Precise re-entry and landing of propellantless spacecraft

Abstract

Spacecraft returning scientific samples or humans from space must be capable of surviving re-entry and landing in a desired location. Traditionally, this has been accomplished via a propulsive de-orbit burn. However, it is not always possible to mount a propulsion system on board a satellite or a capsule. In the case of small satellites deployed from the International Space Station, for example, on-board propulsion systems are forbidden for safety reasons. Our work proposes a new technological solution for re-entering and landing a spacecraft in a desired location from a low Earth orbit using exclusively aerodynamic drag and eliminating the need for chemical propulsion. First, an iterative procedure is utilized to compute the desired state at the re-entry interface (100 km) such that a propagation of the vehicle dynamics in the nominal re-entry drag configuration from this initial state leads to a landing at a desired latitude and longitude on the surface of the Earth. Next, a re-entry point targeting algorithm is utilized to determine the on-orbit ballistic coefficient profile necessary to target the desired re-entry point. Finally, the ballistic coefficient profile during the final hours of the trajectory before the re-entry interface is iteratively modified to correct any remaining along-track error in the landing location. The proposed solution is applied to a small satellite system that is jettisoned from the ISS and is equipped with a deployable heat shield that also serves as a drag device.