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Space Sails Could Bring Used Rockets Back To Earth

Soulskill posted more than 5 years ago | from the how-about-a-space-hoover dept.

Space 76

GordonCopestake writes "An article from New Scientist proposes that all new spacecraft have sails attached to bring them back to earth — a measure that would reduce the amount of garbage in space. From the article: 'The risk to spacecraft from a collision with space debris could be reduced by equipping launchers with a gossamer-thin "sail." The idea is to deploy the sail after the rocket has released its payload to amplify the drag of the last vestiges of the atmosphere, and so force the rocket out of orbit.'" Wired has a related story about the risks faced by the space shuttles as they share orbits with tons of drifting space debris. "... in the 54 missions from STS-50 through STS-114, space junk and meteoroids hit shuttle windows 1,634 times necessitating 92 window replacements. In addition, the shuttle's radiator was hit 317 times, actually causing holes in the radiator's facesheet 53 times."

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Choke (1, Funny)

Anonymous Coward | more than 5 years ago | (#27623587)

We should not stop producing CO2. We are gonna need the heat when all the space junk blocks the sun. Why do humans have a need to choke on their own waste? Are we really a bacteria or something?

Re:Choke (0)

Anonymous Coward | more than 5 years ago | (#27623793)

This has got to be the most retarded thing I've ever heard on Slashdot. Please, go back to YouTube. Your peers there are missing you.

Re:Choke (3, Funny)

julesh (229690) | more than 5 years ago | (#27624649)

Please, go back to YouTube. Your peers there are missing you.

I pray he never learns the word 'sheeple'.

And the old junk? (4, Interesting)

JorDan Clock (664877) | more than 5 years ago | (#27623597)

This might be helpful for rockets launched in 4 or 5 years (Which I think is a very generous estimate on how long something like this would take to be adopted even close to universally.) it doesn't address the issue of all the stuff already up there. How long will the majority of the debris in orbit remain? How effective are these sails when they themselves are punctured by debris? It's a great plan for keeping things from getting worse, but as I understand, a lot of things up there that are in danger of causing damage will be up for quite some time.

Actually, it might, for the larger stuff (3, Interesting)

WindBourne (631190) | more than 5 years ago | (#27623631)

this might be where Private Enterprise wants to step forward and work on getting a space ship to approach a used up sat, and attack a sail to it to force it down the gravity well. With small control units on the sail, this could be really useful. That same tech would be needed for remote servicing of sats anyway, if private enterprise wants to take that on. As to who would pay, well, I would guess that whoever owns the sat would find it cheaper to pay 5-10 million to de-orbit a sat than deal with lawsuits. For the small to medium size, well that will require a totally different approach.

Re:And the old junk? (5, Informative)

Profane MuthaFucka (574406) | more than 5 years ago | (#27623655)

The debris in low orbits where the Shuttle operates will return within just a few years. Higher than that means it stays up longer.

If an object is orbiting twice as high as the shuttle, about 500 miles, it'll stay up roughly a couple centuries. Just a bit higher than that and you're measuring orbital lifetimes in millennia.

Re:And the old junk? (2, Informative)

bit01 (644603) | more than 5 years ago | (#27623907)

The debris in low orbits where the Shuttle operates will return within just a few years. Higher than that means it stays up longer.

Do you know how much of a difference the size of the debris makes? The wikipedia orbital debris entry [wikipedia.org] doesn't say.

---

Don't be a programmer-bureaucrat; someone who substitutes marketing buzzwords and software bloat for verifiable improvements.

Re:And the old junk? (4, Informative)

rcw-home (122017) | more than 5 years ago | (#27624069)

Do you know how much of a difference the size of the debris makes?

Densities of materials vary widely, but as a rule of thumb, mass increases with the cube of an object's size, but drag only increases with the square.

Re:And the old junk? (0)

Anonymous Coward | more than 5 years ago | (#27624087)

A few extra meters outweighs extra kilograms like nothing.. wikipedia entry on Newtonian Gravity [wikipedia.org] says.

Re:And the old junk? (2, Interesting)

Hurricane78 (562437) | more than 5 years ago | (#27624697)

I found the notion pretty impressive, that a piece of shrapnel, only 1 g in weight, is like a 600 kg (~1323 pounds) bike, crashing at them with 600 km/h (~373 mph). Imagine that, with the size of a pencil tip, hitting a window. Now imagine a piece of half a ton doing the same...

