Editing Aerobot (section)

===The Mars aerobot effort===
After the success of the Venus VEGA balloons, Blamont focused on a more ambitious balloon mission to Mars, to be carried on a Soviet space probe.

The atmospheric pressure on Mars is about 150 times less than that of Earth. In such a thin atmosphere, a balloon with a volume of {{convert|5,000 to 10,000|m3|ft3|abbr=off}} could carry a payload of {{convert|20|kg|lb|abbr=off|sp=us}}, while a balloon with a volume of {{convert|100,000|m3|ft3|abbr=off|sp=us}} could carry {{convert|200|kg|lb|abbr=off}}.

The French had already conducted extensive experiments with solar Montgolfieres, performing over 30 flights from the late 1970s into the early 1990s. The Montgolfieres flew at an altitude of 35 kilometers, where the atmosphere was as thin and cold as it would be on Mars, and one spent 69 days aloft, circling the Earth twice.

Early concepts for the Mars balloon featured a "dual balloon" system, with a sealed hydrogen or helium-filled balloon tethered to a solar Montgolfiere. The light-gas balloon was designed to keep the Montgolfiere off the ground at night. During the day, the Sun would heat up the Montgolfiere, causing the balloon assembly to rise.

Eventually, the group decided on a cylindrical sealed helium balloon made of aluminized [[PET film (biaxially oriented)|PET film]], and with a volume of {{convert|5,500|m3|ft3|abbr=off|sp=us}}. The balloon would rise when heated during the day and sink as it cooled at night.

Total mass of the balloon assembly was {{convert|65|kg|lb|abbr=off}}, with a {{convert|15|kg|lb|abbr=off}} gondola and a {{convert|13.5|kg|lb|abbr=off}} instrumented guiderope. The balloon was expected to operate for ten days. Unfortunately, although considerable development work was performed on the balloon and its subsystems, Russian financial difficulties pushed the [[Mars 96|Mars probe]] out from 1992, then to 1994, and then to 1996. The Mars balloon was dropped from the project due to cost.