Water Ice On The Moon Was Just The Beginning Of LCROSS,
LRO Discoveries
Nearly a year after announcing the discovery of water molecules
on the moon, scientists Thursday revealed new data uncovered by
NASA's Lunar CRater Observation and Sensing Satellite, or LCROSS,
and Lunar Reconnaissance Orbiter, or LRO. The missions found
evidence that the lunar soil within shadowy craters is rich in
useful materials, and the moon is chemically active and has a water
cycle. Scientists also confirmed the water was in the form of
mostly pure ice crystals in some places. The results are featured
in six papers published in the October 22 issue of Science.
"NASA has convincingly confirmed the presence of water ice and
characterized its patchy distribution in permanently shadowed
regions of the moon," said Michael Wargo, chief lunar scientist at
NASA Headquarters in Washington. "This major undertaking is the one
of many steps NASA has taken to better understand our solar system,
its resources, and its origin, evolution, and future."
The twin impacts of LCROSS and a companion rocket stage in the
moon's Cabeus crater on Oct. 9, 2009, lifted a plume of material
that might not have seen direct sunlight for billions of years. As
the plume traveled nearly 10 miles above the rim of Cabeus,
instruments aboard LCROSS and LRO made observations of the crater
and debris and vapor clouds. After the impacts, grains of mostly
pure water ice were lofted into the sunlight in the vacuum of
space.
"Seeing mostly pure water ice grains in the plume means water
ice was somehow delivered to the moon in the past, or chemical
processes have been causing ice to accumulate in large quantities,"
said Anthony Colaprete, LCROSS project scientist and principal
investigator at NASA's Ames Research Center in Moffett Field,
Calif. "Also, the diversity and abundance of certain materials
called volatiles in the plume, suggest a variety of sources, like
comets and asteroids, and an active water cycle within the lunar
shadows."
LCROSS Impact Crater NASA Image
Volatiles are compounds that freeze and are trapped in the cold
lunar craters and vaporize when warmed by the sun. The suite of
LCROSS and LRO instruments determined as much as 20 percent of the
material kicked up by the LCROSS impact was volatiles, including
methane, ammonia, hydrogen gas, carbon dioxide and carbon
monoxide.
The instruments also discovered relatively large amounts of
light metals such as sodium, mercury and possibly even silver.
Scientists believe the water and mix of volatiles that LCROSS
and LRO detected could be the remnants of a comet impact. According
to scientists, these volatile chemical by-products are also
evidence of a cycle through which water ice reacts with lunar soil
grains.
LRO's Diviner instrument gathered data on water concentration
and temperature measurements, and LRO's Lunar Exploration Neutron
Detector mapped the distribution of hydrogen. This combined data
led the science team to conclude the water is not uniformly
distributed within the shadowed cold traps, but rather is in
pockets, which may also lie outside the shadowed regions.
The proportion of volatiles to water in the lunar soil indicates
a process called "cold grain chemistry" is taking place. Scientists
also theorize this process could take as long as hundreds of
thousands of years and may occur on other frigid, airless bodies,
such as asteroids; the moons of Jupiter and Saturn, including
Europa and Enceladus; Mars' moons; interstellar dust grains
floating around other stars and the polar regions of Mercury.
"The observations by the suite of LRO and LCROSS instruments
demonstrate the moon has a complex environment that experiences
intriguing chemical processes," said Richard Vondrak, LRO project
scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.
"This knowledge can open doors to new areas of research and
exploration."
By understanding the processes and environments that determine
where water ice will be, how water was delivered to the moon and
its active water cycle, future mission planners might be better
able to determine which locations will have easily-accessible
water. The existence of mostly pure water ice could mean future
human explorers won't have to retrieve the water out of the soil in
order to use it for valuable life support resources. In addition,
an abundant presence of hydrogen gas, ammonia and methane could be
exploited to produce fuel.
LRO Image Of Lunar South Pole NASA Image
LCROSS launched with LRO aboard an Atlas V rocket from Cape
Canaveral, FL, on June 18, 2009, and used the Centaur upper stage
rocket to create the debris plume. The research was funded by
NASA's Exploration Systems Missions Directorate at the agency's
headquarters. LCROSS was managed by Ames and built by Northrop
Grumman in Redondo Beach, CA. LRO was built and is managed by
Goddard.