Sir: I must correct one point in your article, "Nasa takes off in search of stardust" (3 February). The last extraterrestrial sample was returned to Earth by the Soviet robotic craft Luna 24, during August 1976. Apollo 17 took place almost four years earlier. Luna 24 returned a two-metre core of soil from Mare Crisium, a nearly circular basin towards the north-east edge of the visible face of the Moon. The core contained fragments of iron-rich but titanium-poor basalt, similar to some basalts returned by Apollo 17 and to several lunar meteorites.
Hemel Hempstead, Hertfordshire