Nasa Technology News

NASA has ended operational planning activities for the Mars rover Spirit and transitioned the Mars Exploration Rover Project to a single-rover operation focused on Spirit's still-active twin, Opportunity.

This marks the completion of one of the most successful missions of interplanetary exploration ever launched.

Spirit last communicated on March 22, 2010, as Martian winter approached and the rover's solar-energy supply declined. The rover operated for more than six years after landing in January 2004 for what was planned as a three-month mission. NASA checked frequently in recent months for possible reawakening of Spirit as solar energy available to the rover increased during Martian spring. A series of additional re-contact attempts ended today, designed for various possible combinations of recoverable conditions.

"Our job was to wear these rovers out exploring, to leave no unutilized capability on the surface of Mars, and for Spirit, we have done that," said Mars Exploration Rover Project Manager John Callas of NASA's Jet Propulsion Laboratory, Pasadena, Calif.

Spirit drove 4.8 miles (7.73 kilometers), more than 12 times the goal set for the mission. The drives crossed a plain to reach a distant range of hills that appeared as mere bumps on the horizon from the landing site; climbed slopes up to 30 degrees as Spirit became the first robot to summit a hill on another planet; and covered more than half a mile (nearly a kilometer) after Spirit's right-front wheel became immobile in 2006. The rover returned more than 124,000 images. It ground the surfaces off 15 rock targets and scoured 92 targets with a brush to prepare the targets for inspection with spectrometers and a microscopic imager.

"What's really important is not only how long Spirit worked or how far Spirit drove, but also how much exploration and scientific discovery Spirit accomplished," Callas said.

One major finding came, ironically, from dragging the inoperable right-front wheel as the rover was driving backwards in 2007. That wheel plowed up bright white soil. Spirit's Alpha Particle X-ray Spectrometer and Miniature Thermal Emission Spectrometer revealed that the bright material was nearly pure silica.

"Spirit's unexpected discovery of concentrated silica deposits was one of the most important findings by either rover," said Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for Spirit and Opportunity. "It showed that there were once hot springs or steam vents at the Spirit site, which could have provided favorable conditions for microbial life."

The silica-rich soil neighbors a low plateau called Home Plate, which was Spirit's main destination after the historic climb up Husband Hill. "What Spirit showed us at Home Plate was that early Mars could be a violent place, with water and hot rock interacting to make what must have been spectacular volcanic explosions. It was a dramatically different world than the cold, dry Mars of today," said Squyres.

The trove of data from Spirit could still yield future science revelations. Years of analysis of some 2005 observations by the rover's Alpha Particle X-ray Spectrometer, Miniature Thermal Emission Spectrometer and Moessbauer Spectrometer produced a report last year that an outcrop on Husband Hill bears a high concentration of carbonate. This is evidence of a wet, non-acidic ancient environment that may have been favorable for microbial life.

"What's most remarkable to me about Spirit's mission is just how extensive her accomplishments became," said Squyres. "What we initially conceived as a fairly simple geologic experiment on Mars ultimately turned into humanity's first real overland expedition across another planet. Spirit explored just as we would have, seeing a distant hill, climbing it, and showing us the vista from the summit. And she did it in a way that allowed everyone on Earth to be part of the adventure."

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rovers Opportunity and Spirit for the NASA Science Mission Directorate, Washington. For more about the rovers, see: http://www.nasa.gov/rovers and http://marsrovers.jpl.nasa.gov.

A few billion years from now, our Milky Way galaxy will collide with the Andromeda galaxy. This will mark a moment of both destruction and creation. The galaxies will lose their separate identities as they merge into one. At the same time, cosmic clouds of gas and dust will smash together, triggering the birth of new stars.

To better understand collisions like these, astronomers have assembled an atlas of several galactic "train wrecks."

The new images combine observations from NASA's Spitzer Space Telescope, which observes infrared light, and NASA's Galaxy Evolution Explorer spacecraft, which observes ultraviolet light. By analyzing information from different parts of the light spectrum, scientists can learn much more about the collision process than from a single wavelength alone.

