c) More recent missions to Mars include the hugely successful Mars Pathfinder, which landed a small ‘rover’ called Sojourner on the surface to explore a region where there may once have been life.
a) Sojourner has now been effectively switched off, but lasted almost twelve times its expected lifetime.
b) Similarly the lander, which imaged several areas around the landing site (dubbed the Carl Sagan Memorial site) and took atmospheric measurements, lasted a good deal longer than expected.
d) The only unfortunate thing to have arisen from the mission is the naming of the rocks at the landing site (including everything from Scooby Doo to Darth Vader).