[HN Gopher] A bevy of rovers heading for the Moon
___________________________________________________________________
A bevy of rovers heading for the Moon
Author : tectonic
Score : 79 points
Date : 2022-02-16 16:18 UTC (6 hours ago)
(HTM) web link (blog.jatan.space)
(TXT) w3m dump (blog.jatan.space)
| echelon wrote:
| Google's $20 million Lunar XPRIZE [1, 2] ended a few years too
| early in 2018. Would have been exciting had they kept until 2023
| or 2025.
|
| > In the case of the Google Lunar XPRIZE, the audacious
| competition ended without a $20 million grand prize winner. [3]
|
| Seems like they got tired of waiting and redistributed the funds
| to other causes. They didn't realize how close we were.
|
| Sure would have been incredible publicity for Google had they not
| canned it. We'd be talking about the prize every year and with
| every launch, and we'd hold Google in esteem for being pioneers
| in science and space exploration.
|
| Pity.
|
| [1] https://www.xprize.org/prizes/google-lunar
|
| [2] https://en.wikipedia.org/wiki/Google_Lunar_X_Prize
|
| [3] https://www.xprize.org/prizes/google-lunar/articles/a-new-
| er...
| germinalphrase wrote:
| However, you must admit that canceling the program too soon is
| very on brand.
| chewbacha wrote:
| My first reaction to this wondering how long before the face of
| the moon is deformed to an extent visible from earth. Did anyone
| else feel that way too?
| polishdude20 wrote:
| Probably not for a long time. We can't even see human made
| structure on the earth from orbit let alone the moon. Except
| lights at night.
| fennecfoxen wrote:
| We totally can. But the moon is a lot further away.
| jessriedel wrote:
| What structures?
| rhn_mk1 wrote:
| You can't see single buildings from low Earth orbit with the
| naked eye, but human influence can cover huge areas. There
| are artficially constructed lakes. For example:
|
| > On completion, the reservoir flooded a total area of 632
| km2
|
| https://en.wikipedia.org/wiki/Three_Gorges_Dam#Floods,_agric.
| ..
| polishdude20 wrote:
| Oh yeah that's true. Probably hard to do that on the moon
| though :)
| JoeAltmaier wrote:
| Covered in The Tick
| pkaye wrote:
| Even with the largest optical telescope being planned, the man
| made object on the moon would have to be pretty big to see. It
| would probably have to be a few hundred feet in size.
| gataca wrote:
| Will this ever be safe enough to use as a hazardous waste
| disposal system? Can we just send the worst of the worst into the
| sun without too much risk of just spreading it out through the
| atmosphere in case of an explosion.
| Kye wrote:
| Waste is just a resource we don't know how to use yet. Someday
| we'd regret throwing all that fuel into the sun.
| BitwiseFool wrote:
| Fun counter-intuitive space fact, it actually takes much less
| energy to send a space probe out of the solar system than it
| does to send one into the Sun. To fling something into the Sun
| you basically have to get rid of all the kinetic energy that
| was given to us from the Earth's orbit.
|
| Even stranger still is the fact that you have more efficiency
| if you send the probe into the outer solar system first and
| then try to slow down. The Ulysses probe did this:
| https://en.wikipedia.org/wiki/Ulysses_(spacecraft)
|
| Edit:
|
| > _" To fall into the sun a spacecraft would first have to
| escape the earth's gravity, and then after that slow down
| almost completely from the earth's orbital speed of about 30
| km/s (~70,000 mph) around the sun. A four-stage, 3,000 ton
| rocket (about Saturn-V size) could only launch about 150 lbs
| into the sun on a direct trajectory, and it would probably cost
| a little more than $1 billion."_
|
| > _" To escape the solar system and fly off into interstellar
| space, a spacecraft only needs to speed up from earth's orbital
| velocity by about 40% (instead of reducing it by almost 100% to
| fall into the sun). The required delta-v would be about 17-18
| km/s."_
|
| From a simple HTML page with content written by a college
| professor, my favorite kind of webpage!
| https://van.physics.illinois.edu/qa/listing.php?id=43694&t=l...
