High Temperature Acid Resistant Balloon

A Venus mission will require a vehicle for atmospheric exploration and to transport the samples from the Venus surface to the top of the atmosphere. For this purpose it is reasonable (due to the high density of the Venus atmosphere) to use inflatable balloons, which occupy minimal space in the folded position and possess buoyancy upon being inflated. The Venus atmosphere contains hot (up to 460oC) clouds of sulfuric acid. The only kinds of material for an inflatable to withstand such high temperatures are metals.A sequence of operations is proposed to build balloons of different shapes with diffusion bonding of stainless steels or other alloys, which are most resistant against hot 85% sulfuric acid. However, even these materials possess a many times greater corrosion rate than that satisfying the currenttopic requirements on the balloon life time and areal density. In order to provide the required corrosion resistance, the fully bonded balloon will be coated with a thin layer of gold or tantalum by a PVD process or with gold by electroplating so that the entire laminate would possess an areal density of below 1000 g/m3. Building a seamless bellows by PVD is a backup option.