Re:And the old junk? (2, Informative)

Antique Geekmeister (740220) | more than 5 years ago | (#27625519)

It depends tremendously on the orbit and the object. Some 'objects', like dumped urine or water, submlimate. They're still deadly if they hit you from even a slightly different orbit, since we're talking about base speeds of roughly 18,000 mph in low earth orbit: it's the difference between the orbits that determines their relative velocity, and that's easily as much as 10%. (Head-on collisions are basically unheard of: one object would have to be orbiting the other way entirely, and no one does that due to the launch costs of orbiting against the Earth's spin.)

Small objects in low orbits are also subject to normal orbital decay, from the extremely thin atmosphere and very slight gaseous content of ordinary space, which is very thin but very real. Even solar wind can help decay orbits, by providing a consistent though slight thrust in a direction at an angle to that orbit, and depleting the orbit of its angular components. (Tidal effects are not noticeable factors on an object _that_ small.)

Geosynchronous orbits are a whole separate problem: they last much, much, much longer, and that orbital space is getting crowded by junk.

Re:And the old junk? (1)

CrimsonAvenger (580665) | more than 5 years ago | (#27627895)

(Head-on collisions are basically unheard of: one object would have to be orbiting the other way entirely, and no one does that due to the launch costs of orbiting against the Earth's spin.)

Qualifier: polar orbits allow this geometry of impact.

Re:And the old junk? (1)

Antique Geekmeister (740220) | more than 5 years ago | (#27628561)

You're quite correct: I neglected that polar orbits, if launchers don't pay a bit of attention to existing orbits, could easily create such cases.

Mass Catcher (2, Insightful)

StCredZero (169093) | more than 5 years ago | (#27623721)

I wonder if we could operate a remote-controlled Mass Catcher [nasa.gov] ? The one designed for the 1975 Stanford Summer Study would do if you left off the intake grid of cables. It would be a rotating Kevlar cone. Centrifugal force would hold loose regolith in place, which would act to absorb the impact of the intercepted debris. The same rotation would also act as artificial gravity to prevent the escape of secondary splash debris. Using a pellet launcher as a thruster would be safe, since the pellets would be traveling at far above Earth escape velocity.

Re:And the old junk? (2, Interesting)

roystgnr (4015) | more than 5 years ago | (#27627023)

How effective are these sails when they themselves are punctured by debris?

99.999% as effective. At orbital altitudes air doesn't behave like a continuum, just like independent molecules bouncing around. This is bad if you're trying to design a wing (pressure doesn't affect flow in the same way and your lift to drag ratios suck) but great if you're designing a parachute (a small hole will let molecules through at the site of the hole, but won't affect their absorption/reemission or their reflection elsewhere on the parachute). So you shouldn't have to worry about whether the sail is airtight or leaking. If a meteorite punctures a 1mm^2 hole in a 1m^2 sail, that sail will just intercept 0.0001% fewer molecules and generate 0.0001% less drag.

On the other hand, this means you might need more than a 1m^2 sail to begin with - anything that's in the wake of the satellite itself is partly redundant.

Ban space weapons as well (2, Insightful)

GodfatherofSoul (174979) | more than 5 years ago | (#27623601)

When we've got countries blowing up satellites in orbit, that's far worse than a big booster plodding along in a decaying orbit.

Such ban is worthless in so many ways (2, Interesting)

WindBourne (631190) | more than 5 years ago | (#27624763)

Any ban that is worth their salts would have a description wanted, a means to verify, and a means to punish those that break that. BUT, that is impossible to do. Take the case of North Korea. Clinton got NK to agree to not do Nukes. It was absolutely prohibited from doing so. Ok. BUT W came into office and started calling NK names. Instantly, it is found that NK has been doing all the steps that are useful for civilian as well as military while pure civilian steps are missing. IOW, they met the letter of the law, and then looked for an out. W then got an agreement out of NK to shutdown their reactor and give up their pursuit of bombs. Ok, no problem other than the fact that NK has prevented inspectors to go where we KNOW that military work WAS going on. AND again NK pursues OTHER banned pursuits, namely a delivery system. Suddenly, NK is announcing that they will re-pursue the bomb since we want to inspect an obvious missile system.

Now, how does this relate to China? Well, Clinton gave MFN to China back in mid 90's. In return, China was to free their money against the dollar as well as drop their trade barriers in early 2002. Did they? Nope. W did nothing to push, while China racked up monster theft of businesses. Now, we are extremely weak. China refuses to do these things even though EU is now insisting on it. Remains to be seen what will happen there.

