Space Junk Threatens Future Missions
Written by Nancy Atkinson
The U.S. Air Force began upgrading its ability to predict possible collisions in space after two satellites collided in February 2009, and has now done a collision analysis on over 800 maneuverable satellites. They hope to be able to track 500 more non-maneuvering satellites by year's end. But maneuverable satellites aren't the problem. The amount of space debris has risen by 40 per cent in the past four years alone. The Air Force Space Command now tracks 21,000 orbiting objects that are 10 centimeters or more across – including the 800 working satellites – and estimates that there are 500,000 smaller fragments in orbit.
"Our goal now is to do that conjunction assessment for all active satellites, roughly around 1,300 satellites, by the end of the year and provide that information to users as required," said Lieutenant General Larry James, U.S. Strategic Command's Joint Functional Component Command for Space, speaking at the Strategic Space Symposium this week in Omaha, Nebraska.
Some of the 500 satellites still to be assessed cannot be maneuvered in orbit because they are not functioning, or do not carry extra fuel that would be needed to move them once in orbit.
At another conference this week, the European Air and Space Conference in Manchester, UK, Hugh Lewis of the University of Southampton estimated the number of close encounters between objects in orbit will rise 50% in the next decade, and quadruple by 2059. The number of pieces of space debris has risen by 40% in the past four years alone.
Countermeasures by satellite builders and operators to avoid additional space debris are encouraged, but they add to the cost of missions.
Lewis has determined that compared with the 13,000 close approaches per week now, he projects there will be 20,000 a week in 2019 and upwards of 50,000 a week in 2059. From this he predicts that satellite operators will have to make five times as many collision avoidance maneuvers in 2059 as they will in 2019. "There's going to be a big impact," says Lewis. "You're going to need more tracking to remove uncertainty about close approaches and undertake more maneuvers."
Sources: Reuters, New Scientist
Filed under: Space Flight
Tags: space junkRelated stories on Universe Today
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November 3rd, 2009 at 4:42 pm
i doubt that anyone here saw an anime(japanese cartoons ) called Planets :p
anyway the context of the series is in a company that deals with space junk .
it made me reflect on the fact that it really wold be a wonder to know what a century from now , all our satelites will end up being.
in the anime there are many people who end up dead in coffins in space too :p
surly exotic now , but who nows.
November 3rd, 2009 at 5:39 pm
Atmospheric drag will cause some of the fragments to eventually slow down and burn up in the atmosphere, thus clearing away some of the junk.
What we need is for governments to make the (admittedly costly) countermeasures mandatory, because in the long run the danger to astronauts, and increasing damage to equipment due to more frequent collisions, will be more expensive. Make satellite manufacturers put enough fuel in their satellites that they can be deorbited when their mission is complete, and impose stiff fines for any debris released.
November 3rd, 2009 at 6:35 pm
I looked into this back in the 1990s in a problem to asses the expected lifespan of the Hubble mirror. There are a couple of things which should be pointed out. A piece of material with a mass of a gram has the kinetic energy equal of a high powered round. There is also a power law in the distribution of this stuff which predicts far more small particles, such as a millimeter diameter piece of material which can punch through a spacecraft. The other thing is that the stuff "multiples." Orbital debris through collisions with other pieces multiply into numerous smaller pieces.
Eventually the NEO region around the Earth will be cleared of orbital debris. Yet the problem is that it will take several centuries for that to happen.
Cheers LC
November 3rd, 2009 at 6:56 pm
Solution, some independently wealthy individual commission a "cleaner" satellite. This cleaner satellite would be maneuverable, have a very large "mitt" to catch debris, and an arm to grasp and tow larger debris. It would have ladar coupled with ground based tracking to track and close in on debris. The mitt would me made of ballistic grade material which does not disintegrate or shed particles upon impact (the airgel used in collecting comet samples?). The Cleaner would be re-fuelable, maybe at the space station.
The return on the investment would come after launch down the road when high dollar satellites are endangered in orbit, and will need protection.
November 3rd, 2009 at 8:22 pm
lotusface Says:
November 3rd, 2009 at 6:56 pm
I don't think you could ever have enough fuel for such a thing to catch more than a few bits and pieces – remember that we're talking about an area larger than the surface of the Earth, multiplied by a hundred or so kilometers to get the volume of space these bits and pieces orbit in even for material that is close to the Earth!
Maybe you could have something like this on hand to target specific threats, but that would be about it…
November 3rd, 2009 at 8:33 pm
@Astrofiend: Agreed. Lotusface's suggestion, while well intentioned, is probably unrealistic. I agree some solution is necessary to clean up this space junk. Why not program the satellites to exit NEO and fly off toward the edges of the solar system after their missions are completed, as Nexus has suggested?
November 3rd, 2009 at 8:40 pm
There is only one viable option for this problem. Those who sent things up into space must bring it back.
