Using NASA satellite data, scientists have found that groundwater levels in northern India have been declining by as much as one foot per year over the past decade. Researchers concluded the loss is almost entirely due to human activity.

More than 26 cubic miles of groundwater disappeared from aquifers in areas of Haryana, Punjab, Rajasthan and the nation's capitol territory of Delhi, between 2002 and 2008. This is enough water to fill Lake Mead, the largest manmade reservoir in the United States, three times.

A team of hydrologists led by Matt Rodell of NASA's Goddard Space Flight Center in Greenbelt, Md., found that northern India's underground water supply is being pumped and consumed by human activities, such as irrigating cropland, and is draining aquifers faster than natural processes can replenish them. The results of this research were published today in Nature.

The finding is based on data from NASA's Gravity Recovery and Climate Experiment (GRACE), a pair of satellites that sense changes in Earth's gravity field and associated mass distribution, including water masses stored above or below Earth's surface. As the twin satellites orbit 300 miles above Earth's surface, their positions change relative to each other in response to variations in the pull of gravity.

Changes in underground water masses affect gravity enough to provide a signal that can be measured by the GRACE spacecraft. After accounting for other mass variations, such changes in gravity are translated into an equivalent change in water.

"Using GRACE satellite observations, we can observe and monitor water storage changes in critical areas of the world, from one month to the next, without leaving our desks," said study co-author Isabella Velicogna of NASA's Jet Propulsion Laboratory in Pasadena, Calif., and the University of California, Irvine.

Groundwater comes from the natural percolation of precipitation and other surface waters down through Earth’s soil and rock, accumulating in cavities and layers of porous rock, gravel, sand or clay. Groundwater levels respond slowly to changes in weather and can take months or years to replenish once pumped for irrigation or other uses.

Data provided by India's Ministry of Water Resources to the NASA-funded researchers suggested groundwater use across India was exceeding natural replenishment, but the regional rate of depletion was unknown. Rodell and colleagues analyzed six years of monthly GRACE data for northern India to produce a time series of water storage changes beneath the land surface.

"We don't know the absolute volume of water in the northern Indian aquifers, but GRACE provides strong evidence that current rates of water extraction are not sustainable," said Rodell. "The region has become dependent on irrigation to maximize agricultural productivity. If measures are not taken to ensure sustainable groundwater usage, the consequences for the 114 million residents of the region may include a collapse of agricultural output and severe shortages of potable water."

Researchers examined data and models of soil moisture, lake and reservoir storage, vegetation and glaciers in the nearby Himalayas in order to confirm that the apparent groundwater trend was real. The loss is particularly alarming because it occurred when there were no unusual trends in rainfall. In fact, rainfall was slightly above normal for the period. The only influence they couldn't rule out was human.

"For the first time, we can observe water use on land with no additional ground-based data collection," said co-author James Famiglietti of the University of California, Irvine. "This is critical because in many developing countries, where hydrological data are both sparse and hard to access, space-based methods provide perhaps the only opportunity to assess changes in fresh water availability across large regions."

GRACE is a partnership between NASA and the German Aerospace Center, DLR. The University of Texas Center for Space Research in Austin has overall GRACE mission responsibility. GRACE was launched in 2002.

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Labels: discover, earth, india, nasa, space

It began with a furrowed brow, a moment of puzzlement, quickly dismissed.




The date was July 19, 2009. Amateur astronomer Anthony Wesley was photographing Jupiter from his backyard observatory in Murrumbateman, Australia, when something odd caught his eye.



"My attention was fixed on the Great Red Spot, which was setting beautifully over Jupiter's horizon," recalls Wesley. "I almost didn't notice the dark blemish near Jupiter's south pole, and when I did, I put it out of my mind."



It's just another dark storm on Jupiter.



"That's what I thought at first, but something about the dark mark puzzled me, it didn't look right, and I couldn't stop stealing glances at it."







Above: South is up in this July 19th discovery image taken by Anthony Wesley using a 14.5-inch telescope in Murrumbateman, Australia. [more]



Slowly, Jupiter's rotation turned the blemish toward Earth, Wesley got a better look at it, and the truth struck him like a thunderbolt.



It was an impact mark. Something hit the giant planet!



"I had seen the scars caused by fragments of Comet Shoemaker-Levy 9 hitting Jupiter in 1994, so I knew what an impact looked like," he says. "After I'd convinced myself that this was real, I could hardly use the computer. My hands were shaking. It was quite unbelievable."



He quickly emailed his photos to friends and colleagues around the world, and within hours telescopes great and small were turning toward Jupiter to photograph the aftermath of a powerful collision.



"We believe it was a comet or asteroid measuring perhaps a few hundred meters wide," says Don Yeomans of NASA's Near-Earth Object Office at JPL. "If something of similar size hit Earth—we're talking about 2000 megatons of energy--there would be serious regional devastation or a tsunami if it hit the ocean."



In a stroke of luck almost as big as Wesley's, JPL astronomers Glenn Orton and Leigh Fletcher were already scheduled to observe Jupiter on July 20th, barely a day after impact, using NASA's Infra-red Telescope Facility (IRTF) atop Mauna Kea in Hawaii. The 3-meter telescope revealed a fresh cloud of debris about the size of Mars floating among Jupiter's clouds.



Above: An IRTF image of the Jupiter impact debris cloud on July 20, 2009. The cloud appears bright at this wavelength (2.12 microns) because particles in the cloud are reflecting infrared radiation from the sun, explains observer Glenn Orton. [more]



"The object, whatever it was, exploded in Jupiter's upper atmosphere," says Orton. "It blew itself to smithereens. What we're seeing now are bits and pieces of the impactor and possibly some strange aerosols formed by shock-chemistry during the impact."



