Moon Crash, New Maps to Aid Search for Lunar Water

Anne Minard
for National Geographic News
June 17, 2009
The moon is about to get some new visitors—including one on a suicide mission.

A rocket carrying two new NASA probes is slated to lift off from Kennedy Space Center on Thursday, with the first launch opportunity at 5:12 p.m. ET.

The Lunar Reconnaissance Orbiter (LRO) will spend at least a year mapping the moon, including the little-studied lunar poles. (Find out more about lunar exploration.)

LRO will also carry a hitchhiker, an SUV-size probe meant to slam into a shadowy crater near the moon's south pole in search of water ice.

NASA's Lunar Crater Observation and Sensing Satellite (LCROSS) is to careen into the crater in October, gouging a hole about 15 feet (4.5 meters) deep and 100 feet (30 meters) wide.

Weather permitting, sky-watchers with backyard telescopes will have a clear view of the plume sent up by the impact, which scientists will be watching for signs of water amid the lunar debris.

Ice in the Dark?

LRO carries a suite of instruments for taking detailed temperature readings, for looking at the effects of radiation on the lunar surface, and for scoping out good landing sites for future missions, among other tasks.

"Over the course of a year, we will map with high resolution the entire lunar surface," said Rich Vondrak, LRO project scientist at NASA's Goddard Space Flight Center.

The probe will focus mainly on the poles, where permanently shadowed craters might harbor water ice near the surface, making them the most likely places to set up long-term human settlements.

"Those areas of the moon, we actually have very sparse information about," Craig Tooley, LRO project manager at Goddard Space Flight Center in Maryland, said during a recent mission briefing.

"For those regions, we have more complete maps of Mars than the moon."

Moon Crash

LCROSS, meanwhile, is meant to take a more aggressive approach in the search for water ice.

Hints of moon water were first sent to Earth in the 1990s, when the Naval Research Laboratory's Clementine mission detected hydrogen at the lunar poles.

But that data did not reveal whether the element was contained in water (H2O) or other hydrogen-bearing compounds, such as hydrocarbons.

Since then three separate missions have sent probes barreling into the moon, but none of them returned proof of water.

(Read "Moon-Smashing Probes: Are the Data Worth the Damage?")

The LCROSS mission will be the first to specifically look for water within a polar crater.

Plume Watchers

Once launched, LRO will take four days to reach lunar orbit. The probe will then spend several months searching for the best impact site and setting up a prime trajectory.

In early October, LCROSS is slated to fire up its car-size rocket and separate from the orbiter. The probe will then quickly shed the rocket and send it pummeling into the moon at 5,600 miles (9,000 kilometers) an hour.

The rocket's impact is expected to dislodge 220 tons of material, which should fly as far as 30 miles (50 kilometers) from the impact site.

Instruments aboard LCROSS will watch the rocket's impact and send back data on the plume's composition, including whether it contains water. Four minutes later, the probe will fly through the plume on its own collision course.

Telescopes around the world will be trained on the impact site to study the material kicked up by LCROSS's demise.

For those who simply want to watch the spectacle from a backyard telescope, the best viewing conditions will be in the Northern Hemisphere, from Hawaii to as far east as Texas or Mississippi. (See a U.S. map.)

NASA will also host live streaming video of the impact online.

The physical material will expand outward like an upside-down lampshade and then "will be all but settled in four minutes," said Tony Colaprete, a planetary atmospheric scientist at NASA Ames Research Center and the principle investigator on LCROSS.

Aside from the new crater, he added, LCROSS "will not damage the moon in any way."

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