Recent data from NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft has indicated the presence of ice as much as 22 percent of the surface material in a crater located on the Moon's south pole.
A team of NASA and university scientists examined the floor of Shackleton crater on moon using laser light from LRO's laser altimeter. During the course of examination it was found that the floor of the carter appeared brighter in comparison to the neighbouring carters, which is consistent with the presence of small amounts of ice.
This information will certainly help researchers to understand the crater formation and study other uncharted areas of the Moon.
"The brightness measurements have been puzzling us since two summers ago. 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," said Gregory Neumann of NASA's Goddard Space Flight Center in Greenbelt, Md., a co-author on the paper.
The spacecraft mapped Shackleton crater with unprecedented detail with the help of a laser by illuminating the crater's interior and measure its albedo or natural reflectance.
The laser light measured to a depth comparable to its wavelength, or about a micron. The measurement 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 taken by the laser light to revert 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 was named after the Antarctic explorer Ernest Shackleton, and is two miles deep and more than 12 miles wide in area. Like many other craters present at the Moon's south pole, the small tilt of the lunar spin axis means the interior of the carter Shackleton is permanently dark and hence extremely cold.
"The crater's interior is extremely rugged. It would not be easy to crawl around in there," said Maria Zuber, the team's lead investigator from the Massachusetts Institute of Technology in Cambridge in Mass.
While the floor of the crater was relatively bright, Zuber and her colleagues observed that its walls were even brighter. The findings were a bit confusing at first. Scientists however, had thought that if ice were present anywhere in a crater, it would be on the floor, where no direct sunlight penetrates.
The upper walls of the carter Shackleton are illuminated occasionally illuminated that 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. For example, newer material may be exposed along its walls, while ice may be mixed in with its floor," said Zuber.
The details of the study were published in the latest edition of the journal Nature.
-With inputs from ANI
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