A report discusses alternative techniques for controlling the buoyancy, and thus the altitude and landings, of a balloon-borne instrumentation system that would be launched to explore the moon Titan of the planet Saturn. Some of the techniques are based on established concepts of heating or cooling gases in balloons. One technique involves the acquisition or release of gaseous ballast by compressing and liquefying atmospheric gas into a pressure vessel (or allowing the liquefied gas to vent back to the atmosphere); a similar technique involves compressing atmospheric gas into (or releasing it from) a bladder. The simplest and preferred buoyancy technique is to use controlled heating of the helium balloon by means of diverting waste heat from a radioisotope thermoelectric power source.

This work was done by Jack Jones and Jay Wu of Caltech for NASA's Jet Propulsion Laboratory. To obtain a copy of the report, "Preliminary Study of Titan Balloon Buoyancy Techniques," access the Technical Support Package (TSP) free on-line at www.nasatech.com/tsp under the Physical Sciences category. NPO-20656