Three hundred miles above our heads, a chase is in progress. A reconnaissance satellite called ICEYE-X36, made in Finland, is being pursued by a Russian satellite; the two craft are moving at almost five miles per second. The Finnish craft weighs 90kg and looks, to the untrained eye, like a dishwasher attached to a shiny fence. It can see through clouds, and the data it produces is used by the Ukrainian military. Last week, the Russian satellite Kosmos-2612 began to close in on it.