Clunking to Mars - Are the needed parts already up there?

C M Edwards · 2002-05-21 14:22:14

Hello All.

Like the old Mir space station, the international space station Alpha has a limited planned operating lifetime, possibly followed by some unspecified mission extensions. After that, it?s expected to be de-orbited and splashed into the ocean ? destroyed.

Instead of discarding it, what would be required to retrofit it, convert it to function as an Aldrin-style Space Bus, and launch it on a cycling trajectory between Mars and Earth?

A lot, no doubt. NASA probably won?t put it up for grabs, even internally within the agency, until they?ve gotten all they can out of it. The limits of its operating lifetime are partly determined by degrading materials, all of which would have to be replaced for safe use far from Earth. Then there would be fuel, supplies, engines, etc. Still, it could be done. It would be a better fate than ending up as space junk, IMHO, and cost less than building a cycler from scratch.

Speaking of space junk, it stands to reason that there is a lot of useful salvage out there in orbit. For example, I hear there are two or three Russian-built nuclear reactors flying on satellites. If it?s so politically impractical to launch new ones, could these existing reactors in space be salvaged for a trip to Mars? Is their fuel expended, or were they shut down for other reasons? These alone could be worthwhile for a salvage mission.

Expended boosters are likely no longer usable as such, but may contain useful parts. And there?s all sorts of other equipment flying around up there that can no longer fulfill its primary mission but still retains some function.

Then there are fully functioning satellites. A working communications satellite could be purchased from its owners, recovered by a separate (much smaller) vehicle and launched to Mars without costly return to Earth. Certain designs should be sufficient for Mars-Earth relay as is. Other satellite designs, such as weather satellites, could also find favorable employ.

Perhaps a large part of the infrastructure we need to get to Mars is already up there, waiting for us to come back to it.

CME

PS: I don't know what would happen if Russia or the ESA wanted to sell its ISS components and NASA didn't, but I would not be adverse to finding out.

Mark S · 2002-05-21 15:18:07

I really like your thinking regarding the ISS, and I'm trying to think of what modifications would be needed (aside from engines used for earth escape.) The life support loop would need to be closed, so the ISS wouldn't need to rely on Progress resupply ships. And any modules that are not necessary for cycler duties should be discarded. Because the solar panels would be less effective as the station got closer to Mars, they would have to be augmented, possibly with a nuclear reactor.

It is not currently possible to retrieve the Russian reactors that currently orbit the earth. These satellites have been placed in "doomsday orbits" that are quite high above the earth and will not decay for thousands of years.

C M Edwards · 2002-05-21 16:44:58

It is not currently possible to retrieve the Russian reactors that currently orbit the earth. These satellites have been placed in "doomsday orbits" that are quite high above the earth and will not decay for thousands of years.

Hmm... I wonder what the prospects are for an unmanned vehicle to rondezvous with and recover a satellite in high orbit? That is, after all, what we would be talking about in order to reclaim an already launched communications satellite.

Aren't the Progress modules used for the ISS capable of automated rondevous?

CME

Phobos · 2002-05-21 18:28:28

Whether this space junk can be salvaged or not, we might have to capture a lot of this orbital debris anyway just so we can keep going into space with reasonable safety, especially if space elevators become a reality. God forbid if your slowly ascending into the heavens on a space elevator when some dismembered solar panel of Vostok 4000 slams into the cable
at 18000mph and sends you on a joyride back into the Atlantic somewhere. Oh well, I'll try staying on topic next time.

C M Edwards · 2002-05-22 11:54:08

Interested in reactors in space? Check this out! It's a rough analysis of the amount and location of radioactive material in orbit.

http://www.globenet.free-online.co.uk/ianus/npsm1.htm

Surprise! Almost nothing is in an unreachable "doomsday orbit". These devices can be recovered, some (in principle) by Soyuz or Shuttle missions. Some of the material is not worth the price of recovery (such as the RTG's launched to the Moon with Apollo), and other satellites are too risky to capture (such as the unshielded, obviously leaking/disintegrating RORSAT's). However, I believe a recovery mission could be viable.

Multiple reactors are up there for the taking.

CME

Canth · 2002-05-22 14:03:50

The amount of stuff that you need to send up to completely remake an object in space is enormus. Think of all the equipment you'd need to send up, along with replacement parts etc. You would also cut down on the reliability of your craft by using pre damaged used parts. The amount of extra labor you would need to install new communications equipment, shielding, life support systems, storage areas, initial propulsion systems, and so on is astronomical. Using 15 year old car parts (or a 15 year old car) to build a boat or plane just isn't economically competitive, and that is pretty much what you are doing. Untill there is more useful junk up there and a cheaper way of getting to it it is not worth sending the salvage equipment and construction crews necissary to utilize it for other vehicles. Right now and in the near term future it is safer and cheaper to just send up new stuff. You wouldn't wanted to have turned old breaking down
Mir into a cycler, would you? When the ISS is done with it will likely be in similar shape.

