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November
13, 2009: The argument that the Moon is a dry, desolate
place no longer holds water.
At
a press conference today, researchers revealed preliminary
data from NASA's Lunar Crater Observation and Sensing Satellite,
or LCROSS, indicating that water exists in a permanently shadowed
lunar crater. The discovery opens a new chapter in our understanding
of the Moon.
Above:
Visible camera images showing the ejecta plume at about 20
seconds after impact. Credit: LCROSS/NASA [more
images]
"We
are ecstatic," said Anthony Colaprete, LCROSS project
scientist and principal investigator at NASA's Ames Research
Center.
On
Oct. 9th, the LCROSS spacecraft and a companion rocket stage
made twin impacts in crater Cabeus near the Moon's south pole.
A plume of debris traveled at a high angle beyond the rim
of Cabeus and into sunlight, while an additional curtain of
debris was ejected more laterally.
"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," says Colaprete. "The concentration and distribution
of water and other substances requires further analysis, but
it is safe to say Cabeus holds water."
Since
the impacts, the LCROSS science team has been 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 helps identify the composition of materials
by examining light they emit or absorb.
The
team took the known near-infrared spectral signatures of water
and other materials and compared them to the impact spectra
the LCROSS near-infrared spectrometer collected.
 "We
were able to match the spectra from LCROSS data only when
we inserted the spectra for water," Colaprete said. "No
other reasonable combination of other compounds that we tried
matched the observations. The possibility of contamination
from the Centaur also was ruled out."
Right:
Data from LCROSS's near-infrared spectrometer taken 20 to
60 seconds after the impact of the Centaur booster. The smooth
curve corresponds to a model containing water and other compounds--some
of which remain unidentified. A model-fit containing only
water may be found here.
Credit: NASA [larger
image] [more
images]
Additional
confirmation came from an emission in the ultraviolet spectrum
that was attributed to hydroxyl (OH), one product from the
break-up of water (H2O) by 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 and colleagues are
poring over the data to understand the entire impact event,
from flash to crater. The goal is to understand the distribution
of all materials within the soil at the impact site.
"The
full understanding of the LCROSS data may take some time.
The data is that rich," Colaprete said. "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."
Stay
tuned for updates.
Editor: Dr.
Tony Phillips | Credit: Science@NASA
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