Yachtsmen are constantly nagged to keep check of where they are by using conventional methods of navigation to back up and confirm that their GPS equipment is giving the correct position.

Now with the news that two satellites were destroyed in a 17,000 mph crash such advice seems even more important. The trouble is, it seems, that outer space is getting very congested. As The Times points out today we need space traffic control.

Maybe satellites should be fitted with earth-facing mirrors, then when they’ve ceased functioning as electronic aids to navigation they could be used as mechanical aids to navigation and, with tables of their orbits, drawn up by NASA and Imray, the sextant could make a come-back!