NASA moon impact blasted into material that's 5% water - Ars Technica

About a year ago, NASA held a press conference to describe the preliminary results of its analysis of the LCROSS experiment, in which a spent rocket stage plowed into the Cabeus crater at the Moon's south pole. As the impact took place, there was no visible debris plume, but NASA captured it in the UV and IR portions of the spectrum, and was able to announce that there were "significant quantities" of water seen in the debris. Now that the dust has long since settled, a total of six papers and a perspective that describe the results have appeared in Science.

One of the papers describes the impact site in the Cabeus Crater, and other polar craters like it, based on thermal data from the Lunar Reconnaissance Orbiter (LRO). The shaded areas near the craters' walls, which never receive sunlight, should in theory be exceptionally cold, with the only heat coming from radiation by the opposing, sunlit crater wall. An LRO instrument confirms that this is actually the case, producing estimates that these "cold traps" are hovering only 38K above absolute zero.

"Temperatures in the Moon’s larger cold traps are closer to those expected for the poles of Pluto than for Earth’s closest neighbor," the authors conclude.

All of which made Cabeus a great choice to crash a rocket into, since temperatures that cold mean that relatively volatile compounds, including water, don't sublimate (go directly from solid to gaseous form) at appreciable rates, even if no atmosphere is present.

And, as NASA first announced, the infrared instrument that followed the rocket in picked up evidence of water in the impact plume. The new data analysis now goes a long way towards telling us how much is there by estimating both the total size of the plume and the percentage of water in it.

As a separate paper describes it, the debris plume actually became visible in stages. First up was mineral material, the dust and rocks blasted out of the crater by the impact itself. By 30 seconds after impact, however, this material had started to fall back towards the lunar surface, after which the spectrum of the debris cloud became dominated by materials in gaseous form, such as vaporized water. The instrument was also able to estimate the total size of the cloud, which was essential for figuring out the volume of material blasted free by the impact.

Running the numbers, the scientists concluded that the surface material in Cabeus is between five and six percent water, with most of that in the form of pure ice covered by a protective layer of dust. The results confirm that the signal doesn't arise from water incorporated into a mineral, or from compounds like aluminum hydroxide. All told, several hundred kilograms of water were liberated during the LCROSS impact.

Water wasn't the only volatile compound that showed up in the data, however. Signals corresponded to various organic species, including carbon dioxide, carbon monoxide, and various nitrogen and sulfur bonds. And, in a bit of a surprise, hydrogen seems to have been present in its molecular form (a neutral H2 molecule). Presumably, it's absorbed onto the surface of a mineral in the lunar material. Roughly 140kg of hydrogen was blasted free by the impact—by weight, that's more than the magnesium present.

The infrared instrument also may have picked up signs of sodium and silver, while a UV instrument on the LRO mission found signs of mercury, calcium, and magnesium.

All in all, these are pretty significant results. Some of the earlier hints of water on the Moon were consistent with the water being produced as protons are delivered to the Moon's surface by the solar wind. The significant quantities of other volatiles seem to suggest something more complex is going on; "Going by the evolving spectra, the impact released a variety of volatiles besides water, which suggests a variety of possible sources besides solar wind implantation," the authors of one paper conclude. These possible sources would include delivery of material via comets and a more active surface chemistry than anyone expected.

A perspective that describes all of these results suggests that we probably won't learn much more about how these materials got there without going to see them in their native state ourselves. And that's looking a bit more manageable. Assuming we can keep the water free of the mercury that's also present and deal with Pluto-level temperatures, then there should be useful quantities of water present in Cabeus and other cold sinks.

Science, 2010. DOI: 10.1126/science.330.6003.434  (About DOIs).

(The DOI link is for the perspective, which contains references for the other papers.)

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Rover finds signs of buried Martian water - msnbc.com

NASA's stuck Mars rover Spirit has found more evidence that water trickled beneath the Red Planet's surface in the past perhaps within the last few hundred thousand years.

The sandy spot where Spirit got bogged down last year harbors stratified layers of dirt with different compositions close to the surface, a new study reveals. Researchers suspect these layers were caused by seepage of thin films of water on Mars, perhaps from melting frost or snow.

This seepage could have occurred during cyclical climate changes when Mars was tilted more on its axis, researchers said. The water may have moved down into the sand, carrying soluble minerals deeper than less-soluble ones, they added. [ Most Amazing Mars Rover Discoveries ]

The axis tilt of Mars varies over time scales of hundreds of thousands of years. The fact that Spirit found these layers in the dirt rather than locked away in rock further suggests the water was seeping relatively recently, rather than billions of years ago, researchers said.

"Once you freeze that evidence in a rock, it can stay there for a long time," said Bruce Banerdt, a project scientist for the Mars Exploration Rovers project at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "But you don't expect to maintain evidence in loose dirt for long periods of time."

Buried water in Martian history
The relatively insoluble minerals near the surface include what is thought to be hematite, silica and gypsum, according to researchers. Iron-rich ferric sulfates, which are more soluble, appear to have been dissolved and carried down deeper by water, they added.

None of these minerals is exposed at the surface, which is covered by wind-blown sand and dust.

