Performance evaluation of novel accelerometers for future gravimetry missions

Abstract

Dedicated satellite gravimetry missions from the beginning of the 21-st century have provided unique data on mass redistribution processes in the Earth system, e.g., melting of the Antarctic and Greenland ice sheets, sea level changes, droughts, etc. Ongoing climate change underlines the need to continue this kind of measurements with enhanced concepts and sensors. For example, the Mass Change mission is planned to be launched within the next decade in a DLR-NASA partnership. The focus of this study is on the assessment of enhanced ACCs for future gravimetry missions. Drifts of the electrostatic accelerometers (EA) at low frequencies (< 1mHz) are one of the limiting factors in current space gravimetry missions. For this purpose, an enhanced EA with laser-interferometric readout, a so called "optical accelerometer", was modeled and its performance at Low Earth Orbit has been evaluated. Contrary to present-day EAs, which measure capacitively the test mass (TM) displacement and actuate it electrostatically, optical ACC, beside a similar actuation scheme, track the TM with laser interferometry. Here, we introduce general workflow of simulations including the propagation of the satellite dynamics and the modeling of optical ACCs including major noise sources. Also, parametrization of the developed ACC model will be discussed including the effect of different TM weights and TM-electrode housing gaps. Finally, improved results of the recovered gravity field will be shown for various mission scenarios applying optical accelerometry and gradiometry and which are compared to the present-day EAs and quantum sensors performance.