RADIO FREQUENCY BASED NAVIGATION FOR PRISMA AND OTHER FORMATION FLYING MISSIONS IN EARTH ORBITS
- Paper number
IAC-09.C1.4.9
- Author
Dr. Michel DELPECH, Centre National d'Etudes Spatiales (CNES), France
- Coauthor
Mr. Jon Harr, CNES, France
- Coauthor
Mr. Pierre-Yves Guidotti, Centre National d'Etudes Spatiales (CNES), France
- Coauthor
Mr. Thomas Grelier, Centre National d'Etudes Spatiales (CNES), France
- Year
2009
- Abstract
Radio Frequency (RF) metrology represents an appropriate technology for future formation flying missions that will fly beyond GPS access. It will be especially required to perform formation acquisition and guarantee collision avoidance. Such a RF sensor derived from GPS receiver technology has been developed under CNES funding for the PRISMA technology mission to be flown in 2009. This bi-satellites technology mission funded by Sweden in cooperation with several European agencies will demonstrate in LEO autonomous rendezvous and Formation Flying (FF) techniques. CNES contributes by providing the RF sensor and GNC software to perform some FF experiments based on a technology that will be flown for the very first time. This paper will present the major technical challenges related to the implementation of an autonomous navigation system involving tight interaction between RF sensor and GNC software. Performances will be described afterwards for various mission conditions and reusability for subsequent applications will be discussed in the last part. This RF sensor subsystem, providing an inter satellite link service, includes one RF terminal and several antennas on each formation satellite. Each terminal exchanging GPS like signals with the other satellites can therefore compute relative range and line of sight (LOS) measurements of companion satellites. The sensor performs only signal filtering whereas the satellites GNC takes over for relative state estimation. Besides, it must be aided by S/C GNC to achieve initialization (ambiguity removal). The design of the Navigation Function will be fully described in the final paper. Its main task is the estimation of the Chaser S/C relative state with respect to Target S/C with an Extended Kalman Filter that includes a model of each spacecraft absolute dynamics. A critical feature is the estimation of electrical and multi-path biases affecting LOS measurements. Another major task is the sensor handling which involves feeding aiding data and triggering reconfiguration in case of anomaly. Performance characterization has been performed in simulations using detailed models of the RF sensor including multi path maps obtained from measurement campaigns in anechoic chamber. Bias estimation has shown its benefits in the various tests where outstanding performances were achieved for ranges up to 10 km (navigation errors less than 1 cm on distance and 35 cm on lateral position at 10 km range). Further simulations have been also conducted to illustrate what performances could be achieved on future foreseen missions such as Proba3 and Simbol-X and possible adaptation will be discussed.
- Abstract document
- Manuscript document
(absent)