| jermaustin1 wrote:
| Launching into the sun is a VERY difficult achievement. So far
| we've launched one solar probe, and dozens of other probes. It
| launched back in 2018, and still has 3.5 years before it will
| actually reach the sun.
|
| https://en.wikipedia.org/wiki/Parker_Solar_Probe
| shadowgovt wrote:
| It is, indeed, way cheaper to fling it into space beyond the
| solar system with the right planetary alignment.
| dr_orpheus wrote:
| Yes, for reference the capability of the Delta IV Heavy [0]
| (which launched the Parker Solar probe) is ~28,000 kg in to
| LEO. And the Parker solar probe [1] was only 685 kg. I don't
| know how close to the limit of the mass this is to get in to
| this orbit, but it still gives you an idea of the capability
| to get something to the Sun versus in to LEO.
|
| [0] https://en.wikipedia.org/wiki/Delta_IV_Heavy
|
| [1] https://en.wikipedia.org/wiki/Parker_Solar_Probe
| thfuran wrote:
| We don't actually much care about _when_ trash would hit the
| sun. But yes, it 's a huge delta v compared to just getting
| to orbit.
| skykooler wrote:
| Adding a long duration deep space maneuvering system to
| allow the trash to precisely navigate the necessary gravity
| assists would also be far from feasibly economical.
| freudian123 wrote:
| I did some back of the napkin math, USA generates about 2000
| tons of nuclear waste a year[1] and it costs DOE half a billion
| dollars to store it[2].
|
| Instead as you said we could yeet it all into space with like
| 20 starship launches, taking the $100/kg price tag it would
| cost us 2 million dollars to send it to space. Starship
| electronics should be radiation hardened so the unique payload
| shouldn't affect it much. The only risk is starship blowing up
| during launch. That would be a bummer.
|
| There's already a paper discussing this[3].
|
| I love the last line in the paper
|
| 'Both the technology and the need exist. What does not yet
| exist is the will and support of the engineering and political
| communities'
|
| Mind you this came out in 1992, we have far better technology
| now.
|
| [1]https://www.scientificamerican.com/article/nuclear-waste-
| let.... [2]https://earth.stanford.edu/news/steep-costs-nuclear-
| waste-us... [3]https://space.nss.org/wp-content/uploads/Space-
| Manufacturing...
| touisteur wrote:
| But once it's launched it's a lot of potential energy lost
| for ever, no?
|
| Isn't there part of this spent fuel that could be used as
| fuel again? I'm thinking MOX on steroids.
|
| Weren't surgenerators supposed to 'recycle' and reduce
| drastically the amount if 'final waste'? Weren't next-gen
| fission plants supposed to take in even higher rates of spent
| fuel?
| tacLog wrote:
| Your math seems off, 1 ton is 1000kg, but your point still
| stands at $200 million plus the overhead of containment and
| transport to starship. This is far more economical that I
| expected.
|
| But also this is the price to orbit. As the escape velocity
| is 1.5x higher we can probably assume the same or a greater
| increase in cost. Maybe you could just justify a really high
| orbit? It would take a long time for it to build up.
| iso1631 wrote:
| The main risk is taking off, you'd want something well
| protected and capable of surviving starship blowing up at
| any point during ascent, including returning safely to
| earth and impacting. You'd probably want to (unusually)
| launch over land - perhaps Alaska/Canada, to make retrieval
| easier should it fail before reaching orbit.
|
| Once it's in a low orbit, the extra shielding isn't needed
| as much as it's not going to fall back to earth quickly, so
| boosting from there to a high orbit would reduce the mass
| needed to be transported.
|
| In theory you could maybe do it for say $4b/yr all in.
|
| How many orbital solar collectors could you use to
| concentrate energy and beam the equivalent energy currently
| produced by nuclear plants to a desert based collector?
| tacLog wrote:
| Yeah, I didn't even consider this. But at what point does
| orbital solar energy start to make sense?
|
| I wonder what the $/kg before we can just send up solar
| panels that last 100+ years and provide continuous
| microwave beams of clean energy to ground stations.
| paxys wrote:
| I imagine the risk of the rocket blowing up right after
| launch and scattering radioactive waste all over Texas would
| make this a non-starter.
