9 Ideas For Coping With Space Junk

An anonymous reader writes "The space age has filled Earth's orbit with all manner of space junk, from spent rocket stages to frozen bags of astronaut urine, and the problem keeps getting worse. NASA's orbital debris experts estimate that there are currently about 19,000 pieces of space junk that are larger than 10 centimeters, and about 500,000 slightly smaller objects. Researchers and space companies are plotting ways to clean up the mess, and a new photo gallery from Discover Magazine highlights some of the proposals. They range from the cool & doable, like equipping every satellite with a high-tech kite tail for deployment once the satellite is defunct, to the cool & unlikely, like lasers in space."

Comments

Hit or Miss

[teeks99]

That Discover article was pretty hit-or-miss. They nailed the real solution in two of their pieces (tethers and sails), in that the best (easiest, cheapest, only-one-that-will-probably-ever-happen) are technologies that are built into space objects (satellites and boosters) before launch. There's lots of options here from tethers, sails, balloons, or just using existing thrusters. If we can stop leaving big pieces up there (which can run into other big pieces and make LOTS of pieces), the problem will start getting less severe.

On the other hand, on of Discover's pages was about blowing up the debris...this makes sense, until you really think about it. The problem is that when you blow up something, it makes a huge number of new pieces, with all sorts of different velocities and orbits. On average, these pieces will fall to earth more quickly than the unexploded satellite, however, that's just the average. There are many pieces that will stay up there even longer. And when you're talking about things moving that these incredible velocities, it doesn't matter a whole lot if you get hit by a 6,000lb. satellite or a 5lb. piece of a satellite, either one will destroy anything we've put in orbit.

Re:Hit or Miss

[BJ_Covert_Action]

That Discovery article was a total waste of time. It really had little to do with "9 ways of dealing with space junk," and was more along the lines of "9 things that are kind of related that we want to talk about." As you mentioned, a couple of its nine methods of dealing with space junk could really just be grouped into the general theme of, stop putting more up there (deorbit your crap at end of mission). There were only three methods that actually discussed getting rid of existing junk: lasers in space, balls of aerogel to capture stuff, blowing up large chunks of junk. For what it's worth, the exploding method that you mentioned discussed only conducitng such methods at low altitudes which actually does work really well. However, it still leaves a lot of unaddressed crud in the higher LEO bands (like the one the ISS is in). The aerogel glob discussion was also an interesting one, but as the article addressed, aerogel can only really handle tiny stuff like paint chips. The lasers in space is probably the most effective solution, but costs so much in terms of energy generation that it is still a ways off in any large scale deployment.

So what else did the article discuss? Well it mentioned the Kessler effect, which has nothing to do with dealing with space junk, but is just a model used to describe space junk. It mentioned that NASA is now putting more efforts into tracking space junk. This is important, of course, but doesn't qualify as a method for removing it or handling it (excepting the very indirect means of simply avoiding it). Then it talks about shielding spacecraft from space junk. This, of course, is necessary and current practice, but no amount of shielding (presently) will protect you from detached thermal blankets or burnt out Delta stages.

All in all, this article just seemed like a disorganized, loosely-themed, terse ramble. I usually expect better from Discover but was severely disappointed in this particular release.

Re:Hit or Miss

[ComputerInsultant]

What a waste. Even the first page has an obvious error:

the tool kit dropped by astronaut Heide Stefanyshyn-Piper during a spacewalk in 2008

That tool kit re-entered the atmosphere in August of 2009. http://en.wikipedia.org/wiki/Heidemarie_Stefanyshyn-Piper#Lost_tool_bag_during_spacewalk Come on guys. Do some fact checking.

Re:Hit or Miss

[izomiac]

On the other hand, on of Discover's pages was about blowing up the debris...this makes sense, until you really think about it. The problem is that when you blow up something, it makes a huge number of new pieces, with all sorts of different velocities and orbits.

Most problems with lasers can be solved by higher power lasers. Just increase the power output and decrease the delivery time until you can turn any debris you target completely into gas or plasma. For larger objects, target a non-rotating point so it'll turn to gas and push the object out of orbit.

