Aman Chandra, University of Arizona; Jekan Thangavelautham, University of Arizona
Keywords: De-orbit; space debris; CubeSats; inflatables
Abstract:
Small-satellites and CubeSats offer a low-cost pathway to access Low Earth Orbit at altitudes of 450 km and lower thanks to miniaturization and advancement in reliability of commercial electronics. However, at these low altitudes, atmospheric drag has a critical effect on the satellite resulting in natural deorbits within months. As these small systems further increase in reliability and radiation tolerance they will be able readily access higher orbits at altitudes of 700 km and higher, where atmospheric drag has little to no effect. This requires alternative technologies to either de-orbit these small spacecrafts at the end of life or move them to a safe parking orbit. Use of propulsion and de-orbit mechanisms have been proposed, however they require active control systems to be trigged. Other typical de-orbit mechanism rely on complex mechanisms with many moving parts. In this work, we analyze the feasibility of using inflatable de-orbit devices that are triggered passively when a spacecraft is tumbling. Inflatables have already been proposed as hypersonic deccelerators that would carry large payload to the Martian surface. However these systems are quite complex and need to withstand high-forces, temperature and enable survival of a critical payload. Furthemore, inflatables have been proposed as communication antennas and as structures using a class of sublimates that turn into gas under the vacuum of space. These inflatbles system are relatively simple and does not require a specialized inflation system. Furthermore, these inflatable can be rigidized using UV curable resin that hardens the inflatable shell. Inflatables offer the best mass to volume ratio and can be hardened to form solid shells. The proposed inflatable de-orbit device needs to perform several functions, including reducing tumbling followed by setting the dead spacecraft on a path towards orbit degradation. Tumbling reduction requires use of passive mechanisms to provide a suitable counter-torque to a tumbling spacecraft. This can be achieve using Solar Radiation Pressure (SRP). A large enough drag area needs to be created by the inflatable to gradually reduce the orbit of a small satellite and have it on a predictable deorbit trajectory. A large footprint produced by the de-orbit device simplifies ground based tracking. In this work, we analyze the impact of deploying a 1, 2, 3 and 5-meter sized inflatable as de-orbit device. Furthermore, we analyze the total footprint of the de-orbit device on the spacecraft. Alternately, we also consider combined de-orbit device and inflatable communication antennas to determine its figure-of-merit. Our studies show potential feasibility of an inflatable deorbit device for CubeSats at higher altitude in Low Earth Orbit. However, certain unknowns are the subject of further study including long-term effects of UV and solar radiation on the inflatable membranes.
Date of Conference: September 11-14, 2018
Track: Poster