GREENBELT, Md., Aug. 16 (UPI) -- An instrument aboard a NASA
orbiter has detected helium in the moon's tenuous atmosphere,
the space agency said. These remote-sensing observations by the
Lunar Reconnaissance Orbiter confirm measurements taken in 1972
by an experiment deployed on the moon's surface by Apollo 17, a
NASA release reported Wednesday. The instrument aboard the LRO
examined ultraviolet emissions in the tenuous atmosphere above
the lunar surface, detecting helium in measurements spanning
more than 50 orbits. "The question now becomes, does the helium
originate from inside the moon, for example, due to radioactive
decay in rocks, or from an exterior source, such as the solar
wind?" said Alan Stern of the Space Science and Engineering
Division at Southwest Research Institute, Boulder, Colo. "If we
find the solar wind is responsible, that will teach us a lot
about how the same process works in other airless bodies," Stern
said. If additional observations rule out the solar wind, then
radioactive decay o