The space environment around the earth is now littered with both functioning and non-functioning satellites. This is over and above the man-made debris generated as a result of launching these space objects and their density is increasing exponentially with time. If nothing is done about this, the earth will eventually have its own Saturn ring if not a spherical shell of orbiting objects and debris. There is definitely a pressing need for an inexpensive and reliable method of de-orbiting satellites after their mission life has ended. We propose to carryout a for a passively deployable, lightweight, low-compaction ratio bolt-on de-orbit device for satellites. The de-orbiter is packaged into a small bolt-on canister that gets attached to the spacecraft. It stays in the packaged configuration until the end of the satellite mission at which time it is activated deploying the de-orbit element out of its canister, increasing the spacecraft drag area against the atmosphere. For high low-earth orbit starting altitudes where the atmospheric density is extremely low, the de-orbiter drag sail is made to work like a solar sail capitalizing on the solar radiation pressure but in this case to decrease the satellites energy thereby lowering its altitude over time. It is pointed out that using this solar-sailing approach has practically unlimited delta v capability. The innovation in the proposed de-orbiter design is the use of a proprietary shape memory composite material for the structural elements of the de-orbiter. It is foldable and packageable into a small stowed volume and deployment is passively achieved by simply releasing the stored strain energy in the packaged configuration. Tests and measurements performed in the laboratory show that the material formulation we use achieves deployment to the memorized configuration even after the material has been in the folded state for years. When the solar sail mode is used, it can be used to extend the satellite lifetime.
NASA can use the drag sail as de-orbiter devices for satellites in low earth orbit. And for higher starting altitudes where the atmosphere is extremely thin, the de-orbiter is made to work like a solar sail capitalizing on the solar radiation pressure but in this case to decrease the satellite energy to lower the satellite altitude over time. This approach has practically unlimited delta v capability. In fact, the drag solar-sail configuration can be made to work in GEO orbit to place non functioning satellites in higher parking orbits.
The military and commercial sectors will find the de-orbiter design as an inexpensive addition to their payloads to enable de-orbiting their spacecrafts after mission life has ended. When the solar-sail mode of the de-orbiter is turned on, the de-orbiter can be used to increase the satellite lifetime on orbit.