MicroSTAR: NGGM Space Accelerometer Last Developments

Abstract

ONERA laboratory have been providing highly sensitive electrostatic accelerometers involved in all major space Geodesy missions for more than five decades. Since the first mission launched, the accuracy of the accelerometers has significantly improved over time. For instance, the ESA GOCE mission accelerometers exhibited a few 10-12ms-2Hz-1/2 resolution. In a Fundamental Physics application, the T-SAGE accelerometers developed at ONERA allowed to test the Equivalence Principle on board the MICROSCOPE satellite at a level of 10-15, establishing in 2022 the best accuracy ever achieved for the test, besting the previous one attained with Lunar Laser Ranging by two orders of magnitude.Currently, MicroSTAR accelerometers are selected for ESA Next Generation Gravity Mission (NGGM). This mission aims to extend observations provided by GRACE-family satellites, with the same strategy. ONERA’s project is ongoing and the instrument phase C started early 2026. Currently, the mechanical sensor reached TRL-6 while the electronic unit and the overall system achieved TRL-5 with a performance level foreseen of about a few 10-12ms-2Hz-1/2. In the same fashion as the past instruments, the accelerometer is based on the electrostatic suspension of a proof-mass. The position and the attitude of the mass are measured and controlled with capacitive sensors and actuators. One of the main improvements of MicroSTAR is its cubic proof-mass, as opposed to the previous parallelepipedal ones in SuperSTAR-type accelerometers, which allows a high accuracy measurement along and around all three axes.To reach the technical and performance needs of NGGM, improvements in all technological fields are fundamental. In this presentation, the current development of MicroSTAR with its challenges and key strengths will be presented.