Electrostatic space accelerometers for present and future missions

Numerous space applications have required to dale, dedicated accelerometers with ranges and sensitivities optimised for the in-orbit environment. In m icrogravity applications, the vibration levels of the platforms carrying ex periments have to be surveyed or controlled. In Earth observation, the drag measurement of the satellites improves the accuracy of the low orbit recov ery. The accelerometers can also participate in a drag compensation system or constitute a gradiometer aiming at the fine determination of the Earth's gravity field exploiting resolution of 0.1 pg. In the field of Fundamental Physics, European and American projects require even higher sensitivities in the low frequency domain between 10(-4) and 10(-2) Hz. In view of these applications, dedicated accelerometers are being developed, all based on th e electrostatic suspension of a proof-mass. From the experience acquired fr om the GRADIO accelerometer development dedicated to space gradiometry (lat e 80 s), the accelerometer ASTRE has been realised and delivered to ESA for the monitoring of the SPACELAB microgravity environment during the STS-78 shuttle flight in June 96. Cryogenic differential accelerometers are being developed for the in-orbit test of the Equivalence Principle with an accura cy of 10(-17) objective of the GEOSTEP mission studied by CNES. (C) 2000 El sevier Science Ltd. All rights reserved.