What's the most efficient pice of machinery that's able to dig/move lots of dirt and rock quickly?

Question

I read about this contest for making an automated machine that can dig so much dirt and move it to a certain spot autonomously for some kind of thing they're sending to either the moon or mars and was thinking why not just adapt some kind of machinery that already exists to work autonomously (Like a combine that uses GPS navigation). What would be the best piece of machinery to dig and move lots of dirt?

Answer 1

Because, oddly enough, it is probably cheaper to build something new to LAUNCH into space and still be able to work when it got to Mars, than to adapt something that already exists. A backhoe is not space suitable.