A radio-source tracker in space [article]

Erwan Rouillé
2021 Zenodo  
A radio interferometer only measured the electric field at a given set of point distributed in space. The correlation between this measurements can be used to reconstruct an image of the sky. However, in order to do so, the interferometer has to apply phase shifts that are proportional to the distance in between the satellite in the observed direction. Thereby, the interferometer must know the orientation between its satellites and the observed direction. For a ground-based interferomter, this
more » ... s not a problem as the position of the antennas remain unchanged. Nevertheless, for a swarm of satellite around the moon, it is an issue because their relative positions are in constant motion. The objective of this study was to explore the possibility of using the interferomter's imaging capacity to use it like a star tracker. The idea was to figure out if the interferomter was able to know its orientation without using an external element like a GNSS. The principle of a star-tracker is as followed: a camera takes a picture of the sky in the direction it is looking at, the pattern formed by the stars in the image is compared to the ones already known and referenced in a catalog, when a match is found the camera knows how it is orientated in the sky and so does the satellite. For the interferometer, the individual orientations are known but the relative positions of the satellites is measured in an unknown frame named "system frame". This frame has to be linked to the absolute inertial frame in which the celestial bodies are studied.
doi:10.5281/zenodo.5593035 fatcat:oz2t3ivzbrfznpruiibic4qj5e