Advanced aerobots that would be powered by solar photovoltaic batteries and that would be capable of storing energy for occasional operation during short intervals at power levels far beyond those of the photovoltaic batteries have been proposed. Aerobots are robotic balloon-buoyed airborne apparatuses that can be used for exploration of other planets and can be used on Earth for diverse purposes, including monitoring weather, military and law-enforcement surveillance, and entertainment.

The aerobots that have been built thus far utilize various combinations of atmospheric and transported gases for buoyancy control, subject to limitations of available power. The operation of the proposed aerobots would be much less restricted by limitations of available power because they would utilize solar energy and would store excess solar energy in various ways for consumption during such power surges as might be needed for rapid ascents, drilling into the ground, transmitting signals, or other short-term functions.

According to the proposal, part or all of a balloon surface would be covered with solar photovoltaic cells. Detailed calculations show that, with state-of-the-art photovoltaic technology, the mass penalty would be less than 10 percent, since the substrate is already available as the balloon surface. The electric power generated by the cells could be used to electrolyze, compress, liquefy, or freeze a transported or atmospheric gas or to sublimate or boil a frozen or liquid phase of an atmospheric or transported gas. Such physical and chemical manipulations of atmospheric and/or transported gases would be performed to effect changes in buoyancy, to store energy, or to satisfy demands for power surges, depending on circumstances. To cite three examples:

  • Products of electrolysis could be stored in canisters or balloon compartments and later consumed in a fuel cell to generate a surge of electric power.
  • A compressed gas could be released to provide a rapid change in buoyancy and/or a surge of propulsive force, which could be directed horizontally or could be directed wholly or partly vertically to aid or oppose the change in buoyancy.
  • An atmospheric gas could be condensed or frozen to take on ballast and later allowed to warm up toward ambient temperature to release ballast.

This work was done by Kumar Ramohalli of Caltech for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at  under the Machinery/Automation category, or circle no. 189 on the TSP Order Card in this issue to receive a copy by mail ($5 charge).


This Brief includes a Technical Support Package (TSP).
Solar-powered aerobots with power-surge capabilites

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This article first appeared in the April, 1998 issue of NASA Tech Briefs Magazine.

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