Modern miniaturization technologies enable the realization of very small satellites at masses below 1kg, nevertheless limited attitude determination and actuator performances raise challenging control problems. Specific attitude determination aspects discussed at the example of UWE (University of Wuerzburg Experimental satellite), a standardized pico-satellite platform related to technology demonstration and space research. UWE-1 is in orbit since October 2005 and successfully completed its mission on telecommunication experiments. The successor satellite UWE-2 is focusing on an advanced Attitude Determination System (ADS) based on miniature sensors. This paper will address implementation details for the ADS, presenting in particular results from the performance evaluations in simulations and tests.

Abstract:A group of satellites can be classified as a constellation, formation or cluster. Multiple coordinated satellites are described as a formation, if a closed-loop control is adjusted, thus providing a coordinated motion control on basis of their relative positions to preserve the topology (Schilling [2009]). This technology enables various application scenarios, for example, interferometry or in-orbit servicing and it is subject to multiple technological requirements related to formation flying, limited resources or scientific payloads. In the framework of the feasibility study NaKoFo, this paper discusses the potential benefits, drawbacks and problems associated with intersatellite links and relative navigation with pico-and nanosatellites. The requirements of an intersatellite link are analyzed based on frequency, modulation, antenna, power and network protocol. A short overview of adequate communication systems for pico-and nanosatellites is also presented. Technologies for relative position determination are presented and discussed regarding their applicability in small satellite systems as well as their requirements on an intersatellite link.