NASA Spacecraft Reveals Ice Content in Moon Crater

Dwayne Brown

Headquarters, Washington

202-358-1726

dwayne.c.brown@nasa.gov

 

Nancy Neal-Jones / Bill Steigerwald

NASA Goddard Space Flight Center, Greenbelt, Md.

301-286-0039 / 301-286-5017

nancy.n.jones@nasa.gov / william.a.steigerwald@nasa.gov

WASHINGTON -- NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft has returned data that indicate ice may make up as much as 22 percent of the surface material in a crater located on the moon's south pole.

The team of NASA and university scientists using laser light from LRO's laser altimeter examined the floor of Shackleton crater. They found the crater's floor is brighter than those of other nearby craters, which is consistent with the presence of small amounts of ice. This information will help researchers understand crater formation and study other uncharted areas of the moon. The findings are published in Thursday's edition of the journal Nature.

"The brightness measurements have been puzzling us since two summers ago," said Gregory Neumann of NASA's Goddard Space Flight Center in Greenbelt, Md., a co-author on the paper. "While the distribution of brightness was not exactly what we had expected, practically every measurement related to ice and other volatile compounds on the moon is surprising, given the cosmically cold temperatures inside its polar craters."

The spacecraft mapped Shackleton crater with unprecedented detail, using a laser to illuminate the crater's interior and measure its albedo or natural reflectance. The laser light measures to a depth comparable to its wavelength, or about a micron. That represents a millionth of a meter, or less than one ten-thousandth of an inch. The team also used the instrument to map the relief of the crater's terrain based on the time it took for laser light to bounce back from the moon's surface. The longer it took, the lower the terrain's elevation.

In addition to the possible evidence of ice, the group's map of Shackleton revealed a remarkably preserved crater that has remained relatively unscathed since its formation more than three billion years ago. The crater's floor is itself pocked with several small craters, which may have formed as part of the collision that created Shackleton.

The crater, named after the Antarctic explorer Ernest Shackleton, is two miles deep and more than 12 miles wide. Like several craters at the moon's south pole, the small tilt of the lunar spin axis means Shackleton crater's interior is permanently dark and therefore extremely cold.

"The crater's interior is extremely rugged," said Maria Zuber, the team's lead investigator from the Massachusetts Institute of Technology in Cambridge in Mass. "It would not be easy to crawl around in there."

While the crater's floor was relatively bright, Zuber and her colleagues observed that its walls were even brighter. The finding was at first puzzling. Scientists had thought that if ice were anywhere in a crater, it would be on the floor, where no direct sunlight penetrates. The upper walls of Shackleton crater are occasionally illuminated, which could evaporate any ice that accumulates. A theory offered by the team to explain the puzzle is that "moonquakes"-- seismic shaking brought on by meteorite impacts or gravitational tides from Earth -- may have caused Shackleton's walls to slough off older, darker soil, revealing newer, brighter soil underneath. Zuber's team's ultra-high-resolution map provides strong evidence for ice on both the crater's floor and walls.

"There may be multiple explanations for the observed brightness throughout the crater," said Zuber. "For example, newer material may be exposed along its walls, while ice may be mixed in with its floor."

The initial primary objective of LRO was to conduct investigations that prepare for future lunar exploration. Launched in June 2009, LRO completed its primary exploration mission and is now in its primary science mission. LRO was built and is managed by Goddard. This research was supported by NASA's Human Exploration and Operations Mission Directorate and Science Mission Directorate at the agency's headquarters in Washington.

For an image of the crater, visit http://go.nasa.gov/MlzloW.

For more information about NASA's Lunar Reconnaissance Orbiter mission, visit http://www.nasa.gov/lro.

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Liquid Crystal Design

Engineers develop technique to craft new materials using liquid crystals as structural guides

Liquid crystals, ubiquitous in cell-phone screens and computer monitors, were known to science long before engineers realized their utility in displays and other technologies. Now, an international team of researchers has discovered how to use liquid crystals as scaffolding to build novel materials with undiscovered properties.

Reporting their findings in the journal Nature on May 3, the researchers describe a sophisticated computational model for determining how liquid crystals behave within the confines of nanometer-scale droplets containing molecules that lower the surface tensions of liquids, called surfactants.

The researchers, led by University of Wisconsin-Madison engineer Juan de Pablo, show that as the droplets cool, the liquid crystals confine the surfactant molecules, organizing them into discrete structures.

As the researchers adjusted the model's parameters, such as droplet size or surfactant concentration, the simulation revealed that it is possible to use the technique to guide self-assembled structures with a wide range of properties and applications.

For example, the researchers suggest the technique could be used to construct materials from DNA building blocks, allowing unique detectors for biological materials and toxins.

"The researchers have taken a new and exciting approach to the study of liquid crystals, which will have impact in several scientific and technical arenas," adds Mary Galvin, National Science Foundation (NSF) program director for Materials Research Science and Engineering Centers.

NSF supported the research through the University of Wisconsin-Madison's Center on Nanostructured Interfaces, an NSF Center of Excellence for Materials Research and Innovation.