"We're working with the theorists to give our understanding a reality check," said the lead author of a paper on the results, Lauranne Lanz of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass. "Our understanding will really be tested in a few billion years, when the Milky Way experiences its own collision."

Read the full story from the Harvard-Smithsonian Center for Astrophysics at http://www.cfa.harvard.edu/news/2011/pr201117.html

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA. More information is online at http://spitzer.caltech.edu/ and http://www.nasa.gov/spitzer .

Caltech leads the Galaxy Evolution Explorer mission and is responsible for science operations and data analysis. JPL manages the mission and built the science instrument. The mission was developed under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. Researchers sponsored by Yonsei University in South Korea and the Centre National d'Etudes Spatiales (CNES) in France collaborated on this mission.

More information is online at http://www.nasa.gov/galex/ and http://www.galex.caltech.edu

NASA's Cassini spacecraft and a European Southern Observatory ground-based telescope tracked the growth of a giant early-spring storm in Saturn's northern hemisphere that is so powerful it stretches around the entire planet. The rare storm has been wreaking havoc for months and shooting plumes of gas high into the planet's atmosphere.

Cassini's radio and plasma wave science instrument first detected the large disturbance, and amateur astronomers tracked its emergence in December 2010. As it rapidly expanded, its core developed into a giant, powerful thunderstorm. The storm produced a 3,000-mile-wide (5,000-kilometer-wide) dark vortex, possibly similar to Jupiter's Great Red Spot, within the turbulent atmosphere.

The dramatic effects of the deep plumes disturbed areas high up in Saturn's usually stable stratosphere, generating regions of warm air that shone like bright "beacons" in the infrared. Details are published in this week's edition of Science Magazine.

"Nothing on Earth comes close to this powerful storm," says Leigh Fletcher, the study's lead author and a Cassini team scientist at the University of Oxford in the United Kingdom. "A storm like this is rare. This is only the sixth one to be recorded since 1876, and the last was way back in 1990."

This is the first major storm on Saturn observed by an orbiting spacecraft and studied at thermal infrared wavelengths, where Saturn's heat energy reveals atmospheric temperatures, winds and composition within the disturbance.

Temperature data were provided by the Very Large Telescope (VLT) on Cerro Paranal in Chile and Cassini's composite infrared spectrometer (CIRS), operated by NASA's Goddard Space Flight Center in Greenbelt, Md.

"Our new observations show that the storm had a major effect on the atmosphere, transporting energy and material over great distances, modifying the atmospheric winds -- creating meandering jet streams and forming giant vortices -- and disrupting Saturn's slow seasonal evolution," said Glenn Orton, a paper co-author, based at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

The violence of the storm -- the strongest disturbances ever detected in Saturn's stratosphere -- took researchers by surprise. What started as an ordinary disturbance deep in Saturn's atmosphere punched through the planet's serene cloud cover to roil the high layer known as the stratosphere.

"On Earth, the lower stratosphere is where commercial airplanes generally fly to avoid storms which can cause turbulence," says Brigette Hesman, a scientist at the University of Maryland in College Park who works on the CIRS team at Goddard and is the second author on the paper. "If you were flying in an airplane on Saturn, this storm would reach so high up, it would probably be impossible to avoid it."

Other indications of the storm's strength are the changes in the composition of the atmosphere brought on by the mixing of air from different layers. CIRS found evidence of such changes by looking at the amounts of acetylene and phosphine, both considered to be tracers of atmospheric motion. A separate analysis using Cassini's visual and infrared mapping spectrometer, led by Kevin Baines of JPL, confirmed the storm is very violent, dredging up larger atmospheric particles and churning up ammonia from deep in the atmosphere in volumes several times larger than previous storms. Other Cassini scientists are studying the evolving storm, and a more extensive picture will emerge soon.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The mission is managed by JPL for NASA's Science Mission Directorate in Washington. The European Southern Observatory in Garching, Germany operates the VLT in Chile. JPL is a division of the California Institute of Technology in Pasadena.

