LISA technology is now being used for Earth observation and will improve future satellite geodesy missions. GRACE Follow-On will observe the critical indicators of climate change through changes in Earth's gravitational field.
GRACE (Gravity Recovery and Climate Experiment), is a joint US-German satellite mission that has provided new and unexpected insights into the natural processes of the Earth. In the GRACE mission, the distance between two spacecraft is measured using a microwave ranging system. Temporal estimates of the Earth's gravity field are inferred from changes in this distance. The changes in Earth's gravity field in turn can be used to measure indicators of climate change – like polar ice melt or changes in ground water level.
The GRACE Follow-on mission (scheduled for 2017) would refly the identical GRACE spacecraft and instruments, but supplement the micrometre-level accuracy microwave measurement with a laser interferometer with nanometre-level accuracy.
The laser demonstration on GRACE Follow-On will be a partnership between NASA, which will provide the laser, cavity assembly, and ranging processor, the German Research Center for Geosciences (GFZ), and the Albert Einstein Institute, which is responsible for and overseeing the laser ranging instrument and in particular the measurement optics and steering mirror assembly along with instrument integration and testing. For monitoring the Earth gravitational field LISA Pathfinder technology will be employed: The LISA phasemeter is being adapted to the needs of the gravity field mapping mission.
Under this project a consortium of U.S. and German institutions will produce hardware for the laser ranging interferometer to be flown on the GRACE Follow-on mission. This system is expected improve the intersatellite ranging sensitivity by a factor of 25 over the original GRACE mission.