Earth Mass Transport Mission 2 – Proposal For An Earth Explorer 9 Mission
19/09/2016 | 14:00 | Session 1: New missions and concept performance
Author(s): Thomas Gruber and Isabelle Panet
Thomas Gruber and Isabelle Panet
Recently a larger group of European scientists with the support of technological and industrial partners a new gravity field mission was proposed as Earth Explorer 9 to European Space Agency (ESA). The main goal of the proposed mission concept is the long term observation of the time variable gravity field with significantly increased spatial and temporal resolution as it can be performed nowadays with the GRACE or in the near future with the GRACE Follow-On (GRACE-FO) missions. These observations are crucial for long term monitoring of mass variations in the system Earth in order to improve our knowledge about the global and regional water cycle (with the components continental hydrology, ocean, ice, atmosphere) as well as about processes of the solid Earth. Starting from the existing concepts of single pair GRACE and GRACE-FO missions, sensitivity, spatial and temporal resolution shall be increased, such that also smaller scale time variable signals can be resolved, which cannot be detected with the current techniques. For such a mission new and significantly improved observation techniques are needed. This concerns in particular the measurement of inter-satellite distances, the observation of non-gravitational accelerations, the configuration of the satellite orbit and most important the implementation of constellation of satellite pairs. In particular the team proposed a double pair mission concept (Bender type) with a near-polar and an inclined pair. Both pairs shall be equipped with a laser interferometer for distance change observations at the 1E-8 m level, with an accelerometer of the 1E-11 m/s2 class for the observation of non-gravitational forces and with a drag compensation/reduction system to fly at lower orbit heights than current missions of this type. All together this enables a duplication of spatial resolution of mass variability observations, a significant reduction of the striping problem caused by one-directional observations with a single pair and in particular the observation of short term mass variations with reasonable spatial resolution avoiding temporal aliasing to a large extent with all related problems of geophysical model errors.