High-Resolution Topographical Map of Moon released

Astronomers at Arizona State University have used NASA’s Lunar Reconnaissance Orbiter (LRO) to build this jaw-dropping map of the Moon. It’s the highest-resolution, near-global topographic image of our lunar neighbour yet.

The map reveals the Moon’s surface shape, and uses different colours to represent the elevations of the craters, miniature mountains and ridges that dot the surface. White parts are highest, down through red, orange, green, blue and violet, which represents the deepest pits.
The entire map in all of its glory, which is dubbed the the Global Lunar DTM 100 m topographic model (GLD100), shows almost the entire moon with a scale close to 100 meters per pixel.
The map was created with the orbiting probe’s Wide Angle Camera (WAC), a tiny photographic device that can fit in the palm of your hand. But despite its petite body, it can capture a high resolution shot of the Moon with a 70km swath. Because the equatorial distance between orbits is about 30km, the WAC can build a new picture of the Moon every month.
That might sound like overkill, but because the Moon’s lighting changes every month the WAC can build a record of how different rocks reflect and shade the light, to build this 3D topographic atlas.
The little camera can’t quite do it all by itself. The poles of the Moon are in almost perpetual darkness, so the WAC can’t complete the map at the highest latitudes. But never fear, because the LRO’s Lunar Orbiter Laser Altimeter (LOLA) excels at scanning the topography of the poles, it can fill in the gaps.
“Our new topographic view of the moon provides the dataset that lunar scientists have waited for since the Apollo era,” said Mark Robinson, Principal Investigator of the Lunar Reconnaissance Orbiter Camera (LROC) from Arizona State University, in a press release.
“We can now determine slopes of all major geologic terrains on the moon at 100 meter scale. Determine how the crust has deformed, better understand impact crater mechanics, investigate the nature of volcanic features, and better plan future robotic and human missions to the moon.”
The WAC was built by Malin Space Science Systems in San Diego. A very similar camera from the same firm, called the the Mars Reconnaissance Orbiter (MRO) Mars Color Imager (MARCI), is currently orbiting Mars.

Source: Wired UK/Image: NASA

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Mystery of Moon's Lost Magnetism Solved?

One of the abiding mysteries of our moon is why it apparently once had a magnetic field. Now two teams of scientists have offered two separate, but potentially complementary, explanations.

This illustration shows one suggested mechanism for creating an ancient magnetic field on the moon. In this scenario, impacting space rocks on the moon would create instability in the moon's core that could lead to a dynamo that creates a magnetic field. credit: M.-H. Deproost, ORB, Belgique

When Apollo astronauts brought back samples of moon rocks from their lunar landing missions in the 1960s and '70s, some of them shocked scientists by being magnetic. That means that individual rocks might have a magnetic north and south pole and a small magnetic field of their own.
This can happen to rocks with the right minerals inside them, if they cool in the presence of a magnetic field. The problem is, scientists had no idea that the moon had ever had a magnetic field, and were at a loss to explain how that might have happened.

A magnetic field is generated by what's called a dynamo, which is caused by the fluid motion of a conducting material, such as liquid iron. In the case of the Earth's magnetic field, this motion occurs in the planet's outer core, and is caused by the convection of heat.
But the moon isn't large enough for convection to take place. Scientists were at a loss to explain what else might generate the required liquid motion of iron inside the moon, until now.
Stirring it up
In one new proposal, Christina Dwyer of the University of California, Santa Cruz, and her colleagues suggest that the moon's solid-rock middle layer, called its mantle, stirs up its liquid iron core. The researchers think this happens because the moon's core and its mantle rotate around slightly different axes, and the boundary between them is not quite spherical, so their relative motion causes the fluid to mix around.
The strength of this stirring is determined by the angle between the core and the mantle, and the distance between the Earth and the moon, because the tidal gravitational tug from the Earth causes the moon's mantle to rotate differently than the core.

