Preliminary data from the Lunar Crater Observation and Sensing Satellite, or LCROSS, indicated that the mission had successfully uncovered water during the Oct. 9 impacts into the permanently shadowed region of Cabeus crater near the moon's south pole, NASA said on Friday in a press release.
"We're unlocking the mysteries of our nearest neighbor and by extension the solar system. It turns out the moon harbors many secrets, and LCROSS has added a new layer to our understanding," said Michael Wargo, chief lunar scientist at NASA Headquarters in Washington.
NASA successfully crashed two spacecraft into the moon's south pole in a hunt for hidden ice on Oct. 9.
A 2.2-ton Centaur, the upper stage of the Atlas V rocket that carried LCROSS into space, struck the Cabeus crater first at around 5,600 miles (9,000 kilometers) per hour. Four minutes later, the LCROSS, which was equipped with cameras to record the impact, hit the Cabeus crater.
According to NASA, the impact created by the LCROSS Centaur upper stage rocket created a two-part plume of material from the bottom of the crater. The first part was a high angle plume of vapor and fine dust and the second a lower angle ejecta curtain of heavier material. This material has not seen sunlight in billions of years.
Scientists have long speculated about the source of vast quantities of hydrogen that has been observed at the lunar poles. The LCROSS findings are shedding new light on the question of water, which could be more widespread and in greater quantity than previously suspected.
Permanently shadowed regions could hold a key to the history and evolution of the solar system, much as an ice core sample taken on Earth reveals ancient data. In addition, water and other compounds represent potential resources that could sustain future lunar exploration.
Since the impacts, the LCROSS science team has been working almost nonstop analyzing the huge amount of data the spacecraft collected. The team concentrated on data from the satellite's spectrometers, which provide the most definitive information about the presence of water. A spectrometer examines light emitted or absorbed by materials that helps identify their composition.
"We are ecstatic," said Anthony Colaprete, LCROSS project scientist and principal investigator at NASA's Ames Research Center in Moffett Field, California. "Multiple lines of evidence show water was present in both the high angle vapor plume and the ejecta curtain created by the LCROSS Centaur impact. The concentration and distribution of water and other substances requires further analysis, but it is safe to say Cabeus holds water."
The team took the known near infrared spectral signatures of water and other materials and compared them to the spectra collected by the LCROSS near infrared spectrometer of the impact.
"We were only able to match the spectra from LCROSS data when we inserted the spectra for water," said Colaprete. "No other reasonable combination of other compounds that we tried matched the observations. The possibility of contamination from the Centaur also was ruled out."
Additional confirmation came from an emission in the ultraviolet spectrum that was attributed to hydroxyl, one product from the break-up of water by sunlight.
When atoms and molecules are excited, they release energy at specific wavelengths that are detected by the spectrometers. A similar process is used in neon signs. When electrified, a specific gas will produce a distinct color. The ultraviolet visible spectrometer detected hydroxyl signatures just after impact that are consistent with a water vapor cloud in sunlight.
Data from the other LCROSS instruments are being analyzed for additional clues about the state and distribution of the material at the impact site. The LCROSS science team along with colleagues are poring over the data to understand the entire impact event, from flash to crater, with the final goal being the understanding of the distribution of materials, and in particular volatiles, within the soil at the impact site.
"The full understanding of the LCROSS data may take some time. The data is that rich," said Colaprete. "Along with the water in Cabeus, there are hints of other intriguing substances. The permanently shadowed regions of the moon are truly cold traps, collecting and preserving material over billions of years."
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