Re:Hit or Miss

[FinalMidnight]

I wonder at the effectiveness of putting a very large focusable solar reflector in a high orbit, perhaps at LaGrange point 1. Such a solar sail could be used to give thrust to satellites equipped with a sail, or even large bits of space junk. Obviously it wouldn't give much Delta V to junk, but it might give some, and it would be essentially free. Junk in high orbits takes hundreds or thousands of years to de-orbit, and any means of reducing the velocity of said junk would drastically reduce that time. Additionally, with a variable focus the mirror might be pointed at solar cells of existing satellites, which could improve the thrust gained from Ion Drives, assuming enough reaction mass remains to take advantage of the extra watts.

Idle musings. Feel free to shoot me down.

Re:Hit or Miss

[izomiac]

Yes, and the first layer of ionized atoms will scatter the rest of the laser energy, and push on the object... Sigh, you Space Loons are a big, fat ZERO when it comes to reality. Again. THIS AIN'T STAR TREK.

Assuming iron, so M = 55.845, Vaporization point: 3134K, Melting point: 1811 K, Heat of fusion: 13.81 KJ/mol, Heat of vaporization: 340 KJ/mol, Specific heat capacity: 25.10 J/mol/K

v(rms) = (3RT/M)^.5
v(rms) = 37.4 m/s
Assuming you want the laser focused over 4 cm for a 3 cm object:
t = x/v = .5 cm / 3740 cm/s = 134 us

For a 3 cm sphere:
V = 4/3*pi*r^3 = 113 cm^3
m = Vd = 113 cm^3 * 7.874 g/cm^3 = 890 g
890 g / 55.845 g/mol = 16 mol
16 mol * (25.10 J/mol/K * 3134 K + 13810 J/mol + 340000 J/mol) = 7 MJ

So, a 7 MJ burst in 134 us, or 52 GW (roughly, I didn't deal with liquid heat capacity/expansion properly). The most powerful lasers currently in existence are measured in the petawatt range, and an exawatt laser is in the works. That puts us 5 - 8 orders of magnitude higher than what we'd need to fully vaporize a 3 cm ball of iron before the gas had a chance to disperse. While there might be some scatter, you'd still be heating up the ~4 cm ball of gas (the highest energy gas molecules would be > 1 cm away, but that's the point of the whole exercise). I've taken some liberties with the math, but nothing you can't hand-wave away with up to 5 orders of magnitude above the calculated need.

In other words, the "first layer of ionized atoms" don't form a deflector shield that completely scatters laser energy. The center of mass isn't going to warp away faster than the gas can even expand, and it would still just be pushing the object away in the direct path of the laser. This isn't a spaceship battle, you don't fire the laser for 3 seconds at a time.

What problem?

[reverendbeer]

Just send up a guy with a jet pack and a baseball bat...let reentry take care of the rest.

The perfect solution has already been worked out

[TrentTheThief]

This is the solution:

http://en.wikipedia.org/wiki/Salvage_1

Lasers...

[Joce640k]

This guy built a laser which tracks mosquitoes in a room and zaps them. Surely the technology can be adapted...

Re:Lasers...

[BJ_Covert_Action]

You know, I always wanted to talk to that guy for the exact reason you posted. I thought it would be a great university project for some aerospace engineering students to team up with this guy and build a small satellite (~500 kg) that used some combination of high-load capacitors, trickle charge electronics, solar cells, and his laser-tracking technology to basically float around Earth for awhile in a particularly polluted altitude band and just try zapping what ~10 cm pieces of space junk they could find. It would be a great effort for the students, and would act as a wonderful proof-of-concept demonstrator to the big players in the space industry.

Re:Lasers...

[John Hasler]

> ...a wonderful proof-of-concept demonstrator...

What concept do you think it would prove? "Hitting stuff with a laser" is not very hard and has been demonstrated many times, even in space.

Re:Lasers...

[BJ_Covert_Action]

Something along the lines of: "hitting stuff with a laser, in space, on a shoestring (university) budget, on a small, COTs-derived, simple vehicle."

That's a very different proof than "hitting something with a laser in space."

Re:Lasers...

[BJ_Covert_Action]

Oh, also, most of the things we've hit with lasers in space, today, are things whose relative position, velocity, flight path, and orientation are known. Recognizing an anonymous piece of cold debris, targeting it, and maintaining laser contact on it for any decent amount of time is a significantly different problem than targeting the next satellite in a known constellation and establishing a two-way communication protocol between hardware.

Re:Lasers...

[Patch86]

Not to point out the obvious, but killing flies and destroying space junk are two very different things.