November 3rd, 2009 at 9:35 pm
I've just done a rough back-of-the-envelope calculation of how many bits of debris lotusface's scooper satellite could collect and the answer is not very many.
The surface area of the Earth is roughly 5×10^11 square meters, and the low earth orbit region is about 10^6m high. That's a volume of 5×10^17 cubic meters. Let's say there are one million bits of debris up there, so there will be about 2×10^(-12) bits per cubic meter.
Let's say now that the scooper satellite has an effective collecting area of ten square meters (ie. a diameter of about 3.5m or 4 yards). The volume of space it can scour in one orbit will be the area times the length of the orbit. The circumference of the Earth is about 4×10^7m so the cleared volume is something like 4×10^8 cubic meters, which means you'll sweep up about 0.0008 objects per orbit. If an orbit takes 90 minutes (same as the ISS) you'll clear a whopping four or five bits of debris in a year.
November 3rd, 2009 at 9:50 pm
lotusface — your suggestions about catching orbital debris and using "mitts" of aerogels have been seriously proposed! These are not suggested as a way of cleaning up NEO space, but as a sort of shield in front of a spacecraft.
LC
November 3rd, 2009 at 10:36 pm
William928 Says:
November 3rd, 2009 at 8:33 pm
"Why not program the satellites to exit NEO and fly off toward the edges of the solar system after their missions are completed, as Nexus has suggested?"
That would also require a great deal of fuel – even though these objects are in orbit, there would still be a large amount of deltaV required to get them to escape Earth orbit all together. And then you have to make sure that they don't go into an Earth-crossing solar orbit, because that would be even worse than simply having it orbit around up there in the first place! Programming them to gently nudge themselves into the atmosphere and then drop into the Pacific may be feasible. The problem is, I think a lot of the junk is just that – bits of junk that have fallen off or been ejected from craft as they are launched or maneuvered. It would be impossible to fix little rockets and computers to each of these sort of things prior to launch just so they can be deorbited…
November 3rd, 2009 at 11:04 pm
I still think Nukes could be used at the poles of Earth in space high above the orbits to sonic wave the debris into a Ring like Saturns then we could scoop it all back up.The rest would de-orbited and/or be scattered across the solor system..8^)
November 4th, 2009 at 12:17 am
This is a very interesting (for obvious reasons) problems of the commons. Here is a recent article discussing debris mitigation, including two possible concepts along lotusface ideas.
[One solution: use a nerf ball. A large nerf ball. New problem: It snags active vehicles as well. Swat!
lotusface idea is apparently possible according to NASA Orbital Debris Program Office's review, but "complicated and costly". I imagine that you only have to snag satellites faster than they become inactive, and the current debris would de-orbit eventually.
IIRC I've seen estimates, likely here on UT, that ~ 10 of those later gizmos would suffice to decrease debris over time, at the current launching rate. Can anyone confirm? Perhaps it's in the review.]
@ HB:
…, well, yes, no one made any viable suggestion indicating otherwise.
AFAIU, sound waves can travel in space under some specific conditions.
(Dense clouds, I believe. Here is a Bad Astronomy article discussing it: "The exception would be in a nebula, or giant cloud of gas. Sound can travel through a nebula, as gas molecules (or atoms) bump into each other, transmitting the sound wave. But this situation isn't like here on Earth, and sound as we know it wouldn't travel well.")
I doubt this is one of them.
[Maybe you mean some sort of analogous "collision" shock wave, say shocked debris knocking on other debris? I doubt that works either.]
November 4th, 2009 at 12:19 am
Oops! Sorry about my too-early-in-the-morning-and-still-too-little-coffee-in-my-system induced html snafu.
November 4th, 2009 at 5:33 am
The best approach really is to design space systems which don't produce orbital debris. This means deorbiting dead satelites. design shrods which do not separate in debris and so forth.
LC
November 5th, 2009 at 7:24 am
Lawrence Crowell says: "The best approach really is to design space systems which don't produce orbital debris. This means deorbiting dead satellites. design [shrouds] which do not separate in debris and so forth." This has always seemed like an obvious solution to me as well. Sure, initial costs _may_ be higher, but the reduction of this hazard would have long term payoffs (i.e. hazard reduction, collision avoidance). I worry, though, that nations with nascent space programs (or private companies) will not have the capital or incentive to adopt 'waste management' and debris containment policies. While I'm all for more international and private utilization of space, I do see increasing problems with space debris as the cost to launch a payload falls. Perhaps it's time to look at 'regulating' or mandating rules that nations and private companies would be required to follow if they plan flights to LEO, MEO or geosynchronous orbits and beyond (some spacefaring nations are already voluntarily implementing space debris management or abatement). The rapid rise in space programs around the world makes some solution necessary before the danger of space debris threatens us all.