October 12, 2012

Diviner scientists locate iron oxide deposits on the Moon

In a paper recently published in the Journal of Geophysical Research, four Diviner team members estimate the abundance of iron oxide (FeO) at the sites of several volcanic deposits on the Moon’s surface.

Determining the distribution of iron oxide on the lunar surface may hold important clues about the Moon’s geologic history and may also provide an important inventory of lunar resources for future human exploration endeavors.

Billions of years ago, geologic activity on the Moon launched magma from the surface, allowing small bead-like pieces of volcanic glass to solidify in midair. Eons later, Apollo astronauts collected soil samples containing these translucent projectiles and returned them to Earth for analysis. Colored primarily orange, black, and green, the bits of volcanic ejecta are rounded and each about the width of a human hair.

By measuring the thermal properties of lunar samples in an Earthbound laboratory, first-author Carlton Allen developed conclusions about data taken from lunar orbit by the Diviner experiment, onboard the Lunar Reconnaissance Orbiter. To calibrate the spacecraft’s measurements, Allen compared Diviner spectral signatures to the compositions of soils from Apollo landing sites.

Of the three volcanic deposits Allen analyzed, two were rich in iron oxides and volcanic glasses (regions named Aristarchus and Sulpicius Gallus), while the third was not (a region called Rima Fresnel).

Additional authors of this study include researchers Benjamin Greenhagen, Kerri Donaldson Hanna, and David Paige.

To learn more about this study, read the original paper.

October 1, 2012

Diviner team members explain their research in 60 seconds

Diviner team members Jean-Pierre Williams and Emily Foote presented research at the European Planetary Science Congress last week in Madrid, Spain.  Watch as they explain their research in just 60 seconds!

Pierre and Emily Explain their Research in 60 Seconds

February 7, 2012

LPSC Diviner Data Users Forum - First Announcement

The LRO Diviner Science Team will host a public Diviner Data Users Forum on on Sunday, March 18 from 1.30-3pm. The meeting will be located in the Panther Creek conference room of the Woodlands Waterway Marriott Hotel & Convention Center, 1601 Lake Robbins Drive, The Woodlands, Texas 77380. The purpose of the forum will be to acquaint the community with Diviner’s latest high-level mapped data products. These products include global maps of brightness temperature, solar reflectance, composition, rock abundance and thermophysical properties. The forum will also provide an opportunity for potential users to ask questions and provide feedback to the team. Attendance is open to the public.

Agenda

1:30 Diviner Experiment and Dataset Overview (D. Paige)
1:45 Diviner Level 2 Data Products (J. P. Williams)
2:00 Diviner Level 3 Data Products (B. Greenhagen)
2:10 Demo of PDS, ARCGIS, JMoon and LMMP Data Access
2:30 Diviner Foundation Datasets (D. Paige)
2:45 Questions and Discussion (All)

November 20, 2011

Deputy PI interviewed for 365 Days of Astronomy

The 365 Days of Astronomy Project has had a single mission since it was started during the International Year of Astronomy, 2009: publish one podcast per day, 5 to 10 minutes in duration, for all 365 days of 2009. The tradition has continued throughout 2010 and 2011, and today Dr. Ben Greenhagen, deputy principal investigator for the Diviner Lunar Radiometer, gave an interview detailing the mission, and the exciting results gathered so far. To listen to the interview go to: http://365daysofastronomy.org/2011/11/20/november-20th-how-cold-is-the-moon/

September 29, 2011

International Observe the Moon Night 2011

Hosted by UCLA Undergraduate Astronomical Society in association with the Diviner Lunar Radiometer

Date: 8 October 2011
Time: 6.30pm
Location: UCLA Planetarium, Mathematical Sciences Building 8224, Los Angeles, CA 90095-0001

Join the UCLA Undergraduate Astronomical Society for this global moon-watching event. International Observe the Moon Night is a chance for everyone to become acquainted with our companion in the cosmos: brush up on your Moon trivia, learn about the latest results from NASA’s Lunar Reconnaissance Orbiter, and see with your own eyes what our nearest neighbor looks like up close and personal using UCLA’s 14″ telescope.