How does that relate to China's military pursuit? China pushed this banned and trying to get America as well as NATO to lower our military, all the while spying on production of weapons. They are building up 2-4 new nuclear subs a year (1-2 boomers and 1-2 attacks). Of course, they just moved that production into a "hidden underground base" and are trying to prevent the west from seeing the subs from leaving. That was the recent harassment against a US intel ship that was JUST beyond the 200 mile marker. They have been quietly pursuing a quasi-civilian space agency that is ran by the military. No problem, though it is not that open. They have on the board a space station that will be similar to ISS. BUT recently they announced a NEW space station(s) that will be pure military ran. No advantage to it for monitering. None what so ever. The reason is that recon Sats will do a much better job since they can be moved rather quickly compared to manned space station. So what purpose could it have? Ease of adding space weapons.

Space ban is worthless because the one that pushes it has no intention to doing it. And we have no easy way to verify it. More so when said country is still in obvious military cold war.

Re:Such ban is worthless in so many ways (0, Flamebait)

Gothmolly (148874) | more than 5 years ago | (#27626807)

The solution is obvious - nuke the Chinks.

Re:Such ban is worthless in so many ways (1)

GodfatherofSoul (174979) | more than 5 years ago | (#27629203)

You make the assumption that North Korea started mixing household chemicals in their backyard and instantly created their nukes. They had LOTS of help from other countries. The point of a world-wide ban is that you shut down these kinds of conduits. How do you know that China is secretly building nuclear subs BTW? Countries have ways of verifying through espionage.

If there's a space weapons ban, there's practically no way to test without the whole world coming down on you. Your analogies aren't the same as there aren't similar bans in place on nuclear power or nuclear subs.

Re:Such ban is worthless in so many ways (1)

WindBourne (631190) | more than 5 years ago | (#27629741)

How do you know that China is secretly building nuclear subs BTW? Countries have ways of verifying through espionage.
And that is why China is paranoid about the outside world with our aircrafts and boats. We are working hard to spy and to know EXACTLY what their count is, while China is doing their utmost to keep it hidden. 1935 Germany was the same way. In fact, all countries that are gearing up for a war will be that way. Back in the 50's and 60's, America and USSR KNEW that each other were spying on the other and looked the other way. Why? Because we wanted each other to NOT attack. We did not want a war between us.

If there's a space weapons ban, there's practically no way to test without the whole world coming down on you. Your analogies aren't the same as there aren't similar bans in place on nuclear power or nuclear subs.
You are kidding me, right? The space attack will not be via shooting out sats from earth. It will be by Lasers (which is why we need ABL) as well as kinetic weapons. Kinetic weapons are trivial to point and shoot if you have something like say a number of space stations. Just shoot a wide pattern of BBs at the sat's path.
The Chinese demo of shooting out their own weather sat was to show their Politicians that they are getting there. In addition, it was to get us to think that is where they are at. Look, remember the wonderful FBI "spy" tool (carnivore) that everybody on /. carped about for sorting through email or even the opening of the cell phone lines? Now, that more proof is out, ppl should be realizing that the FBI had FAR more advanced tools that they were working with. They just like to put out fake trails. China is the same way.

Woah (3, Interesting)

Idiomatick (976696) | more than 5 years ago | (#27623613)

Those numbers are frigging huge compared to what I thought. 300 measurable hits per mission is crazy. And it will only get worse. I don't think sails are the solution. We need a way to clean it up. (While i liked PlanetES I don't think doing it by hand is very viable)

Re:Woah (3, Informative)

Anonymous Coward | more than 5 years ago | (#27623865)

The 317 hits were over 54 missions. ~6 hits per mission.

Re:Woah (1)

Idiomatick (976696) | more than 5 years ago | (#27627219)

That is JUST the radiator... so windows and radiators ~36 hits per mission. Which is insanely high. These things are impacting at kilometers/second. I don't know why I thought it was 300 earlier.... I think this explains my Linear Algebra exam though :(

Getting bombarded by our own crap (1, Insightful)

Jurily (900488) | more than 5 years ago | (#27623629)

The universe is mocking us for not thinking ahead. Again.

And our reaction? "Let's make those pieces bigger!"

Re:Getting bombarded by our own crap (3, Interesting)

NotQuiteReal (608241) | more than 5 years ago | (#27623997)

The universe is mocking us for not thinking ahead. Again.

Don't anthropomorphise the universe. It doesn't like it. All kidding aside, I am not sure that you said anything. Do you only want to put small things into orbit? Or are you saying we should make sure "what goes up, must come down?"

I think you are saying adding the sails would make the debris bigger, and thus even more of a problem.

Maybe you should have just said "the road to hell is paved with good intentions" and left it at that.

Re:Getting bombarded by our own crap (1)

stephanruby (542433) | more than 5 years ago | (#27624365)

We do need "bigger pieces", we don't want that layer to be too fluid when we start building on it.

Re:Getting bombarded by our own crap (2, Informative)

ring-eldest (866342) | more than 5 years ago | (#27625303)

We are the tubgirl of Sol system.

