Gondola design for Venus deep-atmosphere aerobot operation

Aerobots are balloon-based AEROnautical RoBOTS with autonomous navigation capabilities. An aerobot mission has been proposed for exploration of the upper atmosphere through near-surface regions of Venus. The wide range of atmospheric conditions from the relatively benign upper atmosphere to the hot, high-pressure surface require thermal protection of the scientific instruments, and the mass constraints of a balloon system require that the thermal protection system be lightweight. To meet the thermal control challenges, we propose use of lightweight vacuum dewar technology combined with a phase-change material (PCM) thermal damper. For the proposed aerobot mission, the total thermal control mass is estimated to be 7.1 kg out of a total gondola mass of 25 kg. The design allows 7.3 kg for science instruments and communication hardware. Four kilograms of PCM are required to provide a repeatable 15-hour mission sequence that includes a 3.5-hour descent to the surface, 1 hour of surface operations, a 2.5-hour ascent to the cooler upper atmosphere, and 8 hours to refreeze the PCM. Lastly, aerobot system design tradeoffs are discussed, and the extension of vacuum dewar/PCM technology to outer planet probes is briefly explored.