June 21, 2011

Diviner observes cooling during June 15 total eclipse

Preliminary results from the Diviner Lunar Radiometer show that dayside surface temperatures on the Moon cooled significantly during the June 15th total eclipse.

The following plot shows data taken during successive orbits over a unit of lunar mare situated between 32 and 33 degrees north. The orbit path progressed from east to west (right to left), with each orbit separated by roughly two hours. The first two data swaths were taken before the eclipse, the three center swaths were taken during the eclipse, and the last two swaths were taken after the Moon had reemerged from Earth’s shadow. The data show an average decrease in surface temperature during the eclipse of around 100K, with some locations remaining warmer than others.

Channel 7 brightness temperature plot of mid-latitude maria terrain.

Channel 7 brightness temperature plot of mid-latitude maria terrain.

The fact that some parts of the lunar surface remained warmer than others during the eclipse could be for a number of reasons - degree of cooling is dependent on factors such as how rocky the surface is, how densely packed the soil is, and which minerals it is composed of. The challenge now for the Diviner science team is to deconvolve the eclipse data into useful information that can be used to map each of these properties.

Their job is made more difficult by the fact that not all areas on the Moon’s surface receive equal illumination. At the lunar poles especially, topography plays a big role in determining the amount of illumination a location receives, with low-lying terrain such as the interiors of impact craters typically receiving little to no illumination while slopes that face the sun can receive almost constant illumination.

In the following animation, which shows data taken from seven consecutive orbits over a fresh, rocky impact crater near the lunar north pole, it’s clear that the parts of the surface that were illuminated by the sun prior to the eclipse, such as the crater rim, were the locations that experienced the greatest cooling during the eclipse.

Animation depicting surface cooling during the total lunar eclipse on June 15 2011. The data were taken during seven consecutive orbits over a fresh, rocky impact crater in the lunar north pole (-70E, 82.5N). The white arrow indicates location of the plotted temperatures.

Animation depicting surface cooling during the total lunar eclipse on June 15 2011. The data were taken during seven consecutive orbits over a fresh, rocky impact crater in the lunar north pole (-70E, 82.5N). The white arrow indicates location of the plotted temperatures.

Diviner is one of seven instruments aboard NASA’s Lunar Reconnaissance Orbiter, which is currently orbiting 50 km (30 mi) above the Moon’s surface. It is the first infrared instrument to observe lunar eclipses from orbit. The next chance to observe an eclipse will be in December, 2011.

June 14, 2011

Diviner to observe temperatures during June 15th total eclipse

On June 15th, 2011, sky-watchers across much of the world will be treated to one of nature’s most impressive spectacles – a total lunar eclipse. The eclipse is set to be one of the longest and darkest of the 21st century, lasting just over 100 minutes.

Although it will not be visible in North America, the eclipse provides a rare opportunity for the Diviner Lunar Radiometer to gather valuable information about the lunar surface.

Figure 1. Projection of the lunar north pole showing solar illumination and predicted orbit tracks of NASA's Lunar Reconnaissance Orbiter during the eclipse on June 15, 2011.

Figure 1. Projection of the lunar north pole showing solar illumination and predicted orbit tracks of NASA's Lunar Reconnaissance Orbiter during the eclipse on June 15, 2011.

Figure 2. Projection of the lunar south pole showing solar illumination and predicted orbit tracks of NASA's Lunar Reconnaissance Orbiter during the eclipse on June 15, 2011.

Figure 2. Projection of the lunar south pole showing solar illumination and predicted orbit tracks of NASA's Lunar Reconnaissance Orbiter during the eclipse on June 15, 2011.