The insect laser only needs to wound the insect enough that it is no longer a trouble- badly damage the wings, or cause it bodily injury. The insect then tumbles harmlessly to the ground.

The debris laser needs to do one of two things- either impart enough thermal energy to the junk so that it's trajectory is changed, causing it to de-orbit, or to disintegrate it into such tiny pieces that it no longer poses a threat upon impact. Both of which are likely to need more energy than de-winging a mosquito.

Lasers are easy- we've had them for many years. Tracking the debris is easy- we're doing it now. Having something that can point accurately at something we're tracking- that's easy enough too. Having something that can do all that with enough power to actually be useful, able to do it over and over again without running out of consumables, and do that on a sane budget-that's tricky.

Re:Lasers...

[BJ_Covert_Action]

Having something that can do all that with enough power to actually be useful, able to do it over and over again without running out of consumables, and do that on a sane budget-that's tricky.

Agreed. This is precisely what makes it an interesting and worthwhile engineering project to work on.

Re:Lasers...

[blair1q]

Actually it's the same problem.

Satellite controllers use the radar-tracking derived ephemeris data from NORAD. It's a simple matter of changing a search parameter in the data request to get the debris trajectories.

Re:Lasers...

[physburn]

Nice idea, But the sharks would suffocate in space.

Out of dimension?

[gmuslera]

The average junkyard in earth surface using a relatively few square meters have far more junk than that, and we are talking here of something of orders bigger than the entire earth surface, probably in an area of the size of a medium country you get one piece of more than 10 cm. The article puts it as something packed with junk. Ok, they aren't static, they orbit, and usually at big speeds (several times faster than a bullet), and is a problem with only increases with time, is not something to discard too easily, but still the warning seem a bit exaggerated.

Re:Out of dimension?

[sunking2]

Oh hush. I'm trying to get some grant money!

Re:Out of dimension?

[djdanlib]

You need to get through all the orbits of uncontrolled junk, which takes a lot of calculation and you can only move so fast.

You have to be able to get out of the way of new junk that's moving so fast you can't accelerate quickly enough to wait and see if it might miss you.

Calculation of junk trajectory is only so precise, so you have to leave a 'safety buffer' of sorts.

There's more junk up there than we have cataloged. There will always be new junk, and collisions alter orbits of existing junk such that our known trajectories become inaccurate and we have to relocate and recalculate all the time.

So finding a safe zone which requires the least fuel usage to stay alive is becoming more challenging.

Tiny fragments that wouldn't harm anyone if you threw it at them are deadly, equipment-wrecking projectiles at high velocity. Think about a small piece of metal, like a penny. Not a problem if you drop it on your foot. Not going to destroy a vehicle if you drop if off a towering skyscraper, even. But, in space where there's no[t enough] atmosphere to slow it down or burn it up, it can theoretically approach any speed... and a 1,000 MPH penny is a fearsome entity to a fragile laboratory measurement device. We might not even be able to track that very accurately, but if you guess wrong... you transfer that momentum into multiple new shards of former expensive equipment!

So getting things into space is really getting more complicated and keeping things alive up there takes a lot more calculation and fuel as the probability of stray objects increases. Does that cut down on the exaggeration factor?

Re:Out of dimension?

[rlseaman]

the warning seem a bit exaggerated

Consider that each object (in low Earth orbit) is in a separate orbit. Each pair of orbits crosses twice on opposite sides of the Earth. The eccentricity of each orbit causes the object to traverse a range of altitudes, defining the subset of all the LEO objects that are possible collision risks at any given time. The risk for two particular objects colliding is low, but each object has many other opportunities as it crosses thousands of other orbital tracks each time it circles the Earth. Then integrate over all the objects. The probability is a nested summation - integrated over time.

For example, assume there are about one hundred spacecraft (active and defunct) occupying a particular semimajor axis "zone". Each satellite orbits once every 90 minutes, ie, 16 orbits/day. Each satellite crosses the orbit of another about 200 times in that 90 minutes. Usually the other spacecraft is somewhere else entirely, but there are a lot of opportunities.

Establish a "comfort radius" - say, one kilometer. If Le Petit Prince is sitting on a satellite, he will get very nervous if another spacecraft zooms through this keyhole at 10 km/s. A typical low Earth orbit is about 42,000 of these comfort units long. So the odds (ignoring altitude for the moment) of finding a spacecraft within the same part of the orbit - during each passage - is 1/42,000. Multiply by the 200 opportunities makes this 1/210 (0.5%) per orbit or about 7.5%/day/spacecraft. There are 100 spacecraft in this zone, so that amounts to about 4 close encounters per day (divide in half since it takes two to tango) in which some spacecraft passes directly above or below another by a few kilometers.

