Its hard enough to tackle pollution on Earth, let alone in space. However, the recent NASA UARS spacecraft fall has put the phenomenon of space debris in sharp spotlight. Man-made space objects that are still in orbit but defunct are called orbital debris.
These include several types of items ranging from derelict spacecraft and upper stages of launch vehicles, carriers for multiple payloads, debris intentionally released during spacecraft separation from its launch vehicle or during mission operations. Currently more than 22,000 objects larger than 4 inches are under surveillance. Only about 1,000 of these represent operational spacecraft, the rest are orbital debris.
The higher the altitude, the longer the orbital debris will remain in the Earth’s orbit. Within a month of the UARS spacecraft, German satellite Rosat fell into the Bay of Bengal on an unscheduled re-entry. The lower orbits of the Earth are crowded with satellites, increasing the chances of collision. With two such incidents happening a month apart, there is a serious need to look into this problem.
There are several solutions being proposed. One of the leading solutions is by the Defense Advanced Research Projects Agency (DARPA) which has a plan to recycle billions of dollars worth of non-working satellites. The agency announced last week that there is more than $300 billion worth of satellites drifting through space 22,000 miles from the Earth’s surface. All of these are defunct or obsolete but still have many working parts. Through DARPA’s Phoenix Program, they plan to harvest these parts like antennae and reuse them in new projects. This could save the Defense Department millions of dollars.
Of course, recycling in space is not going to be as easy as recycling on Earth. There is a need for advanced robotics as well as further research into the exact methodologies of bringing space junk home to be broken down. According to David Barnhart, DARPA program manager:
“Satellites in orbit are not designed to be disassembled or repaired, so it’s not a matter of simply removing some nuts and bolts. This requires new remote imaging and robotics technology and special tools to grip, cut and modify complex systems.”
The agency is talking about using a ground-based robotics system and eventually they hope to set up a satellite servicing station. Smaller particles can be destabilized by firing lasers so that they plunge out of orbit and burn up. The challenge for the future, would be using advanced materials technology to ensure that future space crafts can be easily recycled.
Prudent vehicle design and operation is now needed, with unnecessary launch of satellites curbed. Although cleaning up space provides massive technical and economic challenges, a global effort is needed in order to ensure that space debris can be productively reused.
Image Credit: A nearly full Moon sets as the space shuttle Discovery sits atop Launch pad 39A at the Kennedy Space Center in Cape Canaveral, Florida, Wednesday, March 11, 2009. (NASA/Bill Ingalls)