, or something like that.) So if
| you have a 16MP camera, the camera has 8M green, 4M red, and
| 4M blue pixels. This means two things; first of all, if you
| just wanted a black and white image in the first place, a
| color sensor gives _less_ detail than the equivalent black
| and white sensor, and second, you need to do additional
| processing to convert the raw output from the sensor into an
| image that 's usable for anything. The additional processing
| adds latency.
| whuffman wrote:
| Just as a heads up, the HazCams on Perseverance are in fact
| in color (Source: https://link.springer.com/article/10.1007
| /s11214-020-00765-9 - "The Mars 2020 Navcams and Hazcams
| offer three primary improvements over MER and MSL. The
| first improvement is an upgrade to a detector with
| 3-channel, red/green/blue (RGB) color capability that will
| enable better contextual imaging capabilities than the
| previous engineering cameras, which only had a black/white
| capability.") Your observations are correct though - the
| stereo precision is important, so there was additional
| analysis of the stereo depth computation to make sure it
| wouldn't cause an issue.
| nwallin wrote:
| Huh, I guess so. Looking over the study it looks like
| they had issues by looking at dirt in scoops and being
| unable to tell whether it's Martian dirt or a shadow.
|
| I have a feeling I'd be the angry guy in the meeting who
| wouldn't accept the consensus. "but what about latency!
| what about the descend and landing!" _shakes fist_
| rmonroe wrote:
| Nah, your concerns are 100% reasonable - they just
| operate on a different context. On Earth, latency is
| king. On Mars, especially until the Primary Mission is
| complete, it's all about risk mitigation. Since we're
| light-minutes away from Earth, a few frames of latency is
| nothing. At the same time, you want to avoid breaking
| your $3B machine, which is hard to operate given the
| time-of-light delay and comms limitations. Just a
| different set of tradeoffs. IIRC they first tested on-
| device deep learning for hazard avoidance in Curiosity,
| but don't quote me on that.
|
| -Worked at JPL for a few years and have dozens of
| friends, a few in the vision system.
| kharak wrote:
| Thank you for the explanation. That was highly interesting.
| Does anyone else know if the human eye does perceive color
| directly? Is this at all technically possible? And if yes,
| why aren't we doing it with cameras?
| ddingus wrote:
| I believe in purple.
|
| After you get done exploring how we perceive colors
| associated with different wave lengths of light, and how
| nobody really knows whether these are common somehow, or
| unique to each of us, that sentence should bring you both
| a chuckle and some wonder about perception.
| Koshkin wrote:
| From the physiological standpoint human individuals are
| far, far from being unique. The electrochemical reaction
| of a neuron in the cortex which indicates the perception
| of 'red' is pretty much the same in any human (and not
| only).
| ddingus wrote:
| Whether that subjective perception is the same remains
| unknown. We have no solid way to communicate any of that
| yet.
|
| I am inclined to believe it is, but we do not really
| know.
| natosaichek wrote:
| What do you mean by "directly"? Color is a human
| abstraction over the reception intensity of certain
| wavelengths of light.
| Koshkin wrote:
| What do you mean "abstraction"? The colors that I am
| seeing look very concrete to me. (Also, the "wavelength
| theory" of color perception does not explain why TV
| screens work.)
| natosaichek wrote:
| The human retina is composed of cells that are responsive
| to different wavelengths of light. Color is the word that
| we use to describe the subjective sensations associated
| with certain patterns of stimulation of those cells.
| There is no "yellowness" in a bananna. We cannot
| construct an instrument capable of measuring "yellow" as
| such. What we can measure are the intensities of
| wavelengths of light.
|
| We can notice that when people say they perceive "yellow"
| that the spectral intensity graph has certain patterns.
| This is the physical phenomenon that produces the
| sensation of "yellow."
|
| Humans are not good at judging reality introspectively.