On July 23rd, the Hubble Space Telescope took its first pictures of the blast site. Hubble was still undergoing checkout and calibration following the STS-125 servicing mission in May, but this event was too big to skip. Space Telescope Science Institute director Matt Mountain allocated emergency telescope time to a team of astronomers led by Heidi Hammel of the Space Science Institute in Boulder, Colorado.



As usual, Hubble photos stole the show. They revealed a swirling maelstrom of dark cindery debris jostling with natural storms near the top of Jupiter's atmosphere:




Above: A Hubble Space Telescope image of the Jupiter impact scar taken on July 23, 2009, taken using Hubble's new camera, the Wide Field Camera 3 (WFC3). [more]



"The debris cloud is lumpy because of atmospheric turbulence," explains planetary scientist Amy Simon-Miller of the Goddard Space Flight Center. "Polar winds blowing 25 m/s (~55 mph) are causing it to spread out and grow larger. This will make the cloud even easier to see through backyard telescopes."



Judging from the behavior of the Comet Shoemaker-Levy 9 impacts fifteen years ago, she estimates that the 'Wesley debris cloud' could remain visible for many weeks to come. Researchers will put the time to good use. Further studies of the cloud might yet reveal the great unknown:


What hit Jupiter?

"We just don't know," says Yeomans. "No one saw the object prior to impact."

Indeed, there was no warning. The object emerged from darkness, unknown and uncatalogued, and—wham!—before anyone could photograph the body intact, it had become a cloud of debris. (There is a lesson here for Earth, but that is another story.)

The cloud's chemical composition holds clues to the nature of the impactor. Orton says ground-based observers are now analyzing light reflected from the cloud to figure out what it is made of. "If the spectra contain signs of water, that would suggest an icy comet. Otherwise, it's probably a rocky or metallic asteroid."

Meanwhile, it's a big dark mystery—the kind that Wesley can't take his eyes off of. "I am still observing Jupiter almost every night using my 14.5 inch telescope," he says. "The cloud is expanding and taking on some interesting shapes."

"I wonder," he says, "what will happen next?"

Source: NASA

Labels: discover, jupitor, nasa, reserach, sky, space

Forty years ago, Apollo astronauts set out on a daring adventure to explore the Moon. They ended up discovering their own planet.

How do you discover Earth … by leaving it? It all started with a single photograph:

Apollo 8 was the first crewed Saturn V launch and the first time humans were placed in lunar orbit. Mission plans called for the astronauts to photograph possible landing sites for future missions. Before this, only robotic probes had taken images of the Moon's far side.

As the astronauts in their spacecraft emerged from behind the Moon, they were surprised and enchanted by an amazing view of Earth rising over the lunar horizon. Bill Anders quickly snapped a picture of the spectacular Earthrise – it was not in the mission script.

His timing could not have been better. It was Christmas Eve, 1968, the close of one of the most turbulent, fractured years in U.S. and world history. The picture offered a much needed new perspective on "home."

For the first time in history, humankind looked at Earth and saw not a jigsaw puzzle of states and countries on an uninspiring flat map – but rather a whole planet, a fragile sphere of dazzling beauty floating alone in a dangerous void. There was a home worthy of careful stewardship.

The late nature photographer Galen Rowell described this photo as "the most influential environmental photograph ever taken."

"It changed humanity's entire orientation," says Kristen Erickson of NASA. "And similar photos taken by the Apollo 11 through 17 crews reinforced the impact of this first view."

Apollo photos of the big blue marble energized grass-roots green movements and led directly to the modern fleet of Earth observing satellites NASA uses to monitor and predict weather, examine ozone holes, investigate climate change, and much more. Like Anders' camera, these satellites have transformed the way we view the planet we call Earth.

Right: 40 years after Apollo, a fleet of satellites encircle Earth, monitoring and studying our home planet. Image credit: NASA

We gained all this by shooting for the Moon.

The Apollo astronauts were, by their own admissions, profoundly moved and changed when they gazed upon Earth from their unique position in space.

"It changed my life," said Rusty Schweickart, Apollo 9 astronaut.

"…You only see the boundaries of nature from there…not those that are manmade," said Eugene Cernan of Apollos 10 and 17. "It is one of the deepest, most emotional experiences I have ever had."

Apollo 17 was the last crewed Moon mission. Since then, no humans have been to the place where they can float and gaze at the whole Earth. (Note: The crew of the International Space Station has a beautiful view of Earth, but not the whole Earth. Because the space station is in low-Earth orbit, only a portion of the planet can be seen at any one time.)

Soon, we'll be back. Right now, the Lunar Reconnaissance Orbiter is circling the Moon gathering critical data NASA scientists need to plan for renewed human exploration. NASA is once again charting a daring mission to the Moon -- this time to stay.

Above: "The Big Blue Marble." This is one of the last Apollo photos of the whole Earth, taken by the crew of Apollo 17. [more]

There are many compelling reasons to return. Former space shuttle astronaut Joseph Allen thinks our own planet is one of them:

"With all the arguments, pro and con, for going to the Moon, no one suggested that we should do it to look at the Earth. But that may in fact be the most important reason."

In his recent confirmation hearing to take NASA's helm as administrator, former astronaut Charles F. Bolden said, "I dream of a day when any American can launch into space and see the magnificence and grandeur of our home planet."

Until then, a few astronauts will take the ride for all of us, and they'll be carrying cameras a thousand times more advanced than Apollo.

What the space agency shows us will surely expand our vision. It always has.

Labels: apollo, discover, earth, eclipse, moon, nasa