Carbon dioxide, ammonia, silver and more were found in a lunar crater. But where did they come from?
Analysis of a plume rising from impact of spent rocket motor into a lunar crater showed a rich supply of water and a complex mix of other compounds.
How the compounds, which include hydrocarbons and light metals, got to the moon is a mystery.
About 5.6 percent of the mass of the crater can be attributed to water ice alone, the scientists estimate.
A NASA prospecting mission to sample the frozen contents of a lunar crater found not only a rich supply of water, but a tapestry of other minerals, origins unknown.
The compounds, which include ammonia, carbon dioxide, carbon monoxide, sodium and, surprisingly, silver, could have come from the Earth, from the moon's interior, or from comets and asteroids..
Whatever the source, a rich milieu ended up in Cabeus, a small crater in permanent shadow on the moon's south pole.
"It's not like anything we were anticipating. The water by itself was significant. All the other stuff was really startling," Anthony Coleprete, lead scientist for NASA's Lunar Crater Observation and Sensing Satellite (LCROSS) mission, told Discovery News.
LCROSS was devised to follow up on previous detections of hydrogen in the lunar soil made by orbiting spacecraft, to determine if it's bound with oxygen as water, if it's hydrated minerals, or if it's solar protons just stuck in the dirt.
To draw their sample, scientists chose a crater in an area with strong signs of hydrogen and smashed the empty rocket motor that delivered NASA's Lunar Reconnaissance Orbiter (LRO) to the moon last year into it.
The impact carved a hole 70 to 100 feet in diameter and tossed up a fountain of lunar material six feet deep. A plume of debris, dust and vapor rose a half-mile off the ground, high enough to clear the crater's walls and bathe in sunlight.
Strategically positioned for optimal viewing was a shepherding spacecraft, outfitted with instruments to pick apart the plume's chemistry for nearly four minutes, until it too crashed into the crater. LRO and ground-based telescopes also analyzed the plume.
The mission was sponsored by NASA's Exploration division, which is interested in developing missions that make use of indigenous resources.indigenous
If LCROSS had turned up 1 percent water, NASA figures it might be economically viable to extract water from a crater, rather than try to coax it from the soil, where water exists in minuscule amounts.
In Cabeus, approximately 5.6 percent of the mass inside the crater could be water ice alone, Coleprate and colleagues report in a series of papers in this week's Science.
"We've always been told the moon is bone dry and that was the legacy of Apollo and that's true -- in all the samples we picked up," Brown University planetary geologist Peter Schultz told Discovery News.
"It's now a new moon to me. We know there are places we can explore that can tell us brand new things," Schultz said.