| We experience everything heavily filtered through a
| variety of lenses. Our feeling that color is "concrete"
| is not predictive or explanatory... we cannot build
| mechanisms based on it. The idea that our perception of
| color is a result of interactions between certain
| wavelengths of light and certain photosensitive tissues
| in our eyes is both predictive and explanatory. We can
| design systems that have similar types of wavelength
| intensity sensitivity components and measure the physical
| response of those systems. That's how cameras work.
|
| We can reverse the process and take those measured
| wavelength intensities and re-emit them from variable-
| wavelength light sources and produce images. That's how
| you're reading what I've typed right now - the images
| produced by the display you're looking at were generated
| in this fashion.
|
| I'm not sure what you mean by the "wavelength theory" of
| color perception.
| Koshkin wrote:
| > _We cannot construct an instrument capable of measuring
| "yellow" as such._
|
| Of course we can. We can capture the signal sent through
| the optical nerve and then reproduce it as a stimulus
| which will make the brain "see" yellow color.
|
| Besides, humans are capable of distinguishing literally
| millions of colors, of which just a tiny fraction can be
| attributed to measuring particular wavelengths (or, more
| accurately, particular energies of the incident photons).
| In that way the eye is different from the ear (which
| performs a kind of Fourier analysis of the sound wave).
| natosaichek wrote:
| Well, the instrument wouldn't me measuring yellowness...
| it would be measuring electrical impulses that (in some
| individuals) correspond to the (verbally asserted)
| perception of "yellow". "Yellow" is not a characteristic
| of the world; it's a convenient label that humans apply
| to some bucketed sets of sensory perceptions.
|
| I agree that there are sensory perceptions humans are
| capable of perceiving and labeling as colors that cannot
| be attributed to external physical phenomena, but those
| are largely artifacts of the way our brain processes
| signals. For example if you stare at a purple dot for
| some time, then look away, you'll perceive a yellow dot
| where there is no external set of photons corresponding
| to the wavelengths that normally trigger the sensation of
| yellow striking your retina.
|
| This is just more explanation about how "yellowness" is a
| characteristic of our brains, not of the external world.
|
| Or did you mean something other than what I'm referring
| to here? I think that for the vast bulk of humans, the
| vast bulk of the colors they perceive regularly are due
| to photons striking rods and cones in their eyes at
| various intensities, causing color sensations to occur in
| the brain. Do you think something else is happening?
|
| You seem to understand how the eye works, and some
| neuroscience, so I don't understand how you can have the
| questions that you raise about whether we can build
| cameras that sense "color" instead of "light"
| zinekeller wrote:
| Short answer: No. We (the majority anyway, as some are
| colourblind) only perceive lightness, reddish, greenish,
| and bluish. The brain uses the info and effectively
| synthesises the image in our brains.
|
| Long answer: Colour is a very rabbithole topic but
| Captain Disillusion has a summary of it
| (https://youtu.be/FTKP0Y9MVus) and Technology Connections
| has a discussion (https://youtu.be/uYbdx4I7STg).
| nwallin wrote:
| ...it's complicated. Very complicated. However
| complicated you think it is, it's more complicated than
| that. Please note that I'm not an expert in human eyeball
| physiology, I'm just a computer programmer who's tried
| pretty hard to come to a better understanding of how to
| make computer vision better. (I've failed, fyi. Caveat
| emptor.)
|
| The human eye has four basic cell types, rod cells and
| cone cells, and there are three subtypes of cones, short,
| medium, and long. The three subtypes of cone cells sense
| blue, green, and red light more or less directly. Medium
| and long cone cells, which directly detect green and red
| light, almost entirely overlap. [0] It is more accurate
| to say that long cone cells detect yellow light than it
| is to say it detects red light. There is a brain system
| which measures the difference in response between the
| long (red) and medium (green) cells and uses the
| difference to say "aha! this must be red!"
