Safe Release of a Picosatellite from a Small Satellite Carrier in Low Earth Orbit

Abstract

The BIROS satellite, which is scheduled for launch in 2015 into a low Earth orbit, will carry onboard a picosatellite and subsequently release it through a spring mechanism with a fixed velocity. In the frame of the AVANTI experiment, the BIROS satellite will perform proximity maneuvers in a mid-range formation with the picosatellite, based solely on optical navigation through its onboard camera. Therefore it is necessary to keep the relative distance of the two spacecraft within certain limits. This is contradicted by the fact, that the spring mechanism is designed to create a large and safe separation between the two spacecraft. In this paper a maneuver strategy is developed in the framework of relative orbital elements. The goal is to avoid any risk of collision on one side and to mitigate the possibility of formation evaporation on the other side. Main design drivers are several uncertainties—most prominently the performance uncertainty of the release mechanism. The analyzed strategy consists of two maneuvers: the separation itself and a drift reduction maneuver of the BIROS satellite after 1.5 revolutions. Afterwards a third maneuver is to be performed to minimize the residual drift, estimated through an orbit determination with radar tracking. The selected maneuver parameters are validated in a Monte Carlo simulation. It is demonstrated that the risk of formation evaporation is below 0.1% as well as the eventuality of a residual drift towards the carrier. In the latter case formation safety is guaranteed by a passive safety achieved through a proper relative eccentricity/inclination vector separation.