Shoot em up? (3, Informative)

powerslave12r (1389937) | more than 5 years ago | (#27623641)

Well, with the kind of weapons tech being developed (electric eye with lasers?), it shouldn't be a big deal burning down these debris. The problem would be allowing (or acknowledging that *anyone* has) that kinda weaponry up there.

Re:Shoot em up? (2, Informative)

davolfman (1245316) | more than 5 years ago | (#27623927)

Yeah, no. We don't have anywhere near the weapons tech needed to actually vaporize orbiting objects, it would just take too much power. All we can do is push them out of orbit, or scatter them into even more orbits as shrapnel.

Bad idea (4, Insightful)

bigsteve@dstc (140392) | more than 5 years ago | (#27623941)

If you blow up an old booster ... or satellite ... you only make the space junk problem worse. Instead of 1 large lump of junk that is easy to track and (with luck) avoid, you end up with thousands of smaller lumps, each of which would damage or destroy a satellite.

Re:Bad idea (1)

JohnFluxx (413620) | more than 5 years ago | (#27625169)

Thousands of smaller lumps would have a massively larger surface area, so wouldn't they fall a lot faster? So within a year or so they'd be gone, no?

Re:Bad idea (1)

khallow (566160) | more than 5 years ago | (#27628687)

Depends how high the orbit is. The problem is that the orbits that have orbital debris problems also are high enough that it'd take a lot longer than a couple of years for small pieces of orbital debris to deorbit.

Space Debris Big Game Hunting Safaris (2, Funny)

PolygamousRanchKid (1290638) | more than 5 years ago | (#27625701)

Issue licenses to commercial space flight providers. Their spacecraft would be fitted with big-ass laser canons. Rich folks would fork out a few million for the privilege of bagging some space debris.

Each flight would have "Space Hunting Guides & Skinners," grizzled, experienced former government astronauts. The skinner would ensure that there was no smaller junk left over after the kill. It would be burned up in the nightly campfire with a yet-to-be-determined technology.

The guide would say cool stuff, like, "Now you've got to be careful when stalking a Sputnik . . they are crafty little bastards!"

Proud to be White (-1, Troll)

Anonymous Coward | more than 5 years ago | (#27623653)

I am so thankful that I'm White, and not a subhuman monkey ape like Obama.

Obama == Chimp.

Re:Proud to be White (3, Funny)

Jurily (900488) | more than 5 years ago | (#27623755)

Now that you mention it... Maybe we should try launching politicians up there to collect the debris. Or bankers.

Can we build something cheap enough to launch them all?

Re:Proud to be White (1)

Dreadneck (982170) | more than 5 years ago | (#27627295)

Compared to the TARP funds, rocketing those assholes into orbit would be cheap.

Space Snails? (-1, Offtopic)

Anonymous Coward | more than 5 years ago | (#27623659)

Slashdot is becoming more like Geekologie.com everyday, where can I get real nerdy news?

Kreskin said it best: *BSD is Dying (-1, Offtopic)

Anonymous Coward | more than 5 years ago | (#27623723)

It is now official. Netcraft confirms: *BSD is dying

One more crippling bombshell hit the already beleaguered *BSD community when IDC confirmed that *BSD market share has dropped yet again, now down to less than a fraction of 1 percent of all servers. Coming on the heels of a recent Netcraft survey which plainly states that *BSD has lost more market share, this news serves to reinforce what we've known all along. *BSD is collapsing in complete disarray, as fittingly exemplified by failing dead last [samag.com] in the recent Sys Admin comprehensive networking test.

You don't need to be the Amazing Kreskin [amazingkreskin.com] to predict *BSD's future. The hand writing is on the wall: *BSD faces a bleak future. In fact there won't be any future at all for *BSD because *BSD is dying. Things are looking very bad for *BSD. As many of us are already aware, *BSD continues to lose market share. Red ink flows like a river of blood.

FreeBSD is the most endangered of them all, having lost 93% of its core developers. The sudden and unpleasant departures of long time FreeBSD developers Jordan Hubbard and Mike Smith only serve to underscore the point more clearly. There can no longer be any doubt: FreeBSD is dying.

Let's keep to the facts and look at the numbers.

OpenBSD leader Theo states that there are 7000 users of OpenBSD. How many users of NetBSD are there? Let's see. The number of OpenBSD versus NetBSD posts on Usenet is roughly in ratio of 5 to 1. Therefore there are about 7000/5 = 1400 NetBSD users. BSD/OS posts on Usenet are about half of the volume of NetBSD posts. Therefore there are about 700 users of BSD/OS. A recent article put FreeBSD at about 80 percent of the *BSD market. Therefore there are (7000+1400+700)*4 = 36400 FreeBSD users. This is consistent with the number of FreeBSD Usenet posts.