|
| The ratio of short (blue) medium (green) and long (red
| (yellow)) cone cells are roughly 2%, 2/3, and 1/3. The
| cells in your eye which detect blue light are more or
| less a rounding error. The cells which detect green light
| are roughly twice as numerous as the cells which detect
| red (well, yellow) light. If you see a thing and think,
| "man, that's awfully blue," it's not because your eyes
| are telling you "hey, this thing is awfully blue". The
| "blue" signal is barely noticeable in the overall signal;
| but your brain jacks up its responsiveness to the
| minuscule blue signal.
|
| One of the side effects of the completely fucked ratios
| between the three types of cones is that your perception
| of the overall brightness of a thing is mostly down to
| how green it is. This shows up in lots of standards;
| NTSC, JPEG, the whole nine yards. If you've ever
| implemented a conversion between RGB and any luminosity-
| chroma colorspace (YUV, YCbCr, YIQ, NTSC, any of them)
| there's a moment where you'll go "wait a minute this
| doesn't make any fucking sense". You look at the numbers
| and the luminosity channel is just... green, and you know
| that the other two chroma channels are quartered in
| resolution. And you'll think that makes no sense. But
| that's how it works.
|
| Then you'll remember that color sensors have their pixels
| arranged in groups of four, with two green, one red, and
| one blue channel. There must be some green conspiracy.
|
| And there is. It's your brain. It's your eyeballs with
| 2/3 of its cone cells being green sensitive ones.
|
| Those are your cone cells. Rod cells are entirely
| different. It's trivial to say well, cone cells see
| color, rod cells see black and white, but it's more
| complicated than that. Rod cells are excellent in low
| light conditions, cone cells not so much. Cone cells see
| motion very well, rod cells not so much. Cone cells can
| discern fine detail, rod cells do not. Rods and cones are
| not evenly distributed across the retina either; cone
| cells are densely packed in the center, rod cells are
| more common in peripheral vision.
|
| Look at a colorful thing directly; take a note of how
| colorful it is. Now look away from it, so it's only in
| your peripheral vision; take a note of how colorful it
| is. Does it seem just as colorful? It isn't. That's your
| brain fucking with you. Your brain knows it's in your
| peripheral vision and all the colors are muted out there,
| so your brain exaggerates the colorfulness. Cone cells
| are 30 times as dense in the center of your vision as
| they are just outside the center of your vision. [1]
| That's why you can read a word directly where you're
| looking but it's very difficult to read elsewhere.
|
| The reality is that your retinas give a fucking mess of
| bullshit to your brain, and the brain is the most
| incredible image processing system conceivable. It takes
| bullshit that makes no damn sense and -- holy shit I
| forgot to talk about blind spots.
|
| Ok, so your rods and cones have a light sensitive thing,
| with a wire in the back, and all the wires get bundled up
| in the optic nerve that goes to the brain. Here's the
| thing: they're fucking plugged in backwards. The wires go
| forward, and are bundled up between your retinas and the
| stuff you're looking at. The big fat optic nerve
| therefore constitutes a large chunk of your vision where
| you can't see anything. Your brain just.. _invents stuff_
| where the optic nerve burrows through your retina.
|
| Other weird stuff. If it's bright, the rods and cones
| send no signal, if it's dark, they send a strong signal.
| It's inverted. There's apparently a very good reason for
| this but I don't remember what it is. Also, the rods
| continuously produce a light sensitive substance that
| amplifies the light sensitivity but is destroyed in the
| process. It takes a long time to build up a reserve. This
| is why it takes time to "build up" your dark vision, and
| why it's so easily destroyed by lighting a cigarette. The
| physiology of "ow it's bright" as opposed to "it's
| bright" isn't just on your retinas, it's also on your
| eyelids and your iris, but more importantly, it's shared
| between your two eyes. This is why closing one eye makes
| it less painful when you go from a dark place to a bright
| place.
|
| The point is, the study of human vision is not the study
| of the human eye. The study of human vision is the study
| of the human brain.
|
| Much of what we do with color spaces and image
| compression is dictated by our stupid smart eyeballs and
| our stupid smart brains. Video codecs compress with 4:2:0
| chroma subsampling because the brain's gonna decompress
| that shit better than a computer can anyway. Cameras have
| twice as many green sensitive pixels as blur or red
| pixels because the eye resolution is much sharper in
| green than other colors. More advanced image and video
| compression schemes will try harder to account for human
| eye-brain physiology.
