Space

June 20, 2012

NASA spacecraft reveals ice content in Moon crater

Elevation (left) and shaded relief (right) image of Shackleton, a 21-km-diameter (12.5-mile-diameter) permanently shadowed crater adjacent to the lunar south pole. The structure of the crater’s interior was revealed by a digital elevation model constructed from over 5 million elevation measurements from the Lunar Orbiter Laser Altimeter.

NASA’s Lunar Reconnaissance Orbiter 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 the June 23 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, D.C.




All of this week's top headlines to your email every Friday.


 
 

 
nasa-hubble

NASA unveils celestial fireworks as official image for Hubble 25th Anniversary

The brilliant tapestry of young stars flaring to life resemble a glittering fireworks display in the 25th anniversary NASA Hubble Space Telescope image, released to commemorate a quarter century of exploring the solar system an...
 
 
NASA illustration

NASA awards radiation challenge winners, launches next round

NASA illustration This illustration depicts our heliosphere, showing the approximate locations of Voyager 1 and Voyager 2 spacecraft. Galactic cosmic rays originate outside the heliosphere and stream in uniformly from all direc...
 
 
NASA photograph

Celebrate with NASA as agency commemorates Hubble’s 25th anniversary

NASA’s Hubble Space Telescope is turning 25 this year. The observatory has transformed our understanding of our solar system and beyond, and helped us find our place among the stars. NASA is celebrating the Hubble Space T...
 

 

ULA unveils America’s new rocket

https://www.youtube.com/watch?v=emmeil-0u5k&feature=player_embedded United Launch Alliance unveiled its Next Generation Launch System April 13 at the 31st Space Symposium. The new rocket, Vulcan, will transform the future of space by making launch services more affordable and accessible. The NGLS brings together decades of experience on ULA’s reliable Atlas and Delta vehicles, combin...
 
 
NASA/JHU APL/Carnegie Institution of Washington

NASA spacecraft achieves unprecedented success studying Mercury

NASA/JHU APL/Carnegie Institution of Washington NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft traveled more than six and a half years before it was inserted into orbit around Merc...
 
 

NASA selects American small business, research institution projects for further development

NASA has selected 149 research and technology proposals from American small businesses and research institutions that will enable NASA’s future missions into the solar system and beyond while benefiting America’s technology-driven economy right here on Earth. The selected proposals now will enter into negotiations for contract awards as part of Phase II of the agency’s...
 




0 Comments


Be the first to comment!


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>