Lunar eclipses occur when the Sun, Moon and Earth are aligned so that the Earth is positioned between the Sun and Moon in such a way that it blocks the Sun’s rays, casting a shadow over the Moon. In the outer part of the shadow or ‘penumbra’ the Sun’s rays are only partially blocked, but in the center of the shadow, the ‘umbra’, there is no direct sunlight at all. A total lunar eclipse occurs when the Moon travels completely into the umbra.

Figure 2 shows the Moon’s near-central path through the penumbra and umbra on June 15. The times of each stage of the eclipse are displayed in the upper right-hand corner. The penumbral eclipse (“P1”) begins when the Moon first enters the Earth’s penumbra. This is followed by a partial eclipse (“U1”), as the Moon first enters the umbra. The total eclipse (“U2”) will begin as soon as the Moon travels completely into the umbra, and the point of greatest eclipse will occur when the Moon reaches the center of this darkest region. U3, U4 and P4 indicate the ends of the total, partial and penumbral eclipse, respectively. Source: http://eclipse.gsfc.nasa.gov/eclipse.html

Figure 3 shows the Moon’s near-central path through the penumbra and umbra on June 15. The times of each stage of the eclipse are displayed in the upper right-hand corner. The penumbral eclipse (“P1”) begins when the Moon first enters the Earth’s penumbra. This is followed by a partial eclipse (“U1”), as the Moon first enters the umbra. The total eclipse (“U2”) will begin as soon as the Moon travels completely into the umbra, and the point of greatest eclipse will occur when the Moon reaches the center of this darkest region. U3, U4 and P4 indicate the ends of the total, partial and penumbral eclipse, respectively. SOURCE: http://eclipse.gsfc.nasa.gov/eclipse.html

As the Moon passes into Earth’s shadow on June 15th, its dayside will be plunged into darkness, resulting in a rapid cooling of its surface. However, not all parts of the Moon’s surface will cool equally; rocks and boulders for example, because of their smaller surface area relative to their mass, will cool more slowly than fine-grained dust and sand.

The Diviner Lunar Radiometer, which will be measuring lunar surface temperatures continuously throughout the entire eclipse period, will be able to observe this difference in cooling rate, allowing scientists to deduce what lies just beneath the surface.

Animation showing predicted lunar surface temperatures during the June 15th eclipse

“This is an unprecedented opportunity to learn more about the uppermost few millimeters of the Moon,” says David Paige, principal investigator for Diviner. “Unlike on Earth, which takes 24 hours to rotate through one full day, the typical day-night cycle on the Moon lasts around 29 Earth days, so lunar dusk and dawn usually extend over a number of days.”

“During a total lunar eclipse, the Moon is essentially experiencing a day-night cycle that lasts only a matter of hours, so it’s going to be interesting to see how the surface responds.”

“You might imagine how it will respond if you’ve ever walked into the shadow of a building on a warm, sunny day - as you walk into the shadow, you are effectively walking into an eclipse, and as the building blocks the Sun’s rays you can usually notice a marked drop in temperature.”

“This effect is much more pronounced on the Moon, where there is no atmosphere to insulate the surface, so heat is lost much more rapidly into space. And of course, unlike in the case of the building on a sunny day, during a real eclipse there is no surrounding sunlit area to act as a heat source.”

During the eclipse, Diviner will target ten specific regions on the lunar surface. These regions were chosen because they represent a wide range of lunar terrains, from seemingly smooth areas, to regions that appear to be relatively rocky; and from dark, iron-rich locations in the lunar maria to light, iron-poor locales in the lunar highlands. The rest of the instruments on LRO will be switched off to conserve energy.