Due to the troubles of Walnut Creek, abysmal sales and so on, FreeBSD went out of business and was taken over by BSDI who sell another troubled OS. Now BSDI is also dead, its corpse turned over to yet another charnel house.

All major surveys show that *BSD has steadily declined in market share. *BSD is very sick and its long term survival prospects are very dim. If *BSD is to survive at all it will be among OS dilettante dabblers. *BSD continues to decay. Nothing short of a miracle could save it at this point in time. For all practical purposes, *BSD is dead.

Fact: *BSD is dying

Moon or obiting junkyard (2)

ender06 (913978) | more than 5 years ago | (#27623743)

Instead of sending it back to earth, why not just keep it out there, but collect it all to one central location? We paid once already to launch it out there, and we know we want increase our space presence, so why not have a junkyard where you can go get stuff to recycle? Or, crash it into the moon and build your moon base near it, then you can keep adding to and utilizing it.

Re:Moon or obiting junkyard (4, Informative)

Rakishi (759894) | more than 5 years ago | (#27623867)

Space is not earth.

Moving things in space and keeping them from crashing into the atmosphere requires energy. Energy means fuel and fuel means you need to pay to send it up. Docking objects in space requires complex electronics which means even more mass to send up.

Recycling requires a highly advanced and complex industrial base which doesn't exist in space. If it did then you wouldn't need the junk since you can mine your own raw materials.

mission expectation (0, Offtopic)

r00t (33219) | more than 5 years ago | (#27623763)

You're going to get a hole in your radiator.

You're going to get hit in the window 30 times.

Two windows will need to be replaced.

Re:mission expectation (0)

Anonymous Coward | more than 5 years ago | (#27660331)

but seriously, why in hell they put windows here?

i just got off the toilet (-1, Troll)

Anonymous Coward | more than 5 years ago | (#27623777)

i shit out an obama.

plop!

Re:i just got off the toilet (-1, Troll)

Anonymous Coward | more than 5 years ago | (#27623787)

Obama smells like shit. Looks like one too.

Re:i just got off the toilet (0)

Anonymous Coward | more than 5 years ago | (#27623911)

WTF is up with these Obama is shit posts!?

These are fucking tasteless and annoying. Post a legitimate criticism if you must (and there are plenty; just read /. for five minutes), but please stop being a fucking 13 year old.

(and yes, I know I'm feeding the trolls)

Re:i just got off the toilet (-1, Troll)

Anonymous Coward | more than 5 years ago | (#27624085)

The fascinating thing about Obama is that despite the fact that he will be president for a few years, it is all for naught--the plain truth is that he will be a nigger all his life.

Hit or Miss or Hit (5, Insightful)

DynaSoar (714234) | more than 5 years ago | (#27623857)

"For the final stage of an Ariane 5 launcher, the conical sail would need to have an area of about 350 square metres and be supported by an inflatable mast 12 metres long."

And the expected time to reentry is 25 years.

Good luck on keeping something inflated in space for 25 years. And that's not even considering the probability that the the mast, and the much higher probability that the large sail, will be hit by orbiting debris during that time and torn to shreds

Re:Hit or Miss or Hit (3, Insightful)

camperdave (969942) | more than 5 years ago | (#27624213)

Good luck on keeping something inflated in space for 25 years.

Inflate it with a plastic foam resin that hardens into a "solid" mast.

Should We Be Surprised? (0)

ks*nut (985334) | more than 5 years ago | (#27623977)

So the same species that has brought us to the brink of destruction by fouling its own nest has so polluted the near-space environment that it is no longer safe to send humans up there. What a shock! When's the last time you looked up to see if you could see anything "up there?" Like a star or a planet or, shudder, a neighboring galaxy? Relatively few people do that anymore because of all of the f'ing lights we think are so important and make us so secure!

Not with a bang but a whimper.

Making solar sails (4, Interesting)

Kim0 (106623) | more than 5 years ago | (#27623985)

Here is my idea for making an extra light solar sail:

http://kim.oyhus.no/Solar_sail.html [oyhus.no]

Kim0

Re:Making solar sails (2, Insightful)

wagnerrp (1305589) | more than 5 years ago | (#27624687)

This is not a solar sail, this is aero-braking.

Re:Making solar sails (1)

Kim0 (106623) | more than 5 years ago | (#27629541)

No, it is not aero-breaking,
because of all the holes, which let air through.