You may have heard the news: Comet Elenin is coming to the inner-solar system this fall. Comet Elenin (also known by its astronomical name C/2010 X1), was first detected on Dec. 10, 2010 by Leonid Elenin, an observer in Lyubertsy, Russia, who made the discovery "remotely" using the ISON-NM observatory near Mayhill, New Mexico. At the time of the discovery, the comet was about 647 million kilometers (401 million miles) from Earth. Over the past four-and-a-half months, the comet has – as comets do – closed the distance to Earth's vicinity as it makes its way closer to perihelion (its closest point to the sun). As of May 4, Elenin's distance is about 274 million kilometers (170 million miles).

"That is what happens with these long-period comets that come in from way outside our planetary system," said Don Yeomans of NASA's Near-Earth Object Program Office at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "They make these long, majestic, speedy arcs through our solar system, and sometimes they put on a great show. But not Elenin. Right now that comet looks kind of wimpy."

How does a NASA scientist define cometary wimpiness?

"We're talking about how a comet looks as it safely flies past us," said Yeomans. "Some cometary visitors arriving from beyond the planetary region – like Hale-Bopp in 1997 -- have really lit up the night sky where you can see them easily with the naked eye as they safely transit the inner-solar system. But Elenin is trending toward the other end of the spectrum. You'll probably need a good pair of binoculars, clear skies, and a dark, secluded location to see it even on its brightest night."

Comet Elenin should be at its brightest shortly before the time of its closest approach to Earth on Oct. 16 of this year. At its closest point, it will be 35 million kilometers (22 million miles) from us. Can this icy interloper influence us from where it is, or where it will be in the future? What about this celestial object inspiring some shifting of the tides or even tectonic plates here on Earth? There have been some incorrect Internet speculations that external forces could cause comet Elenin to come closer.

"Comet Elenin will not encounter any dark bodies that could perturb its orbit, nor will it influence us in any way here on Earth," said Yeomans. "It will get no closer to Earth than 35 million kilometers [about 22 million miles]. "

"Comet Elenin will not only be far away, it is also on the small side for comets," said Yeomans. "And comets are not the most densely-packed objects out there. They usually have the density of something akin to loosely packed icy dirt.

"So you've got a modest-sized icy dirtball that is getting no closer than 35 million kilometers," said Yeomans. "It will have an immeasurably miniscule influence on our planet. By comparison, my subcompact automobile exerts a greater influence on the ocean's tides than comet Elenin ever will."

Yeomans did have one final thought on comet Elenin.

"This comet may not put on a great show. Just as certainly, it will not cause any disruptions here on Earth. But there is a cause to marvel," said Yeomans. "This intrepid little traveler will offer astronomers a chance to study a relatively young comet that came here from well beyond our solar system's planetary region. After a short while, it will be headed back out again, and we will not see or hear from Elenin for thousands of years. That's pretty cool."

NASA detects, tracks and characterizes asteroids and comets passing relatively close to Earth using both ground- and space-based telescopes. The Near-Earth Object Observations Program, commonly called "Spaceguard," discovers these objects, characterizes a subset of them, and predicts their paths to determine if any could be potentially hazardous to our planet.

JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington, DC. JPL is a division of the California Institute of Technology in Pasadena.

Astronomers, including a NASA-funded team member, have discovered a new class of Jupiter-sized planets floating alone in the dark of space, away from the light of a star. The team believes these lone worlds were probably ejected from developing planetary systems.

The discovery is based on a joint Japan-New Zealand survey that scanned the center of the Milky Way galaxy during 2006 and 2007, revealing evidence for up to 10 free-floating planets roughly the mass of Jupiter. The isolated orbs, also known as orphan planets, are difficult to spot, and had gone undetected until now. The newfound planets are located at an average approximate distance of 10,000 to 20,000 light-years from Earth.

"Although free-floating planets have been predicted, they finally have been detected, holding major implications for planetary formation and evolution models," said Mario Perez, exoplanet program scientist at NASA Headquarters in Washington.

The discovery indicates there are many more free-floating Jupiter-mass planets that can't be seen. The team estimates there are about twice as many of them as stars. In addition, these worlds are thought to be at least as common as planets that orbit stars. This would add up to hundreds of billions of lone planets in our Milky Way galaxy alone.