March 15, 2011

New Diviner Data including High Level Data Products available through NASA PDS

The Diviner team is providing new data relating to the surface characteristics of the moon. The data are available to the public through the Geoscience Node of the NASA Planetary Data System. The archived dataset includes Experimenter’s Data Records (EDR), Reduced Data Records (RDR),  High Level Data Products and calibration and catalog information for the first 17 months of the mission. The High Level Data Products include gridded visual brightness and infrared brightness temperatures (Level 2); and derived fields such as rock abundance, nighttime regolith temperature and surface mineralogy, which will be created with the aid of topographic data and models (Level 3). The data are in the form of more than 1700 global digital maps at a range of resolutions that can be easily overlain on other lunar datasets. The PDS also provides a Diviner RDR Query tool that can be used to create maps and a Lunar Data Explorer tool that allows users to search for data from the Lunar Reconnaissance Orbiter, Clementine and Lunar Prospector Missions.

Diviner Visual Brightness Global Map 1PPD

Diviner Channel 1 gridded visual brightness map for October, 2009. (1PPD)

Diviner Global Infrared Brightness Temperature Map 1PPD

Diviner Channel 7 gridded daytime brightness temperatures for October, 2009. (1PPD)

Diviner Channel 7 gridded nighttime brightness temperatures for October, 2009. (1PPD)

Diviner Channel 7 gridded nighttime brightness temperatures for October, 2009. (1PPD)

Bolometric temperature map (1PPD): The bolometric brightness temperature is a measure of the spectrally integrated flux of  infrared radiation emerging from the surface. We use bolometric temperature rather than the brightness temperatures in the individual Diviner spectral channels because it is more directly related to the heat balance of the surface. Regardless of the complexity of the scene, if the region within a Diviner footprint is in a state of radiative equilibrium, then there will be a balance between the absorbed flux of solar radiation and the emitted flux of infrared radiation. Furthermore, since bolometric temperature is a measure of the spectrally integrated infrared flux leaving the surface, it is directly relevant to determining infrared heating rates in the shadowed regions of impact craters, where absorbed infrared radiation from warmer crater walls dominates the heat balance.

Bolometric temperature map (1PPD): The bolometric brightness temperature is a measure of the spectrally integrated flux of infrared radiation emerging from the surface. We use bolometric temperature rather than the brightness temperatures in the individual Diviner spectral channels because it is more directly related to the heat balance of the surface. Regardless of the complexity of the scene, if the region within a Diviner footprint is in a state of radiative equilibrium, then there will be a balance between the absorbed flux of solar radiation and the emitted flux of infrared radiation. Furthermore, since bolometric temperature is a measure of the spectrally integrated infrared flux leaving the surface, it is directly relevant to determining infrared heating rates in the shadowed regions of impact craters, where absorbed infrared radiation from warmer crater walls dominates the heat balance.

Diviner Global Rock Abundance Map 1PPD

Diviner Global Rock Abundance Map (32PPD): Each sample represents the areal fraction of the surface covered by rock fragments as estimated using the technique described in Bandfield et al. (2011). Data is derived from Diviner data collected from July 5, 2009 through November 30, 2010. Data were restricted to local times of 1930 to 0530 with the solar incidence angles greater than 90 degrees, latitudes between 60N and 60S, emission angles less than 15 degrees, brightness temperatures less than 200K. Several data quality constraints were used as well (quality flag for calibration – 0; quality flag for miscellaneous – 0; noise quality flag – 0 to 1). Data from diviner spectral channels 6, 7, and 8 were binned at 32 pixels per degree in ten separate one hour increments of local time from 1930 to 0530. This map represents the 2230 bin. Because of the groundtrack walk and local time drift of Lunar Reconnaissance Orbiter observations, most surfaces are covered by only a single observation. In some cases, surfaces are covered by multiple observations acquired ~6 or 12 months apart.

