Much ado has been made of the Mars Rovers and the use of a vehicle to
explore the moon in the 1970s.

I was curious if there was enough atmosphere on a planet like Mars
that Astronauts could utilize Ultralights in their exploration and if
so, what would the make-up of the ultralight aircraft be, considering
the lightweight materials utilized to construct the lunar rover in the
late 1960s? Would there be enough atmosphere to support a parachute
recovery system as well?

Also, the Army experimented with inflatable aircraft in the 1950s/
1960s...would the "inflate-a-plane" idea find use in space exploration
if adequate atmosphere existed to support an ultralight operation?

It would seem to me that if there were enough atmosphere on Mars to
support Ultralights, an astronaut could cover greater ground in
exploration, especially considering the STOL capability of such an
aircraft. VTOL is nice, but an engine failure could cause a mission
abort. A dual engine failure could maroon astronauts. In regards to
the rovers, if the vehicle breaks down, it's a long way to walk back
to base camp on very little oxygen.