| acchow wrote:
| Could we not put it in a thick lead box which is designed
| to survive explosions?
| paxys wrote:
| Thicker box = more weight = $$$. Plus is _anything_
| really resistant to thousands of tons of rocket fuel?
| shakezula wrote:
| We already make containers that can tolerate being
| pummeled head on by freight trains without leaking, so I
| imagine that we could definitely engineer something
| similar for space travel.
| acchow wrote:
| Sure, more weight but at the bargain price of $100/kg
|
| Could it be resilient enough? I have no idea. I'm a
| programmer.
| jessriedel wrote:
| If Starship flies as much and is as safe as SpaceX
| predicts, they will have enough data to show _empirically_
| that Starships launches have an expected risk below 0.1%
| (i.e., it won 't rely on theoretical models). That 0.1%
| isn't nothing, but it could easily be acceptable if the
| nuclear waste disposal Starship flight is launched from a
| sea platform (which is currently a planned Starship
| capability) in the middle of the Pacific. For instance,
| it's already been well argued that dilution of radioactive
| waste in the oceans could also provide a good disposal
| option, leading to a worldwide increase in background
| radiation that is much smaller than the baseline levels.
|
| (There are a lot of important details here, including (1)
| the disputed argument that some isotopes might be
| preferentially concentrated by some organisms to high
| levels in any dilution scenario and (2) that an explosion
| of Starship in the Pacific would not dilute the radioactive
| waste as uniformly as a dedicated waste dilution program.
| My comment is just trying to point out that this could
| plausibly be acceptably safe and more careful analysis
| would be needed to check.)
| branko_d wrote:
| I know this is beside your point, but launching directly into
| the sun requires more energy than throwing outside our solar
| system altogether, as Scott Manley nicely explains here:
|
| https://youtu.be/i5XPFjqPLik
| dylan604 wrote:
| The launch of this material is probably safer than the
| transportation of that material to the loading/launch facility.
| vkou wrote:
| It's not, the probability of a SpaceX rocket spectacularly
| exploding is somewhere around ~1%. They'd need 860 more
| problem-free launches to hit ~0.1%.
|
| The probability of a truck spectacularly exploding on its way
| to the launch facility is way less than 0.1%. In fact, it's
| astronomically lower than 0.1%.
| jessriedel wrote:
| > They'd need 860 more problem-free launches to hit ~0.1%
|
| For what it's worth, SpaceX claims that they intend to
| reach this level of safety by literally performing
| thousands of launches. Time will tell if they can do that.
| inimino wrote:
| You can't calculate probabilites that way when the process
| itself is improving.
| bongoman37 wrote:
| tastyfreeze wrote:
| Throwing all our radioactive waste into space seems like a
| shortsighted waste of a non-renewable resource. Once humans
| pull it out of the ground there isn't a natural process on
| Earth to create more.
| jessriedel wrote:
| If it was put in a very high Earth orbit or solar orbit, it
| could be retrieved in the future, if desired.
| tacLog wrote:
| > Will this ever be safe enough to use as a hazardous waste
| disposal system? Can we just send the worst of the worst into
| the sun without too much risk of just spreading it out through
| the atmosphere in case of an explosion.
|
| I don't think it is impossible that launch capabilities become
| safe enough to lower the risk to something some people might
| consider acceptable. However the physics of it won't change. To
| even get into earths orbit we have to accelerate anything going
| up to an average of 7.8 Km/s, where to escape orbit to anywhere
| else it's 11.8 Km/s.
|
| I think the amount of energy to do that will always be the
| primary reason why this just isn't practical. Assuming you are
| advanced enough to be considering this, I would hope that your
| society is stable enough for long term containment and
| processing.
| iso1631 wrote:
| A space elevator could fling it out to escape velocity if you
| can build the containment vessel to survive a fall at
| terminal velocity (way lower than orbital velocity). Energy
| wouldn't be a problem for a civilization with the capability
| of building such an elevator, as there's plenty of solar, and
| raising 1 ton to GEO uses a trivial amount of energy.
