Category: Earth Observation

The beauty of science is that nothing is for certain. There are times when scientists think they have something figured out and then nature throws them for a loop. Just such an event happened last fall when the Sun erupted in some massive, record-shattering explosions that hurled billion of tons of electrified gas toward Earth.

Scientists realize that space is dangerous for unprotected satellites and astronauts, but they thought that they had found a small safe zone around Earth’s radiation belt — a shelter from these dangerous solar storms. It turns out that when the solar storm is strong enough, even this safe zone can become a major hot zone for dangerous radiation.

“Space weather matters — we now know that no matter what orbit we choose, there is the possibility that a spacecraft could get blasted by a significant dose of radiation. We need to take this into account when designing spacecraft. We also need to the ability to continuously monitor space weather so satellite operators can take protective measures during solar storms,” said Dr. Daniel Baker, Director of the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder.

The region is more of a gap between the two Van Allen radiation belts that surround Earth. The two belts resemble one donut inside the other. The belts are comprised of high-speed electrically charged particles trapped in the Earth’s magnetic field. It can almost be thought of as a giant umbrella in space shielding Earth from these space events.

The safe zone is considered prime real estate for satellites in “middle Earth orbits” because they would be exposed to relatively small doses of radiation and cost less to build. While there are currently no satellites in that particular orbit, many are being seriously considered including some from the Air Force.

To call the Sun active in late October / early November is an understatement. Within a two-week period, the Sun released an unusually high number of coronal mass ejections (CMEs) into space, and experienced explosions many times more powerful than anything ever observed. For some perspective, flares are usually ranked by number and class. A large flare might be X-2, for example. The Nov. 4 flare was ranked X-28, although more precisely, “off the scale” because it was hard to get an exact measurement. To add to the drama, the Sun is headed into its period of minimum activity within its 11-year cycle, making the number and intensity of the fall flares unusually high. The maximum and most active period occurred around 2000-2001.

Fortunately the science community has a number of satellites to track solar comings and goings. The Solar, Anomalous and Magnetospheric Particle Explorer (SAMPEX) satellite flies through the Van Allen radiation belts, taking measurements of the particle types and their energy and abundance. It observed the formation of a new belt in the safe zone on Oct. 31, 2003. That new belt made the safe zone hazardous for more than five weeks until the radiation was able to drain away and be absorbed by our Earth’s atmosphere. Other satellites helped researchers track the solar storms as they generated auroras on Earth, and spread out to Mars, Jupiter, Saturn, and the very edges of the solar system.

“This was an extreme event, a natural experiment that will be used to better understand how radiation belts work,” summed up Dr. Baker. “We were fortunate to have a suite of spacecraft in place to observe this event. This is why it’s important to systematically and continuously observe space weather, because there is always the potential to be surprised by nature.”

Original Source: NASA News Release

When people talk about something moving at a glacial pace, they are referring to speeds that make a tortoise look like a hare. While it is all relative, glaciers actually flow at speeds that require time lapses to recognize. Still, researchers who study Earth’s ice and the flow of glaciers have been surprised to find the world’s fastest glacier in Greenland doubled its speed between 1997 and 2003.

The finding is important for many reasons. For starters, as more ice moves from glaciers on land into the ocean, it raises sea levels. Jakobshavn Isbrae is Greenland’s largest outlet glacier, draining 6.5 percent of Greenland’s ice sheet area. The ice stream’s speed-up and near-doubling of ice flow from land into the ocean has increased the rate of sea level rise by about .06 millimeters (about .002 inches) per year, or roughly 4 percent of the 20th century rate of sea level increase.

Also, the rapid movement of ice from land into the sea provides key evidence of newly discovered relationships between ice sheets, sea level rise and climate warming.

The researchers found the glacier’s sudden speed-up also coincides with very rapid thinning, indicating loss of ice of up to 15 meters (49 feet) in thickness per year after 1997. Along with increased rates of ice flow and thinning, the thick ice that extends from the mouth of the glacier into the ocean, called the ice tongue, began retreating in 2000, breaking up almost completely by May 2003.

The NASA-funded study relies on data from satellites and airborne lasers to derive ice movements. The paper appears in this week’s issue of the journal Nature.

