Our Moon has a new moon: a small artificial satellite called Ladee – the Lunar Atmosphere and Dust Environment Explorer. Costing just under US$300 million (£185m) – a bargain – it is a little smaller than a Smart car, a little larger than a Tardis: 7.8ft tall, with a hexagonal cross section 4.7ft in diameter.Nasa launched it with an assembly of rockets built from old Peacekeeper inter­continental ballistic missiles. Originally designed to send nuclear bombs to the USSR, these rockets are strictly controlled under a US-Russian arms treaty: the small facility at Wallops Island, off Virginia, is one of the few places allowed to launch them. Thus, a bit before midnight on 6 September, the rockets’ red glare was visible from nearby Washington DC. These rockets