Ebb and Flow in science

After a year of flying in circles, Ebb and Flow have made a last landing, their work done, their fuel depleted and their resting place chosen well away from future tourist attractions.

The two Nasa spacecraft, more formally known as the Gravity Recovery and Interior Laboratory, have been flying around the Moon while scientists used the data they sent back to study lunar gravity. It's the kind of science that draws little public interest - no Apollo 13 drama here, no Neil Armstrong, just another chapter in the annals of scientific understanding. Coming at a time when manned space flight is in the doldrums, the project does not generate stirring thoughts of human expansion beyond our home planet.

But it all helps. What Ebb and Flow have taught us about the thickness of the moon's crust will surely be of use some day, in taking some advantage of lunar geology, in planning lunar buildings or in some way we can't even glimpse yet. Science is like that.

And scientists look ahead, which is why Ebb and Flow were driven into a lunar hillside far from the relics of the Apollo landings. Someday there'll be tourism there - and a Starbucks, no doubt - and it wouldn't do to smash up the most venerable heritage sites within a 384,400km radius.