Are you for real?
They both orbit around the Sun, so more often than once a year the Earth goes between Mars and Sun (because Mars goes slower around the Sun)
They don´t control the rovers with a live remote control feed, obviously, regardless of distance, the distance is alway to big far that. They send daily instructions to drive x meters in this or that direction, then send us pictures of surroundings so we can send you more instructions tomorrow. (basically)
Learn something before talking, pls.