Accounting for altitude requires a bit more physics (inverse square law and all that), but basically amounts to a similar argument of dividing the altitude range traversed by each satellite into comfort zones. The odds of passing through the keyhole drop, but not dramatically - and the orbit crossings keep piling up about a hundred thousand per day per altitude range. With each close encounter, the odds of an impact are basically very simple. What is the volume of a typical spacecraft divided by the 1 km^3 volume? (The second spacecraft either will or won't be occupying the same volume at the moment of closest approach.) Satellites can be surprisingly large - Hubble is about the size of a schoolbus - but figure a Volkswagen van or at least a Beetle.

Bear in mind that this is just one particular altitude range, the same thing is happening at different altitudes. Some spacecraft are in highly elliptical orbits and cross through several such zones. In short, what seems to be a three dimensional problem is really one dimensional. After the spacecraft collision a couple of years ago some of us were scribbling on a blackboard. A physical model would be needed to get the precise answers, but a ball park figure is that we can expect the apparently astronomically rare event of two LEO spacecraft colliding to happen about once per decade (in the absence of active station keeping). Then account for all the debris, not just complete spacecraft.

Re:Hmm

[Sir_Lewk]

Why shouldn't it be hard? Large changes in velocity require large amounts of fuel. Doesn't matter if you are "speeding up" or "slowing down". That's why so many of these ideas involve working out a way for satellites to increase their drag after a time.

The real problem...

[fahrbot-bot]

...like lasers in space.

The main obstacles being shark deployment and survivability.

I think this applies...

[badboy_tw2002]

Hi there! Your post advocates a

( ) technical ( ) legislative ( ) market-based ( ) vigilante

approach to fighting space junk. Your idea will not work. Here is why it won't work. (One or more of the following may apply to your particular idea, and it may have other flaws which used to vary from state to state before a bad federal law was passed.)

( ) Junkers can easily use it to create more space junk
( ) Space stations and other legitimate space uses would be affected
( ) No one will be able to find the guy or collect the money
( ) It is defenseless against brute force space dumps
( ) It will stop space junk for two weeks and then we'll be stuck with it
( ) Users of space will not put up with it
( ) NASA will not put up with it
( ) The space police will not put up with it
( ) Requires too much cooperation from space junkers
( ) Requires immediate total cooperation from everybody at once
( ) Many space users cannot afford to lose business or alienate potential employers
( ) Space junkers don't care about other junk in their junk
( ) Anyone could anonymously destroy anyone else's career or business

Specifically, your plan fails to account for

( ) Laws expressly prohibiting it
( ) Lack of centrally controlling authority for space
( ) Launches in foreign countries
( ) Difficulty of searching for tiny junk in all of space
( ) Asshats
( ) Jurisdictional problems
( ) Unpopularity of weird new taxes
( ) Public reluctance to accept weird new forms of money
( ) Huge existing investment in space
( ) Armies of worm riddled broadband-connected Windows boxes
( ) Eternal arms race involved in all space junk collection policies
( ) Extreme profitability of space junk
( ) Joe jobs and/or identity theft
( ) Technically illiterate politicians
( ) Extreme stupidity on the part of people who do business with space junkers
( ) Dishonesty on the part of space junkers themselves
( ) Fuel costs that are unaffected by space junk
( ) Outlook

and the following philosophical objections may also apply:

( ) Ideas similar to yours are easy to come up with, yet none have ever
been shown practical
( ) Any scheme based on opt-out is unacceptable
( ) We should be able to talk about space Viagra without being censored
( ) Countermeasures should not involve missles
( ) Countermeasures should not involve more junk
( ) Countermeasures must work if phased in gradually
( ) Sending things to space should be free
( ) Why should we have to trust you and your space garbage company?
( ) Incompatiblity with space licenses
( ) Feel-good measures do nothing to solve the problem
( ) I don't want the government cleaning up space
( ) Killing them that way is not slow and painful enough

Furthermore, this is what I think about you:

( ) Sorry dude, but I don't think it would work.
( ) This is a stupid idea, and you're a stupid person for suggesting it.
( ) Nice try, assh0le! I'm going to find out where you live and burn your
house down!

