Begging a crust

There's an unassuming building at the Johnson Space Center in Houston, Texas, that is home to some exceedingly precious rubble: more than 300 kilograms of lunar rock.

The grey fragments of Moon range from fine grains of sand to rocks the size of basketballs. They were brought back between 1969 and 1976, mainly by the US Apollo missions, along with a tiny amount from Russia's robotic Luna missions.

Since their arrival, these rocks have helped scientists to understand much of what we know about the Moon today. Data from them were crucial in supporting the idea that the Moon was formed by a giant impact with the early Earth, for example.

You might think that after 30 years of analysing and reanalysing these samples mission scientists have learned all they could possibly want know.

Not so, says Randy Korotev of Washington University in St Louis. "People are developing new techniques all the time, which are helping us to pinpoint the dates of pivotal events in the Moon's history," he says. In 2005, for example, fragments of Apollo rock were used to pin down the exact age of the Moon1. Analysis of the elements halfnium and wolfram in the rock showed that the Moon is 4.527 billion years old, give or take 10 million years -- an improvement over previous datings of 4.56 to 4.29 billion years. ...

•	Begging a crust NASA has a lot of moon rock, but is it enough? Nature.com (UK), Friday, Sept. 1, 2006 Byline: Lucy Heady