LISA-like Laser Ranging for GRACE Follow-on

The Gravity Recovery and Climate Experiment (GRACE) mission successfully demonstrated that low-orbit satellite-to-satellite tracking is a powerful tool to analyze spatial and temporal changes in Earth's gravity field. Especially hydrological mass transports are well-resolved. To continue longterm observations, a GRACE follow-on mission is planned for 2017 which will almost be an identical copy of the GRACE mission. Additionally, for technological demonstration, a Laser Ranging Interferometer is planned supplementary to the conventional microwave ranging device to potentially improve the intersatellite range measurements. The frequency band of interest for Earth gravity observations coincides with the LISA frequency band, thus LISA technology can be inherited. We describe the basic concept of the Laser Ranging Interferometer for GRACE follow-on and present a testbed to investigate its functionality and key components