Targeting the Moon’s ‘Wettest Spots’
Earth attacks the moon tomorrow, bent on plundering that most precious of resources: water.
"Things are looking great. We're headed right for the target," says Daniel Andrews of NASA's Ames Research Center, head of the $79 million Lunar Crater Observation and Sensing Satellite (LCROSS) mission. "The very latest data suggest we are headed for one of the very wettest spots on the moon."
If all goes well, on Friday about 7:30 a.m. ET, the two parts of the LCROSS spacecraft will smack into the lunar surface at nearly 6,000 mph, sending up plumes of moon dust - perhaps full of ice - 6.2 miles high above the moon's Cabeus crater.
"There is a very good chance we will see results," says planetary scientist Bernard Foing of the European Space Agency, who is not part of the mission. "Cabeus crater is perfect. Some areas are always in shadow, so we are quite certain these are some of the coldest places for ice in the solar system," as low as minus 360 degrees Fahrenheit.
Tonight, the LCROSS "shepherd" spacecraft should drop its booster rocket and turn to observe its descent. After the booster hits the crater, blasting out a hole 90 feet deep, the shepherd will pass through the plume. After analyzing the plume, the shepherd then blasts into the crater itself four minutes later, creating a second hole 60 feet deep.
"We are trimming the trajectory as we go," Andrews says.
Dating back at least to 1999, when a lunar mission detected water signatures from the supposedly bone-dry moon, NASA scientists have pondered whether ice left from comet impacts may have pooled and cooled in the permanently shaded potholes - probably strangers to sunlight for billions of years - dotting the lunar poles. In 2004, when the Bush administration pushed for moon bases, glaciers hidden in those craters looked attractive as water and fuel sources for future moon colonists.
Last month, Science magazine reported evidence of water migrating out of the lunar soil in the solar wind, or streams of gas particles from the sun, and perhaps some of the water ended up in those shaded craters. "What's still not clear is whether there is enough water there to be meaningful," Andrews says; "meaningful" could be anything from 1% to 10% of the plume containing water.
"Water on the moon has haunted us for years," says William Hartmann of the Planetary Science Institute. "It's all part of humanity's quest to understand our nearby cosmic environment."
LCROSS should detect whether at least 0.5% of the plume contains water. If the results point to water deposits, Foing says, a next step would be a lander drilling about 6 feet deep into the crater, enough to reveal whether veins of ice lie in exploitable layers on the moon. The 1967 Outer Space Treaty forbids spacefaring nations from claiming lunar territory but allows research bases while calling for avoiding "harmful contamination."
NASA's Lunar Reconnaissance Orbiter, which launched with LCROSS June 18, will observe the plumes, as will the Hubble Space Telescope and observatories on Earth. Amateur astronomers with a view of the moon should be able to see the impacts with telescopes 10 inches wide or larger.