NASA rocket on crash course with moon
The largest array of spacecraft and Earth-bound telescopes ever assembled will be watching before dawn Friday for a brilliant flash of light from a deep and permanently shadowed crater near the moon's South Pole.
That flash will signal the climax of a mission from NASA's Ames Research Center in Mountain View, where scientists are seeking conclusive evidence of whether copious quantities of water exist just beneath the lunar surface.
At 4:30 a.m. Friday - give or take a minute or two - a spacecraft named LCROSS will send its 2-ton, upper-stage spent rocket crashing into the crater to raise a 6-mile-high cloud of rock and dust.
That cloud of debris, emerging from the dark crater into brilliant sunlight, will be analyzed by sensitive instruments aboard LCROSS and by detectors aboard a fleet of orbiting spacecraft and numerous telescopes on Earth wherever the moon is visible.
Amateur astronomers with telescopes in the 10- to 12-inch range may be able to catch the distant flash of the LCROSS impact, but the plume will not be visible to the naked eye.
The newly refurbished Hubble Space Telescope, UC Santa Cruz's Lick Observatory atop Mount Hamilton near San Jose, the powerful Keck and Gemini North telescopes on Mauna Kea in Hawaii, and observatories in Arizona and New Mexico are focused on the target crater, named Cabeus, and will take images of the flash from the blast.
Each telescope and spacecraft carries different suites of analytic instruments operating at different wavelengths to detect all the chemicals in the bright dust cloud.
Four minutes after the blast, LCROSS itself - with all its data from the debris cloud transmitted back to the Ames Center - will deliberately crash into the same crater and send up a much smaller debris cloud that also might be visible to scientists on Earth and all the orbiting spacecraft.
LCROSS, which stands for Lunar Crater Observation and Sensing Satellite, was launched in June and has been orbiting the moon, carrying the upper-stage Centaur rocket that sent it into space. On Friday, LCROSS will send the Centaur into the crater.
It's an extremely tricky job to aim a 2-ton object flying in space at a target only a few yards wide, while using controls on Earth nearly 240,000 miles away.
The engineers "have commanded the spacecraft to fire a series of trajectory correction maneuvers to get us on target, and we have another maneuver on the books yet in case we need it," Anthony Colaprete, the mission's chief scientist, said Wednesday in an e-mail.
"We're just finishing up the last of our rehearsals and the team is anxious but focused," he said. "The training is really paying off and everyone knows exactly the job they need to do."
The LCROSS mission has attracted such wide attention that officials at the Ames Research Center have invited the public to spend all night outdoors at the research center's campus at Moffett Field. They will offer free movies, entertainment and scientific explanations.
Several thousand are expected, and when the impact occurs, they will be shown wide-screen Internet feeds of the flash from the Hubble space telescope and other observatories while Ames scientists explain what's happening.
The mission may reveal what scientists are seeking: new knowledge about the moon's interior - and, for some, a future source of water for astronauts and fuel for their rockets.
Viewing the lunar impact
-- NASA's video feed begins at 3:15 a.m. Friday at www.nasa.gov/ntv
-- Two physicists from the Exploratorium will be at the Lick Observatory feeding images and commentary from 3:10 a.m. at www.explo.tv
-- The Chabot Space and Science Center in Oakland will open its doors to the public at 3 a.m. and show a video feed from NASA starting at 3:30 a.m. continuing through to the 4:30 a.m. impact. Images from Chabot's large reflecting telescopes will be fed online at www.chabotspace.org/webcams/nelliecam.asp
E-mail David Perlman at firstname.lastname@example.org