Gravity Recovery and Climate Experiment (GRACE)
GRACE is a joint project between the National Aeronautics and Space Administration (NASA) and the Deutsches Zentrum für Luft- und Raumfahrt (DLR). The key partners of the Science Data System are the University of Texas Center for Space Research (CSR), the Jet Propulsion Laboratory (JPL), and the German Research Centre for Geosciences (GFZ).
The primary science objective of the GRACE mission is to measure the Earth’s gravity field and it’s time variability with unprecedented accuracy for a better understanding of Earth's water reservoirs over land, ice and oceans. The increase in accuracy has been achieved by utilizing two (twin) satellites following each other on the same orbital track. To consider precise attitude and non-gravitational forces both satellites are equipped with star cameras and accelerometers. The position and velocity of the satellites is measured using onboard GPS antennae and (for validation purposes) SLR retro-reflectors. Additionally, the twin satellites are interconnected by a K-band microwave link to measure the exact separation distance and its rate of change to an accuracy of better than 0.1 µm/s. These measurements are directly coupled to the seasonal and sub-seasonal variations in the continental hydrological cycle, to ice mass loss in the large glacier systems in Greenland or Antarctica, to long wavelength ocean circulation processes or to the transport of ocean heat to Earth’s poles. Consequently, since its launch in March 2002 this fundamental dataset has enabled dramatic improvements of seasonal and inter-annual climate change estimates.
The secondary science objective of the GRACE mission is to obtain about 150 very precise globally distributed vertical temperature and humidity profiles of the atmosphere per day using the GPS radio occultation technique.
As mission lifetime of GRACE is limited, NASA and GFZ are currently implementing a GRACE-FO (Follow-on) mission which is due for launch early 2018.
To get access to the different GRACE (Level-1B or Level-2) data and documentation (monthly newsletters and various project related documentation) via FTP please follow the link on the left hand side. Here, the “Guide to Available Data” provides further useful information on recent data distribution. Please also read the latest GRACE SDS Newsletters!