The CHaracterising ExOPlanets Satellite (CHEOPS) mission has acquired its first images. This confirms that the telescope and instrument are functioning correctly and were not damaged during launch. Further functional tests will now follow before the investigation of exoplanetary systems begins. The telescope cover was opened on 29 January 2020.
The image shows the first star field observed by CHEOPS. The blurring of the image is intentional, and the imaging of the stars as distorted triangles exactly matches the optical properties of the telescope. The telescope has been 'defocused' to increase the precision of the measurements. The light coming from a star is distributed over many pixels. This averages out variations in the satellite's pointing and small differences in pixel sensitivities. The brightness of the star is determined by reading out all the pixels in a circle surrounding it. In this way, very small changes in brightness caused by a transiting planet can be accurately measured.
The German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) has supplied hardware for the instrument and, on the ground, DLR is contributing its extensive expertise in data evaluation. The mission will study exoplanets from a Sun-synchronous Earth orbit at an altitude of 700 kilometres.
