A crater on the moon that is a prime target for human exploration may be tantalizingly rich in ice, though researchers warn it could just as well hold none at all.
The scientists investigated Shackleton Crater, which sits almost directly on the moon’s south pole. The crater, named after the Antarctic explorer Ernest Shackleton, is more than 12 miles wide (19 kilometers) and 2 miles deep (3 km) — about as deep as Earth’s oceans.
The interiors of polar craters on the moon are in nearly perpetual darkness, making them cold traps that researchers have long suspected might be home to vast amounts of frozen water and thus key candidates for human exploration. However, previous orbital and Earth-based observations of lunar craters have yielded conflicting interpretations over whether ice is there.
For instance, the Japanese spacecraft Kaguya saw no discernible signs of ice within Shackleton Crater, but NASA’s LCROSS probe analyzed Cabeus Crater near the moon’s south pole and found it measured as much as 5 percent water by mass. [Photos: Searching for Water on the Moon]
Now scientists who have mapped Shackleton Crater with unprecedented detail have found evidence of ice inside the crater.
NASA’s Lunar Reconnaissance Orbiter essentially illuminated the crater’s interior with infrared laser light, measuring how reflective it was. The crater’s floor is more reflective than that of other nearby craters, suggesting it had ice.
“Water ice in amounts of up to 20 percent is a viable possibility,” study lead author Maria Zuber, a geophysicist at the Massachusetts Institute of Technology, told SPACE.com.
Don’t get your hopes up, though. The amount of ice in Shackleton Crater “can also be much less, conceivably as little as zero,” Zuber cautioned.
This uncertainty is due in part to what the researchers saw in the rest of the crater. Bizarrely, while the crater’s floor was relatively bright, Zuber and her colleagues observed that its walls were even more reflective.
Scientists had thought that if highly reflective ice were anywhere in a crater, it would be on the floor, which live in nearly permanent darkness. In comparison, the walls of Shackleton Crater occasionally see daylight, which should evaporate any ice that accumulates.
The researchers think the reflectance of the crater’s walls is due not to ice, but to quakes. Every once in a while, the moon experiences shaking brought on by meteor collisions or the pull of the Earth. These “moonquakes” may have caused Shackleton’s walls to slough off older, darker soil, revealing newer, brighter soil underneath.
Whether or not the crater floor is brightly reflective due to ice or other factors is also open to question.This split-view image shows an elevation map (left) and shaded relief (right) of the 21-kilometer-wide Shackleton Crater. The crater’s structure is shown in false color from data by NASA’s LRO probe. Image released June 20, 2012. CREDIT: NASA/GSFC/SVS
“The reflectance could be indicative of something else in addition to or other than water ice,” Zuber said. For instance, the crater floor might be reflective because it could have had relatively little exposure to solar and cosmic radiation that would have darkened it.
Zuber noted that the measurements only look at a micron-thick portion of Shackleton Crater’s uppermost layer. “A bigger question is how much water might be buried at depth,” Zuber said, adding that NASA’s GRAIL mission will investigate that possibility.
“We would like to study other lunar polar craters in comparable detail,” Zuber said. “There is much to be learned here.”
What does all this mean? Will the current occupants of the Moon share the water with us humans?
I wouldn’t bet on it.
We’re being relegated to catching asteroids.
Scientist’s claim that by using the Moon, they can determine that the Earth is habitable and thus, astrophysicists can find extrasolar Earth-like worlds:
Scientists looking at Earthshine reflected from the moon have concluded that, indeed, there is life on our planet. Though the result may be obvious, the findings can help in the search for life on other worlds.
This is not the first time that researchers have tried to see what the Earth would look like when viewed remotely. For example, the Voyager 1 spacecraft’s famous Pale Blue Dot image shows the Earth from nearly 4 billion miles away, giving a rough idea of what extraterrestrial telescopes looking at our planet would observe.
The recent study tried to get an outsider perspective from slightly closer to home. The sun’s rays hit the surface of the Earth and are reflected through the atmosphere. Most of that light escapes into the blackness of space but some of it bounces off the moon.
“Essentially, we use the moon as a giant mirror to look back at the Earth,” said astronomer Michael Sterzik of the European Southern Observatory in Chile, who co-authored the new paper out in Nature on Feb. 29.
This light contains a great deal of information. Break the light from a distant star into a spectrum and you can determine what elements are present.
One day, when scientists can directly detect light from an Earth-like planet, they may be able to check if its atmosphere contains things like oxygen, nitrogen, and methane. If present, these gases may represent biosignatures for distant life.
In addition to checking the Earthshine’s color, Sterzik and his team looked at the polarization, or direction, of the light waves bouncing off the moon. They were able to match the polarized light to different models, where our planet’s surface contained potential percentages of things like oceans, continents, and vegetation.
The model that best fit the polarized light contained a combination of these elements that looked exactly like, well, Earth. Though it may seem trivial at first glance, the finding has profound implications in the search for extraterrestrial life, said astronomer Darren Williams at Penn State Erie, The Behrend College, who was not involved with the study.
“It’s a demonstration that we have a fighting chance of learning what the surface of a distant planet is like,” he said.
Recently an “Earth-like” world was found ( https://dad2059.wordpress.com/2012/02/22/alien-planet-discovered-at-a-nice-safe-distance/ ) , but without a “Moon” to reflect light from.
Currently we do not have the technology to find a planet with moons. But the embattled James Webb Telescope would be capable of finding such planets.
Maybe by the end of this decade, we’ll have a list of actual Earth-type planets to study, either by stronger telescopes, advanced space probes or a combination of both.
I’m not betting on the space probes though.
Finally some coherent Chinese moon probe (Chang’e 2) photos are released, along with one of the Chinese bosses of course.
Released with some fanfare (that’s the Chinese premier, Wen Jiabao, there. [Editor’s note: originally had Jiabao as the “head of state”; that would actually be the president, Hu Jintao, not the premier, Jiabao]), the images get more or less straight to the point: they’re of the Bay of Rainbows (Sinus Iridium), which China has slated to be the potential landing location of it’s Chang’e-3 rover mission.
Check out the official Chinese release page for all the images 🙂 (A rough translation notes the last image is labeled as “antarctic”, so it’s unclear if that’s also a Bay of Rainbows crater, or one near the lunar south pole.)
I find the crater at the Lunar South Pole kind of interesting, kind of looks like a blast area for propulsion.
Which feeds into the artificial Moon theory.
No way, eh?