"Our survey is like a population census," said David Bennett, a NASA and National Science Foundation-funded co-author of the study from the University of Notre Dame in South Bend, Ind. "We sampled a portion of the galaxy, and based on these data, can estimate overall numbers in the galaxy."

The study, led by Takahiro Sumi from Osaka University in Japan, appears in the May 19 issue of the journal Nature.

The survey is not sensitive to planets smaller than Jupiter and Saturn, but theories suggest lower-mass planets like Earth should be ejected from their stars more often. As a result, they are thought to be more common than free-floating Jupiters.

Previous observations spotted a handful of free-floating, planet-like objects within star-forming clusters, with masses three times that of Jupiter. But scientists suspect the gaseous bodies form more like stars than planets. These small, dim orbs, called brown dwarfs, grow from collapsing balls of gas and dust, but lack the mass to ignite their nuclear fuel and shine with starlight. It is thought the smallest brown dwarfs are approximately the size of large planets.

On the other hand, it is likely that some planets are ejected from their early, turbulent solar systems, due to close gravitational encounters with other planets or stars. Without a star to circle, these planets would move through the galaxy as our sun and other stars do, in stable orbits around the galaxy's center. The discovery of 10 free-floating Jupiters supports the ejection scenario, though it's possible both mechanisms are at play.

"If free-floating planets formed like stars, then we would have expected to see only one or two of them in our survey instead of 10," Bennett said. "Our results suggest that planetary systems often become unstable, with planets being kicked out from their places of birth."

The observations cannot rule out the possibility that some of these planets may have very distant orbits around stars, but other research indicates Jupiter-mass planets in such distant orbits are rare.

The survey, the Microlensing Observations in Astrophysics (MOA), is named in part after a giant wingless, extinct bird family from New Zealand called the moa. A 5.9-foot (1.8-meter) telescope at Mount John University Observatory in New Zealand is used to regularly scan the copious stars at the center of our galaxy for gravitational microlensing events. These occur when something, such as a star or planet, passes in front of another, more distant star. The passing body's gravity warps the light of the background star, causing it to magnify and brighten. Heftier passing bodies, like massive stars, will warp the light of the background star to a greater extent, resulting in brightening events that can last weeks. Small planet-size bodies will cause less of a distortion, and brighten a star for only a few days or less.

A second microlensing survey group, the Optical Gravitational Lensing Experiment (OGLE), contributed to this discovery using a 4.2-foot (1.3 meter) telescope in Chile. The OGLE group also observed many of the same events, and their observations independently confirmed the analysis of the MOA group.

NASA's Jet Propulsion Laboratory, Pasadena,Calif., manages NASA's Exoplanet Exploration program office. JPL is a division of the California Institute of Technology in Pasadena.

More information about exoplanets and NASA's planet-finding program is at http://planetquest.jpl.nasa.gov.

When NASA's Opportunity Mars rover uses an onboard navigation capability during backward drives, it leaves a distinctive pattern in the wheel tracks visible on the Martian ground.

The pattern appears in an image posted at http://photojournal.jpl.nasa.gov/catalog/?IDNumber=PIA14129.

The rover team routinely commands Opportunity to drive backward as a precaution for extending the life of the rover's right-front wheel, which has been drawing more electrical current than the other five wheels. Rover drivers can command the rover to check for potential hazards in the drive direction, whether the rover is driving backward or forward. In that autonomous navigation mode, the rover pauses frequently, views the ground with the navigation camera on its mast, analyzes the stereo images, and makes a decision about proceeding.

When the drive is backward, the drive-direction view from the navigation camera is partially blocked by an antenna in the middle of the rover. Therefore, at each pause to check for hazards, the rover pivots slightly to the side to get a clear view. If it sees no hazard, it turns back to the direction it was going and continues the drive for about another 4 feet (1.2 meters) before checking again. This set of activities leaves tracks showing the slight turnout on a rhythmically repeated basis, like a dance step.

Opportunity has driven more than 1.6 miles (about 2.6 kilometers) since leaving "Santa Maria" crater in late March and resuming a long-term trek toward the much larger Endeavour crater. Opportunity has now driven more than 18 miles (29 kilometers) on Mars.

