The Hubble Space Telescope has detected oxygen in moon minerals that future explorers could use for breathing, to make electricity, and for rocket fuel.  Scientists say the findings will help them determine whether the amounts available in the lunar soil will be enough for future astronauts to use.

The orbiting Hubble observatory is usually aimed at extremely distant areas of the universe. But for a few days in August, the U.S. space agency, NASA, pointed it at the moon to look at the landing sites of the Apollo 15 and 17 missions of the early 1970s and a 45-kilometer wide impact crater on a plateau never visited by astronauts.

The Apollo missions had returned rock samples containing an oxygen-bearing mineral called ilmenite. Planetary scientist Mark Robinson of Northwestern University near Chicago says planners of future moon missions want to know if the plateau region contains an equally rich amount of ilmenite.

"All the minerals you find on the moon have oxygen in them, but ilmenite is special in the sense that it is relatively easy to break it apart to get to the oxygen," said Mr. Robinson.

The Hubble telescope was trained on these sites because its camera has filters that let it see in two regions of ultraviolet light and sense minerals on the moon's crust by the way their colors reflect in this part of the spectrum. Mr. Robinson compares the situation to sunglasses, which filter out some light and lets other wavelengths in.

"So by putting these sunglasses on at different times on the Hubble, we're able to create these black and white images in different wavelengths that we can use to discriminate subtle colors on the surface," he added.

Mr. Robinson and other university and NASA researchers are using the rocks returned by Apollo astronauts to help calibrate the light Hubble saw reflected from the Apollo landing sites. They can then compare this light with light from the crater area to determine how much oxygen-bearing ilmenite the region contains.

NASA Hubble scientist Jennifer Wiseman is part of the project.

"Future human expeditions to the moon could benefit by being able to use resources on the site instead of having to carry, for example, all of their life support up with them. So this is an important step to preparing a do-able program of lunar exploration," she explained.

NASA is preparing to renew exploration of the moon with the 2008 launch of a satellite called the Lunar Reconnaissance Orbiter, the first of several robotic missions that will lead to a human landing in 2018. The agency says the overall program will have value for scientists learning how the moon, Earth, and the other planets formed. It will also serve as the basis for later exploration of Mars.

The Lunar Reconnaissance Orbiter will take the best images yet of the moon's terrain to measure its chemical makeup and help the space agency look for possible landing sites. NASA moon scientist Michael Wargo says that it will provide data on potential resources that humans could tap when they return.

"The quality of the measurements that were made by Hubble are going to allow us prior to the launch of Lunar Reconnaissance Orbiter to help the team start to target where are the places that we want to look carefully at," said Mr. Wargo.

Targeting Hubble toward the moon was a technical challenge. It was designed to look at objects billions of kilometers away. Such distant bodies appear still during the brief time it takes to photograph them, so Hubble's aim can be steady. But the nearby moon appears to the observatory as relatively fast moving, so to track it and take 60 pictures, the telescope had to spin in a way it does not usually do. NASA's chief moon exploration scientist, Jim Garvin, says it was as if a blind person tried to throw a ball perfectly 60 times to someone running 50 meters away.

"That's the job Hubble had to do at the moon. It was a noteworthy undertaking. This is in some sense the miracle on the moon," said Mr. Garvin.

NASA says the Hubble images will require many months of analysis to determine the amount of ilmenite, and therefore oxygen, at the potential lunar landing site.