|
| [0]
| https://upload.wikimedia.org/wikipedia/commons/0/04/Cone-
| fun...
|
| [1] https://upload.wikimedia.org/wikipedia/commons/3/3c/H
| uman_ph...
| POiNTx wrote:
| My guess is lower image size, which means image can get
| transferred faster.
| txg wrote:
| This is the right answer. The camera (and its 8 siblings)
| are capable of color HD imaging - the sensor has a Bayer
| filter. This image used a binning mode to produce a
| downsampled frame that could be more rapidly transferred
| back over the lower bandwidth comms used during landing.
| Binning combines the Bayer pattern and so color information
| is lost.
|
| Also doesn't help that there is a (transparent) lens cover
| in front of the lens obscuring the view.
| Azrael3000 wrote:
| That is most certainly correct. They also mentioned that
| these are images from engineering cameras, so they are
| normally responsible for navigation. The real HD footage
| will come in over the next hours as the bandwidth just is
| not large enough.
|
| Elon Musk needs to provide some Starlink sats for a better
| connection.
| _Microft wrote:
| Starlink would most certainly be of little direct use
| here.
|
| What I could imagine is having Starlink satellites around
| Mars that allow to route data from rovers anywhere on the
| planet to a dedicated high-performance communications
| platform that handles communication with Earth.
| teraflop wrote:
| In fact that's exactly what they're doing: the Mars
| Reconnaissance Orbiter is serving as a communications
| relay, as it did for previous landers.
|
| It's just that since there have never been more than a
| handful of spacecraft active on Mars at any given time,
| there's currently no point in spending huge amounts of
| money to launch a whole constellation of satellites for
| continuous coverage.
| Sharlin wrote:
| Not only the MRO, but other orbiting assets as well,
| particularly NASA's MAVEN and ESA's TGO. Even the
| venerable 2001 Mars Odyssey is still used as needed, I
| think.
| m4rtink wrote:
| Even ESAs Mars Express is still around - since 2003!
| davidmr wrote:
| And a photographer! MRO took what might be my very
| favorite picture of all time:
| https://www.space.com/16946-mars-rover-landing-seen-from-
| spa...
| m4rtink wrote:
| Could be still a nice exercise if someone could compute
| how many Starlinks could a Falcon Heavy throw to Mars
| transfer orbit & if they could be able to actually
| capture into Martian orbit by their default means of
| propulsion (do they actually have any high thrust engines
| ?).
| nothis wrote:
| Anyone know the bandwidth they're working with, at least
| roughly?
| kibwen wrote:
| Here's a page with data about the Deep Space Network:
|
| https://mars.nasa.gov/msl/mission/communications/#data
|
| _" The data rate direct-to-Earth [from Mars] varies from
| about 500 bits per second to 32,000 bits per second"_
| zokier wrote:
| Clarification, that is for the old Curiosity rover. The
| page for Perseverance has some additional information
|
| > 160/500 bits per second or faster to/from the Deep
| Space Network's 112-foot-diameter (34-meter-diameter)
| antennas or at 800/3000 bits per second or faster to/from
| the Deep Space Network's 230-foot-diameter (70 meter-
| diameter)
|
| for high-gain antenna, and
|
| > Approximately 10 bits per second or faster from the
| Deep Space Network's 112-foot-diameter (34-meter-
| diameter) antennas or approximately 30 bits per second or
| faster from the Deep Space Network's 230-foot-diameter
| (70-meter-diameter) antenna
|
| for the low-gain antenna, which I believe the first two
| images were sent through
|
| https://mars.nasa.gov/mars2020/spacecraft/rover/communica
| tio...
| m4rtink wrote:
| Maybe it was the low gain antenna but via MRO or other
| orbiter? 30 bits per second seems like a bit too slow to
| get even the two small images back so quickly.
