Nasa, the US space agency, is celebrating its 50th birthday this summer with an eclectic series of events. They range from air shows to gala dinners, from family picnics at Nasa centres to astronauts throwing ceremonial pitches at baseball games.

But sadly Nasa can offer no space spectacular to mark the anniversary of its formation in 1958 – in shocked response to the Soviet Union’s launch of Sputnik, the world’s first artificial satellite.