Harrison: Where are you from? order bupropion online The NASA rovers from Sojourner on have revolutionized planetary exploration. Where the first landers were static platforms that would have missed a Martian army if it passed by beyond a hill, rovers can go where the science is. Unfortunately, as anyone who’s gone off-roading can tell you, unpaved terrain is not a very friendly place for wheeled vehicles and Mars is particularly unfriendly. This was dramatically shown when the NASA rover Spirit ended its career by getting stuck in soft sand 30 million miles from the nearest tow truck.