Water evidence seen in lunar impact plume

Physics Today : The Moon is wetter than previously believed, say NASA scientists Friday, reporting the results of the Lunar CRater Observation and Sensing Satellite (LCROSS) impact probe, that slammed into lunar polar craters a month ago ."There’s water, and it is not just a little water, but significant amounts,” says NASA’s Anthony Colaprete, chief science investigator for the LCROSS in a press conference earlier today.The LCROSS Centaur upper stage rocket was used to create a plume on the 9 October by smashing into the permanently shadowed region of Cabeus crater near the moon’s south pole.The resulting impact 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.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 about 26 gallons of water."We are ecstatic,” said Colaprete, “multiple lines of evidence show water was present in both the high angle vapor plume and the ejecta curtain created by the 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.” A short tripLCROSS was launched on the 18 June as a companion mission to the Lunar Reconnaissance Orbiter . After separating from LRO, the LCROSS spacecraft held onto the spent Centaur upper stage rocket of the launch vehicle, executed a lunar swingby and entered into a series of long looping orbits around the Earth.After traveling approximately 113 days and nearly 9 million kilometers, the Centaur and LCROSS separated on final approach to the moon.Traveling as fast as a speeding bullet, the Centaur impacted the lunar surface shortly after 4:31 am PDT Oct. 9 with LCROSS watching with its onboard instruments. Approximately four minutes of data was collected before the LCROSS itself impacted the lunar surface. Related News Picks Plume from lunar impact seen Lunar impact experiment worked as planned Lunar crash to create a 10 kilometer plume of dust Related News Stories Water found in moon crater USA Today NASA discovers ‘significant’ amount of water on moon Washington Post