| extropy wrote:
| That's rover directly to earth, when reconnaissance
| orbiter is used to relay it's around 2 mbit to orbiter.
| smilespray wrote:
| It's from a hazard camera, which is not used for main
| photography. Better images will come soon.
| ehsankia wrote:
| Worth noting that these first pictures are sent in the
| first seconds after touchdown, you can even still see the
| dust in the air from the landing (even if it was craned
| down to reduce dust). It also explains the very low
| resolution in general, they want to get confirmation ASAP,
| no time for high quality high resolution images.
| nerfhammer wrote:
| would dust stay in the air longer or shorter than on
| Earth?
|
| also is it technically correct to call the Martian
| atmosphere "air"?
| DonHopkins wrote:
| Yes, but it's not technically correct to call Martian
| seismic tremors "earthquakes".
|
| https://www.imdb.com/title/tt0080745/goofs
|
| Flash Gordon (1980) Goofs
|
| At the very beginning of the film, Ming and his henchman
| are discussing "an obscure body in the SK system", which
| the inhabitants refer to as the planet "Earth",
| pronounced as if the word is completely foreign to them.
| However, at that moment, Ming activates a button on his
| console labeled "Earth Quake".
|
| http://bobcanada92.blogspot.com/2020/10/flash-gordon-
| logic.h...
| nerfhammer wrote:
| Star Trek calls them "quakes" I noticed
| ajross wrote:
| Dust falls much, much faster on Mars. The density of
| Mars's surface atmosphere is ~160x lower than on Earth.
| mrec wrote:
| Right. One "proof" advanced by Moon landing conspiracy
| theorists was that dust settled much faster in videos
| than it should if it were _really_ in Lunar gravity.
| js2 wrote:
| Miriam Webster says yes to part two:
|
| > the mixture of invisible odorless tasteless gases (such
| as nitrogen and oxygen) that surrounds the earth
|
| > also : the equivalent mix of gases on another planet
|
| I would naively guess yes to part one but it's
| complicated: Mars has less gravity, much less atmospheric
| pressure, colder temps, and greater gravitational
| influence from its moons than Earth. Wikipedia says the
| mechanism of the planet's dust storms isn't well
| understood.
|
| https://en.wikipedia.org/wiki/Atmosphere_of_Mars#Dust_and
| _ot...
| themeiguoren wrote:
| The low resolution and fuzz is also because they still
| have the lens caps on - they are of course transparent
| lens caps in case the explosive bolts that will release
| them fail. Redundancy!
| interestica wrote:
| This is one of the cooler things that I learned today.
| Could they go even further: make the caps themselves
| lenses+filters. Take photos. And then blow them off for
| new photos.
| [deleted]
| hiharryhere wrote:
| I heard on the live stream that it was taken by a camera that
| is used by the driving system.
|
| Guessing its black and white/high contrast to help see rocks
| etc. And probably much lower res, smaller file size too for
| transferring.
| ijustlovemath wrote:
| Just an enthusiast, no real answers, but here's a guess:
|
| These are hazard cameras, designed to be inputs into the
| guidance algorithms on board. It might make sense for such a
| camera to be B/W to reduce on board processing required.
| There's also a glass cover on them, and a lot of dust from
| the landing, so that may be obscuring true color if the
| cameras do in fact take color images.
|
| Also they may have just transmitted a lower quality B/W image
| to get something back to Earth quickly, since higher res
| images take longer to uplink.
| neals wrote:
| It's an "engineering cam" that's not really meant for taking
| nice pictures, more to see where the thing is going. There'll
| be some better Instagram selfies soon though.
| [deleted]
| robinjfisher wrote:
| This was explained on the feed. It's from a lower-res safety
| camera mainly used for object avoidance on the ground. High
| definition images will be available later.
| interestica wrote:
| https://mars.nasa.gov/mars2020/multimedia/raw-images/
|
| It seems that NASA is being awesome and making all raw
| images available as they get them. So far just the 2-ish.
