A Compact Laser Ranging Interferometer for the SENSORIS Mission

Abstract

Satellite gravimetry missions such as GRACE-FO allow tracking of mass transport on global scales. These missions utilise low-low satellite-to-satellite tracking (LL-SST) where two spacecraft reside in similar orbits and their relative motion is tracked. The gravity field is reconstructed once per month, limited by the use of a single pair of spacecraft. The SENSORIS mission proposes a constellation of many CubeSat’s built from commercial-off-the-shelf components performing high-low satellite-to-satellite tracking (HL-SST) via GNSS. Whilst compromising on the spatial resolution, significantly increased temporal resolution (1 solution per day) allows for improvements on the currently insufficient background modelling, thus improving the results of the future MAGIC-constellation consisting of GRACE-C and NGGM. Future improvements to the SENSORIS mission concept shall evolve to LL-SST via implementation of a Laser Ranging Interferometer (LRI) similar to GRACE-FO. Given limitations of the CubeSat architecture, a significant reduction in the size, weight and power of the LRI is required. We present our first steps towards a compact LRI. While the initial expected ranging performance will probably not match that achieved by previous missions with larger spacecraft, these steps represent an important start to developing a compact LRI for future geodesy missions.