Autonomous Formation Flying at DLR's German Space Operations Center (GSOC)

Paper number

IAC-07-D1.2.01

Author

Mr. Thomas Rupp, German Aerospace Center (DLR), Germany

Coauthor

Mr. Simone D'Amico, German Aerospace Center (DLR), Germany

Coauthor

Dr. Oliver Montenbruck, German Aerospace Center (DLR), Germany

Coauthor

Prof. Eberhard Gill, Delft University of Technology (TU Delft), The Netherlands

Year

2007

Abstract

In the upcoming years, significant changes in the profile of satellite missions are expected as scientists and managers want to benefit from multi-satellite missions.
Among others, distributed or virtual satellite platforms will create a completely new class of space missions, where not one single spacecraft or payload segment has to be operated but a formation or constellation of satellites. A “formation” designates multiple satellites in close proximity and is typically characterized by demanding navigation and control requirements.

In principle satellites can be flown in a formation either by ground control or in autonomous mode. In the first case guidance, navigation and control tasks are primarily performed on-ground with tight constraints in terms of ground-station visibility. This introduces severe limitations on the achievable control accuracies. On the contrary on-board autonomy guarantees superior performance and prompt response to contingencies. The continuously increasing demand of spatial and temporal resolution for aperture synthesis can only be satisfied by space-borne autonomous formation flying systems. Furthermore drastic cost reductions can be expected.

With this perspective in mind, GSOC has implemented a dedicated research and development program on “Autonomous Spacecraft Navigation and Formation Flying”. It was initiated in 1998 and has since then made numerous contributions in the area of space-borne GPS receiver technology, precision relative navigation and autonomous orbit control of satellite formations as a prerequisite for spacecraft autonomy.

Practical experience in the operation of a two-satellite formation has now been gained since 2002 within the frame of the GRACE mission. In an effort to move to shorter baselines with intrinsically higher navigation and control requirements, GSOC is now supporting the Swedish Space Cooperation in the implementation of the PRISMA formation flying demonstration mission which will be launched in 2009. Key contributions include a GPS based navigation system enabling highly accurate absolute and relative positioning of the two spacecraft at separations of 0.1-10 km as well as guidance and control concepts for safe proximity operations. Here GSOC’s Space-borne Autonomous Formation Flying Experiment (SAFE) will be conducted to demonstrate a fully autonomous, robust and precise formation flying of spacecraft. Also launched in 2009, the German TerraSAR-X/TanDEM-X radar satellites will be Europe’s first space mission equipped and operated routinely with an autonomous formation flying system. Dedicated functions for formation guidance, navigation and control will be implemented on-board the TanDEM-X spacecraft to enable a simple and robust formation control in order to ease on-ground operations and to reach the scientific goals.

Abstract document

IAC-07-D1.2.01.pdf

Manuscript document

IAC-07-D1.2.01.pdf (🔒 authorized access only).

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