Global Aerospace Corporation is developing a Gossamer Orbit Lowering Device (GOLD) for safe and efficient removal from Low Earth Orbit (LEO) of dangerous space junk. The patented GOLD system concept uses a very large ultra thin balloon envelope to increase the aerodynamic drag by a factor of several hundred. This will cause the space junk to enter the earth’s atmosphere quickly and burn up. It will reduce the natural orbit decay of some objects from centuries to months. The computer-generated figure below illustrates a GOLD system de-orbiting a large scientific observatory.
The envelope material is thinner and lighter than sandwich bag material. It takes a very small amount of gas to inflate it in the almost perfect vacuum of space. The system will work even though it will get punctured many times by small debris objects and tiny meteoroids. Despite these small holes, the total leak rate will be very small. The pressurization system will very easily keep up with the leakage. In the very unlikely event that a large object hits the very thin envelope, it will not cause that large object to break up into new fragments. Therefore, the operation itself of GOLD cannot make the orbital debris environment worse as could be the case with some alternative de-orbit concepts that others have suggested like electromagnetic tethers, gravity gradient tapes and boom-supported films that can have a dangerously large effective Area-Time-Product for collisions with operating satellites.
Although the ultra thin envelope could be the size of a sports field (100 m diameter) when inflated, it is so thin that it can be folded and stowed in a surprisingly small volume (a medium size suitcase). There are three possible applications of GOLD. It is most economical to attach it to a spacecraft or rocket upper stage before launch and deploy it after the end of mission. However, GOLD could be attached to existing large debris objects using an orbital robot. For large dense objects that could pose a hazard to people or property on the ground during reentry, GOLD can be used to aim the reentry safely into an ocean.
We tend to think of space as being a complete vacuum, but there are enough molecules and atoms out to several hundred miles to produce a small but noticeable drag that slowly reduces the orbital altitude of spacecraft. GOLD takes advantage of this effect and increases it by a factor of several hundred. The air at these altitudes has a very small density. Sun spot activity is known to follow an eleven-year cycle, with an associated cycle in the radiation coming from the sun. At “solar max”, the extra radiation causes the Earth’s atmosphere to bloom outward, increasing the average air density in LEO by a factor of three. When GOLD is attached to a spacecraft, it is usually beneficial to wait until solar max to use it because it then brings down that satellite three times faster than average.
GOLD can be integrated onto the satellite prior to launch or attached to derelict satellites by robots to begin active debris removal from the most important orbital regions. De-orbit from LEO can be reduced, in some cases, from many centuries to as little as a few months and for a tiny fraction of the cost of a spacecraft. Such a system can assist civilian, commercial and military space satellite operators in meeting their obligations to mitigate the growing space debris problem in a cost effective and low risk way. This invention has been patented under US Patent # 6,830,222.
In summary, the operation of GOLD has a lower risk of disabling other operational satellites and a lower risk of creating large orbit debris objects than competing de-orbit concepts or the derelict satellite itself. In addition, GOLD does not require an operating satellite to provide attitude stabilization or power as with propulsive de-orbit. GOLD can be integrated onto the satellite prior to launch or attached to derelict satellites by robots. De-orbit from LEO can be reduced, in some cases, from many centuries to as little as a few months. Finally, GOLD can assist civilian, commercial and military space satellite operators in meeting their obligations to mitigate the growing space debris problem in a cost effective and low risk way. |
