[HN Gopher] NASA space copter ready for first Mars flight
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NASA space copter ready for first Mars flight
Author : dnetesn
Score : 133 points
Date : 2021-04-10 11:58 UTC (11 hours ago)
(HTM) web link (phys.org)
(TXT) w3m dump (phys.org)
| totetsu wrote:
| i guess i skim read news too much because i thought this happened
| last week.
| lucb1e wrote:
| Last week I almost thought it flew, but then it actually said
| "survived first night" not "survived first flight". And now I
| spot "first Mars flight" in the headline and thought it again
| but... nope, now it's "ready to fly". Like, great, let me know
| when it does.
| arendtio wrote:
| When I read such articles I imagine SpaceX dropping their own
| rover in a few years that will autonomously drive around and
| gather more data in 30 days than NASA had in 30 years.
|
| However, it will also manage to get stuck/kill itself within the
| 30 days ;-)
| spookthesunset wrote:
| One thing spacex seems to do better is "eye candy". They'd make
| sure that copter would transmit high quality video of its
| flight... constraints be damned.
|
| Eye candy is very important for getting the public excited
| about these missions. More public excitement == more money and
| easier recruiting.
| imglorp wrote:
| This is my concern about SpaceX applying its superpower to
| Mars. Rapid prototype iteration on Mars is orbital time: you
| wait 2 years for the next launch window and then ~7 months for
| travel, blow something up and learn lessons, repeat next
| window.
|
| Hopefully they do some rapid iterating on Starship Moon
| missions and get some of the blowing up out of the way early.
| dylan604 wrote:
| I expect SpaceX to be prepped to launch multiple rockets per
| window.
| imglorp wrote:
| In production, of course yes.
|
| In iterating development, you would expect one at a time so
| a bug would not affect a whole fleet.
| cma wrote:
| Musk said SpaceX would have a mars mission (not manned) on
| every earth/mars rendezvous starting in 2018. He originally
| said it was going to use dragon. And then he said manned
| missions starting in 2024.
|
| https://en.wikipedia.org/wiki/SpaceX_Mars_program#2016_plans
|
| They backed out of that but are still claiming they will do the
| manned around-the-moon trip in 2023 using Starship, and haven't
| backed down from point-to-point earth passenger travel by 2028
| for cheaper than a business class flight.
|
| https://www.vox.com/2018/4/11/17227036/flight-spacex-gwynne-...
| ("Shotwell estimated the ticket cost would be somewhere between
| economy and business class on a plane ")
| 14 wrote:
| I once witnessed a person take their brand new electric rc
| helicopter place it on the ground and before I knew it the thing
| flipped over and smashed itself on the ground. I have a lot of
| respect for them taking their time; this could work incredibly
| well or for some unforeseen reason smash into the ground. In my
| situation it was the loss of signal that caused the accident when
| the pilot admitted to accidentally shutting off his controller
| right at that moment.
| qwertox wrote:
| RC helicopter flying has evolved into something really insane
|
| https://www.youtube.com/watch?v=AXSfFLGeVZA&t=156s
|
| https://www.youtube.com/watch?v=E24JIetETAE&t=91s
| amiramir wrote:
| Thanks for links. I had no idea. I tried flying an RC copter
| some time ago (piston engine) and getting it to hover was a
| nerve-wracking triumph. These folks and electric motors have
| taken it into another dimension.
| pengaru wrote:
| The nitro helis are no slouches either, they're all capable
| of insane 3D maneuvers in the right hands.
|
| The exhaust plume of a nitro doing the same things is kind
| of more interesting IMHO, it's like a telltale in a wind
| tunnel test. I'm surprised they don't put a smoke bomb on
| the electrics during these demos.
| spookthesunset wrote:
| Not just electric motors but cheap, high quality flight
| controllers. That and kickass batteries.
| xwdv wrote:
| Oh wow, can a full size helicopter do that? Would be amazing
| to see at an air show.
| mrunseen wrote:
| I don't think so, engines on RC aircraft are quite powerful
| compared to their weight which isn't a case with "real"
| aircraft. There's a number of issues that can happen (and
| probably kill the crew) but it's the most fundamental
| issue.
|
| Only event I know of is this: https://www.reddit.com/r/next
| fuckinglevel/comments/jmtvch/tu...
| ajuc wrote:
| I think that's a few too many Gs for human pilots.
| [deleted]
| mobilemidget wrote:
| The solar panel on the YouTube thumbnail looks quite dusty.
| imglorp wrote:
| I wonder if the rotor wash will clean them off or kick up more
| dust and make them worse.
| hnedeotes wrote:
| "Musk, get to tha choppa!"
