Eugene Cernan was the last man to walk on the Moon in December 1972. But a drawing he made while orbiting Earth's only natural satellite is back in the news, after it sparked a scientific mystery that may well be solved by the end of the year.
Mr Cernan sketched the strange streams of light he saw coming from the Moon's dark side, which always faces away from Earth. On the weekend, Nasa launched its Lunar Atmosphere and Dust Environment Explorer (Ladee), a spacecraft that, according to the agency's website, will "address long-standing unknowns".
In other words, it's designed to find out what causes this phenomenon by orbiting the Moon and closely examining its thin atmosphere for 100 days before a controlled crash landing on the surface.
By then, China's Chang'e 3 vehicle will also have landed, as part of a programme that might see humans walking on the Moon again in the early 2020s. Inevitably, there is talk of a colony.
The original Moon landings inspired the world. That same space race also brought about great innovation and invention. It's reassuring to know that the spirit of adventure that drove those Apollo missions persists even today.
