busyNASA Instruments Reveal Water Molecules on Lunar Surface
PASADENA, Calif. -- NASA scientists have discovered water molecules in
the polar regions of the moon. Instruments aboard three separate
spacecraft revealed water molecules in amounts that are greater than
predicted, but still relatively small. Hydroxyl, a molecule consisting of
one oxygen atom and one hydrogen atom, also was found in the lunar soil.
The findings were published in Thursday's edition of the journal
Science.
NASA's Moon Mineralogy Mapper, or M3, instrument reported the
observations. M3 was carried into space on Oct. 22, 2008, aboard the
Indian Space Research Organization's Chandrayaan-1 spacecraft. Data from
the Visual and Infrared Mapping Spectrometer, or VIMS, on NASA's Cassini
spacecraft, and the High-Resolution Infrared Imaging Spectrometer on
NASA's Epoxi spacecraft contributed to confirmation of the finding. The
spacecraft imaging spectrometers made it possible to map lunar water
more effectively than ever before.
The confirmation of elevated water molecules and hydroxyl at these
concentrations in the moon's polar regions raises new questions about
its origin and effect on the mineralogy of the moon. Answers to these
questions will be studied and debated for years to come.
"Water ice on the moon has been something of a holy grail for lunar
scientists for a very long time," said Jim Green, director of the
Planetary Science Division at NASA Headquarters in Washington. "This
surprising finding has come about through the ingenuity, perseverance and
international cooperation between NASA and the India Space Research
Organization."
From its perch in lunar orbit, M3's state-of-the-art spectrometer
measured light reflecting off the moon's surface at infrared wavelengths,
splitting the spectral colors of the lunar surface into small enough bits
to reveal a new level of detail in surface composition. When the M3
science team analyzed data from the instrument, they found the
wavelengths of light being absorbed were consistent with the absorption
patterns for water molecules and hydroxyl.
"For silicate bodies, such features are typically attributed to water
and hydroxyl-bearing materials," said Carle Pieters, M3's principal
investigator from Brown University, Providence, R.I. "When we say 'water
on the moon,' we are not talking about lakes, oceans or even puddles.
Water on the moon means molecules of water and hydroxyl that interact
with molecules of rock and dust specifically in the top millimeters of
the moon's surface.
The M3 team found water molecules and hydroxyl at diverse areas of the
sunlit region of the moon's surface, but the water signature appeared
stronger at the moon's higher latitudes. Water molecules and hydroxyl
previously were suspected in data from a Cassini flyby of the moon in
1999, but the findings were not published until now.
"The data from Cassini's VIMS instrument and M3 closely agree," said
Roger Clark, a U.S. Geological Survey scientist in Denver and member of
both the VIMS and M3 teams. "We see both water and hydroxyl. While the
abundances are not precisely known, as much as 1,000 water molecule
parts-per-million could be in the lunar soil. To put that into
perspective, if you harvested one ton of the top layer of the moon's
surface, you could get as much as 32 ounces of water."
For additional confirmation, scientists turned to the Epoxi mission while
it was flying past the moon in June 2009 on its way to a November 2010
encounter with comet Hartley 2. The spacecraft not only confirmed the
VIMS and M3 findings, but also expanded on them.
"With our extended spectral range and views over the north pole, we were
able to explore the distribution of both water and hydroxyl as a function
of temperature, latitude, composition, and time of day," said Jessica
Sunshine of the University of Maryland. Sunshine is Epoxi's deputy
principal investigator and a scientist on the M3 team. "Our analysis
unequivocally confirms the presence of these molecules on the moon's
surface and reveals that the entire surface appears to be hydrated
during at least some portion of the lunar day."
NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the M3
instrument, Cassini mission and Epoxi spacecraft for NASA's Science
Mission Directorate in Washington. The Indian Space Research
Organization built, launched and operated the Chandrayaan-1 spacecraft.
For additional information and images from the instruments, visit:
http://www.nasa.gov/topics/moonmars .
For more information about the Chandrayaan-1 mission, visit:
http://isro.gov.in/Chandrayaan/htmls/home.htm .
For more information about the EPOXI mission, visit:
http://www.nasa.gov/epoxi .
For more information about the Cassini mission, visit:
http://www.nasa.gov/cassini .
