Small robots that can move around on the surface of a planet are called space shuttles.

No. "Shuttle" has been pretty much used to indicate shuttling

between Earth and Earth-orbit.

The devices that have tooled around on the surface of Mars

have been referred to as "rovers". That was also the nickname

of the buggy on which the Apollo astronauts moved around on

the Moon in the early 1970s ... the "lunar rover".