Surface Water Ocean Topography Ka-band Radar Interferometer Payload Thermal Design Challenges
The proposed Surface Water Ocean Topography mission would be a joint NASA/CNES mission with a launch baseline in 2020. This would be the first mission capable of precise measurements of continental water levels (lakes, rivers) as well as improving knowledge of ocean topography which ultimately would aid in climate modeling and predictions. The primary instrument, the Ka-band Radar Interferometer, includes stringent requirements in order to meet the primary mission science goals. Two features that would drive the thermal design are large electronics dissipation (1 kW range) that would need to be co-located and tight temporal stability requirements (<0.05°C/min) in a low earth orbit environment. This has led to a thermal architecture involving high-conductance thermal pallets and loop heat pipes in order to transport the waste heat as well as working closely with Systems and Mechanical engineering teams to ensure both flight attitudes and strategic placement of radiators would be able to help meet the thermal stability requirements. Design trades are being conducted to optimize the thermal architecture given the flight system resource constraints. Risks have also been identified along with mitigation plans, one of which is a testbed developed to validate that the requirements could be met.