Kim0

This job is rather like... (2, Interesting)

BikeHelmet (1437881) | more than 5 years ago | (#27624255)

It's rather like taking a stroll down Main St. in one of those western cowboy movies.

Anyone know how powerful a big electro magnet would have to be to suck debris within say... a mile, towards it?

Re:This job is rather like... (1)

WindBourne (631190) | more than 5 years ago | (#27626423)

Does a mag work on aluminum, Fuels, Insulation, Paint Flecs, and Titanium?

Re:This job is rather like... (0)

Anonymous Coward | more than 5 years ago | (#27634873)

As any solution is likely to be less than 100% effective, why not try an idea that might be marginally effective?

Why not have rare earth magnets in orbit gathering up anything that's ferrous? It's not that bad of an idea.

Water and Aerogels (1)

TiberSeptm (889423) | more than 5 years ago | (#27624387)

You could vent water vapor in the path of denser groupings of debris. This would allow you to sap kinetic energy from clouds of debris without incredibly fancy or expensive lasers. Still, getting large volumes of water up into space is itself a costly endeavor and might only be cost effective in bringing down denser debris clouds or groupings. Add that to the fact that water vapor will disperse and descend rather quickly and this might only be viable as a way to clean up right after a debris creating event occurs.

Aerogels are a possible means of collecting and de-orbiting debris. Unlike water vapor, these materials would not disperse as rapidly and could be used to sweep out regions of debris by providing enough resistance to slow them down and drop them out of orbit. The problem here is that the materials with the requsite properties don't nescessarily exist yet- if you consider mass production and low cost to be requisite properties. Ideally the aerogel would be one that could be produced on-site; meaning it could be carried in a dense component form and sprayed out into space. Carrying fully formed areogel into space for the purpose of debris collection would prove impractical due to the large volumes required- though the low mass required makes the idea of on-site production appealing.

There are several promising aerogels - particularly alumina based compounds - that are already used for capturing high velocity particles. The trick would be creating a mechanism capable of generating them in orbit.

Re:Water and Aerogels (1)

iiiears (987462) | more than 5 years ago | (#27629037)

Imaginative - practical why? This is slashdot after all. - grin

Where's Scotty when you need him? (2, Funny)

rts008 (812749) | more than 5 years ago | (#27624563)

Space sails? That's so low tech.

It's obvious we need deflector dishes and shields.

Star Trek has taught us that much!

Re:Where's Scotty when you need him? (-1, Troll)

Anonymous Coward | more than 5 years ago | (#27624633)

True, but remember, Obama is a nigger.

This is the reason space travel will never happen (1)

Joce640k (829181) | more than 5 years ago | (#27624745)

The problem with space travel won't be the engines or how to recycle the used food, it'll be all the rocks constantly beating on the hull.

Re:This is the reason space travel will never happ (1)

WindBourne (631190) | more than 5 years ago | (#27626451)

Which is why bigelow's BA-330 is interesting. About a foot of material as well as sealing that ABSORBS the item, rather than trying to reflect it. For distance travel, do the smart thing and put that in a metal can.

Such a Waste (3, Interesting)

32771 (906153) | more than 5 years ago | (#27625521)

I think that any mass in orbit is far more valuable there than back on earth. It still has all the energy the owner has paid for by launching it in the first place, and at ~$1000 per kg in LEO that is nothing to sneeze at. I think the solar sails should be used to cart the stuff into a higher orbit where the parts can be stored with less effort.

The problem is that whatever we sent up is not built for reusability it would seem. Without a decent plan to produce something from space junk I guess nobody is going to worry about where the hardware in orbit goes beyond its eol, it has paid for the launch costs already why worry about much costlier manufacturing in orbit. Then it is also safer to just drop the stuff. This proposal is more of the same shortsighted thinking however. We will continuously put stuff into orbit, why let it decay back to earth if there could be a continuous reuse of material in orbit? Something goes up nothing comes down!

The space junk problem could finally lead to better planning for the future. Somebody could come up with an in orbit manufacturing and launch facility which buys the energy + material value of your satellite/booster. Its main bussiness would be in orbit manfacturing and launch of hardware with a certain orbit.

I would venture a guess and say that we already have the technology to make this work today. So it is time to check whether this could become a viable business model.

Re:Such a Waste (2, Interesting)

khallow (566160) | more than 5 years ago | (#27627133)

And as long as that material is uncontrolled, it easily can destroy anything else that has been launched for $5,000 or more per kg.

PS, your cost is incorrect, especially if we're just talking energy. It takes only somewhere on the order of $10-20 per kg in energy to put something in orbit. The cost of objects in orbit isn't due to the energy of the objects. Currently, the Russians are the cheapest. And they might go down to $3,000-4,000 per kg to put things in orbit.