| dr_orpheus wrote:
| Spacecraft that use RTGs have to do quite a bit to ensure that
| the risk of the radioactive contamination is low. It is pretty
| expensive both technologically and to go through all the
| regulatory hurdles. So I think getting to a place where this is
| feasible is still a very long way off.
|
| https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge...
| josefresco wrote:
| Love the Orbital Index. A weekly _Space_ treat in my email inbox
| for sure!
|
| Subscribe link: https://orbitalindex.com/subscribe/
| tectonic wrote:
| Thank you!
| tectonic wrote:
| For some reason, HN's link isn't going directly to the lunar
| rovers item, which is here:
| https://orbitalindex.com/archive/2022-02-16-Issue-156/#the-u...
|
| Thank you Jatan for his excellent contribution to today's issue
| of Orbital Index. Here's his longer form version as well:
| https://blog.jatan.space/p/lunar-rovers-launching-in-2020s
| dang wrote:
| That's because HN's software replaces URLs with canonical URLs
| when it finds one, and the submitted page includes
| https://orbitalindex.com/archive/2022-02-16-Issue-156/ as a
| canonical URL.
|
| In this case, though, the author's own source is more in
| keeping with the HN guidelines (" _Please submit the original
| source. If a post reports on something found on another site,
| submit the latter._ ") so I've replaced the URL above with that
| one. Thanks!
|
| https://news.ycombinator.com/newsguidelines.html
| squarefoot wrote:
| > a Starship launching three times per week could put as much
| mass into orbit as has been launched by the entire world to date
| (~15,500 tons).
|
| Finding a free spot to place all those objects without too much
| risk of collisions might become quite a challenge.
| http://www.stuffin.space/
| iso1631 wrote:
| It amazes me how empty space is. There's about a dozen objects
| on that map over California at the moment, at various heights.
|
| Now sure things are moving fast
| shadowgovt wrote:
| Very excited about this mission for several reasons.
|
| The variety of rovers (different companies, different processes,
| different energy and propulsion) are quite exciting. It'll be
| useful to compare their efficacy.
|
| But also significant is the overall mission design. A rover swarm
| where every individual member is expendable has been bandied
| about at NASA for at least 18 years. It lets the mission take
| more risks: if you see an interesting rock over rough terrain or
| a cave or outcropping that might harbor water ice, you're not
| going to risk a whole _Perseverance_ on checking it out. But it
| might be worth risking one Iris or a couple COLMENA.
| dylan604 wrote:
| "To illustrate this monumental change in capacity, Musk pointed
| out that in a single year, a Starship launching three times per
| week could put as much mass into orbit as has been launched by
| the entire world to date (~15,500 tons). "
|
| While that sounds impressive, the whole 3 starships per week for
| a year part just makes this seem ridiculous. Is Musk personally
| going to pay the <$10million per launch? <$10m x 3 x 52 =
| $1.56billion. That's just the launch. Never mind the expense of
| the payload being lofted into orbit. Nor the amount of time
| required to produce all of that payload. 3x per week is just an
| insane amount of launches.
| Fatnino wrote:
| So for ~ the cost of one SLS launch spacex could put more into
| space that all of history.
|
| At this price points this low for mass to orbit it starts being
| reasonable to forgo technologies like super light materials,
| and reclaiming every molecule of water you bring up. You can
| build payloads for super cheap in a conventional terrestrial
| fashion and ignore the weight.
| dylan604 wrote:
| This is similar to the coversation of only having 128k memory
| forcing extremely tight programming vs multiple GBs of memory
| where you can do whatever you want and put recommendations on
| your users to have a minimum amount of memory.
|
| Just because you can be lazy doesn't mean it's the best way.
| snek_case wrote:
| I don't think the software analogy works super well. In the
| case of software there's been a real performance loss over
| time as code became generally less optimized. In the case
| of space hardware or space stations, not having to use
| ultra-specialized materials means a potentially huge
| reduction in cost, which will enable plenty of new use
| cases. Space will become hugely more accessible as launch
| costs and space hardware costs both go down tremendously.
| Nobody is really losing here, except maybe the slow,
| bloated, old school space industry.
