GRACE and GRACE-FO

GRACE
Illustration of the twin GRACE satellites
NamesGRACE-1 and GRACE-2[1][2]
Tom and Jerry[1][2]
ESSP-2A and ESSP-2B[3]
Mission typeGravitational science
OperatorNASA · DLR
COSPAR ID
  • 2002-012A
  • 2002-012B
SATCAT no.27391 and 27392
Websitewww.csr.utexas.edu/grace
Mission durationPlanned: 5 years
Final: 15 years, 7 months, 9 days
Spacecraft properties
BusFlexbus[3]
ManufacturerAstrium
Launch mass487 kg (1,074 lb) each[4]
Dimensions1.942 × 3.123 × 0.72 m (6.4 × 10.2 × 2.4 ft)[4]
Start of mission
Launch date17 March 2002, 09:21 (2002-03-17UTC09:21) UTC[5]
RocketRokot-KM #2[3]
Launch sitePlesetsk LC-133/3[3]
ContractorEurockot
End of mission
Declared27 October 2017 (2017-10-28)[6]
Decay dateGRACE-1: 10 March 2018,
     06:09 UTC[7]
     45°54′S 20°24′E / 45.9°S 20.4°E / -45.9; 20.4
GRACE-2: 24 December 2017,
     00:16 UTC[8]
     63°54′N 160°54′W / 63.9°N 160.9°W / 63.9; -160.9
Orbital parameters
Reference systemGeocentric
Semi-major axis6,873.5 km (4,271.0 mi)
Eccentricity0.00182
Perigee altitude483 km (300 mi)
Apogee altitude508 km (316 mi)
Inclination89.0°
Period94.5 minutes
Epoch17 March 2002, 04:21 UTC[5]

The Gravity Recovery and Climate Experiment (GRACE) was a joint mission of NASA and the German Aerospace Center (DLR). Twin satellites took detailed measurements of Earth's gravity field anomalies from its launch in March 2002 to the end of its science mission in October 2017. The two satellites were sometimes called Tom and Jerry, a nod to the famous cartoon. The GRACE Follow-On (GRACE-FO) is a continuation of the mission on near-identical hardware, launched in May 2018. On March 19, 2024, NASA announced that the successor to GRACE-FO would be Gravity Recovery and Climate Experiment-Continuity (GRACE-C), to be launched in or after 2028.[9]

By measuring gravity anomalies, GRACE showed how mass is distributed around the planet and how it varies over time. Data from the GRACE satellites is an important tool for studying Earth's ocean, geology, and climate. GRACE was a collaborative endeavor involving the Center for Space Research at the University of Texas at Austin, NASA's Jet Propulsion Laboratory, the German Aerospace Center and Germany's National Research Center for Geosciences, Potsdam.[10] The Jet Propulsion Laboratory was responsible for the overall mission management under the NASA ESSP (Earth System Science Pathfinder) program.

The principal investigator is Byron Tapley of the University of Texas Center for Space Research, and the co-principal investigator is Christoph Reigber of the GeoForschungsZentrum (GFZ) Potsdam.[11]

The two GRACE satellites, GRACE-1 and GRACE-2, were launched from Plesetsk Cosmodrome, Russia, on a Rockot (SS-19 + Briz upper stage) launch vehicle on 17 March 2002. The spacecraft were launched to an initial altitude of approximately 500 km at a near-polar inclination of 89°. During normal operations, the satellites were separated by 220 km along their orbit track. This system was able to gather global coverage every 30 days.[12] GRACE far exceeded its 5-year design lifespan, operating for 15 years until the decommissioning of GRACE-2 on 27 October 2017.[6] Its successor, GRACE-FO, was successfully launched on 22 May 2018.

In 2019, a glacier in West Antarctica was named after the GRACE mission.[13][14]

  1. ^ a b "GRACE 1". National Space Science Data Center. NASA. Retrieved 17 August 2016.
  2. ^ a b "GRACE 2". National Space Science Data Center. NASA. Retrieved 17 August 2016.
  3. ^ a b c d "GRACE (ESSP 2)". Gunter's Space Page. Retrieved 10 December 2017.
  4. ^ a b "GRACE Launch: Press Kit" (PDF). NASA. March 2002. Retrieved 11 December 2017.
  5. ^ a b "Trajectory Details: GRACE 1". National Space Science Data Center. NASA. Retrieved 23 May 2019.
  6. ^ a b NASA (27 October 2017). "Prolific Earth Gravity Satellites End Science Mission". Jet Propulsion Laboratory. Retrieved 31 October 2017.
  7. ^ "Decay Data: GRACE-1". Space-Track. 10 March 2018. Retrieved 11 March 2018.
  8. ^ "Decay Data: GRACE-2". Space-Track. 24 December 2017. Retrieved 13 February 2018.
  9. ^ "US, Germany Partnering on Mission to Track Earth's Water Movement". NASA Jet Propulsion Laboratory (JPL). 19 March 2024. Retrieved 21 March 2024.
  10. ^ "Grace Space Twins Set to Team Up to Track Earth's Water and Gravity". NASA/JPL. Archived from the original on 5 June 2011. Retrieved 14 August 2009.
  11. ^ "Mission Overview". University of Texas. 19 November 2008. Archived from the original on 15 May 2009.
  12. ^ "Gravity Anomaly Maps and The Geoid". Earth Observatory. NASA. 30 March 2004. Retrieved 14 March 2018.
  13. ^ Amos, Jonathan (7 June 2019). "Antarctic glaciers to honour 'satellite heroes'". BBC News. Retrieved 29 September 2019.
  14. ^ "Antarctic Glaciers Named After Satellites". European Space Agency. 7 June 2019. Retrieved 29 September 2019.