This model would explain why the moon used to have a magnetic field, but no longer does. That's because the angle between the mantle and the core has narrowed over time, while the distance between the moon and the Earth has widened, causing the tidal forces to steadily decrease. While these forces used to be enough to generate a dynamo inside the moon, they aren't anymore.
Based on their calculations, the researchers estimate the lunar magnetic field might have lasted for about a billion years, somewhere between around 2.7 billion and 4.2 billion years ago.
"Based on what we know about stirring, and everything we know about fluid motion, we can find no reason that this would not work," Dwyer told SPACE.com. "All the flags are go, and now this needs to be taken to the next level to get tested."
Dwyer said her research team had studied the basic scenario, but hopes that scientists who specialize in modeling the complex physics of dynamos will now step in to investigate whether this could explain what happened on the moon.
The researchers reported their theory in the Nov. 10 issue of the journal Nature.

Violent impacts
But theirs isn't the only possible solution to the moon's mystery.
In the same issue of Nature, Michael Le Bars of the French National Center for Scientific Research and the Université Aix-Marseille in France, along with his colleagues, propose another explanation for the ancient lunar magnetic field.

Le Bars' team also suggests that the moon's mantle might have stirred up the liquid in its core. However, they offer a different impetus for this stirring. Instead of tidal interactions between the Earth and the moon, the researchers posit that impacts by large space rocks slamming into the moon have changed its rotation rate, causing differential motion between the mantle and the core.

While the first scenario would cause steady stirring while the Earth and moon were the right distance apart, the second picture would induce brief periods of especially strong stirring of the core, creating spikes of a magnetic field on the moon.
While either option may be correct, it's also possible that both mechanisms played a role in causing an ancient magnetic field on the moon.

"The two studies are thought-provoking and may be complementary," Dominique Jault, a researcher at ETH Zürich in Switzerland and the Université Joseph-Fourier in France, who was not involved in either new study, wrote in an accompanying essay in the same issue of Nature. "Future palaeomagnetic experiments on samples from very old lunar rocks will enable their theories to be tested."
Via Space.com

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The Moon Is Bursting With Precious Titanium

    Credit: NASA/GSFC/Arizona State University

    A new map of the moon has uncovered a trove of areas rich in titanium, which could one day be mined.

THE GIST

• New maps show rich abundances of titanium in the solidified lava flows on the moon.
• The element is mostly found in a mineral that also contains iron and oxygen.
• Titanium deposits, which could be mined for future use, also reveal history of moon’s volcanic eruptions.

The discovery was made thanks to a camera aboard the US Lunar Reconnaissance Orbiter, which swept the surface of the Moon, scrutinising it in seven different light wavelengths. Click to enlarge this image.
Lava flows that turned into rocks on the moon are enriched with titanium in concentrations far higher than what is found on Earth. The precious material could be used to construct equipment for lunar and other spacecraft.
Detailed maps from a robotic NASA science satellite circling the moon show deposits as rich as about 18 percent, planetary geologist Jeffrey Gillis-Davis, with the University of Hawaii, told Discovery News.
“Up to 3 percent is considered high on Earth,” he said.
Why parts of the moon are so flush with titanium is a bit of a mystery, but scientists are taking advantage of the find to figure out the moon’s volcanic history. As the moon cooled and solidified, some elements, like titanium, didn’t mix well so they formed as a separate layer inside. The titanium was later tossed onto the moon’s surface during volcanic eruptions.
“I can identify all these different lava flows because they have a different composition, and that different composition is likely reflecting different sources within the mantle that it came from,” Lunar Reconnaissance Orbiter associate project scientist Noah Petro, with NASA’s Goddard Space Flight Center in Greenbelt, Md., told Discovery News.
Prized on Earth for its strength, ability to resist corrosion and light weight, titanium on the moon, which is mostly found in mineral called ilmenite, could be mined and processed for future use.
The compound, which contains titanium, iron and oxygen, could be heated to free the oxygen so it could be used for breathing or making rocket fuel. It also is studded with particles from the solar wind, including hydrogen and a rare form of helium, called helium 3, a fuel for a proposed fusion reactor.
“One of the things you want to do before you go back to the moon is figure out where your resources are and what your resources are,” Gillis-Davis said.
Scientists’ first confirmation that titanium exists on the moon came from analysis of the samples brought back by NASA’s Apollo missions. Six landings occurred between 1969 through 1972. Two previous robotic probes, Clementine and Lunar Prospector, added a global perspective. Lunar Reconnaissance Orbiter, or LRO, is making maps using a different imaging technique and with higher resolution than previously possible.
The spacecraft currently is orbiting 50 kilometers (31 miles) above the moon. At the end of the year, LRO will be shifted into an elliptical, fuel-saving orbit that drifts as far as 130 miles from the moon. The team is expected to submit a proposal to extend operations beyond 2012.
The research was presented at the European Planetary Science Congress in France last week.
(Discovery News )