| handedness wrote:
| The world is a complicated place, Hobbes.[1]
|
| The lower "HazCams" hazard avoidance cameras (which captured
| those initial photos) are there to detect hazards (rocks,
| trenches, etc.). They are stereoscopic, lightweight, and high
| resolution.
|
| My guess is that using color sensors would have either
| increased the 3D mapping precision or added
| weight/power/bandwidth requirements, or otherwise been less
| robust in that environment.
|
| Those cameras were also pre-deployed for the landing phase
| and likely transmit more quickly due to the lower data
| information. The other cameras were shielded for the landing
| phase.
|
| The navigation and other cameras are in color, and I expect
| we'll be seeing better images shortly.
|
| [1] This comes to mind whenever a question like that is
| asked: http://4.bp.blogspot.com/-CWM1zDcmWXs/TroD0VsX4WI/AAAA
| AAAAAV...
| whuffman wrote:
| FYI - the HazCams on Perseverance are in fact in color
| (this is new, they were black and white on Curiosity)!
| Stereo precision was a concern based on the switch to color
| sensors, so there was some algorithmic work done to make
| sure it wouldn't cause an issue. (Source: https://link.spri
| nger.com/article/10.1007/s11214-020-00765-9 - "The Mars
| 2020 Navcams and Hazcams offer three primary improvements
| over MER and MSL. The first improvement is an upgrade to a
| detector with 3-channel, red/green/blue (RGB) color
| capability that will enable better contextual imaging
| capabilities than the previous engineering cameras, which
| only had a black/white capability.")
| handedness wrote:
| Interesting, I didn't know that. I knew the Cachecam was
| color, but somehow missed that detail, despite actually
| seeing the camera in person at one point...
| m4rtink wrote:
| Wow, real upgrades all around compared to Curiosity!
|
| What are they going to do next ? Put on board a solar
| powered Mars helicopter ?? ;-)
| jxcl wrote:
| > My guess is that using color sensors would have either
| increased the 3D mapping precision or added
| weight/power/bandwidth requirements, or otherwise been less
| robust in that environment.
|
| I think you meant to say decreased? In which case I think
| you would be correct! Camera pixels are made up of these
| things called photosites which don't by themselves record
| color, only brightness. In order to record color
| information, the photosites are placed behind a Bayer
| filter[1], which effectively reduces the resolution of the
| camera by 3, because in order to get the color of a pixel
| you need its red, green and blue component. Bayer filters
| also frequently have a small blurring filter in front of
| them to make sure that nearby photosites with different
| color filters get the information they need.
|
| If you're looking for the highest resolution image
| possible, black and white is the way to go!
|
| [1]: https://en.wikipedia.org/wiki/Bayer_filter
| m4rtink wrote:
| That's why "real" space cameras usually have color
| filters on a carousel before the sensor - they take 3
| pictures each with different filter and BAM, color!
|
| That way you get high regulation as well as color. You
| can also have some special (infrared, ultraviolet, etc.)
| Filters on the carousel, not just RGB.
| dylan604 wrote:
| >and BAM, color!
|
| and BAM, false color! FTFY
| handedness wrote:
| > I think you meant to say decreased?
|
| I did, thank you. I think my brain had already skipped
| ahead to the added weight/complexity concept while my
| fingers were stuck on that part of the sentence.
|
| I should probably read things after I type them...
| handedness wrote:
| And by "increased" I meant the "decreased" kind...
| kube-system wrote:
| Here's the answer from NASA:
| https://youtu.be/gm0b_ijaYMQ?t=6240
| ArtWomb wrote:
| Greetings from Jezero Crater! Really doesn't look alien. RLike
| the high mesa of New Mexico sans flora ;)
| gillytech wrote:
| The shadow features are fantastic!
| interestica wrote:
| NASA is making the raw images of everything available:
|
| https://mars.nasa.gov/mars2020/multimedia/raw-images/
| ape4 wrote:
| Today's images are from Sol 0. Zero-based counting rules.