C M Edwards · 2002-05-23 07:23:54

Hello Canth.

Think of all the equipment you'd need to send up, along with replacement parts etc. You would also cut down on the reliability of your craft by using pre damaged used parts. The amount of extra labor you would need to install new communications equipment, shielding, life support systems, storage areas, initial propulsion systems, and so on is astronomical.

Sounds like my old car.

Actually, as someone who's used to travelling around in ratted-out vehicles, I can safely say that the cost of trying to upgrade an existing vehicle that has reached the end of its usefulness typically costs more than it's worth. "The end of its usefulness" is usually a euphemism for "broken down".

However, I take issue with your statement that it's always better to send up new ones than to use what's there, because it implies that: a) the only satellites that anybody will sell, rent or abandon are already broken; and b) there are no broken satellites worth recovering.

I submit that needed materials that it is not within our present capacity to lift would be economically viable to salvage and recover. For example, much is made of RLV's, but a lot of the convincing designs I've seen have payload capacities far less than the size of some space station modules. If you're a private company that suddenly has cheap access to space but lack the ability to put up heavy modules, you might look seriously at buying used instead.

I suspect that nuclear reactor fuel will also become a viable prospect for salvage. Many of those reactors in space have orbits expected to decay in the next few centuries. It's possible that it may become economically viable to go get them even if they're never used, just to keep them out of the atmosphere.

Hmm...

CME

Canth · 2002-05-24 14:15:16

I think there may well be a market in getting rid off space debris which is dangerous to spacecraft and a somewhat seprate buisness of getting rid of things we don't want burned up in the atmosphere. These businesses could allow a company to get together enough money for space salvage. There is a small suply of space salvage and a nonexistent demand for it. I think that it might be more cost effective to reproses space junk it into low tech parts like debris and radiation shields and simple reflectors for intensifying sunlight on solar panels. These could reduce the cost of launching many kinds of missions while requiring a smaller but still significant one time launch. I still doubt their economic feasibility however many of the same technologies could be used in mining in space. A space debris reprossesing mission could possibly be a useful proving flight for some, although not most, asteroid mining techniques. This would increase the return from such a mission as it would help with futre missions.

quasar777 · 2002-06-02 10:46:28

This is why we need a manned geostationary orbital space station. as far as used parts being maybe defective, "we" may eventually build an orbital & or lunar smelter, among other things. any defective materials could be melted down. this is the argument i use often for moon returns. folks seem to think we need a "museum" on the moon,that`s a fine sentiment, but there is defective equipment there not suitable for a museum. if as almost everyone nowadays wants mars & completely bypass the moon, moon junk should belong to the first salvage consortium to get at it. i noticed zubrin uses the selfsame notion w/ mars equipment. "we" need to catalogue all usable spacejunk if possible. we may be surprised as to how much readily usable/smeltable equipment /materials are available beyond the "well". i`m glad to see someone finally adressing this issue. nowadays many seem to be wanting to leapfrog in space, not realizing there are issues & projects closer to "home". time & again i`ve heard the argument against moon returns (we can`t build a marscraft from moon materials) this doesn`t take into account moonjunk. after all, many speak of moonmining. there are other scenarios besides marsdirect, just think of how much less deltav would be needed from lunorbit,lunarface, Lpoint, GEO, nearth bodies, etc.. besides deltav, badradtime also is less on such missions.

C M Edwards · 2002-06-03 11:21:59

It might be a good idea for items launched to Mars, the Moon, or into space in general, to be recyclable.

Hmm...

CME

Tom Jolly · 2002-06-03 19:59:58

Hi, CM. Brilliant idea, using space junk to fab a new vehicle, especially for the nukes. I happen to know for a fact that there are complete satellites in orbit, unused, fuel and all, that are "pet rocks" due to launch screw-ups. If someone could salvage those, it'd be a boon for everyone concerned. Some of them can't communicate with the ground at all; the main power buses never even turned on.

Of course, delta-V from satellite to satellite might kill you. A 60 degree change of inclination is paramount to a full 7.5kps delta-V change, might as well launch from Earth. Best to find an orbit with as many salvagable satellites in or near it to as possible so no inclination changes are required.

On the other hand, if you're going from an equitorial orbit to a North/South inclination, you can use charged tethers to electrically change your orbital inclination, which would mean reducing your refueling requirements. And, you can use the equitorial bulge to drift your orbit to get the ascending nodes aligned, so that's a freebie. I don't know if the charged tether technique is one-way or not; does anyone know if it can bring you back to equatorial?

Canth, you bring up a valid point; I once heard that it would cost less to outfit and send up an expended shuttle booster tank than it would cost to clean and outfit one that was up there for "free". That, of course, is due in part to the mass of the components that go inside, and the cost of EVA's, so the point is arguable. Still, the nice thing about salvaging nukes is that you don't have to okay their launch with the environmentalists. And, the MAIN reason it would cost so much to salvage anything is that we don't already have a presence up there doing it. I think you could make money just by deorbiting stuff for others.

