BepiColombo - Revisiting the Correction of MERTIS Geometry

Kurzfassung

During the Earth-Moon flyby on April 10th, 2020, the MERTIS instrument [1, 2] on board the BepiColombo spacecraft observed the Moon in the mid-infrared spectrum. Initial geometric correction [3] focused on minimizing the cumulated offset between the expected signal position from MERTIS SPICE [4] data and the observed signal in the 1-dimensional spatial data of MERTIS. However, the limited lunar coverage (5 to 6 pixels) and the ~8° phase angle resulted in a pixel-size limited ground resolution with difficult detection of the actual lunar limb. In particular, at the shadowed limb low surface temperatures caused low radiance levels in the measurement, hindering precise alignment. Here, we present a novel approach to improve the geometric correction by mapping radiance data of the lunar observation to a global 1x1 degree raster and aligning it to a modeled temperature distribution [5].