* * *
NASA Spacecraft Sees Ice on Mars Exposed by Meteor Impacts
PASADENA, Calif. -- NASA's Mars Reconnaissance Orbiter has revealed
frozen water hiding just below the surface of mid-latitude Mars. The
spacecraft's observations were obtained from orbit after meteorites
excavated fresh craters on the Red Planet.
Scientists controlling instruments on the orbiter found bright ice
exposed at five Martian sites with new craters that range in depth from
approximately half a meter to 2.5 meters (1.5 feet to 8 feet). The
craters did not exist in earlier images of the same sites. Some of the
craters show a thin layer of bright ice atop darker underlying material.
The bright patches darkened in the weeks following initial observations,
as the freshly exposed ice vaporized into the thin Martian atmosphere.
One of the new craters had a bright patch of material large enough for
one of the orbiter's instruments to confirm it is water-ice.
The finds indicate water-ice occurs beneath Mars' surface halfway between
the north pole and the equator, a lower latitude than expected in the
Martian climate.
"This ice is a relic of a more humid climate from perhaps just several
thousand years ago," said Shane Byrne of the University of Arizona,
Tucson.
Byrne is a member of the team operating the orbiter's High Resolution
Imaging Science Experiment, or HiRISE camera, which captured the
unprecedented images. Byrne and 17 co-authors report the findings in the
Sept. 25 edition of the journal Science.
"We now know we can use new impact sites as probes to look for ice in the
shallow subsurface," said Megan Kennedy of Malin Space Science Systems in
San Diego, a co-author of the paper and member of the team operating the
orbiter's Context Camera.
During a typical week, the Context Camera returns more than 200 images
of Mars that cover a total area greater than California. The camera team
examines each image, sometimes finding dark spots that fresh, small
craters make in terrain covered with dust. Checking earlier photos of the
same areas can confirm a feature is new. The team has found more than
100 fresh impact sites, mostly closer to the equator than the ones that
revealed ice.
An image from the camera on Aug. 10, 2008, showed apparent cratering
that occurred after an image of the same ground was taken 67 days earlier.
The opportunity to study such a fresh impact site prompted a look by the
orbiter's higher resolution camera on Sept. 12, 2009, confirming a
cluster of small craters.
"Something unusual jumped out," Byrne said. "We observed bright material
at the bottoms of the craters with a very distinct color. It looked a lot
like ice."
The bright material at that site did not cover enough area for a
spectrometer instrument on the orbiter to determine its composition.
However, a Sept. 18, 2008, image of a different mid-latitude site showed
a crater that had not existed eight months earlier. This crater had a
larger area of bright material.
"We were excited about it, so we did a quick-turnaround observation,"
said co-author Kim Seelos of Johns Hopkins University Applied Physics
Laboratory in Laurel, Md. "Everyone thought it was water-ice, but it was
important to get the spectrum for confirmation."
Mars Reconnaissance Orbiter Project Scientist Rich Zurek, of NASA's Jet
Propulsion Laboratory, Pasadena, Calif., said, "This mission is designed
to facilitate coordination and quick response by the science teams. That
makes it possible to detect and understand rapidly changing features."
The ice exposed by fresh impacts suggests that NASA's Viking Lander 2,
digging into mid-latitude Mars in 1976, might have struck ice if it had
dug 10 centimeters (4 inches) deeper. The Viking 2 mission, which
consisted of an orbiter and a lander, launched in September 1975 and
became one of the first two space probes to land successfully on the
Martian surface. The Viking 1 and 2 landers characterized the structure
and composition of the atmosphere and surface. They also conducted
on-the-spot biological tests for life on another planet.
NASA's Jet Propulsion Laboratory in Pasadena manages the Mars
Reconnaissance Orbiter for NASA's Science Mission Directorate in
Washington. Lockheed Martin Space Systems in Denver built the spacecraft.
The Context Camera was built and is operated by Malin Space Science
Systems. The University of Arizona operates the HiRISE camera, which
Ball Aerospace & Technologies Corp., in Boulder, Colo., built. The Johns
Hopkins University Applied Physics Laboratory led the effort to build
the Compact Reconnaissance Imaging Spectrometer and operates it in
coordination with an international team of researchers.
To view images of the craters and learn more about the Mars
Reconnaissance Orbiter, visit http://www.nasa.gov/mro or
http://marsprogram.jpl.nasa.gov/mro/ .
September 25 2009, 02:53:10 UTC 11 years ago