“In many climate models glaciers are treated as responding slowly to climate change,” said Ian Joughin, the study’s lead author. “In this study we are seeing a doubling of output beyond what most models would predict. The ice sheets can respond rather dramatically and quickly to climate changes.” Joughin conducted much of this research while working at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. Joughin is currently a glaciologist at the Applied Physics Laboratory at the University of Washington, Seattle.

The researchers used satellite and other data to observe large changes in both speeds and thickness between 1985 and 2003. The data showed that the glacier slowed down from a velocity of 6700 meters (4.16 miles) per year in 1985 to 5700 meters (3.54 miles) per year in 1992. This latter speed remained somewhat constant until 1997. By 2000, the glacier had sped up to 9400 meters (5.84 miles) per year, topping out with the last measurement in spring 2003 at 12,600 meters (7.83 miles) per year.

“This finding suggests the potential for more substantial thinning in other glaciers in Greenland,” added Waleed Abdalati, a coauthor and a senior scientist at NASA’s Goddard Space Flight Center, Greenbelt, Md. “Other glaciers have thinned by over a meter a year, which we believe is too much to be attributed to melting alone. We think there is a dynamic effect in which the glaciers are accelerating due to warming.”

Airborne laser altimetry measurements of Jakobshavn’s surface elevation, made previously by researchers at NASA’s Wallops Flight Facility, showed a thickening, or building up of the glacier from 1991 to 1997, coinciding closely with the glacier’s slow-down. Similarly, the glacier began thinning by as much as 15 meters (49 feet) a year just as its velocity began to increase between 1997 and 2003.

The acceleration comes at a time when the floating ice near the glacier’s calving front has shown some unusual behavior. Despite its relative stability from the 1950’s through the 1990s, the glacier’s ice tongue began to break apart in 2000, leading to almost complete disintegration in 2003. The tongue’s thinning and breaking up likely reduced any restraining effects it had on the ice behind it, as several speed increases coincided with losses of sections of the ice-tongue as it broke up. Recent NASA-funded research in the Antarctic Peninsula showed similar increases in glacier flow following the Larson B ice shelf break-up.

Mark Fahnestock, a researcher at the University of New Hampshire, Durham, N.H., was also a co-author of this study.

Original Source: NASA News Release

This Envisat image was acquired over northern Chile’s Atacama Desert, the driest place on Earth outside of the Antarctic dry valleys.

Bounded on the west by the Pacific and on the east by the Andes, the Atacama Desert only knows rainfall between two and four times a century. The first sight of green in this Medium Resolution Imaging Spectrometer (MERIS) image occurs some 200 kilometres west of the coast, at the foothills of the Western Cordillera, where wispy white clouds start to make an appearance.

There are some parts of the desert where rainfall has never been recorded. The only moisture available comes from a dense fog known as camanchaca, formed when cold air associated with ocean currents originating in the Antarctic hits warmer air. This fog is literally harvested by plants and animals alike, including Atacama’s human inhabitants who use ‘fog nets’ to capture it for drinking water.

The landscape of the Atacama Desert is no less stark than its meteorology: a plateau covered with lava flows and salt basins. The conspicuous white area below the image centre is the Atacama Salt Flat, just to the south of the small village San Pedro de Atacama, regarded as the centre of the desert.

The Atacama is rich in copper and nitrates ? it has been the subject of border disputes between Chile and Bolivia for this reason – and so is strewn with abandoned mines. Today the European Southern Observatory (ESO) has located in high zones of the Atacama, astronomers treasuring the region’s remoteness and dry air. The Pan-American Highway runs north-south through the desert.

Along the Pacific coast, the characteristic tuft-shape of the Mejillones peninsula is visible, where the town of Antofagasta lies just south of Moreno Bay on the southern side of the formation.

This MERIS full resolution image was acquired on 10 January 2003 and has a spatial resolution of 200 metres.

Original Source: ESA News Release

Visible from 800km away in space is the verdant rainforest that covers the distinctive Bird’s Head or Doberai Peninsula of the island of New Guinea, together with the Bomberai Peninsula below it.

This Envisat Medium Resolution Imaging Spectrometer (MERIS) acquisition shows the western part of New Guinea, just before Borneo as the single largest island in the tropics and the second largest island in the world after Greenland.

New Guinea is divided between the independent nation of Papua New Guinea on its eastern side, and the easternmost – and single largest – province of Indonesia, Papua, the western half of which is seen here.