| bruce511 wrote:
| Depends on your definition of "best". Programming for 128K
| takes massive skill. Having multiple gigabytes allows more
| people to participate, and to prioritize other attributes
| than "low memory", typically faster and cheaper. So you get
| say a better UX, with better error handling, for less
| money.
|
| Which one is "best"? Well depends if you are skills & money
| rich, or skills and money poor. Clearly both are best,
| depending on what you are optimizing for.
|
| Up to now launches have been highly optimized for weight.
| Optimizing for other priorities (like cost) will change the
| rules of the game.
| FpUser wrote:
| ">Programming for 128K takes massive skill."
|
| It does not. What it does not tolerate is mediocre level
| which seems to be taking over the world lately.
| larkost wrote:
| To program simple things, maybe not. But if you are
| trying to do something complex then having a severe
| memory limit adds one more area of complexity to the
| process.
|
| If you can remove areas of complexity then you are doing
| three things: 1. allowing mediocre people to accomplish
| the same goals as used to take skilled programmers,
| largely by throwing hardware at the problem (this seems
| to be the source of your complaint) 2. letting skilled
| programmers accomplish the same task in less time (again
| by throwing hardware at the problem) 3. making even more
| complicated things possible for skilled programmers
|
| I certainly see the value in your complaint about things
| like the Slack app using Electron to make the UI easy to
| build (at the cost of my hardware performance), but that
| is a business optimizing for costs, rather than trying to
| optimize more for quality. Please assign the blame where
| it belongs.
| brimble wrote:
| Concur. I've done some programming for a platform that
| gave me way less than 128k to work with, and it's not
| rocket science. In some ways it's a hell of a lot
| _easier_ than, say, web development.
|
| It just forces you to be aware of certain things that are
| tremendously wasteful of memory and cycles, but which
| don't matter on "modern" hardware.
|
| And by "don't matter" I mean "do matter a whole bunch,
| but your _particular_ contribution to the problem is
| likely to be small enough that it won 't help much if you
| spend the time to do it right, so why bother"
| trasz wrote:
| Under that assumption, modern software would have a
| better UX and be more reliable than the software written
| "back then". And from my experience it's the exact
| opposite - modern software, like Slack, is not only
| slower and less functional than old counterparts, like
| IRC; it's also much less reliable.
| jlmorton wrote:
| > it's also much less reliable.
|
| The software, or the service? Because IRC is not
| typically associated with tremendous reliab...*
|
| * User has quit due to excess flood
| trasz wrote:
| Both. "User has quit" doesn't seem to happen in Slack,
| because Slack doesn't report stuff like that. But the
| problem goes deeper - Slack often fails at very basic
| functionality, like failing deliver messages until much
| later or duplicating them. It's helloworldware with a lot
| of marketing money to pretend to be a technically sound
| solution.
| acchow wrote:
| Why isn't IRC much more popular?
| shadowgovt wrote:
| Because it turns out to be a colossally chatty and
| stateful protocol in an era of stateless mobile devices.
| Plus it's not HTTP... the rule at the network layer these
| days is basically "80 and 443 are open; every other port
| is good-luck-to-you."
|
| OP's assertions it was more reliable are assuming a very
| static network. Modern protocols (Slack included) are
| far, far more reliable on a highly-unreliable transport
| layer.
| trasz wrote:
| Not true. Or rather: in theory what you are saying would
| be true, however in case of Slack it simply doesn't work:
| Slack handles unreliable transport worse than IRC - IRC
| never dropped or duplicated messages; you could reconnect
| to IRC client under a tmux session from anywhere and it
| would just work.
| trasz wrote:
| No business model, I think - and thus no money for
| infrastructure, further r&d, and marketing.
| gameswithgo wrote:
| For sure, but the best way to program say, a game, now
| definitely is not to go to the same lengths as people went
| to on the original Nintendo.
|
| There is a happy medium between using Unity and hand tuning
| every line of assembly.
| throwaway0a5e wrote:
| The lazy way broadened society's access to computing which
| has had all sorts of positive knock on effects.
| beamatronic wrote:
| You could use waste water as propellant
| dividedbyzero wrote:
| > So for ~ the cost of one SLS launch spacex could put more
| into space that all of history.
