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GRACE (Gravity Recovery and Climate Experiment) mission is a joint project between the National Aeronautics and Space Administration (NASA) and Deutsches Zentrum für Luft- und Raumfahrt (DLR). The twin satellites were built by Astrium and launched together with a Rockot in 2002, the mission is operated by the German Satellite Operations Centre and after ten years the mission is still producing outstanding results.

The primary science objective of GRACE is to measure the Earth's gravity field and it's time variability with unprecedented accuracy. The secondary science objective is to obtain approximately 150 very precise globally distributed vertical temperature and humidity profiles of the atmosphere per day using the GPS radio occultation technique.

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GRACE operational issue: Planned switch-on of Microwave Assemblies

19 January 2015

The GRACE-A and -B Microwave Assemblies (MWA) and Accelerometer Instrument Control Units (ICU) have been switched-on again on:

  • 07 January 2015, 12:03 UTC: GRACE-A and GRACE-B ICU
  • 13 January 2015, 5:32 UTC: GRACE-A MWA (continuously on since 23:40, before ca. 7-12 minutes off each orbit)
  • 13 January 2015, 5:32 UTC: GRACE-B MWA (continuously on since 06:42)

GRACE operational issue: Planned switch-off of Microwave Assemblies

10 December 2014

The GRACE-A and -B Microwave Assemblies (MWA) and Accelerometer Instrument Control Units (ICU) were switched-off on:

  • 3 December 2014, 14:58 UTC: GRACE-B MWA
  • 4 December 2014, 14:09 UTC: GRACE-A MWA
  • 6 December 2014, 14:04 UTC: GRACE-A and GRACE-B ICU

Both activities are related to battery load reduction.

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Mission Data:

The GRACE Level 1B and Level 2 science data and corresponding documentation is publicly available at the two GRACE archives:

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Facts and figures
Operators German Satellite Operations Centre (GSOC)
Date of launch: 17 February 2002
Status: Operating nominally in 2015 (mission status regularly updated at UTCSR)
Orbit Height 447 km (as of 29 Mar 2012)
Orbit Type Near-polar (89.5 degrees)
Onboard Sensors provided under TPM - GPS receiver
- Star camera sensors
- Accelerometer system
- K-Band satellite-to-satellite tracking system
- Laser Retro-reflector