Next Generation GNSS for Navigation of Future SAR Constellations

Paper number

IAC-06-C1.8.06

Author

Prof. Werner Enderle, The Engineers Australia, Australia

Coauthor

Dr. Hauke Fiedler, German Aerospace Center (DLR), Germany

Coauthor

Mr. Sergio De Florio, German Aerospace Center (DLR), Germany

Coauthor

Mr. Friedrich Jochim, German Aerospace Center (DLR), Germany

Coauthor

Mr. William Kellar, Queensland University of Technology, Australia

Coauthor

Mr. Shannon Dawson, Queensland University of Technology, Australia

Coauthor

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

Year

2006

Abstract

The next Generation of Global Satellite Navigation Systems (GNSS - GPS and Galileo) will provide enhanced performance with respect to signals, services, quality and quantity of measurements, availability, integrity and accuracy. Since in 2004, the European Commission (EC) and the USA signed an agreement about the compatibility and interoperability between GPS and Galileo, the combined use of both systems and respective measurements will have a significant impact on the design of future navigation systems in general. 

The upcoming potential for the development of new navigation systems is very important in the context of future, more challenging and complex requirements for space missions, especially into the Low Earth Orbit (LEO). One of the key elements for future missions is the maximization of onboard autonomy. This is especially true for the realization of new Synthetic Aperture Radars (SAR) mission concepts, based on formation flying in close formation (less than 30m distance) in LEO and dedicated to SAR interferometry missions. Such concepts may be based on onboard navigation concepts for real time orbit and attitude control. The requirements for onboard orbit determination depend on the requested SAR interferometric baseline and thus on the SAR frequency band used. For future SAR missions, relative position accuracy of less than 1mm in case of X-band observations will be required. 

This paper deals with investigations related to orbit- and attitude determination based on GPS and Galileo measurements. In this context the visibility conditions including link-budgets for GPS and Galileo satellites for a SAR formation flying mission into LEO will be analyzed and discussed. Special attention will be given to performance parameters like availability of GNSS satellites, accuracy of position solution, orbit- and attitude solutions, and geometry with the corresponding DOP figures.     

We present results from simulations for a SAR formation flying mission. Applicability and advantages and limitations of GNSS based concepts for orbit- and attitude determination in the context of SAR formation missions in LEO will be outlined and discussed in detail.

Abstract document

IAC-06-C1.8.06.pdf

Manuscript document

IAC-06-C1.8.06.pdf (🔒 authorized access only).

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