Is There Oxygen on the Moon?

Never mind the moon’s utter lack of atmosphere, there’s plenty of air to breathe up there—provided you know where to look. With NASA once again planning human moon exploration, that’s become an increasingly important matter. This week, the Hubble Space Telescope may have provided some critical answers.

It is the moon’s small mass and low gravity that prevents it from keeping hold of even a tenuously thin atmosphere. But oxygen needn’t exist only in gaseous form above the ground. It can also be entrained safely in certain kinds of rocks. Gather the rubble and either treat it with chemicals or blast it with heat, and you can free up unlimited quantities of oxygen both for breathing and for rocket fuel.

The lunar mineral that may hold the most oxygen promise is ilmenite, a titanium oxide brought back from the moon’s Taurus-Littrow region by the Apollo 17 crew in 1972. To determine how heavy the ilmenite concentrations are at that site and to look for other outcroppings as well, NASA recently decided to conduct telescope surveys of four lunar regions: Taurus-Littrow, Hadley-Apennine—landing site of Apollo 15—the unexplored Aristarchus impact crater and nearby Schroter’s Valley. Though ground-based telescopes would ordinarily be suitable for this work, in this case they wouldn’t do, since the scientists were looking for ultraviolet reflections of ilmenite, a frequency of light absorbed by Earth’s atmosphere. The only way to conduct the work was to get above that blinding blanket and look across clear, airless space. When Hubble did that, it quickly spotted paydirt.

The telescope found what appears to be ilmenite deposits not only at the Apollo 17 site, where it was known to be, but also in Schroter’s Valley and in especially high concentrations in Aristarchus crater. Aristarchus would make an especially good landing site for future geologists, because the impacts that create craters blasts away surface material, providing a detailed look far below ground. Combine that with the ready lode of oxygen-rich ilmenite, and you’ve got a prime spot for a future moon base.

Striking as the Hubble images are, there is one thing they couldn’t reveal. The telescope’s giant eye can see lunar objects no smaller than 60 yards across. Somewhere in Taurus-Littrow and Hadley-Apennine are the comparatively tiny, truck-sized descent stages of the Apollo lunar modules, left behind when the crews blasted off. Neither of those metal relics has been seen in the more than 30 years since human beings last walked on the moon. Only if the U.S. actually commits itself to its new lunar plans will they be seen again any time soon.