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"The lack of exposures at the surface indicates the preferential dissolution of ferric sulfates must be a relatively recent and ongoing process since wind has been systematically stripping soil and altering landscapes in the region Spirit has been examining," rover deputy principal investigator Ray Arvidson of Washington University in St. Louis, explained in a statement.

The new study, which appears in the Journal of Geophysical Research, is based on observations made by Spirit before it stopped communicating with Earth in March of this year. The findings contribute to an accumulating set of evidence that Mars may harbor small amounts of liquid water at some periods during ongoing climate cycles.

Spirit, its rover twin Opportunity and other NASA Mars missions have found evidence of wet Martian environments billions of years ago that may have been favorable for life. Observations by the Phoenix Mars Lander in 2008 and various orbiters since 2002 have identified buried layers of water ice at high and middle latitudes and frozen water in polar ice caps.

Spirit still sleeping
The twin Mars rovers finished their three-month prime missions in April 2004, then kept exploring in bonus missions. One of Spirit's six wheels quit working in 2006.

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In April 2009, Spirit's left wheels broke through a crust at a site called "Troy" and churned into soft sand. A second wheel stopped working seven months later. Spirit could not maneuver into a position slanting its solar panels toward the sun for the winter, as it had done for previous winters.

Engineers anticipated it would enter a low-power, silent hibernation mode, and the rover stopped communicating March 22 of this year. Spring begins next month at Spirit's site, and NASA is listening to see if the rover reawakens, officials said.

"Most of us have high hopes," Banerdt told SPACE.com. "Our models say she could start communicating any day now. But we also recognize that this is an extremely risky situation for Spirit, and there are so many unknowns that we just can't be sure."

Among those unknowns, according to Banerdt: how much dust blankets Spirit's solar panels, how cold the rover's interior got and the current surface conditions where it bogged down.

Researchers took advantage of Spirit's months at Troy last year to examine in great detail soil layers the wheels had exposed, along with neighboring surfaces. Spirit made 13 inches of progress in its last 10 backward drives before energy levels fell too low for further driving in February.

Those drives exposed a new area of soil for possible examination if Spirit does awaken and its robotic arm is still usable, researchers said.

"With insufficient solar energy during the winter, Spirit goes into a deep-sleep hibernation mode where all rover systems are turned off, including the radio and survival heaters," said rover project manager John Callas of JPL. "All available solar array energy goes into charging the batteries and keeping the mission clock running."

The rover is expected to have experienced temperatures colder than it ever has before, and it may not survive. If Spirit does get back to work, the top priority is a multi-month study that can be done without driving the rover, researchers said.

The study would measure the rotation of Mars through the Doppler signature of the stationary rover's radio signal with enough precision to gain new information about the planet's core. The rover Opportunity has been making steady progress toward a large crater, Endeavour, which is now approximately 5 miles away.

© 2010 Space.com. All rights reserved. More from Space.com.

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Solar cells for electricity, hot water to top White House - MiamiHerald.com

WASHINGTON — The most famous house in America is going solar.

The White House soon will have solar panels to supply the first family's hot water and some of its electricity, the Department of Energy announced Tuesday.

It's not yet clear whether the panels will be visible to tourists from below, but environmentalists and clean energy advocates hope that the buzz will give solar a boost, just as first lady Michelle Obama's vegetable garden got more people buying seeds.

The White House solar panels will be a demonstration project to show that "American solar technologies are available, reliable and ready for installation in homes throughout the country," the Energy Department said in a statement.

"This project reflects President Obama's strong commitment to U.S. leadership in solar energy and the jobs it will create here at home. Deploying solar energy technologies across the country will help America lead the global economy for years to come," Energy Secretary Steven Chu said in a statement.

Bill McKibben, the founder of 350.org — a campaign to find climate change solutions in communities around the world — said in a statement that the White House "did the right thing."

"If it has anything like the effect of the White House garden, it could be a trigger for a wave of solar installations across the country and around the world," he said.

President Jimmy Carter installed 32 solar panels on the roof of the White House above the Oval Office in 1979 to heat water in the staff kitchen, according to the National Museum of American History in Washington, which acquired one of them. President Ronald Reagan removed them in 1986.

McKibben obtained one of the old White House panels and drove it from Maine to Washington last month, trying to push the administration toward taking action on climate change.

After Tuesday's announcement, White House officials said solar had been in the plans since the early days of the administration.

Chu said in a blog post Tuesday that the new solar panels would be on the roof by the end of next spring.

The Energy Department will take bids from companies that want to install the panels and water heater. Among its criteria will be how well a company "showcases American technology, products and knowhow," said Christine Glunz, a spokeswoman for the White House Council on Environmental Quality.

The department expects the solar-powered system to produce about 19,700 kilowatt hours of electricity a year. Based on Washington commercial rates, that would mean an electricity bill savings for a typical household of $2,300 per year. The additional savings on hot water would be about $1,000.

The department is investing in the next generation of solar power, and it says that innovation and new technologies will make solar energy cost-competitive with conventional electricity across the country.

Solar today generates less than 1 percent of the nation's electricity. The costs of photovoltaic panels have been declining, however. The solar industry says that scaling up the use of solar would lower the cost further and make it competitive with coal and natural gas.

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