Investigating modified gravitation with ESA's Fundamental Physics Explorer
- Paper number
IAC-06-A3.4.08
- Author
Dr. Andreas Rathke, EADS Astrium GmbH, Germany
- Coauthor
Dr. Dario Izzo, European Space Agency (ESA)/ESTEC, The Netherlands
- Year
2006
- Abstract
Currently there is a growing interest in the fundamental physics community in a class of gravitational theories called Modified Newtonian Dynamics (MOND), which are capable of explaining the dynamics of galaxies without the ad-hoc invocation of an exotic matter component, the so-called dark matter. In particular, there is an active discussion about the possibility of testing the MOND model with the upcoming LISA-Pathfinder mission.
A recent analysis has identified the saddle points of the Newtonian potential (not the Lagrange points) of the Sun-Earth or Earth-Moon System as suitable locations for testing the MOND paradigm. Unfortunately, these regions are inaccessible to a test by the LISA-Pathfinder mission (the paper explains why). However in the framework of its Cosmic Vision Programme ESA is considering a flexible drag-free fundamental-physics platform, the Fundamental Physics Explorer (FPE), which might be suitable for a test of MOND at the saddle point.
The FPE will be a 3-axis stabilized, drag-free satellite platform, designed for low-altitude (500-700 km), Sun-synchronous orbits. Suitability for higher orbits can easily be implemented at little mass penalty and without added complexity if taken into account at an early stage of the design. However the delta-V capabilities of the FPE will be quite limited due to its overall concept.
We assess how the saddle-point of the Newtonian potential of the Sun-Earth system or Earth-Moon system can be investigated by the FPE, in order to test MOND. The limitations of the FPE architecture, in particular concerning Δ V, telecommunications and lifetime are fully taken into account.
This paper has two focuses: Firstly, system requirements for the FPE platform to successfully carry out the envisaged test of MOND are assessed. Particular emphasis is put on the experiment layout and on the performance requirements. Secondly, the mission analysis for the design of the transfer and the operational orbits is addressed. These aspects pose some interesting problems because the saddle points of the Newtonian potential have never before been considered as the targets of a space mission. Consequently, an exhaustive trajectory design for missions to the saddle points is carried out. The space of trajectories to the saddle points is explored by a multiobjective optimisation with respect to arrival Δ V and transfer time. Operational orbits for the investigation of the saddle points are presented. These orbits are the result of a careful trade-off on maximising the time in the region of interest, maximising the operational time for the drag-free system of the satellite and minimizing the station keeping Δ V requirements.
- Abstract document