Technology validation of the autonomous formation flying sensor for precision formation flying

A Radio Frequency (RF) based sensor, called the Autonomous Formation Flying (AFF) sensor, has been developed to enable deep space precision formation flying by measuring the relative range and bearing angles between multiple spacecraft. The AFF sensor operates at Ka-band and uses signal-processing schemes inherited from the Global Positioning System (GPS). The key features of the AFF sensor are: (a) it operates autonomously without the aid of spacecraft or ground control, (b) it simultaneously provides a wide field of view and accurate angle and bearing angle measurements and it provides accuracy better than 2 cm and 1 arcmin (1-σ) near the bore-sight of the antenna, and (c) it provides telemetry among the constellation elements. In this paper we describe the key technology challenges, the approach to resolving them through analysis and testbed activities, and the results of the testbed activities.