When NASA’s InSight mission reached Mars last year, it wasn’t alone. It was accompanied by two tiny satellites called CubeSats, or in this case, MarCO, for Mars Cube One. They were the first CubeSats ever to visit the Red Planet. The pair, nicknamed EVE and WALL-E, after Pixar’s fictional robots, relayed information from InSight’s descent. But their real mission was simply to show off their abilities so far from home and prove that such small missions – the total MarCO program only cost $18.