Zubrin's proof-of-concept Mars 'Gashopper'
The gashopper would get its electricity from a large set of solar panels built on top of its wings. It would use this electricity to retrieve carbon dioxide from the Martian atmosphere, and then store it as a liquid inside the aircraft. When enough gas was stored up to make a flight, it would heat up a hot bed of pellets and then pass the CO2 through it. Now hot, the gas would act as a propellant, and allow the gashopper to lift off vertically from the surface of Mars. Once airborne, it could then fire more gas out a rear thruster and begin flying as an airplane, using its large wings for lift and maneuverability. When it was ready to land, the aircraft could slow its airspeed, and then touch down gently as a vertical lander.
sounds like the design is based on proof-of-concept for Mars Direct insitu refueling, rather than based on the most efficient design for mobile Mars probes.
I would have thought balloons were a much better way - floating around at low altitude during the day, and then gently coming to rest at night, during which surface measuremnts can be done.
Anyway, the Pioneer persists in his own singular vision:
