New Technology Needed to Clean the Heavens

Who is responsible for outer-space litter? And if you drop something when your out there in orbit, does it just float around? Or is it a loose cannon?

They make so much noise, the garbage collectors. “Crash! Bang! Hey, grab that one there!” The Swiss are much more genteel it seems. They are planning to use robots to clean the heavens. Singapore can’t be far behind.

n the world of spaceships and rockets “Space Junk” is a big problem. NASA has a special name for it and what it does: FOD, Foreign Object Damage. A wrench that was “dropped” by an astronaut on a spacewalk can blow a hole through the next $billion dollar satellite quite easily. It would be like a bullet going through a plastic airplane. Consider that a bullet from a high-powered rifle might be traveling at 2900 feet/second. A lost wrench in orbit could hit a spacecraft or astronaut at twice the orbital velocity of 17,000 miles/hour. That is at 49,867 feet/second.

NASA has elaborate rules and procedures for all, extra vehicular activities (EVAs), or space walks to tether tools and manage parts used for a job in space. They also have designed spacecraft and spacesuits to mitigate FOD, to some degree, with armor, layers, and backup systems.

The US Air Force maintains a tracking facility to track orbiting debris and even flies satellites to monitor it. When China shot down an obsolete weather satellite in 2007 there was an outcry worldwide about the mass of floating garbage it created. All spacefaring nations, China included, have to be responsible for this. It could be China’s own astronauts who are killed by it.

The Swiss announcement is more about saying “Switzerland has the technology to fly robot spacecraft” than it is about cleaning up space junk. Most large chunks of space garbage are easy to track and avoid. It is the little bits like a single screw or lost safety line that are the hard items to track and clean up. But any attempt to manage the problem, the Swiss included, is good.

For debris and derelict spacecraft, boosters, and equipment in low earth orbits (LEO) gravity will eventually remove them from orbit in reasonable amounts of time. Russian and American spacecraft are nudged or fall from orbit on their own regularly, as do the smaller bits associated with them and their launch. Operational spacecraft like the International Space Station (ISS) and Space Telescope (HST) require boosts from visiting spacecraft to keep them in their orbits. This is called Orbital Decay. In the next decade of the 2020′s it will be time to de-orbit the ISS. That will be quite a light show. Without regular additions of energy to the orbit of the HST it will return to Earth in less than 25 years on its own.

On the other end of the orbital spectrum are the geosynchronous satellites (GEO). GEO is 22,236 miles above the earth. This is where all the communications satellites fly. At 6876 miles per hour they orbit the earth every 24 hours. This means that they can sit over one point on the equator all the time as they match the rotation of the earth. At that altitude the orbits last for tens-of-thousands of years. Deorbiting used up vehicles from that altitude is unrealistic and disruptive to everything in orbit below them. They are disposed of by raising their orbits even higher. Above GEO there is a huge cloud of “Flying Dutchmen” abandoned space vehicles. There are more added every year. Archeology for the future…