| travisgriggs wrote:
| Isn't "space copter" a bit of a misnomer? Isn't a copter a device
| with whirring blades tilted just so to cause thrust through a
| fluid medium (to wit, a propeller)? And isn't space defined often
| as that place where there is no such fluid like medium? So
| wouldn't it make more sense for it to be called a "Mars Copter"?
| _Microft wrote:
| _" The current plan for the first-ever attempt at powered,
| controlled flight on another planet is [...] to take off from
| Mars' Jezero Crater on Sunday at 10:54 pm US eastern time (0254
| GMT Monday) and hover 10 feet (3 meters) above the surface for a
| half-minute, NASA said."_
|
| Set your alarms :)
|
| If the given time is actually take off, we can expect images from
| the flight at the earliest around 11:10pm (E(S?)T)/ 03:31 AM
| (GMT) as Earth and Mars are currently at a distance of 15 light
| minutes from each other.
|
| If they don't have a live feed, I would watch their Twitter
| account just in case. Useful links:
|
| https://mobile.twitter.com/NASAPersevere
|
| https://mars.nasa.gov/mars2020/
|
| Edit: see reply by samizdis for another, better link
| _joel wrote:
| I'm not sure there will be images that quickly, just the
| telemetry to confirm if it was successful or not.
| janmo wrote:
| The bitrate Earth/Mars is very low. It will take a lot more.
| xiphias2 wrote:
| Would setting up 60 Starlink satellites in a line to
| transmit between the two help?
| _Microft wrote:
| Eventually it is going to be laser communications, I
| think. They are going to test deep space laser
| communications on the upcoming "Psyche"-mission,
| launching in 2022. The target asteroid will be at a
| distance of approximately 15 lightminutes (according to
| Wolfram Alpha) from Earth in 2026 when the probe is
| expected to arrive there. This is as far from Earth as
| Mars currently is. They hope to increase the bandwidth by
| an order of magnitude or two (i.e. 10-100 times). The
| link is supposed to be bidirectional, so the spacecraft
| can receive optical transmissions as well. I assume this
| laser uplink is more proof of concept than actually
| needed?
|
| https://en.wikipedia.org/wiki/Psyche_(spacecraft)#Science
| _pa...
|
| https://en.wikipedia.org/wiki/Deep_Space_Optical_Communic
| ati...
| Space_Dude wrote:
| You're right that the future of deep space communications
| is optical. There's a forum on Reddit:
| https://reddit.com/r/lasercom
| jvanderbot wrote:
| You can't fix latency. You could increase data rate
| though.
|
| I'm working on a multi-sat huge data rate, huge latency
| idea under the NASA NIAC program at the moment. If we
| continue to be concerned mostly with latency, then data
| rate will always be severely limited.
|
| Sorry, no permalink, it's right on my page:
|
| https://josh.vanderhook.info/index#2021-03-niac-
| announcement
| xiphias2 wrote:
| Hard drives? :)
|
| Sounds like back to DVD Netflix days. What's cool is that
| Reed Hastings planned to use internet from the start, but
| also knew that the tech is not ready.
| nvahalik wrote:
| No. It's not a power or signal quality problem. It's a
| speed-of-radio waves problem.
|
| Mars is really far away. And unfortunately we don't have
| something like an Ansible to make communication instant.
| jvanderbot wrote:
| Latency and bitrate are both affected by distance.
| Bitrate scales down roughly by 1/d squared. Latency
| scales up by o(d) obviously. In theory, multiple small
| hops could keep power high over a long distance. On
| practice, the different sun-centered orbits the relays
| would operate on mean you'd have a _lot_ of them. That 's
| spendy.
|
| Also, there's a spectrum limit on Earth side or else we
| could blast signals back with very wide bandwidth
| spookthesunset wrote:
| Going real wideband would run into antenna efficiency
| issues. Designing an antenna that can handle a massively
| large bandwidth has a hell of a lot of engineering trade
| offs involved.
| maxov wrote:
| This is a really clean explanation, thank you! Is the
| O(1/d^2) decrease in bitrate due to the inverse square
| law for radiation intensity?
| maxov wrote:
| I think this situation is a good illustration of latency
| vs bandwidth. Latency is unavoidable due to the speed of
| light, but there's no physical barrier to bitrate aside
| from power consumption.
|
| Seems like the best bitrate we have from Mars is MRO at
| ~5 megabits/s which is enough for standard definition
| video. I'm certain we have the technology to push it
| higher, but it would be expensive and it seems it's not
| really needed for existing projects.
| dredmorbius wrote:
| Nit, though I'm going a bit (pun status unspecified)
| beyond my paygrade here: bandwidth is ultimately limited
| by the _frequency_ of the trandsmission channel, though
| multiple channels can be multiplexed. This is the heart
| of Claude Shannon 's work.