| mam2 wrote:
| live or fear.. you have to chose
| ortusdux wrote:
| They have a live telemetry animation web app, but I am currently
| getting a 503 from cloudfront.
|
| https://eyes.nasa.gov/apps/mars2020/
| shadowgovt wrote:
| Yeah, it was accessible until they mentioned it in the
| livestream.
|
| To their credit, I've watched NASA spend decades getting better
| at Internet services and generally being an online presence.
| Improvements year-over-year have been noteworthy. But I still
| have to chuckle a little bit that they triggered a DDOS protect
| by name-dropping themselves.
|
| Ad Internet Per Aspera, you crazy spacers ;)
| raylus wrote:
| Thanks!! Also wanted to mention, NASA is separate from JPL
| for the most part as far as web services go.
| shadowgovt wrote:
| Great work today.
| mhh__ wrote:
| The telemetry they have up on the wall is based off a project
| that they have open sourced too (Open MCT), or at least it
| looks like it.
| alach11 wrote:
| Watching the stream, it's striking the difference in employee age
| between NASA and SpaceX. I won't speculate on the reasons, but I
| wish the best to the Perseverance team!
| shironandon wrote:
| unsure why you think that is relevant, bub. Interested in their
| religion, political views, and sexual preferences as well?
| klohto wrote:
| Stop picking up fights, that wasn't the point of the comment
| at all.
| johnchristopher wrote:
| I thought they were young people in the NASA video. Does that
| mean people at SpaceX are older ?
| flyinglizard wrote:
| It's also remarkable that the NASA workforce is 99% women, as
| evident from this broadcast.
| chasd00 wrote:
| hah they probably don't let the kids near the really important
| buttons ;)
| dharmab wrote:
| Remember that not all the staff could be at NASA today due to
| COVID policies. Most of the team is at home.
| avereveard wrote:
| I don't think the video show a representative sample of the
| employee at either company; I suspect picks where selected for
| stage presence with a touch of preference for diversity.
| tambourine_man wrote:
| https://www.youtube.com/watch?v=gm0b_ijaYMQ
|
| Live feed
| ggm wrote:
| Here in oz its not live
| meepmorp wrote:
| I guess technically it's on an 11 minute delay for the whole
| planet.
| ggm wrote:
| Well yes, but I meant I watched continuously from 06:45 to
| 07:15 and it was replay of pre-recorded videos of the rover
| and no indication on screen it had landed.
| rablackburn wrote:
| odd, I'm in Aus too and I watched the entire thing live
| with no issues (assuming you're in QLD on EST)
| ggm wrote:
| I am. Maybe I turned away at the wrong crucial 30
| seconds.
|
| (Edit) I checked the JPL clean feed and none of the last
| two hours of feed is what I saw being sent on NASA live.
| I got a walk around the robot, and social media about the
| kids who named it, and talking heads. Bizarre.
| jaegerpicker wrote:
| Seeing the engineers and scientists celebrating the successful
| landing was one the best things I've seen in a LONG while. Very
| live affirming and inspiring to me!
| BurningFrog wrote:
| Is part of the joy that they now have secure jobs for years to
| come?
| soheil wrote:
| Most common assumption by outsiders is that they're happy
| that their many years of effort came to fruition, but I think
| a big part of is that they will be working on this mission
| for the foreseeable future as you point out. They get to tell
| their kids I worked on this mission, it was successful and
| then we made the rover do X, Y and Z in the next few years.
| AnimalMuppet wrote:
| I think it's mostly the joy that their past decade or two of
| work wasn't wasted.
| jaegerpicker wrote:
| Maybe but for me I think it would the joy of completing such
| a massive task so well. They literally just achieved
| something that no one else in history has.
| acomjean wrote:
| It is the fifth rover... But still super impressive feat,
| with years of detailed planning. I boogles my mind thinking
| about all the bits of engineering put together to make this
| happen.
|
| I can't wait to see what it sends back. Always celebrate
| your successes.