According to the World Wildlife Fund, New Guinea as a whole is home to the world’s third largest block of unbroken tropical rainforest and contains as many distinct bird and plant species as Australia in just one-tenth its land area – including unique animals such as tree kangaroos and almost all the world’s birds of paradise. Its many tribes speak around 1100 different languages, making it home to almost one fifth of global languages.

The shape of New Guinea is often compared to a bird, with its westernmost extremity as its head. Attached to what is already an ecologically rich island, the Bird’s Head Peninsula is a particular treasure house.

Its beaches are nesting sites for endangered Leatherback turtles, while the montane rainforest of its northeastern highlands ? including the 63000-hectare Arfak Mountains Nature Reserve – is renowned for its many species of bird-wing butterflies and birds.

The relative inaccessibility of the rugged terrain of the Arfuk Mountains means this habitat remains largely intact, although being close to the expanding population centre of Manokwari it is increasingly encroached upon by road construction, expansion of commercial agriculture and ranching.

The southern part of the Bird’s Head Peninsula is made up of lowlands and coastal swamps, through which long rivers run down from the mountains to the sea, as is the Bomberai Peninsula seen below it.

Until 2002 Papua was known as Irian Jaya, meaning ‘Victorious Hot Land’. In 1969 it was the last former Dutch East Indian colony to come under Indonesian rule. Sometimes called Indonesia’s “Wild East”, the territory is the subject of increasing interest by oil and mineral companies.

This image was acquired on 20 March 2004 by MERIS in full resolution mode, providing 300-metre spatial resolution.

Original Source: ESA News Release

A NASA-funded earthquake forecast program has an amazing track record. Published in 2002, the Rundle-Tiampo Forecast has accurately forecast the locations of 15 of California’s 16 largest earthquakes this decade, including last week’s tremors.

The 10-year forecast was developed by researchers at the University of Colorado (now at the University of California, Davis) and from NASA’s Jet Propulsion Laboratory, Pasadena, Calif. NASA and the U.S. Department of Energy funded it.

“We’re elated our computer modeling technique has revealed a relationship between past and future earthquake locations,” said Dr. John Rundle, director of the Computational Science and Engineering initiative at the University of California, Davis. He leads the group that developed the forecast scorecard. “We’re nearly batting a thousand, and that’s a powerful validation of the promise this forecasting technique holds.”

Of 16 earthquakes of magnitude 5 and higher since Jan. 1, 2000, 15 fall on “hotspots” identified by the forecasting approach. Twelve of the 16 quakes occurred after the paper was published in Proceedings of the National Academy of Sciences in Feb. 2002. The scorecard uses records of earthquakes from 1932 onward to predict locations most likely to have quakes of magnitude 5 or greater between 2000 and 2010. According to Rundle, small earthquakes of magnitude 3 and above may indicate stress is building up along a fault. While activity continues on most faults, some of those faults will show increasing numbers of small quakes, building up to a big quake, while some faults will appear to shut down. Both effects may herald the possible occurrence of large events.

The scorecard is one component of NASA’s QuakeSim project. “QuakeSim seeks to develop tools for quake forecasting. It integrates high-precision, space-based measurements from global positioning system satellites and interferometric synthetic aperture radar (InSAR) with numerical simulations and pattern recognition techniques,” said JPL’s Dr. Andrea Donnellan, QuakeSim principal investigator. “It includes historical data, geological information and satellite data to make updated forecasts of quakes, similar to a weather forecast.”

JPL software engineer Jay Parker said, “QuakeSim aims to accelerate the efforts of the international earthquake science community to better understand earthquake sources and develop innovative forecasting methods. We expect adding more types of data and analyses will lead to forecasts with substantially better precision than we have today.”

The scorecard forecast generated a map of California from the San Francisco Bay area to the Mexican border, divided into approximately 4,000 boxes, or “tiles.” For each tile, researchers calculated the seismic potential and assigned color-coding to show the areas most likely to experience quakes over a 10-year period.

“Essentially, we look at past data and perform math operations on it,” said James Holliday, a University of California, Davis graduate student working on the project. Instrumental earthquake records are available for Southern California since 1932 and for Northern California since 1967. The scorecard gives more precision than a simple look at where quakes have occurred in the past, Rundle said.

