The Venus Geoscience Aerobot Mission Study (VEGAS) was a four-month analysis of a semiautonomous, altitude-controlled balloon mission to Venus. The study focuses on a Delta launch in the
2007 timeframe, with a nominal 100-day balloon mission and orbiter telecom relay. After the initial balloon and payload deployment in the Venusian atmosphere, the balloon is capable of repeated excursions from altitudes of 60 km to the surface. Active control of altitude is achieved using a “phase change fluid” buoyancy control, whereby the planet’s lapse rate is used to periodically condense, trap, and boil a “phase change liquid”. Limited horizontal mobility is achieved by using real-time wind pattern predictions. The mean circumnavigation time of seven
days and the extensive altitude coverage affords unique science objectives including long-duration passive atmospheric: measurements, atmospheric/surface interactions and cycling, global high-resolution near-surface imagery, and remote surface mineralogy and geology. Key technologies required are addressed including thermal control, high temperature balloon envelopes, power generation, and autonomous state determination (navigation and control).

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