| Rebelgecko wrote:
| I wouldn't be surprised if a lot of the engineers who worked
| on EDL move on to other projects in the coming weeks
| notum wrote:
| Any JPL/NASA HN users that could comment? That would be beyond
| awesome!
|
| Great job, mission!
| raylus wrote:
| JPL Engineer here, any questions I could convey to the slack
| I'll be glad to feed back to HN
| m4rtink wrote:
| How much overlap is there now that two similar yet 10 years
| different rovers are in operation ? Is it possible to share
| some of the human/software/planning resources or are they
| basically two separate efforts by this points ?
|
| Also, do the Rover Drivers still live on the Mars time that
| makes their working hours shift by 45 minutes every day, like
| in the good old MER days ? ;-)
| Nekhrimah wrote:
| Any idea on the timeframe for unfurling the robotic arm? And
| doing the test drive?
|
| Thanks for your efforts towards the fantastic result today.
| prox wrote:
| I just want to thank you all for the wonderful time tonight,
| we've been watching with the family. Amazing accomplishment!
| myself248 wrote:
| "Slack" is actually the answer to one of the questions I was
| going to ask, about internal communication!
|
| Hmm, another: Given that it's roughly a decade since MSL
| Curiosity, what were y'all (Perseverance team members) doing
| when Curiosity launched and landed? How many of today's team
| were in school back then, or what's the generational turnover
| and overlap like?
|
| What's everyone's "favorite" failed Mars mission that
| would've changed everything if it'd succeeded?
| vagrantJin wrote:
| Sick!
|
| Will this rover make contact with its forebears at some
| point?
| krysp wrote:
| Awesome achievement! What was the part of the mission you
| were most concerned about / most likely to go wrong?
| michaelt wrote:
| Awesome stuff.
|
| I couldn't help but wonder, while I watched the feed: What
| are the people in mission control doing during the landing?
|
| Obviously they're monitoring telemetry - but what else?
| Presumably the time delay precludes them triggering anything
| critical manually, and making post-launch software changes
| would be frowned upon?
| helmholtz wrote:
| They're all going to get wasted tonight, mate.
| throwawaygimp wrote:
| thats Mars 'tonight', of course
| fetacheese wrote:
| I have serious doubts that this actually happened
| tristanb wrote:
| why?
| fetacheese wrote:
| why not
| chrononaut wrote:
| I included this the other day in the previous Perseverance thread
| but if you're excited for the Perseverance EDL video hopefully
| Doug Ellison's composite video of Curiosity's landing (from a
| single camera) can tie folks over in the mean time!
| https://www.youtube.com/watch?v=RZioPhfxnSY
| dtjohnnyb wrote:
| Have we any idea when that video will be released (roughly).
| sabujp wrote:
| can't wait for the choppah
| pjfin123 wrote:
| Exciting time to be alive!
| Daho0n wrote:
| I stopped watching videos like these when they started chanting
| like some crazy cult when things went well (USA! USA! USA!). No
| wonder we can't just get along.
| frabbit wrote:
| Certainly took away from the experience for me. Also the
| constant clapping was irritating along with the guy going "yes,
| yess" towards the end.
|
| Not enough info, too much "personality" and "team work". Waste
| of time watching it really.
| Ftuuky wrote:
| I'm not american but still enjoyed the landing very much. They
| sent a freaking nuclear-powered jeep to the surface of another
| planet, they can gloat all they want.
| Daho0n wrote:
| I'm not saying anything bad about the landing. It was a great
| feat. I just find the chanting often done in US videos
| disgusting.
| sidcool wrote:
| Isn't the funding coming from US citizens? And NASA is
| American after all. I don't see what could be the problem
| here.
| jbd28 wrote:
| Too bad for you to just be happy for these government
| employees then. USA! USA!
| rnikander wrote:
| I wish they'd put a robot like this on Europa. Something that
| could drill into the ice and look for life in the (possible)
| ocean underneath.
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(page generated 2021-02-19 23:00 UTC)