“In California, quake activity happens at some level almost everywhere. This method narrows the locations of the largest future events to about six percent of the state,” Rundle said. “This information will help engineers and government decision makers prioritize areas for further testing and seismic retrofits.”

So far, the technique has missed only one earthquake — a magnitude of 5.2 — on June 15, 2004, under the ocean near San Clemente Island. Rundle believes this “miss” may be due to larger uncertainties in locating earthquakes in this offshore region of the state. San Clemente Island is at the edge of the coverage area for Southern California’s seismograph network. Rundle and Holliday are working to refine the method and find new ways to visualize the data.

Other forecast collaborators include Kristy Tiampo, the University of Western Ontario, Canada; William Klein, Boston University, Boston; and Jorge S. Sa Martins, Universidad Federal Fluminense, Rio de Janeiro, Brazil.

For images and updated scorecard maps on the Internet, visit http://www.nasa.gov/vision/earth/environment/0930_earthquake.html.

JPL is managed for NASA by the California Institute of Technology in Pasadena.

Original Source: NASA/JPL News Release

NASA scientists took infrared (IR) digital images of Mount Saint Helens’ last week. The images revealed signs of heat below the surface one day before the volcano erupted last Friday in southern Washington. The images may provide valuable clues as to how the volcano erupted.

Scientists flew an IR imaging system aboard a small Cessna Caravan aircraft over the mountain to acquire the data. “Based on the IR signal, the team predicted an imminent eruption,” said Steve Hipskind, acting chief of the Earth Science Division at NASA’s Ames Research Center (ARC), Moffett Field, Calif.

“We were seeing some thermal artifacts in the floor of the Mount Saint Helens’ crater in southern Washington,” said Bruce Coffland, a member of the Airborne Sensor Facility at ARC. ” We flew Thursday and used the 50-channel MODIS/ASTER Airborne Simulator (MASTER) digital imaging system. We are working to create images from the IR data that depict the thermal signatures on the dome,” Coffland added.

MASTER is an airborne simulator instrument similar to the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) high-resolution infrared imager carried on NASA’s Terra Earth observation satellite. Scientists plan to fly the MASTER instrument again over the volcano early this week.

The ARC airborne sensor team was in the area taking data for a United States Geological Survey (USGS) study examining some of the effects of the 1980 Mount Saint Helens’ eruption. “This had been planned for some time, and we were there totally by coincidence,” Coffland said. The science objectives for the USGS study were to outline the boundaries of the lava flows associated with Mt. St. Helens’ previous eruptions in 1980.

“We flew four flight lines over the mountain,” Coffland said. “It’s a continuous scan image, eight miles long (13 kilometers) and about 2.3 miles (3.7 kilometers) wide.” There were four adjoining flight lines flown for Joel Robinson, an investigator at USGS, Menlo Park, Calif.

After the plane landed, technicians downloaded data from a computer hard drive, and began to process the data to produce an image format for use by scientists. NASA will post the pre and post eruption infrared images on the Web.

Sky Research, based in Ashland, Ore. provided the Cessna Caravan, a propeller driven, single-engine airplane that carried the IR imager.

To access images on the Internet as they become available, visit:

Mt. St. Helens and http://masterweb.jpl.nasa.gov/

Original Source: NASA News Release

Since 2002, when the Larsen B ice shelf broke away from the coast of the Antarctic Peninsula, scientists have witnessed profound increases in the flow of nearby glaciers into the Weddell Sea. These observations were made possible through NASA, Canadian and European satellite data.

Two NASA-funded reports, appearing in the Geophysical Research Letters journal, used different techniques to arrive at similar results. Researchers from NASA’s Jet Propulsion Laboratory (JPL), Pasadena, Calif., NASA’s Goddard Space Flight Center (GSFC), Greenbelt, Md., and the National Snow and Ice Data Center (NSIDC), Boulder, Colo., said the findings prove ice shelves act as “brakes” on the glaciers that flow into them. The results also suggest climate warming can rapidly lead to rises in sea level.

Large ice shelves in the Antarctic Peninsula disintegrated in 1995 and 2002, as a result of climate warming. Almost immediately after the 2002 Larsen B ice shelf collapse, researchers observed nearby glaciers flowing up to eight times faster than prior to the breakup. The speed-up also caused glacier elevations to drop, lowering them by as much as 38 meters (124 feet) in six months.