Diviner Global Soil Temperature Map 1PPD: Each sample represents the rock-free regolith surface temperature as estimated using the technique described in Bandfield et al. (2011).  Data is derived from Diviner data collected from July 5, 2009 through November 30, 2010.  Data were restricted to local times of 1930 to 0530 with the solar incidence angles greater than 90 degrees, latitudes between 60N and 60S, emission angles less than 15 degrees, brightness temperatures less than 200K. Several data quality constraints were used as well (quality flag for calibration – 0; quality flag for miscellaneous – 0; noise quality flag – 0 to 1).  Data from diviner spectral channels 6, 7, and 8 were binned at 32 pixels per degree in ten separate one hour increments of local time from 1930 to 0530. This map represents the 2230 bin. Because of the groundtrack walk and local time drift of Lunar Reconnaissance Orbiter observations, most surfaces are covered by only a single observation.  In some cases, surfaces are covered by multiple observations acquired ~6 or 12 months apart.

Diviner Global Soil Temperature Map (32PPD): Each sample represents the rock-free regolith surface temperature as estimated using the technique described in Bandfield et al. (2011). Data is derived from Diviner data collected from July 5, 2009 through November 30, 2010. Data were restricted to local times of 1930 to 0530 with the solar incidence angles greater than 90 degrees, latitudes between 60N and 60S, emission angles less than 15 degrees, brightness temperatures less than 200K. Several data quality constraints were used as well (quality flag for calibration – 0; quality flag for miscellaneous – 0; noise quality flag – 0 to 1). Data from diviner spectral channels 6, 7, and 8 were binned at 32 pixels per degree in ten separate one hour increments of local time from 1930 to 0530. This map represents the 2230 bin. Because of the groundtrack walk and local time drift of Lunar Reconnaissance Orbiter observations, most surfaces are covered by only a single observation. In some cases, surfaces are covered by multiple observations acquired ~6 or 12 months apart.

Christiansen Feature Map (1PPD): The CF position is the wavelength of a major mid-infrared emissivity peak near 8-microns.  It is a measure of silicate composition and shifts to shorter wavelengths for feldspathic lithologies (e.g. highlands) and longer wavelengths for mafic lithologies (e.g. maria).  The CF position is also correlated with geochemical composition (generally shorter CF position for higher Si, Na, Ca and longer for higher Fe, Mg).  The CF position is calculated from Diviner channels 3, 4, and 5 radiances.  Each radiance is binned and averaged and then converted to brightness temperature.  The three point brightness temperature spectrum is solved quadratically to determine the maximum brightness temperature.  Emissivity values are then calculated for channels 3, 4, and 5.  The emissivity spectrum is solved quadratically to determine the CF position.

Christiansen Feature Map (32PPD): The CF position is the wavelength of a major mid-infrared emissivity peak near 8-microns. It is a measure of silicate composition and shifts to shorter wavelengths for feldspathic lithologies (e.g. highlands) and longer wavelengths for mafic lithologies (e.g. maria). The CF position is also correlated with geochemical composition (generally shorter CF position for higher Si, Na, Ca and longer for higher Fe, Mg). The CF position is calculated from Diviner channels 3, 4, and 5 radiances. Each radiance is binned and averaged and then converted to brightness temperature. The three point brightness temperature spectrum is solved quadratically to determine the maximum brightness temperature. Emissivity values are then calculated for channels 3, 4, and 5. The emissivity spectrum is solved quadratically to determine the CF position.

Model-calculated depths at which water ice would be lost to sublimation at a rate of less than 1 kg/m2 per billion years.

Model-calculated depths at which water ice would be lost to sublimation at a rate of less than 1 kg/m2 per billion years.

February 10, 2011

LRO Diviner LPSC Data Users Forum - Sunday, March 6 at 1 pm

The LRO Diviner Science Team will host a public Diviner Data Users Forum on Sunday, March 6 from 1 to 2:30 pm in the Waterway 4 Ballroom at the Woodlands Waterway Marriott Hotel in Houston TX. The purpose of the forum will be to acquaint the community with Diviner’s new high-level mapped data products. These products include global maps of brightness temperature, solar reflectance, composition and thermophysical properties.  This extensive new dataset will be made available via the NASA PDS Geosciences Node on March 15, 2011. The forum will also provide an opportunity for potential users to ask questions and provide feedback to the team. This is a public meeting and all are invited.

