Space Sails Could Bring Used Rockets Back To Earth

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."

Comments

And the old junk?

[JorDan Clock]

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.

Re:And the old junk?

[Profane MuthaFucka]

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?

[bit01]

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 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?

[rcw-home]

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?

[Hurricane78]

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?

[Antique Geekmeister]

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?

[roystgnr]

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

[GodfatherofSoul]

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

Woah

[Idiomatick]

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

[Anonymous Coward]

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

Actually, it might, for the larger stuff

[WindBourne]

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.

Shoot em up?

[powerslave12r]

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?

[davolfman]

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.

Mass Catcher

[StCredZero]

I wonder if we could operate a remote-controlled Mass Catcher? 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.

Moon or obiting junkyard

[ender06]

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

[Rakishi]

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.

Re:Proud to be White

[Jurily]

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?

Hit or Miss or Hit

[DynaSoar]

"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

[camperdave]

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

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

Bad idea

[bigsteve@dstc]

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.

Making solar sails

[Kim0]

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

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

Kim0

Re:Making solar sails

[wagnerrp]

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

Re:Getting bombarded by our own crap

[NotQuiteReal]

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.

This job is rather like...

[BikeHelmet]

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?

Where's Scotty when you need him?

[rts008]

Space sails? That's so low tech.

It's obvious we need deflector dishes and shields.

Star Trek has taught us that much!

Re:Choke

[julesh]

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

I pray he never learns the word 'sheeple'.

Such ban is worthless in so many ways

[WindBourne]

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:Getting bombarded by our own crap

[ring-eldest]

We are the tubgirl of Sol system.

Such a Waste

[32771]

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

[khallow]

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.

why bring them back down?

[advocate_one]

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?

Space Debris Big Game Hunting Safaris

[PolygamousRanchKid]

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!"