“Glaciers in the Antarctic Peninsula accelerated in response to the removal of the Larsen B ice shelf,” said Eric Rignot, a JPL researcher and lead author of one of the studies. “These two papers clearly illustrate, for the first time, the relationship between ice shelf collapses caused by climate warming, and accelerated glacier flow,” Rignot added.

Rignot’s study used data from European Space Agency Remote Sensing Satellites (ERS) and Canadian Space Agency RADARSAT satellite. The United States and Canada share a joint agreement on RADARSAT, which NASA launched.

Scambos and colleagues used five Landsat 7 images of the Antarctic Peninsula from before and after the Larsen B breakup. The images revealed crevasses on the surfaces of glaciers. By tracking the movement of crevasses in sequence from one image to the next, the researchers were able to calculate velocities of the glaciers.

The surfaces of glaciers dropped rapidly as the flow sped up, according to ICESat measurements. “The thinning of these glaciers was so dramatic that it was easily detected with ICESat, which can measure elevation changes to within an inch or two,” said Christopher Shuman, a GSFC researcher and a co-author on the Scambos paper.

The Scambos study examined the period right after the Larsen B ice shelf collapse to try to isolate the immediate effects of ice shelf loss on the glaciers. Rignot’s study used RADARSAT to take monthly measurements that are continuing. Clouds do not limit RADARSAT measurements, so it can provide continuous, broad velocity information.

According to Rignot’s study, the Hektoria, Green and Evans glaciers flowed eight times faster in 2003 than in 2000. They slowed moderately in late 2003. The Jorum and Crane glaciers accelerated two-fold in early 2003 and three-fold by the end of 2003. Adjacent glaciers, where the shelves remained intact, showed no significant changes according to both studies. The studies provide clear evidence ice shelves restrain glaciers, and indicate present climate is more closely linked to sea level rise than once thought, Scambos added.

Original Source: NASA News Release

Seen through the eyes of the Multi-angle Imaging SpectroRadiometer aboard NASA’s Terra satellite, the menacing clouds of Hurricanes Frances and Ivan provide a wealth of information that can help improve hurricane forecasts.

The ability of forecasters to predict the intensity and amount of rainfall associated with hurricanes still requires improvement, particularly on the 24- to 48-hour timescales vital for disaster planning. Scientists need to better understand the complex interactions that lead to hurricane intensification and dissipation, and the various physical processes that affect hurricane intensity and rainfall distributions. Because uncertainties in representing hurricane cloud processes still exist, it is vital that model findings be evaluated against actual hurricane observations whenever possible. Two-dimensional maps of cloud heights such as those provided by the Multi-angle Imaging SpectroRadiometer offer an unprecedented opportunity for comparing simulated cloud fields against actual hurricane observations.

The newly released images of Hurricanes Frances and Ivan were acquired Sept. 4 and Sept. 5, 2004, respectively, when Frances’ eye sat just off the coast of eastern Florida and Ivan was heading toward the central and western Caribbean. They are available at: http://photojournal.jpl.nasa.gov/catalog/PIA04367.

The left-hand panel in each image pair is a natural-color view from the instrument’s nadir camera. The right-hand panels are computer-generated cloud-top height retrievals produced by comparing the features of images acquired at different view angles. When these images were acquired, clouds within Frances and Ivan had attained altitudes of 15 and 16 kilometers (9.3 and 9.9 miles) above sea level, respectively.

The instrument is one of several Earth-observing experiments aboard Terra, launched in December 1999. The instrument acquires images of Earth at nine angles simultaneously, using nine separate cameras pointed forward, downward and backward along its flight path. It observes the daylit Earth continuously and every 9 days views the entire globe between 82 degrees north and 82 degrees south latitude. It was built and is managed by NASA’s Jet Propulsion Laboratory, Pasadena, Calif. JPL is a division of the California Institute of Technology in Pasadena.

More information about the Multi-angle Imaging SpectroRadiometer is available at: http://www-misr.jpl.nasa.gov/.

Original Source: NASA/JPL News Release

Managers and meteorologists at NASA’s Kennedy Space Center (KSC) are closely monitoring Hurricane Ivan as it approaches the United States through the Caribbean Sea.

