Imagine that you are flying your drone on a planet 180 million kilometres away. It takes 20 minutes for your command to reach the planet – and the pictures you see of what is happening are 20 minutes old. You cannot take evasive or corrective action if anything goes wrong, it would take too late. This is the type of situation that the NASA's engineers did not wish to experience on the first flight of the "Ingenuity" helicopter on Mars on April 19.

All the planning and calculations paid off. Just after 12 pm British Summer Time, a NASA engineer announced to mission control that “all data sets are nominal”. This, of course, is space-talk for: “We are incredibly happy, everything has gone well”. A few minutes later, the data - a rather unprepossessing graph. But it was sufficient for the engineers in mission control to clap and cheer.