Re:I think this applies...

[IICV]

...
( ) Dishonesty on the part of space junkers themselves
( ) Fuel costs that are unaffected by space junk
( ) Powerpoint ...

There, fixed that for you. I'm certain that bad Powerpoint presentations will still be creating tons of space debris after we're all dead.

Orbital Junk

[UninformedCoward]

Nuke it from orbit. It's the only way to be sure.

wait...

Re:Orbital Junk

[Yvan256]

I guess that would be "just detonate the nukes already in orbit" in that particular case.

Re:Hmm

[grub]

They should just move the Earth from the encircling space junk.

Re:Incinerator

[GodfatherofSoul]

The same reason you don't carry your car to work to save gas money.

Statistics...

[Sir_Lewk]

...that is not how they work.

There are no 669,725 people that are in any more danger than anyone else. There isn't a 1/10,000 chance that it will hit each person, there is a 1/10,000 chance that it will hit any person. In other words, for every ten-thousand pieces of space junk that fall, you might get a single casualty.

If you think these are particularly bad odds, then I have some bad news about your car...

Simple is Better

[YetAnotherBob]

A simple solution might be to send up a sounding rocket to the altitude where a typical debris cloud is and just release a cloud of nitrogen gas. the cloud will fall soon into the atmosphere, the sounding rocket will too. the debris field will have a short time in a very low density gas cloud, and drop in it's orbit. Normal decay will then reduce the overall problem.

Presumably, the AF knows where the debris is. Look for any clusters. Publish where and when it is going to be taken out. Unless someone objects, with a why, then do it. Probably find out who owns a lot of the back satellites that way.

Begin to get rid of the litter. We won't finish until after we start. Right now, there is no cleanup.

Maybe a first test run, then, when we can predict the outcome, a regular program of removal.

Re:Economic solution:

[oldmac31310]

I expect the frozen bags of urine would be a top selling item. Great idea!

The answer is simple: Funding.

[Remus Shepherd]

We don't need new strategies for getting objects down from space. We know how to get them down. When a satellite has outlived its usefulness, you reserve enough fuel so that it can deorbit itself.

The problem is that satellites are expensive and rare still, so we don't want to give them up. So we keep the missions up there for years past their expected lifetime, with the result that they don't have deorbiting fuel left over when they finally break down enough that they're no good to us anymore.

An example: I work with Landsat 5. It was launched in 1982 with a 5 year mission plan. It's still up there, 28 years later, and still a vital piece of the US remote sensing strategy. The next similar satellite won't be launched until 2012. Although it had a deorbiting plan that would have sunk it into the atmosphere a few years after it was decommissioned, that plan was waived. The current plan is to put it into an orbit that will leave it as space debris for 1000 years before it gets low enough to burn in.

If we had funded the satellite program enough, there would have been several follow-on missions and L5 would not still be essential. We would have been able to deorbit it without complaint if there were others that could have taken its role.

Fund space and you won't have space problems. Don't fund it and it'll become a graveyard. Simple as that.

Re:Economic solution:

[IrquiM]

Apart from the danger of monopoly and people being left outside? Nope

Re:Why all this talk about shooting it down?

[John Hasler]

We've already spent billions getting it up there, why not recycle it? Create a recycling station in orbit.

Every bit of trash is in a different orbit. It takes expensive fuel to change orbits. Collecting it all in one place would cost more than simply launching the same amount of stuff from the surface.

Re:The perfect solution has already been worked ou

[slick7]

This is the solution:

http://en.wikipedia.org/wiki/Salvage_1

Two words...Fly paper.

Re:Economic solution:

[c6gunner]

I'd say the shipping costs would be quite low, actually. Fast delivery times too. You could place your order, grab a baseball glove, head out to the back yard, and receive your package 5 minutes later.

space sharks

[mariospants]

Cybernetic space sharks would easily take care of the problem of keeping the burgeoning space whale population under control. As we all know, the space whales keep orbital junk under control... wait, I think I'm getting ahead of myself here...

Totally Lunatic Idea

[jman.org]

I hear folks on the moon are looking for raw materials. Why not just build a recycling center there? We've already expended energy getting all that stuff out of the gravity well, would make sense to help build up our Lunar presence with no-longer-needed materials hanging around in orbit.