Small satellites have been built as cubes for twenty years, not for any reason to do with spaceflight but because that is the shape of the dispenser that pushes them out of the rocket. Four spacecraft shaped like dinner plates, a metre across and 2.5 centimetres deep, have now spent six months in orbit testing the alternative. The prize is very low orbit, where cameras see more and signals travel faster. Here is why shape decides who gets there.