The latest computer models have the powerful storm moving west and farther away from KSC’s location on Florida’s east central coast (visit the National Hurricane Center for the latest forecasts and tracks).

With forecasters expecting KSC to receive maximum winds around 40 knots and four to six inches of rain from Ivan on Tuesday, NASA managers are planning to reopen KSC to its 14,000 employees Monday, as originally scheduled. With that model in mind, the KSC director will make a final decision about reopening on Sunday.

About 1,500 damage assessment and support personnel have spent the past week working to get KSC operational after last weekend’s hit from Hurricane Frances. Workers are continuing to prepare KSC this weekend for reopening and for Hurricane Ivan.

When KSC opens, about 700 employees will report to alternative worksites, because their buildings were damaged by Frances and require extensive repairs. All KSC employees will have facilities with power, air conditioning, voice and data communications.

NASA will provide updates about the Kennedy Space Center and Hurricane Ivan as new information becomes available. When information for KSC employees is available, it will be posted at http://www.nasa.gov/kennedy.

Original Source: NASA Update

For the first time, scientists have demonstrated that precise measurements of Earth’s changing gravity field can effectively monitor changes in the planet’s climate and weather.

This finding comes from more than a year’s worth of data from the Gravity Recovery and Climate Experiment, or Grace. Grace is a two-spacecraft, joint partnership of NASA and the German Aerospace Center.

Results published in the journal Science show that monthly changes in the distribution of water and ice masses could be estimated by measuring changes in Earth’s gravity field. The Grace data measured the weight of up to 10 centimeters (four inches) of groundwater accumulations from heavy tropical rains, particularly in the Amazon basin and Southeast Asia. Smaller signals caused by changes in ocean circulation were also visible.

Launched in March 2002, Grace tracks changes in Earth’s gravity field. Grace senses minute variations in gravitational pull from local changes in Earth’s mass. To do this, Grace measures, to one-hundredth the width of a human hair, changes in the separation of two identical spacecraft in the same orbit approximately 220 kilometers (137 miles) apart.

Grace maps these variations from month to month, following changes imposed by the seasons, weather patterns and short-term climate change. Understanding how Earth’s mass varies over time is an important component necessary to study changes in global sea level, polar ice mass, deep ocean currents, and depletion and recharge of continental aquifers.

Grace monthly maps are up to 100 times more accurate than existing ones, substantially improving the accuracy of many techniques used by oceanographers, hydrologists, glaciologists, geologists and other scientists to study phenomena that influence climate.

“Measurements of surface water in large, inaccessible river basins have been difficult to acquire, while underground aquifers and deep ocean currents have been nearly impossible to measure,” said Dr. Byron Tapley, Grace principal investigator at the University of Texas Center for Space Research in Austin, Texas. “Grace gives us a powerful new tool to track how water moves from one place to another, influencing climate and weather. These initial results give us great confidence Grace will make critical contributions to climate research in the coming years,” he added.

“The unparalleled accuracy of the Grace measurements opens a number of new scientific perspectives,” said Dr. Christoph Reigber of GeoForschungsZentrum Potsdam in Germany. “Observations of mass variations over the oceans will assist in interpreting annual signals in long-term sea-level change that have become an important climate change indicator,” Reigber said.

Dr. Michael Watkins, Grace project scientist at NASA’s Jet Propulsion Laboratory, Pasadena, Calif., said the results mark the birth of a new field of remote sensing. “Over the past 20 years, we’ve made primitive measurements of changes in Earth’s gravity field over scales of thousands of kilometers, but this is the first time we’ve been able to demonstrate gravity measurements can be truly useful for climate monitoring,” he said.

“The Grace gravity measurements will be combined with water models to sketch an exceptionally accurate picture of water distribution around the globe. Together with other NASA spacecraft, Grace will help scientists better understand the global water cycle and its changes,” Watkins added.

The University of Texas Center for Space Research has overall mission responsibility. German mission elements are the responsibility of GeoForschungsZentrum Potsdam. Science data processing, distribution, archiving and product verification are managed under a cooperative arrangement between JPL, the University of Texas and GeoForschungsZentrum Potsdam.

For more information about Grace on the Internet, visit http://www.csr.utexas.edu/grace or http://www.gfz-potsdam.de/grace. For information about NASA programs on the Internet, visit http://www.nasa.gov.

Original Source: NASA/JPL News Release