|
| Could they? I think they still have to prove they are able to
| deliver that kind of cadence at that price point. They aim to
| get there and I hope they do, but spaceflight being as
| fiendishly hard as it is, I wouldn't take their marketing
| claims as fact just yet.
| hungryforcodes wrote:
| Wow! Cheap! Each Space Shuttle launch was at least $500mm. And
| we still don't have anything that can go to orbit with the same
| versatility -- without the Space Shuttle Hubble would have been
| disabled ages ago. So much for the rocket people...
| s5300 wrote:
| Well, if price of BTC 2x's he can pay that tab pretty easily.
| No reason for him not to.
|
| And that much starship launch volume is invaluably more than
| the rovers or whatever they'd be bringing up. Quick & dirty
| reliability test for the world to see, launch turnover times,
| etc
| ttul wrote:
| With launch costs 100x lower than historical norms, there is
| plenty of space cargo that becomes economically viable. I don't
| think SpaceX will have any trouble filling those launches. I am
| surprised there isn't already a venture fund dedicated to
| funding space startups so that they can exploit Starship
| economics.
| beambot wrote:
| While I don't know of any dedicated space funds off-hand,
| there are _hundreds_ of venture funds that dabble in space
| endeavors: https://signal.nfx.com/
| ttul wrote:
| SpaceX ought to start their own venture fund to fill their
| vehicles with things.
| jsnodlin wrote:
| dylan604 wrote:
| How much of that space cargo is payload ready for a vehicle
| that hasn't been finalized in design yet? How long does it
| take to fit that cargo into that ship once it is finalized?
| Able to meet the 3x/week launch schedule?
|
| It's obviously just a stat to make it sound impressive, but
| it is just totally impractical. I could easily say that with
| a launch every day, that capacity could be met in just 6
| months! Fuck, with a measly 2 launches a day, we could do it
| this quarter!! Stats are sometimes meaningless, and when they
| are coming from this particular individual, they have to be
| taken with rather large grains of salt.
| themgt wrote:
| They're averaging 1x a week with Falcon 9 which requires
| throwing away an upper stage and Merlin engine each time.
| So yeah you "could easily say" whatever you want, but this
| hot take that SpaceX is just talking bullshit like any
| rando internet commentator is getting a bit old.
| dylan604 wrote:
| Averaging 1x a week is not the same thing as 1 a week.
|
| The bullshit quotes coming from Musk are what's getting
| old. People calling him out on that bullshit is not the
| stale part. His rhetoric is getting quite boring.
| samstave wrote:
| SpaceX will certainly have a ship called the ESS Jimmy Carter
| --> Which, just like the submarine, will have the ability to
| capture a satellite pull it into bay and fiddle with it...)
|
| But it will be launched as a service to "recover space garbage"
| but really it will be a satellite capture program..
| colechristensen wrote:
| I mean, he made $120 billion in 2021, so sure why not.
| naskwo wrote:
| How much CO2 does each launch emit into the atmosphere?
| shadowgovt wrote:
| A lot, but it doesn't come near a primary pollution source
| (and would have to get far past Musk's wildest dreams for
| frequency before it got near becoming one).
| wongarsu wrote:
| Elon is banking on low launch costs creating lots of demand.
| Whether that pays off has to be seen: for conventional
| satellites the launch cost hasn't been the biggest factor by
| far, but we are now seeing more satellites that profit from low
| launch costs (mainly earth observation and internet services),
| and there are at least some projects in the pipeline for things
| that make sense to manufacture in space (like optical fiber).
| But demand takes time to materialize, and SpaceX has to somehow
| stay solvent until then.
| Ancapistani wrote:
| I don't think it's unreasonable to assume that the demand
| will be there.
|
| At $2,800/kg, I'm curious enough to start looking at options
| for a _personal_ satellite. It's unlikely that would be
| viable, because the cost of the communications and
| stationkeeping hardware would be prohibitive. I'd be
| interested in sharing space on a "F/OSS" orbiter of some
| type, but I've not seen any projects that would make such an
| idea viable.