|
| For deep-space transmission, other factors apply, though
| if you're operating in the right frequencies, the
| background noise level is low (at least as compared to
| Earth where there are numerous competing signals of
| terrestrial origin). And whilst signal/noise ratio does
| impose limits, there's only so much that boosting volume
| dB will achieve before you hit the channel limits
| themselves.
|
| To increase bandwith beyond channel limits, you'd have to
| multiplex channels, which would involve different
| frequencies, different transmission routes (say, to
| widely-separated relay systems), or both. For physical
| media (e.g., fibre) this is relatively easy. For
| broadcast, given mass and energy budgets of spacecraft,
| probes, and rovers, the problems are harder.
|
| Encoding, redundancy, error-correction, and retransmit
| protocols can all increase the ultimate reliability of
| the signal, though these impose other costs, notably on
| bitrate or at least time until the transmission is
| _confirmed_.
| [deleted]
| extropy wrote:
| The time from mars to Earth is 3-20 minutes depending on
| orbit. Perseverance to MRO is 2 mbits/sec but only when
| it's overhead of the rover. MRO to Earth is 0.5 - 4 mbits
| per second.
|
| While it takes around 10 seconds to transmit an image at
| 2mbit/s, the whole system has several store and forward
| steps adding significantly more delay. And a bunch of
| starlink-like satellites in medium orbit would for sure
| help to bridge the gap.
| _joel wrote:
| It might help reduce the affect of attenuation at a cost
| of more latency in the processing chain. This could help,
| afaik it's only been tested to Mars and not in production
| https://en.wikipedia.org/wiki/Laser_communication_in_spac
| e
| [deleted]
| [deleted]
| maxov wrote:
| Interesting. I am not a rocket scientist, but I think
| there's a few fundamental problems with doing this:
|
| 1. You can't keep the satellites in a "line" between
| Earth and Mars, as objects in orbits of larger radii
| travel slower and so have longer orbital periods. This is
| the reason why for example geosynchronous orbits are only
| possible at a particular distance. They would only align
| with some frequency, which I'd guess would be closer to a
| geologic timescale than a human one. I think the fact
| that Mars and Earth's orbits are slightly eccentric only
| makes this harder.
|
| 2. A solution to the above could be launching way more.
| But launching so many satellites carrying enough fuel to
| escape Earth's gravity well would be prohibitively
| expensive compared to cost of LEO of existing Starlink
| satellites.
|
| 3. Starlink satellites are only designed to transmit
| maybe a few hundred km? In any case that's 5 orders of
| magnitude smaller than the distance between Mars and
| Earth. You'd need dramatically more power consumption to
| transmit effectively over those distances, which is why
| existing bitrates are so low.
|
| Anyway this is pretty cool, I found a NASA dashboard that
| also shows bitrates for current spacecraft:
| https://eyes.nasa.gov/dsn/dsn.html
| dredmorbius wrote:
| Those units, e.g., 24. 25. 26 for Goldstone, are
| _bitrates?_ Bits /second?
| maxov wrote:
| I think those are just identifiers for the telescopes. If
| you click on the telescope to expand you can see what
| it's communicating with and some info about the link, and
| the bitrates are closer to e.g. 20 Kbit/s - 1.0 Mbit/s.
| dredmorbius wrote:
| Thanks. The dataviz is unclear.
| ape4 wrote:
| I hope there is a movie eventually.
| _joel wrote:
| The direct earth to rover comms is slow but it's a lot
| quicker via MRO as it has a higher gain antenna.
|
| https://mars.nasa.gov/mars2020/spacecraft/rover/communicati
| o...
| dima55 wrote:
| They had a software glitch, and the flight was pushed back a
| few days while they investigate.
| samizdis wrote:
| According to NASA [1]: _Perseverance is expected to obtain
| imagery of the flight using its Navcam and Mastcam-Z imagers,
| with the pictures expected to come down that evening (early
| morning Monday, April 12, in Southern California). The
| helicopter will also document the flight from its perspective,
| with a color image and several lower-resolution black-and-white
| navigation pictures possibly being available by the next
| morning._
|
| [1] https://www.nasa.gov/press-release/nasa-s-mars-helicopter-
| to...
| d--b wrote:
| They're quite confident. 3m is pretty high. Is there a reason
| not to hover at 1m? Maybe the lower gravity makes it
| acceptable...
| birktj wrote:
| Ground effect? But I would assume with such low atmospheric
| density the effect is probably not so strong.
| JshWright wrote:
| What risks would be reduced by dropping the max altitude from
| 3m to 1m?
| d--b wrote:
| Obviously not an expert here. But here on Earth I would
| happily jump 1m but I'd probably break a leg from 3m.
|
| Somebody must have decided that a 3m test flight was the
| best option. Maybe it's because if something fails, at
| least they may collect 1 picture at 3m high, and that's
| better than 1 picture at 1m...
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