And what will a space salvage business make? Down the road, I'm sure something will come up. But the problem with these ideas is that there's no market now, but there is a space junk problem. It makes no sense to try to save the little bit of mass in orbit now at a risk of hindering humanity's presence in space for centuries to come.

Re:Such a Waste (1)

32771 (906153) | more than 5 years ago | (#27628761)

I made a silly mistake about calculating the cost to orbit, it had something to do with converting between pounds and kilograms. I assumed $2000/pound through a russian launch (my source: www.futron.com/pdf/resource_center/white_papers/FutronLaunchCostWP.pdf).

I agree with you that looking only at the energy would be too narrow a focus. Launch costs include ground operations and other things whereas the launcher itself isn't even the biggest part of the costs.

One could use different technologies once in orbit. It might only take an ion engine to get from the junkyard/manufacturing orbit to LEO or geostationary orbit. It still would take fuel but if you focus more on increasing exhaust velocity than differential mass the powerplant mass you have to produce/collect/bring up from earth is the part you have to worry more about. A solar sail might require even less materials to be brought up from earth.

Regarding your last point, I'm wondering how the space junk is distributed. Most LEO space junk is probably not so much of a problem because it will come down by itself. I just think that careful space junk management in some further out orbit which is not frequently used might be only a bit more expensive than dropping junk into the athmosphere. We are not doing it yet so why not consider it. A junk yard is probably a more manageable thing too. If junk is securely clustered together it is easier to maintain its position until we are actually able to use it for something else. So I don't suggest we just leave things as they are and wait until the perfect solution comes along but to work towards a better solution which might save us a number of launches later.

What might ultimately bring the junk yard idea down is shrinking launch costs and this is something which is seen as the main goal nowadays. The reason I find junk collection/manufacturing in orbit great is that it could ultimately lead to people living and working in space as opposed to only running a research station which requires more terrestrial intervention. It would be a step towards a human pressence in space whereas just dropping the junk means cementing the status quo - space bussiness is for satellites.

Re:Such a Waste (1)

khallow (566160) | more than 5 years ago | (#27642901)

As I understand it, launch costs usually don't make up a large portion of the overall costs of a space mission, but they are the decisive factor. The problem is that launch costs are the ante, the minimum amount that a mission will cost even if everything else is free. For example, if you have a satellite that weighs 1 tons, it'll cost $5 million or more to put up. If your desired return on investment is 20% per year (reasonable for a high risk start up), then you need to make at least a million dollars a year just to cover the loss in return on investment from launch costs. Further, there are trade offs between more efficient use of mass and volume, and cost. The end result is most satellites end up with launch costs around 10-20% of the satellite, this pricing usually applies even to satellite constellations. The sole exceptions seem to be the two extremes. Usually when a launch represents the overwhelming cost of the mission, it is because the vehicle is still unproven. You can get donated payload space and/or dummy payloads because the launch provider can't afford to launch a real payload (due to insurance costs for an unproven launch vehicle). At the other extreme are defense and a few specialized communication satellites that are extremely expensive. In those cases, the satellite owner often wants (but can't get) more reliable launch services, and the unusually low launch costs can indicate a sort of "impedance mismatch" between the payload and vehicle with a better fit occurring if money can be spent to improve the reliability of the vehicle.

Second, again as I understand it, the lowest viable low Earth orbits (LEO) have high air resistance and over time clean themselves of orbital debris. The higher LEO orbits, about 700 miles up, I think, where GPS, Iridium, and some other satellites orbit, are the biggest problem. There debris collects due to being relatively busy orbits (and due to some orbiting upper stages too) and having much lower air resistance. The van Allen belts are relatively clear of debris aside from some launch stages (usually from satellites being placed in geosynchronous Earth orbit or GEO), I think. Then there's the span of space above the van Allen belts called MEO (middle Earth orbit) which is usually clear of debris (due to lack of use), but which experiences a higher radiation environment than LEO and may actually be outside of Earth's magnetic field. There's virtually no air resistance even over millennia. So any debris which forms here, will probably stay for a long time. Finally, there's GEO which due to the high population of satellites, especially spent, out of control satellites has the potential for generating considerable space debris.

Re:Such a Waste (1)

Rakishi (759894) | more than 5 years ago | (#27665711)

I think that any mass in orbit is far more valuable there than back on earth. It still has all the energy the owner has paid for by launching it in the first place, and at ~$1000 per kg in LEO that is nothing to sneeze at.

There's already plenty of mass in space, we can cart up rocks from the moon for a pittance if we wanted to. The problem is that all that mass is useless since the cost of manufacturing things in space would be insane.

