The target of a NASA probe due to crash into the moon appear above. The dots at the center of the image of the lunar crater indicate the impact points.
EUROPLANET
NASA plans a surgical strike on the moon on Friday, hoping to hit water.
The operation, scheduled for 7:30 a.m. EDT, will unfold live on the Internet, as well as under the watchful eyes of dozens of amateur and professional astronomers and orbiting observatories, including the Hubble Space Telescope.
The delicate task has been precisely planned so that Earth's view will be through a dip in the high walls of a lunar crater, with the sun shining low across the rim. The best view will come from the Lunar Crater Observation and Sensing Satellite, known as LCROSS, specifically designed for this one mission.
Late Thursday night, LCROSS will release a 50,817-pound empty rocket body its been flying with since launch from Cape Canaveral, Fla., on June 18. Empty of fuel and sterilized by the sun, the Centaur motor will impact inside an old, large crater on the moon’s south pole, a place where the sun never shines. The crater’s walls keep part of the pit in permanent darkness, keeping temperatures as low as about minus-370 degrees Fahrenheit, colder than Pluto.
Flyovers by several spacecraft show unmistakable signs of hydrogen. Scientists speculate the hydrogen may be bound with oxygen to make water that has been in a lunar deep freeze for billions of years.
"We're very optimistic that we're going to sample the best possible place in the south pole," LCROSS lead scientist Anthony Calaprete told Discovery News.
The Centaur's crash should kick up about 300,000 to 350,000 tons of material from the crater floor, about five tons of which should soar past the crater's rim and into sunlight.
LCROSS and other instruments will quickly scan the debris for chemical signs of water. Then it too will crash into the crater, about 2.2 miles away from the Centaur, creating a second, smaller debris plume for study.
NASA's Office of Exploration is sponsoring the mission, with the goal of finding out if the moon has water and other resources that could be used by future human visitors or colonists.
"The principle purpose is to identify if resources are there and if they are accessible," said Colaprete, with NASA's Ames Research Center in Mountain View, Calif. "It's to pave the way for making decisions about where to go down the line."
Scientists, who recently discovered that the moon is wrapped in a thin but unmistakable layer of water vapor, want to unravel the mystery of how water got to the moon, a story that may also shed light on where Earth's water came from.
"We got a lot of water from somewhere and the moon may have some of the answers to these questions," Colaprete said.
Previous studies found traces of water in volcanic glass retrieved from the moon during the Apollo missions of 1969-1972.
That water came from inside the moon, said Alberto Saal, associate professor of geological sciences at Brown University.
"The debate is whether water came from meteorites and comets or was it water from another source that got trapped as a gas," Saal said.
NASA has set up a Web site (http://apps.nasa.gov/lcross/ ) for astronomers to post images of the impact. The event will be broadcast live on NASA TV. (http://www.nasa.gov/multimedia/nasatv/index.html )
Tags: NASA, Night, Spacecraft, The Moon, Water
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