More information

October 21, 2010

Diviner results indicate presence of widespread ice on the Moon

Scientists from NASA’s Diviner Lunar Radiometer Experiment team published research in this week’s issue of Science that points to the widespread presence of water ice in large areas of the lunar south pole.

The Diviner Lunar Radiometer aboard NASA’s Lunar Reconnaissance Orbiter (LRO) has made the first-ever infrared measurements of temperatures in the permanently shadowed craters at the lunar poles. In October 2009, Diviner also made the first infrared observations of a controlled planetary impact when LCROSS, the companion spacecraft to LRO, slammed into one of the coldest of these craters in an experiment to confirm the presence or absence of water ice.

David Paige, Principal Investigator of the instrument, and lead author of one of two Science papers based on its observations, used temperature measurements of the lunar south pole obtained by Diviner to model the stability of water ice both at and near the surface.

“The temperatures inside these permanently-shadowed craters are even colder than we had expected. Our model results indicate that in these extreme cold conditions, surface deposits of water ice would almost certainly be stable,” says Paige, “but perhaps more significantly, these areas are surrounded by much larger permafrost regions where ice could be stable just beneath the surface.”

This lunar ‘permafrost’ would be analogous to the high-latitude terrain found on the Earth and on Mars, where sub-freezing temperatures persist below the surface throughout the year.

“These permafrost regions may receive direct sunlight at certain times of the year, but they maintain annual maximum subsurface temperatures that are sufficiently cold to prevent significant amounts of ice from vaporizing,” says Paige.

Given that these lunar permafrost regions are not in permanent shadow, surface lighting and thermal conditions in these locations would be far more hospitable for humans, which makes them of prime interest for future manned missions to the moon. Subsurface water ice deposits are also likely to be more stable than surface deposits of water ice because they are protected from bombardment by ultraviolet radiation and energetic cosmic particles.

“We conclude that large areas of the lunar south pole are cold enough to trap not only water ice, but other volatile compounds (substances with low boiling points) such as sulphur dioxide, carbon dioxide, formaldehyde, ammonia, methanol, mercury and sodium.”

LRO Diviner Lunar Radiometer Experiment surface temperature map of the south polar region of the Moon. The data were acquired during September and October, 2009 when south polar temperatures were close to their annual maximum values. The map shows the locations of several intensely cold impact craters that are potential cold traps for water ice as well as a range of other icy compounds commonly observed in comets. The approximate maximum temperatures at which these compounds would be frozen in place for more than a billion years is shown next to the scale on the right. The LCROSS spacecraft was targeted to impact one of the coldest of these craters, and many of these compounds, including water, were observed in the LCROSS ejecta plume.  Credit: UCLA/JPL/GSFC/NASA.

LRO Diviner Lunar Radiometer Experiment surface temperature map of the south polar region of the Moon. The data were acquired during September and October, 2009 when south polar temperatures were close to their annual maximum values. The map shows the locations of several intensely cold impact craters that are potential cold traps for water ice as well as a range of other icy compounds commonly observed in comets. The approximate maximum temperatures at which these compounds would be frozen in place for more than a billion years is shown next to the scale on the right. The LCROSS spacecraft was targeted to impact one of the coldest of these craters, and many of these compounds, including water, were observed in the LCROSS ejecta plume. Credit: Based on a figure in the journal Science (UCLA/JPL/GSFC/NASA).

A representative cross-section of these substances was detected by the LCROSS near-infrared spectrometers when its upper stage rocket impacted into Cabeus crater, ejecting a host of material that was previously buried beneath its surface.

The impact site was situated within a permanently-shadowed part of Cabeus with an average annual temperature of 37 K (-393 °F), making it one of the coldest locations near the lunar south pole. Temperature data from Diviner played a key role in the selection of Cabeus as the target for LCROSS, and when it came time for impact, Diviner scientists and engineers made sure that the instrument had a front row seat: Diviner targeted the impact site for 8 orbits spaced roughly 2 hours apart, the closest of which was timed to pass by 90 seconds after impact. It observed an enhanced thermal signal on this and two subsequent orbits.

