Dragonfly: Detailed Thermal Control System Design

Dragonfly is a NASA New Frontiers mission that will send a rotorcraft lander to Titan, which has low gravity and a dense 94K cryogenic nitrogen atmosphere. The lander Thermal Control System (TCS) uses fans to circulate Titan atmosphere internally, distributing heat from its MMRTG power source to all internal components. In the last two years, the system design has evolved significantly, with special attention paid to improving the thermal control system design in multiple areas to reach a CDR level of maturity. Lander air inlet temperatures, previously controlled via wall-mounted heat exchangers, are now controlled using a composite external ducting system and airflow diverter mechanism mounted to the lander belly. The primary lander insulation material was updated to Solimide 16 after extensive testing, as Rohacell foam was found to be prone to cracking and deformation. Additionally, to increase system robustness on the launch pad after MMRTG integration, a venting system was added to create a flowpath between the lander and its external environment to prevent battery overheating. This paper will provide an overview of the matured thermal control system design and will document key changes implemented since Mission PDR to close the design with sufficient temperature margin, heat leak margin, and control authority.