When the rover has done its drilling down through the Mars outer crust down to about six feet, the little green men will emerge in an angry mood and with super technology will fly down to earth and take over.
This will make the scientists and evolutionists very happy since it comes from their belief that the other planets were/are populated with aliens.
On the other hand what may happen is that the drill will discover martian rock, martian rock and more martian rock.