Opportunity and its twin rover, Spirit, completed their three-month prime missions on Mars in April 2004. Both rovers continued in years of bonus, extended missions. Both have made important discoveries about wet environments on ancient Mars that may have been favorable for supporting microbial life. Spirit has not communicated with Earth since March 2010.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover Project for the NASA Science Mission Directorate, Washington.

The Spacecraft Assembly Facility of NASA's Jet Propulsion Laboratory in Pasadena, Calif., was constructed in 1961 to support NASA's Ranger and Mariner missions to the moon, Venus and Mars.

America had entered the Space Age just three years earlier, with the launch of the JPL-built Explorer 1 spacecraft.

The Spacecraft Assembly Facility, also known as JPL Building 179, originally had just one high bay, the large chamber now named High Bay 1. It is about 80 feet by 120 feet (about 24 by 36 meters). In contrast to the cleanliness standards for spacecraft assembly today, in the early days of the facility, personnel were even permitted to smoke inside this high bay.

All JPL-built spacecraft through the Viking Orbiters (launched to Mars in 1975) were built in High Bay 1. At times during the 1960s, as many as five different spacecraft were being assembled at the same time in the facility.

After the original construction of the high bay, the System Test Complex on the south side of the high bay's windows was added. A second high bay, about 70 feet by 70 feet (21 meters by 21 meters) was finished in 1976 to support the Voyager Project. Spacecraft assembled in High Bay 2 have included Voyager 1 and 2, Galileo and Cassini.

The project being assembled and tested in High Bay 1 in spring 2011 is the Mars Science Laboratory, including its rover, Curiosity. The mission is scheduled for launch in November 2011. Mars rovers Spirit and Opportunity were also built in High Bay 1.

Emblems on the wall of High Bay 1 represent all the missions (spacecraft and instruments) that were assembled in the Spacecraft Assembly Facility, regardless of which high bay was used. These include the first successful missions to Venus, Mars, Jupiter, Saturn, Uranus and Neptune, as well as Earth's moon. The facility has also built Earth-science instruments, plus Wide Field and Planetary Cameras that flew on the Hubble Space Telescope.

Both of the high bays are certified to a cleanliness level of Class 10,000, which means that there are less than 10,000 particles of 0.5 micron (half a millionth of a meter or yard) or larger in size per cubic foot of air volume. It is a great place to work if you have allergies. The filtration systems in the high bays are effective in reducing both particulates as well as hydrocarbons. The system maintained acceptable levels even when a brush fire raged near JPL in 2009.

Personnel working in the high bay wear protective clothing to minimize particles and bacteria reaching the spacecraft and the facility. All the equipment that enters the high bay is cleaned first with approved solvents (usually isopropyl alcohol). Both high bays are equipped with continuous remote monitoring for environmental conditions and cleanliness levels to ensure system safety and quick response to anomalous conditions.

More information about JPL is online at: http://www.jpl.nasa.gov . Follow us via social media, including Facebook and Twitter. Details are at: http://www.jpl.nasa.gov/social . A live feed of Curiosity being built and tested in High Bay 1, with a chat feature available most days, is online at: http://www.ustream.tv/nasajpl .

NASA's Dawn spacecraft has obtained its first image of the giant asteroid Vesta, which will help fine-tune navigation during its approach. Dawn is expected to achieve orbit around Vesta on July 16, when the asteroid is about 188 million kilometers (117 million miles) from Earth.

The image from Dawn's framing cameras was taken on May 3 when the spacecraft began its approach and was approximately 1.21 million kilometers (752,000 miles) from Vesta. The asteroid appears as a small, bright pearl against a background of stars. Vesta is also known as a protoplanet, because it is a large body that almost formed into a planet.

"After plying the seas of space for more than a billion miles, the Dawn team finally spotted its target," said Carol Raymond, Dawn's deputy principal investigator at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "This first image hints of detailed portraits to come from Dawn's upcoming visit."

Vesta is 530 kilometers (330 miles) in diameter and the second most massive object in the asteroid belt. Ground- and space-based telescopes obtained images of the bright orb for about two centuries, but with little surface detail.

