NASA's close call underscores the dangers of space junk
It doesn’t quite look like the rings of Saturn just yet, but Earth may one day have its own encircling band of particles if we don’t get our space junk under control. A lot of today’s technology relies on satellites quite a bit for connectivity. But while space is infinite, there is a surprisingly narrow band where most satellites can effectively roam, especially if they require geosynchronous orbit, as most of those engaged in communications activities do.
When satellites cease to function or break apart, it could be a very long time, sometimes more than 50 years, before they give up their parking spot and spiral back to Earth. Not only does this hog the road for other spacecraft, but it also creates a hazard that can take out other craft trying to operate in the same area.
Case in point: NASA recently reported a close call with its Fermi Gamma-ray Space Telescope at the end of March. An automated e-mail from the agency’s NASA's Robotic Conjunction Assessment Risk Analysis (CARA) alerted Fermi’s team that it was on course for “an unusually close encounter with Cosmos 1805, a defunct spy satellite dating back to the Cold War.”
Cosmos, an old Soviet spacecraft weighing in at 3,100 pounds, had a relative speed of 27,000 mph to Fermi; a collision would not only destroy both satellites but the explosion would be equal to 2.5 tons of high explosives, NASA said.
NASA was able to use Fermi’s thrusters, intended to take it out of orbit at the end of its life, to push Fermi out of harm’s way, but the incident shows what agencies making use of satellites are up against and how they’re working to track what’s in orbit.
The U.S. Strategic Command keeps, and openly shares, a list of tens of thousands of object in space, the Defense Department’s Armed With Science website has noted. Anyone can view the database after registering with the site.
NASA also is trying to get a handle on exactly how much junk is up there, but it’s a pretty big task. GCN reported on the Space Based Surveillance Network plans back in 2010. After a long delay, the first pathfinder satellite in that network is now online. Its job will be to find and track all of that debris, though it likely can’t do it alone.
More recent plans call for a janitor satellite that would grapple inoperable junk and send it spiraling back into the atmosphere. That sounds more like a warrior satellite to me, not a janitor, but in any case, the CleanSpace One looks really cool if we can ever get it launched and working.
Another method that has been proposed by NASA and Cornell University doesn’t involve any extra satellites at all. Instead, telescopes on the ground would target orbiting satellites with powerful lasers. But instead of a Star Wars-like explosion, which would only create more junk, the lasers would slow the satellites down, which would cause them to lose orbit and fall back to Earth, burning up in the atmosphere.
In the future, long-term orbiting junk may be less of a problem. With NASA experimenting with low-cost satellites that are essentially souped-up cell phones, there may no longer be a need to put objects in orbit for 50 years to defray the costs. The smart-phone satellites being tested right now cost less than $10,000 each. Their orbit is expected to decay, forcing them to burn up in the atmosphere, within about two weeks. But even if we adopt more disposable satellites for some tasks, more permanent ones will still remain, and the field of junk is already pretty thick.
Something will need to be done to clean up space, because future advancements can’t be held back by older, obsolete ones. And in any case, any sufficiently advanced society needs to abide by the same cardinal rule taught to five-year-olds everywhere: learn to clean up after yourselves.
Posted by John Breeden II on May 03, 2013 at 9:39 AM