PRETTY – A CubeSat mission for passive reflectometry and dosimetry

Earth observation is one of the main space applications. Monitoring climate change and predicting its further development requires the use of advanced technologies to measure all aspects that influence the climate, such as changes in the Earth's ice and water levels. The CubeSat mission PRETTY (Passive REflecTometry and DosimeTrY) has been designed to measure these influences on climate and hosts two scientific payloads. The first payload is a passive reflectometry system, which uses direct and from the earth surface reflected GPS signals for Earth observation, and especially for the observation of differences in height of ice and sea surfaces. The ground footprint for reflection measurements is about 15 km x 15 km. This resolution allows to improve our understanding of the overall ocean energy transport and its role in the Earth's climate change. The second payload is used to monitor ionising radiation onboard the spacecraft PRETTY. The radiation environment is correlated with the status of the electronic systems of the satellite bus and the payload systems, which allows the assessment of the impact of space radiation on the CubeSat commercial-off-the-shelf (COTS) components. The dosimeter system has been developed to determine the total ionising dose (TID) of cosmic radiation, based on radiation-sensitive field-effect transistors (RADFETs) and floating gate dosimeters (FGDOS) with an accuracy of up to 20 mrad. The launch of the PRETTY satellite is scheduled for early 2022.