For more information, read the full University of Wisconsin-Madison press release.

 -NSF-

Ecosystem Effects of Biodiversity Loss Rival Climate Change and Pollution

First comprehensive effort to compare biodiversity loss to other human-caused environmental changes

Loss of biodiversity appears to affect ecosystems as much as climate change, pollution and other major forms of environmental stress, according to results of a new study by an international research team.

The study is the first comprehensive effort to directly compare the effects of biological diversity loss to the anticipated effects of a host of other human-caused environmental changes.

The results, published in this week's issue of the journal Nature, highlight the need for stronger local, national and international efforts to protect biodiversity and the benefits it provides, according to the researchers, who are based at nine institutions in the United States, Canada and Sweden.

"This analysis establishes that reduced biodiversity affects ecosystems at levels comparable to those of global warming and air pollution," said Henry Gholz, program director in the National Science Foundation's Division of Environmental Biology, which funded the research directly and through the National Center for Ecological Analysis and Synthesis.

"Some people have assumed that biodiversity effects are relatively minor compared to other environmental stressors," said biologist David Hooper of Western Washington University, the lead author of the paper.

"Our results show that future loss of species has the potential to reduce plant production just as much as global warming and pollution."

Studies over the last two decades demonstrated that more biologically diverse ecosystems are more productive.

As a result, there has been growing concern that the very high rates of modern extinctions--due to habitat loss, overharvesting and other human-caused environmental changes--could reduce nature's ability to provide goods and services such as food, clean water and a stable climate.

Until now, it's been unclear how biodiversity losses stack up against other human-caused environmental changes that affect ecosystem health and productivity.

"Loss of biological diversity due to species extinctions is going to have major effects on our planet, and we need to prepare ourselves to deal with them," said ecologist Bradley Cardinale of the University of Michigan, one of the paper's co-authors. "These extinctions may well rank as one of the top five drivers of global change."

In the study, Hooper, Cardinale and colleagues combined data from a large number of published studies to compare how various global environmental stressors affect two processes important in ecosystems: plant growth and the decomposition of dead plants by bacteria and fungi.

The study involved the construction of a database drawn from 192 peer-reviewed publications about experiments that manipulated species richness and examined their effect on ecosystem processes.

This global synthesis found that in areas where local species loss during this century falls within the lower range of projections (losses of 1 to 20 percent of plant species), negligible effects on ecosystem plant growth will result, and changes in species richness will rank low relative to the effects projected for other environmental changes.

In ecosystems where species losses fall within intermediate projections of 21 to 40 percent of species, however, species loss is expected to reduce plant growth by 5 to 10 percent.

The effect is comparable to the expected effects of climate warming and increased ultraviolet radiation due to stratospheric ozone loss.

At higher levels of extinction (41 to 60 percent of species), the effects of species loss ranked with those of many other major drivers of environmental change, such as ozone pollution, acid deposition on forests and nutrient pollution.

"Within the range of expected species losses, we saw average declines in plant growth that were as large as changes in experiments simulating several other major environmental changes caused by humans," Hooper said.

"Several of us working on this study were surprised by the comparative strength of those effects."

The strength of the observed biodiversity effects suggests that policymakers searching for solutions to other pressing environmental problems should be aware of potential adverse effects on biodiversity as well.

Still to be determined is how diversity loss and other large-scale environmental changes will interact to alter ecosystems.

"The biggest challenge looking forward is to predict the combined effects of these environmental challenges to natural ecosystems and to society," said J. Emmett Duffy of the Virginia Institute of Marine Science, a co-author of the paper.

Authors of the paper, in addition to Hooper, Cardinale and Duffy, are E. Carol Adair of the University of Vermont and the National Center for Ecological Analysis and Synthesis; Jarrett Byrnes of the National Center for Ecological Analysis and Synthesis; Bruce Hungate of Northern Arizona University; Kristen Matulich of University of California, Irvine; Andrew Gonzales of McGill University; Lars Gamfeldt of the University of Gothenburg; and Mary O'Connor of the University of British Columbia and the National Center for Ecological Analysis and Synthesis.

 -NSF-

The Milky Way's 100 Billion Planets

This artist's illustration gives an impression of how common planets are around the stars in the Milky Way. The planets, their orbits and their host stars are all vastly magnified compared to their real separations. A six-year search that surveyed millions of stars using the microlensing technique concluded that planets around stars are the rule rather than the exception. The average number of planets per star is greater than one. This means that there is likely to be a minimum of 1,500 planets within just 50 light-years of Earth.

The results are based on observations taken over six years by the PLANET (Probing Lensing Anomalies NETwork) collaboration, which was founded in 1995. The study concludes that there are far more Earth-sized planets than bloated Jupiter-sized worlds. This is based on calibrating a planetary mass function that shows the number of planets increases for lower mass worlds. A rough estimate from this survey would point to the existence of more than 10 billion terrestrial planets across our galaxy.

The results were published in the Jan. 12, 2012, issue of the British science journal Nature.

Image Credit: NASA, ESA, and M. Kornmesser (ESO)