I just about died when they deorbited the Mir. No matter how much it sucked, the solar panels were still putting out lots of juice; and, of course, every pound of mass up there cost $10K to get there. What a waste to bring ANY of it back down.

TJ

Dayton3 · 2002-06-04 19:43:43

There is an issue. While some artifacts in orbit might be usefull, rounding them up, from various orbits and such would burn a tremendous amount of fuel.

Probably more trouble than launching new equipment in the first place.

Dayton3 · 2002-06-04 19:45:17

There is an issue. While some artifacts in orbit might be usefull, rounding them up, from various orbits and such would burn a tremendous amount of fuel.

Probably more trouble than launching new equipment in the first place.

Mark S · 2002-06-05 09:55:28

Space salvage will become useful and economical once we have unmanned, ion-powered space tugs to round it up. The high efficiency of the ion engines will reduce fuel costs and make space salvage, even the disposal of space junk, an economic boon.

Josh Cryer · 2002-06-05 10:15:54

Ion power space tugs? Would that even be feasible? Isn't the whole point of ion propulsion to move small mases over long distances over a period of time? I think an ion drive only pushes at like one newton. Not sure, though. I just know it's small.

Garbage in orbit is extremely hard to find, not to mention catch. I'm not sure we'd be garbage colleting any time soon. Most satellites that break are purposely thrown into the ocean. So what bits are actually garbage?

Since we're relatively new to space exploration, I'd say that space is much like a pristine forest, in that respect.

Josh Cryer · 2002-06-05 10:16:40

Oops! Sorry. Double post.

quasar777 · 2002-06-05 15:03:37

i understand geojunk is slower & hopefully easier to find than leojunk.

Josh Cryer · 2002-06-05 16:02:11

GEO = slow orbit, lots of space.

LEO = fast orbit, less space.

I would say finding garbage that isn't on record (like not on the NORAD database or something) would be extremely difficult, if impossible. Space is utterly huge. Especially at GEO. So if you lose track of a satellite, consider it gone. It wouldn't surprise me if satellites we've been tracking for so long aren't actually where they are supposed to be.

Catching them would be easy, just match their orbit. But you have to ask yourself if it's really worth it...

quasar777 · 2002-06-05 18:38:30

in order for us to really develop space, we should concentrate on building another station. we will need fueling depots, etc.. preferably have one in geo & an Lpoint. that way missions could go to either moon or mars. in the meantime radiation experiments could be conducted more efficiently out there.

Josh Cryer · 2002-06-05 19:12:31

LEO or GEO fueling stations aren't really necessary. The best intersteller spaceship design would be one which requires little or no fuel. I mean, it's obvious, really. Use the sun to power you. So solar panels (no fuel), or dusty plasma sails (very small ammounts of fuel) are the way to go; if the latter is feasible, it would be the most efficient ship possible.

Shaun Barrett · 2002-06-05 19:15:04

I think Mark S is right with his robotic ion powered tugs. All this stuff we're talking about is in orbit so the really hard work is already done.
If you attach a low thrust engine to an old satellite and just keep pushing in the right direction for long enough, you should be able to put that satellite almost anywhere you want to. I think the essence of Mark's argument is that time doesn't matter for robots and ion engines ... if it takes your automated tug 3 months to boost something from LEO to geosynchronous orbit, who cares?! It's a case of 'slow and steady wins the race'.
The more I think about it, the more I like it! Nice one, Mark!

Tom Jolly · 2002-06-06 08:13:28

Salvage in GEO, hadn't thought of that. That would be gravy; everything in the same orbit, almost nothing for delta-V to go from satellite to satellite. An ion thruster would work great in such a setting, assuming you weren't in a hurry.

I think it would be amusing for someone to go up with the pretense of satellite repair and deorbit, then start "salvaging" active satellites for a Mars mission. Space pirates! And just try shooting him down...

Mark S · 2002-06-06 08:28:33

Shaun, that was my point exactly. I can just imagine a 21st century "Sanford and Son," salvaging old satellites and selling them from their orbiting junkyard.

Returning the satellites to earth will be a bigger problem, as none of them have thermal protection systems. On-orbit repair might be a better solution. It might also be possible to build an unmanned shuttle that could deploy a solar-electric engine after it reached orbit. It would collect satellites for a year or so and then deorbit and land on a runway.

quasar777 · 2002-06-06 10:05:46

they may seem unnecessary, but if there are folks wanting to got the moon they would be a jumping off point, as some believe lunar trips require more deltav. & besides we need a base for spacejunk research & radiation experiments which can`t be done in leo bcuz it`s below the van allen belt. it`s trying to kill 2 birds w/ 1 stone.

quasar777 · 2004-04-12 17:52:36

i had to bump this thread. we should have another look @ salvaging materials in space &/or planetary surfaces.

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Re: Clunking to Mars - Are the needed parts already up there?

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