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.


 
 

 

Headlines January 30, 2015

News: Taliban claims responsibility for attack on Americans at military base near airport - The Taliban claimed responsibility Jan. 30 for a shooting incident at a military base attached to Kabul’s international airport yesterday that killed three American civilian contractors and an Afghan national, saying the attacker had infiltrated the ranks of the security forces. Commission...
 
 

News Briefs January 30, 2015

Military judge weighs restrictions on Gitmo female guards A military judge is deciding whether to continue restricting the use of female guards at Guantanamo. Navy Capt. J. Kirk Waits heard closing arguments Jan. 29 at the base in Cuba during a pretrial hearing for Abd al-Hadi al-Iraqi. Waits didn’t say when he will rule. Hadi...
 
 
Air Force photograph by 1st Lt. Jake Bailey

Cope South experts exchange knowledge, techniques

Air Force photograph by 1st Lt. Jake Bailey TSgt. Sam Bishop, center left, and SSgt. Jeffrey Stephens discuss propeller maintenance with Bangladesh air force maintainers, from the 101st Special Flying Unit, during exercise Cope...
 

 

Air Force names 2-star to lead F-35 Integration Office

With the initial operating capability date of the F-35 Lightning II quickly approaching, the Air Force appointed Maj. Gen. Jeffrey Harrigian as the director of a larger Air Force F-35 Integration Office, Feb. 1. In addition to gaining new leadership, the F-35 Integration Office will also grow from a staff of four to 12 and...
 
 
boeing-ana2

Boeing announces ANA’s commitment to more jetliners

Airline continues fleet modernization with Boeing airplanes Boeing and All Nippon Airways announced Jan. 30 the airline’s intent to purchase three 787-10 Dreamliners to add additional flexibility to the airline’s 787 fleet....
 
 
Air Force photograph by Scott M. Ash

Air Force risks becoming too small to succeed under sequestration

Air Force photograph by Scott M. Ash Air Force Chief of Staff Gen. Mark A. Welsh III testifies before the Senate Armed Services Committee Jan. 28, 2015, in Washington, D.C., as Commandant of the Marine Corps Gen. Joesph F. Dunf...
 




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>