Satellite Formation Flying and Rendezvous

Abstract

GNSS has come to play an increasingly important role in satellite formation-flying and rendezvous applications. In the last decades, the use of GNSS measurements has provided the primary method for determining the relative position of cooperative satellites in low Earth orbit. More recently, GNSS data have been successfully used to perform formation-flying in highly elliptical orbits with apogees at tens of Earth radii well above the GNSS constellations. Current research aims at distributed precise relative navigation between tens of swarming nanoand micro-satellites based on GNSS. Similar to terrestrial applications, GNSS relative navigation benefits from a high level of common error cancellation. Furthermore, the integer nature of carrier phase ambiguities can be exploited in carrier phase differential GNSS (CDGNSS). Both aspects enable a substantially higher accuracy in the estimation of the relative motion than can be achieved in single-spacecraft navigation. Following historical remarks and an overview of the state-of-the-art, this chapter addresses the technology and main techniques used for spaceborne relative navigation both for real-time and offline applications. Flight results from missions such as the Space Shuttle, PRISMA, TanDEM-X, and MMS are presented to demonstrate the versatility and broad range of applicability of GNSS relative navigation, from precise baseline determination on-ground (mm-level accuracy), to coarse real-time estimation on-board (mto cm-level accuracy).