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The NASA/German Space Agency (DLR) Gravity Recovery and Climate Experiment/GRACE Follow-on (GRACE and GRACE-FO) platform consists of two identical satellites that act in unison as the primary instrument. The two satellites comprising each mission orbit one behind the other in the same orbital plane at an approximate distance between the two satellites of 220 km (137 miles). 

As the satellite pair circles Earth, areas of slightly stronger gravity affect the lead satellite first, pulling it toward the planet and away from the trailing satellite. As the satellites continue along their orbital path, the trailing satellite passes over the gravity anomaly and is pulled toward the lead satellite. An extremely precise ranging system aboard both GRACE and GRACE-FO detects minute changes in the distance between the satellite pairs.

Learn more about GRACE/GRACE-FO

Type

Earth Observation Satellite

Data Center

PO.DAAC

Launch

GRACE: March 17, 2002 GRACE-FO: May 22, 2018

Objective

Measure Earth's gravity
The above animation was creating using the Jet Propulsion Laboratory (JPL) Tellus Mascon Release 06.1 v03 product derived from GRACE/GRACE-FO, covering April 2002 to Sept. 2022. Credit: PO.DAAC

A general rule of thumb for choosing which data set to use: most non-expert users interested in hydrology, ice mass, and ocean bottom pressure mass change should look at the MASCON gridded data products (e.g. 10.5067/TEMSC-3MJ634 and 10.5067/TEMSC-3JC634) and the globally averaged Level 4 time series products (10.5067/TEMSC-AT634, 10.5067/TEMSC-GT634, and 10.5067/TEMSC-OT634). These products combine the records from GRACE and GRACE-FO into a longer time series and are added to monthly. 

Advanced users wanting gridded fields based on the traditional spherical harmonic basis functions, or users looking at gravity field analysis, sensitivity studies, and solid Earth processes should consult the Level 2 spherical harmonic gravity field products and Level 3 Tellus products. Note there are different solutions provided from each of the three GRACE project partners.

The GRACE/GRACE-FO mission is a collaboration between NASA's Jet Propulsion Laboratory (JPL) and and the German Research Centre for Geosciences (GFZ) with additional contributions from The University of Texas Center for Space Research (CSR).

Access general documentation and technical notes for GRACE/GRACE-FO.

Instruments Aboard GRACE/GRACE-FO

Instrument Name Operational Date(s) Spectral Resolution Type of Instrument
GRACE Interferometer March 17, 2002 - present Spectrometer/Radiometer
GRACE-FO Laser Ranging Interferometer (GRACE-FO LRI) 2018 - present Positioning/Navigation

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