I think the solar sails should be used to cart the stuff into a higher orbit where the parts can be stored with less effort.

They aren't putting solar sails on these things in case you haven't realized.

So you want to spend mass to send up complex (and fragile likely) solar sails with complex guidance systems? Solar sails which, asfaik, have never been shown to actually work yet and that are not used by any existing system for orbit maintenance yet? Systems that are likely to fail, by pure chance, at some point and create more hard to track junk in non-decaying orbits than they could possibly prevent?

The problem is that whatever we sent up is not built for reusability it would seem.

There's a reason for that, look at the Hubble and how much it costs to repair it even though it was designed to be repaired.

Without a decent plan to produce something from space junk I guess nobody is going to worry about where the hardware in orbit goes beyond its eol, it has paid for the launch costs already why worry about much costlier manufacturing in orbit. Then it is also safer to just drop the stuff. This proposal is more of the same shortsighted thinking however. We will continuously put stuff into orbit, why let it decay back to earth if there could be a continuous reuse of material in orbit? Something goes up nothing comes down!

The space junk problem could finally lead to better planning for the future. Somebody could come up with an in orbit manufacturing and launch facility which buys the energy + material value of your satellite/booster. Its main bussiness would be in orbit manfacturing and launch of hardware with a certain orbit.

I would venture a guess and say that we already have the technology to make this work today. So it is time to check whether this could become a viable business model

Manufacturing capabilities in space would probably require sending up ten to a hundred times more mass than we've done up to this point in total. You're underestimating just how complex space craft are and how much industry is behind them. Given that it's inefficient to bother saving the crap since by the time it's useful it'll be an insignificant fraction of all the stuff in space.

Probably the only way that manufacturing things in space would be viable is if launch costs went down significantly at some point (be it cheaper launch mechanisms or cheaper sources of raw materials). In that case the value of that material in space is even less since it doesn't matter if it cost $2000/lb but only that it costs $20/lb then.

Competing technology (1)

ChrisMaple (607946) | more than 5 years ago | (#27625555)

Pointy sticks to spear the space trash.

why bring them back down? (2, Interesting)

advocate_one (662832) | more than 5 years ago | (#27625607)

use the sails to move them into higher designated parking orbits so the materials can later be used up there when we need to start assembling craft in space... it costs an enormous amount to put mass up there, why waste the energy invested?

Re:why bring them back down? (1)

MobyDisk (75490) | more than 5 years ago | (#27636211)

Are you planning to build a space station from flecks of paint, foam, and metal? Unlike in cartoons [slashdot.org] , you can't just build anything from random metal parts.

Re:why bring them back down? (1)

advocate_one (662832) | more than 5 years ago | (#27643083)

we're talking about booster stages and satellites here, not fragments, that's another problem... if the spent booster stages and defunct satellites can be moved up to a parking orbit using solar sails, then there'll be a much smaller debris problem in the main orbits as these defunct parts won't be colliding with each other in the prime orbits.

Re:why bring them back down? (1)

Rakishi (759894) | more than 5 years ago | (#27665761)

First of all because atmospheric drag slows things down and robs them of energy. Going to a higher orbit requires increasing velocity and adding energy. In other words, the laws of physics prevent your scheme from working.

There are other reasons I can think of but I think this one is enough.

I have an idea (1)

Dreen (1349993) | more than 5 years ago | (#27626671)

And it involves sending a lot of baseball players to space, with steady supplies of baseball bats.

garbage collection (1)

foniksonik (573572) | more than 5 years ago | (#27627143)

Why not take this further. Shoot up rockets with big sails attached for the sole purpose of collecting space debris. put them in an orbit then deploy their sails or parachutes so they will catch a swath of debris. if the rocket is traveling slightly faster than the debris the sail wont be punctured and it will fill up before losing its velocity and then falling out of orbit.

Re:garbage collection (1)

ScooterComputer (10306) | more than 5 years ago | (#27637155)

Yeah, what foniksonik said. A space seine seems to be a no-brainer to me, since they now have the "net".

"Terminator Tethers" might be cheaper (1)

sdpinpdx (66786) | more than 5 years ago | (#27628733)

http://www.tethers.com/TT.html [tethers.com]

I saw Robert L Forward talk about this at a con years ago.

Tethers better than sails? (1)

XNormal (8617) | more than 5 years ago | (#27628999)

Instead of atmospheric drag a conductive tether moving through the Earth's magnetic current generates a current and radiates the heat from tether resistance. The dissipated energy will eventually bring the satellite down. The technique has been developed by Tethers Unlimited and the late Dr. Robert Forward [wikipedia.org]

http://www.tethers.com/TT.html [tethers.com]

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