Paul Hayne, UCLA graduate student and lead author of the second paper appearing in Science, was monitoring the data in real-time as it was sent back from Diviner.

“During the fly-by 90 seconds after impact, all seven of Diviner’s infrared channels measured an enhanced thermal signal from the crater. The more sensitive of its two solar channels also measured the thermal signal, along with reflected sunlight from the impact plume. Two hours later, the three longest wavelength channels picked up the signal, and after four hours only one channel detected anything above the background temperature.”

Diviner brightness temperature measurements of the lunar surface near the LCROSS impact site in Cabeus crater. (A) Before and after images of the LCROSS impact site in each of five different Diviner channels, with the thermal emission from the impact circled in the right-hand column, taken approximately 90 seconds after the Centaur impacted the lunar surface. (B) Pre-impact surface temperatures in Cabeus crater recorded by Diviner indicate the LCROSS impact site ('x') was only 40 degrees Celsius above absolute zero just before the impact. Credit: The Journal Science.

Diviner brightness temperature measurements of the lunar surface near the LCROSS impact site in Cabeus crater. (A) Before and after images of the LCROSS impact site in each of five different Diviner channels, with the thermal emission from the impact circled in the right-hand column, taken approximately 90 seconds after the Centaur impacted the lunar surface. (B) Pre-impact surface temperatures in Cabeus crater recorded by Diviner indicate the LCROSS impact site ('x') was only 40 degrees Celsius above absolute zero just before the impact. Credit: The journal Science.

Scientists were able to learn two things from these measurements: firstly, they were able to constrain the mass of material that was ejected outwards into space from the impact crater; secondly, they were able to infer the initial temperature and make estimates about the effects of ice in the soil on the observed cooling behavior.

“Diviner’s solar channel measured scattered sunlight from the impact plume over an area of 140 km2 (54 sq mi). Using this measurement we were able to place constraints on the mass of the cloud at between 1,200 kg and 5,800 kg (2,700 - 12,800 lbs), which is consistent with measurements by the LCROSS Shepherding Spacecraft,” says Hayne. “This is important because the cloud mass is used to estimate the abundance of water observed by the LCROSS spectrometers.”

“In addition, we determined that in order to agree with the data from each of Diviner’s channels, the impact must have heated a region of 30 to 200 m2 (320 – 2150 ft2) to at least 950 K (1250 °F). This concentrated region was surrounded by a larger, lower temperature component that would have included the surrounding blanket of material excavated by the impact.”

Given that ice within soil pore spaces influences cooling because it uses up heat energy in the process of sublimating, and conducts heat more efficiently than lunar soil does, scientists were able to use Diviner’s measurements of cooling at the impact site to place constraints on the proportion of volatiles present.

“The fact that heated material was still visible to Diviner after four hours indicates LCROSS did not hit a skating rink; the ice must have been mixed within the soil,” says Hayne, “we estimate that for an area of 30 to 200 m2, the steaming crater could produce more than enough water vapor to account for what was observed by LCROSS over a four minute period.”

“Although Cabeus crater is typical of the coldest areas on the moon today, we have determined that billions of years ago, smaller craters with steeper walls would have made more favorable cold-traps,” says Paige, “it is therefore possible that the craters which have accumulated the most ice are not the coldest ones.”

The results presented in both papers represent strong evidence in support of the theory that volatiles have been delivered to the moon by impacts by icy bodies from the outer solar system and then ‘cold-trapped’ at the lunar poles.

The research covered here is from two of six papers published in Science by scientists from LCROSS and LRO. The research was funded by NASA.

Full text versions of the articles published in Science can be found here:

Diviner Lunar Radiometer Observations of the LCROSS Impact
Diviner Lunar Radiometer Observations of Cold Traps in the Moon’s South Polar Region

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