MAGIC – The value of the second pair

The main objective of the joint ESA/NASA Mass-change And Geoscience International Constellation (MAGIC) is to extend the mass transport time series from previous gravity missions such as GRACE and GRACE-Follow on with significantly enhanced accuracy, spatial and temporal resolutions. The concept is based on a joint ESA/NASA Mission Requirements Document (MRD). The first pair of the MAGIC Constellation will be implemented via a Germany-USA fast-paced cooperation to ensure continuity of observations of GRACE-Follow On, with some potential ESA in-kind contributions. The second pair will be implemented via a Europe-USA cooperation with some potential NASA in-kind contributions. The target launch date will be compatible to maintain at least 4 years of combined operations.

The current baseline scenario consists of a polar pair (P1) at an altitude of 488 km and an inclination of 89° without ground track control, and an inclined pair (P2) at 397 km and 70° inclination with a 5-day repeat sub-cycle, in order to ensure ground track homogeneity and a constant quality of resulting near-real time service products.

In the frame of extensive full-fledged numerical simulations with realistic error assumptions regarding instrument performances and background model errors, the expected performance of the resulting short- to long-term gravity field products is evaluated. In this contribution, the main focus lies on the quantification of the added value of P2 and the relative contributions of P1 and P2 to the combined constellation solution. In particular, the achievable performance for short-term products (daily, 5-day) will be evaluated. In addition, we will analyze and quantify the value of P2 alone over the regions covered by the 70° inclined orbit. From the processing side, using spherical harmonics as base functions, this requires also an adequate treatment of the polar gap areas. Finally, we will match all results against the MRT/MRTD requirements and will evaluate the impact on various fields of science and service applications (continental hydrology, cryosphere, oceans, solid Earth, geodesy).