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Sc/Earth Had Two Moons, New Model Suggests

Earth may have once had two moons, but one was destroyed in a slow-motion collision that left our current lunar orb lumpier on one side than the other, scientists say.

Astronomers have long been puzzled by the differences between the side of the moon that always faces Earth—the near side—and the side that always faces away, the far side. The topography of the near side is relatively low and flat, while that of the far side is high and mountainous with a much thicker crust.

According to a new computer model, this discrepancy can be explained if a smaller "companion moon" collided with our moon's far side early in its history. Such a collision would have left the far side splattered with especially hard rocky material that now forms the current lunar highlands.

For the theory to work, the smaller moon must have crashed into the larger one at about 4,400 miles (7,081 kilometers) an hour.

"This is the slowest possible collision the two massive bodies could have if they fell into each other’s gravity," explained study co-author Erik Asphaug, a planetary scientist at the University of California, Santa Cruz (UCSC).

At this relatively slow speed, the far-side collision wouldn’t have been energetic enough to melt rock or carve out a crater. But it would have been forceful enough to plaster material from the smaller moon onto the larger moon.

"It's like a car crash, where you have crumpled bumpers but you don't melt the cars as they're colliding," Asphaug said. "This is the same kind of phenomenon."

The new theory, by Asphaug and UCSC postdoctoral researcher Martin Jutzi, is detailed in the current issue of the journal Nature.

According to their model, the two moons coexisted peacefully for about 80 million years, each in its own stable orbit. The moons were the same color and composition, but one was about three times larger than the other, Asphaug said.

"Our moon looked like a big dinner plate in the sky ... and when it set, there was this other moon trailing it by about 60 degrees," he said.

This brief period of lunar harmony was shattered, according to the model, when natural gravitational interactions with Earth caused both moons to drift farther away from our planet. The sun's gravitational tug then destabilized the smaller moon’s orbit and caused it to fall into its larger sibling.

Though not very energetic, the collision would have ejected trillions of tons of lunar debris into space, obscuring both moons for several days.

"When the dust cleared, you had one moon that might have looked similar to our moon today," Asphaug said.

For up to a million years after the event, Earth would have been bombarded by moon bits of various sizes, the biggest of which could have been as much as 62 miles (100 kilometers) across.

"You'd have meteors raining down all over the sky for a long period of time," Asphaug said, though there probably would have been no life yet on Earth to witness the spectacular sky shows.

Lunar Smashup Opens Up "Cool Problems"

Astronomer Jeffrey Taylor of the University of Hawaii said the new moon theory is very interesting and worth further investigation.

Asphaug and Jutzi's model not only accounts for the moon's asymmetry, Taylor said, but the findings also explain the fates of the smaller, companion satellites that another theory predicts should have formed alongside our moon.

One of the leading theories for how our moon formed is that it was born after a Mars-size planet crashed into Earth shortly after the solar system's formation about 4.5 billion years ago.

Scientists think the earlier smashup created a ring of molten rock debris around Earth, which eventually coalesced into several bodies, including our current moon.)

But "if that's the case, what happened [to the smaller moons]? This is one thing that could have happened to them," said Taylor, who was not involved in the study.

The new theory isn't without its problems, however. For example, it doesn't explain why the lumpy far side of our moon shows a high concentration of aluminum, Taylor said.

If the two moons had formed from the same material, as is assumed, the companion moon—and its splatterings—should have been low in aluminum, like our own moon's interior.

However, this problem could be resolved by future lunar studies, Taylor said, and it's not a serious enough reason to dismiss the theory.

"If anything," he said, "it just opens up more cool problems to work on."

Credit: National Geographic News

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