After the successful Global Coverage of the Digital Elevation Model, the TanDEM-X Science phase was initiated in September of 2014, dedicated to the demonstration of innovative techniques and experiments. The TanDEM-X Science phase had a large impact on the TerraSAR-X/TanDEM-X Mission Planning System. The two main challenges were the formation flying changes and the activation of a new acquisition mode, the so called Dual Receive Antenna (DRA) acquisition mode. This paper describes all actions and quantitative analyses performed in order to achieve the twofold target of the Mission Planning System: a) support the new TanDEM-X mission's requirements, while b) proceed seamlessly with the TerraSAR-X mission fulfilling both its scientific and commercial demands. Regarding the first objective, several system reconfigurations are presented which were executed either due to the new flying formations or due to enabling the new DRA acquisition mode. In parallel, various analyses are included for the ground station visibilities of each formation and the distribution of the Sand X-Band contacts. For the second objective, it is presented how, via new concepts and mechanisms, it was possible to continue the TerraSAR-X mission undisturbed. Statistical analyses depict their successful integration and performance in the operational system. As a heritage of the TanDEM-X Science phase, the statistical analyses have become a very useful tool for the daily operations of both satellites and missions.

The history of the TerraSAR-X and TanDEM-X mission planning system is briefly presented. In addition to the not trivial demands of the first years, special attention is given to the challenges of recent years. Here the TanDEM-X science phase, conducted between 2014 and 2016, is the most prominent feature. It is shown how agile software engineering methods can help to keep the already achieved system robustness, and how further enhancements can easily be incorporated.

International audienceFormation Flying opens the possibility to conceive and deploy giant solar coronagraphs in space permanently reproducing the optimum conditions of a total eclipse of the Sun ("artificial" eclipse) thus giving access to the inner corona with unprecedented spatial resolution and contrast (low stray light). The first opportunity to implement such a coronagraph "ASPIICS" will be offered by the European Space Agency (ESA) PROBA-3 technology mission devoted to the in-orbit demonstration of formation flying technologies. Two spacecrafts separated by about 150 m form a giant externally-occulted coronagraph: the optical part hosted by one spacecraft remains entirely protected from direct sunlight by remaining in the shadow of an external occulter hosted by the other spacecraft. We developed and tested a scale-model 'breadboard' (i.e., 30m) of the PROBA-3/ASPIICS Formation Flying coronagraph. The investigations focused on two metrology systems capable of measuring both the absolute pointing of the coronagraph (by sensing the projected shadow and penumbra produced by the external occulting disk) and the alignment of the formation (by re-imaging light sources located on the rear-side of the occulting disk with the optical part of the coronagraph). In this contribution, we will describe the demonstrator and report on our results on the crucial question of the alignment and pointing in space of long instruments (> 100 m) with an accuracy of a few arcsec. This study has been conducted in the framework of an ESA "STARTIGER" Initiative, a novel approach aimed at demonstrating the feasibility of a new and promising technology on a very short time scale (six months)

International audienceFormation Flying is now considered to be the most promising and effective approach to deploy the forthcoming generation of very large instruments in space. PROBA-3 is a technology mission devoted to the in-orbit demonstration of formation flying techniques and technologies. PROBA-3 will implement a giant coronagraph (called ASPIICS) that will both demonstrate and exploit the capabilities and performances of formation flying. ASPIICS is distributed on two spacecrafts separated by 150m, one hosting the external occulting disk and the other the optical part of the coronagraph. ASPIICS will incorporate metrology units which will allow determining both the absolute pointing and the relative alignment of the formation. Photosensors located around the entrance pupil of the coronagraph will determine the absolute positioning of the instrument by sensing the penumbra behind the occulting disk. Light sources located on the rear-side of the occulting disk will allow verifying the alignment of the formation. We carried out a complete numerical simulation of the metrology system and showed how corrections are derived from the measurements to be applied to each spacecraft in case of misalignments. This simulation was validated by a scaled model of the coronagraph developed at Laboratoire d'Astrophysique de Marseille. This study has been conducted in the framework of an ESA "STARTIGER" Initiative, a novel approach aimed at demonstrating the feasibility of a new and promising technology on a very short time scale (six months)

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