Space: FutureMissions

© ESA - AOES Medialab

Germany plays a leading role in the area of spaceborne gravimetry. In all of the missions CHAMP, GRACE and GOCE, German participants were prominent. This is true both in research and academia as it is in technology and industry. The key players from these communities are represented in this project, which, on the one hand, aims at developing technological concepts for the next generation of gravity field satellite missions and, on the other hand, undertakes to solve the most pressing geodetic problems with the current generation of gravity field satellite missions.

The outcome of this project would be a roadmap for future gravimetric satellites in the post-GRACE and post-GOCE era. Most focus will be on the mid-term future. That is to say, the project will at least lead to a description of feasible mission scenarios that may in due time serve as a response to a call-for-missions from space agencies. To put it more directly: 3 year after project kick-off we would be able to propose a gravimetric satellite mission to e.g. the European Space Agency (ESA). However, the project will also scrutinize existing and upcoming technologies for long-term future gravity missions.

The word feasible in the previous paragraph denotes that the proposed mission scenarios will not only be able to meet the geoscientific requirements, which will be corroborated through extensive closed-loop simulations, but will also be realistic from the perspective of technology readiness and from the perspective of system engineering and cost efficiency.

To guarantee such an outcome, the project is broken down into the following three modules (main work packages):
- Geodesy (MWP100)
This main work package establishes a full-fledged simulation facility to assess future gravity mission scenarios for meeting the scientific requirements. In view of the enormous amount of simulations involved, several simulation strategies are pursued.
The three fundamental problems of spaceborne gravimetry are dealt with in this main work package: superposition of gravitational sources (separation), aliasing of high-frequency signals into gravity solutions (dealiasing through configurations), sensitivity of gravitational observable (in situ modeling, formations).
A further key element is a dedicated analysis of the individual sensors and the integrated system confronted with the science requirements. Metrology and system constraints are imported from MWP200 and MWP300, science objectives are provided to them. Feasibility constraints are fed back from MWP300.

Metrology (MWP200)
Conventionally, metrology work packages of a satellite project proposal would appear as subwork package within the main systems work package. Here, however, metrology plays a central role in the design of future gravimetric satellite missions. Therefore, a separate MWP on metrology covers the technologies for future missions, both available and those under development: microwave ranging, laser-based HAALDM, frequency combs and, to a small
extent, atomic interference.
MWP200 has an interface to geodesy (MWPI00) through the sensor analysis work packages WP140 and WP150, where sensor performance is translated into a geodetic stochastic model. Moreover, MWP200 is closely linked to the main systems work package (MWP300).

System (MWP300)
This main work package covers all activities that lead from one or several given mission scenarios with associated science requirements to a satellite system that can be developed and built within time and cost constraints, and that meets the performance requirements. Key elements of this work package are "system performance", "platform design and feasibility" and "control systems". Several metrology technologies and their constraints for system design are
imported from WP200.

Co-ordinaton:
Prof. Dr. Nico Sneeuw
Geodetic Institute
University Stuttgart

Partners:
University Stuttgart
University Hannover
University Bonn
GFZ Potsdam
SpaceTech GmbH
MenloSystems GmbH
Kayser-Threde GmbH