|
| At $100/kg... I'd figure it out, if only to say that I'd done
| so. At that price I'd be trying to figure out a way to stream
| video from a microsatellite of orbit, de-orbit, and re-entry
| just to show the couple of "flat earthers" I know what's
| obvious to the rest of us. Let them pick the camera and lens
| so they can't fall back to "It's a fisheye lens!".
|
| In all seriousness, though - at $100/kg, you'll see all kinds
| of entities trying things that have never been practical
| before just to see if they'd work.
| dylan604 wrote:
| NASA used a commodity CPU for their Martian drone, so just
| start there. See what an RPi4 or something could do. If it
| works for any amount of time at all, then it's a success.
| If it lasts the entire duration before re-entry, then it's
| a resounding success.
|
| If launches are that cheap, just keep throwing junk up
| until you find out where the line for good enough is.
| hedgehog wrote:
| The guy has hundreds of billions of dollars in assets so he
| could pay the bill himself. There are some easy things to fill
| launch capacity at that scale: fuel (especially methane),
| water, scaffolding, and inflatable modules for pressurized work
| (habitat, service, storage, hangars, etc). The play is to be
| the biggest landlord in space.
| jsnodlin wrote:
| That's like saying having hundreds of airplanes in the sky at
| all times is an an insane amount in 1930.
| escapecharacter wrote:
| Isn't the Earth going to run out of mass and shrink away to
| nothing at this rate?
| tacLog wrote:
| I can't tell if this is sacarstic or not but I decided to do
| the math.
|
| Mass of earth: 5.972 x 10^24 kg
|
| Launch capacity per year: 15,500 tons
|
| Years to get rid of earth: 385,290,322,580,645,161 years.
|
| I think if we every have to worry about this it becomes more
| a question of where are we going? And do we have enough
| carbon to cycle for fuel to do this.
| jlmorton wrote:
| Also worth noting that the Earth receives about 43 tons of
| new mass every day, mostly from meteorites. Coincidentally,
| this works out to 15,695 tons of new mass every year.
| Arcuru wrote:
| You might be interested in https://what-if.xkcd.com/7/
|
| > Is there enough energy to move the entire current human
| population off-planet?
| tacLog wrote:
| I didn't account for the decreased gravity over time as you
| chip away at the planet. Woops!
| tastyfreeze wrote:
| Over that time span you should probably account for the
| 48.5 tons of material that falls to Earth annually as
| well.
| acchow wrote:
| Are we going to run out of some chemical elements?
| iso1631 wrote:
| Gravitational binding energy of Earth is about 10^32
| joules, so you'd need to pump that much in to dismantle
| Earth. The entire solar output reaching Earth is about
| 10^17 Watts, so it would take 10^8 years to dismantle Earth
| without leaving it if you could capture every Joules as it
| entered the atmosphere
|
| On the other hand if you could capture the Sun's entire
| output - not just that arriving at Earth - you'd have
| enough energy to do it in a week or two.
| Ancapistani wrote:
| Wouldn't the reduced mass of the Earth's sphere of
| influence be reduced over time, thereby reducing the
| energy required to launch subsequent payloads?
| iso1631 wrote:
| Yes, there's all sorts of odd things that would happen
| with rotational energy too, hence you don't need as much
| as if you calculated it based on lifting 1kg at a time
| from the earth's surface. You'd need about 10^32 joules.
| If you didn't account for that you'd need about twice as
| much energy, which is about 10^32 joules.
|
| In theory you could simply vaporize the earth with
| antimatter, converting it to energy, rather than trying
| to disasemble it. That would produce far more energy than
| the gravitational binding energy, so unless you happen to
| have a planet sized lump of antimatter around you'd have
| to generate it with more than 10^32 joules.
| acchow wrote:
| Yes
| msadowski wrote:
| One more to the list: GITAI is hoping to send a centaur-like
| rover with a robot torso in mid-2020[0]. Given that the current
| version is using some off the shelf sensor I have no idea how
| realistic is this timeline though.
|
| [0] https://gitai.tech/en/2022/02/10/gitai-develops-lunar-
| roboti...
___________________________________________________________________
(page generated 2022-02-16 23:01 UTC)