Precise Range And Range-Rate Equipment | PRARE

The picture on the left shows components of a PRARE ground station. The picture on the right shows the PRARE time system for determining the clock parameters of the PRARE space segment.
left: Components of a PRARE ground station right: PRARE time-system for the determination of clock parameter of the PRARE space segment (C. Falck, GFZ)

The PRARE-system (Precise Range And Range-Rate Equipment) was developed in Germany in the eighties to measure distances and relative velocities between special PRARE ground stations and PRARE space segments on various satellites. By means of these measurements it is possible to determine the satellites orbits and coordinates of the PRARE ground stations very precisely. The PRARE measurement principle (determination of signal travel times and frequency Doppler shifting) is basically very similar to those of the US GPS-system or the French DORIS-system. Compared with GPS and DORIS, PRARE allows, being designed as a two frequency two way system, a more direct monitoring of parameters being relevant for the system accuracy (e.g., clock parameters and system-internal signal travel times).

A globally distributes network of PRARE ground stations (development at DORNIER, resp. ND-Satcom) was installed and operated on behalf of ESA (European Space Agency), tracking the satellites ERS-1 (1991), Meteor 3-7 (1994-1995) and ERS-2 (1995-2007) (space segments by Timetech resp. Kayser Threde). After the foundation of the GFZ and direction of department 1 by Prof. Dr. Dr. h.c. Reigber (formerly Deutsches Geodätisches Forschungsinstitut, DGFI), it was GFZ Section 1.2 being responsible for the system operation and PRARE product provision since 1992 (formerly DGFI). The operation of the PRARE-system was ceased in January 2007, mainly due to ground station aging and cost reasons (no funding since 2004).

Project Partners:

  • ESA (European Space Agency)
  • DARA (German Agency for Space Affairs, now German Space Agency at DLR (German Aerospace Center))
  • TimeTech GmbH, Stuttgart, Germany
  • Agenzia Spaziale Italiana (ASI), Matera, Italia
  • Alfred-Wegener-Institute (AWI), Bremerhaven, Germany
  • Astronomical Observatory Kitab (AOK), Kitab, Uzbekistan
  • Astronomical Observatory La Plata (AOLP), La Plata, Argentina
  • Center for Space Research (CSR), Austin, Texas, USA
  • Council for Scientific and Industrial Research (CSIR), Pretoria, South Africa
  • Delft Technical University (DUT), Delft, Netherlands
  • Institute for Applied Geodesy (IfAG), Leipzig and Wettzell, since 6.8.1997 BKG, Germany
  • Indian Space Research Organisation (ISRO), Bangalore, India
  • Jet Propulsion Laboratory (JPL), Pasadena, California, USA
  • Laboratoire de Géologie-Géophysique de Nouméa (ORSTOM, IRD), New Caledonia
  • National Institute of Aeronautics and Space (LAPAN), Jakarta, Indonesia
  • Nippon Institute of Polar Research (NIPR), Tokio, Japan
  • Proudman Oceanographic Laboratory (POL), Birkenhead, UK
  • Research Center of Astronomy and Geophysics (AGRC), Ulaan Baatar, Mongolia
  • Shanghai Observatory (SAOB), Shanghai, China
  • Statens Kartverk (SK), Honefoss, Norway
  • University of Copenhagen (UC), Kopenhagen, Denmark

Project Duration:

  • GFZ: 1993 - 2007
    (before DGFI: 1988 - 1992)

Funding:

  • German Agency for Space Affairs (DARA)
    Support codes: 50 EE 9305, 50 EE 9539 and 50 EE 9904

Reference:

overview
back to top of main content