Evaluation of NGGM mission concepts by full satellite system simulation including 3D range observable
Abstract
The GRACE mission delivered the most accurate temporal gravity field solutions of the Earth. It's successor, GRACE follow-on is continuing it's legacy since May 2018. The time series of monthly gravity fields revealed mass redistribution in in the near surface layer of the Earth with unprecedented accuracy, since 2002. This assessed a completely new observable in geoscience disciplines like cryosphere, ocean, atmosphere and solid Earth. Despite the groundbreaking success and relevance of the GRACE mission(s) for Earth observation and climate science, no further mission is planned after GRACE follow-on, yet. Future gravimetry mission concepts have been proposed nnder the name Next Generation Gravity Mission (NGGM) and have been analyzed for a while. In the GRACE community the so called Bender-configuration (two GRACE pairs, one on a polar and one on a less inclined orbit, ~63°) is in favor. In this contribution we present simulation results for different classes of NGGM scenarios. We are focussing on pendulum-style missions as their performance are found to be superiour to the Bender-style configuration. All mission concepts are simulated including attitude control. Realistic instrument noise models are used to generate observation data for accelerometer (ACC), inter satellite ranging (KBR and LRI), kinematic orbit solution (GNV) and star camera (SCA). In the gravity recovery process we use the variational equation approch. As for real GRACE data processing, we use all mentioned observations and determine calibration parameters, for example for the ACC data. Furthermore we investigate the use of an additional observable: the three dimensional (3d) range between the satellites. We use a relative positioning algorithm, adapting concepts from multi-vehicle cooperative positioning, to obtain this 3d-range form GNSS pseudo ranges. We found that the lower degrees can be enhanced by using this additional observable for scenarios that have cross-track or radial components in the inter satellite ranging. However, for a GRACE type missionwhere the much more accurate KBR measurement is more or less oriented in the same direction as the 3d-range the inclusion of this observable does not enhance the accuracy further.
- Publication:
-
43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E2134R