Mission managers expect Vesta's gravity to capture Dawn in orbit on July 16. To enter orbit, Dawn must match the asteroid's path around the sun, which requires very precise knowledge of the body's location and speed. By analyzing where Vesta appears relative to stars in framing camera images, navigators will pin down its location and enable engineers to refine the spacecraft's trajectory.

Dawn will start collecting science data in early August at an altitude of approximately 1,700 miles (2,700 kilometers) above the asteroid's surface. As the spacecraft gets closer, it will snap multi-angle images, allowing scientists to produce topographic maps. Dawn will later orbit at approximately 200 kilometers (120 miles) to perform other measurements and obtain closer shots of parts of the surface. Dawn will remain in orbit around Vesta for one year. After another long cruise phase, Dawn will arrive in 2015 at its second destination, Ceres, an even more massive body in the asteroid belt.

Gathering information about these two icons of the asteroid belt will help scientists unlock the secrets of our solar system's early history. The mission will compare and contrast the two giant bodies shaped by different forces. Dawn's science instruments will measure surface composition, topography and texture. Dawn will also measure the tug of gravity from Vesta and Ceres to learn more about their internal structures. The spacecraft's full odyssey will take it on a 5-billion-kilometer (3-billion-mile) journey, which began with its launch in September 2007.

Dawn's mission to Vesta and Ceres is managed by JPL for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Ala.

The University of California in Los Angeles is responsible for overall Dawn mission science. Orbital Sciences Corp. of Dulles, Va., designed and built the spacecraft. The framing cameras were developed and built under the leadership of the Max Planck Institute for Solar System Research in Katlenburg-Lindau in Germany, with significant contributions by the German Aerospace Center (DLR) Institute of Planetary Research in Berlin and in coordination with the Institute of Computer and Communication Network Engineering in Braunschweig. The framing camera project is funded by NASA, the Max Planck Society and DLR.

New data analysis from NASA's Galileo spacecraft reveals a subsurface ocean of molten or partially molten magma beneath the surface of Jupiter's volcanic moon Io.

The finding heralds the first direct confirmation of this kind of magma layer at Io and explains why the moon is the most volcanic object known in the solar system. The research was conducted by scientists at the University of California, Los Angeles; the University of California, Santa Cruz;, and the University of Michigan, Ann Arbor. The study is published this week in the journal Science.

"Scientists are excited we finally understand where Io's magma is coming from and have an explanation for some of the mysterious signatures we saw in some of the Galileo's magnetic field data," said Krishan Khurana, lead author of the study and former co-investigator on Galileo's magnetometer team at UCLA. "It turns out Io was continually giving off a 'sounding signal' in Jupiter's rotating magnetic field that matched what would be expected from molten or partially molten rocks deep beneath the surface."

Io produces about 100 times more lava each year than all the volcanoes on Earth. While Earth's volcanoes occur in localized hotspots like the "Ring of Fire" around the Pacific Ocean, Io's volcanoes are distributed all over its surface. A global magma ocean about 30 to 50 kilometers (20 to 30 miles) beneath Io's crust helps explain the moon's activity.

"It has been suggested that both the Earth and its moon may have had similar magma oceans billions of years ago at the time of their formation, but they have long since cooled," said Torrence Johnson, a former Galileo project scientist based at NASA's Jet Propulsion Laboratory in Pasadena, Calif. He was not directly involved in the study. "Io's volcanism informs us how volcanoes work and provides a window in time to styles of volcanic activity that may have occurred on the Earth and moon during their earliest history."

NASA's Voyager spacecraft discovered Io's volcanoes in 1979, making that moon the only body in the solar system other than Earth known to have active magma volcanoes. The energy for the volcanic activity comes from the squeezing and stretching of the moon by Jupiter's gravity as Io orbits the largest planet in the solar system.

Galileo was launched in 1989 and began orbiting Jupiter in 1995. Unexplained signatures appeared in magnetic field data from Galileo flybys of Io in October 1999 and February 2000. After a successful mission, the spacecraft was intentionally sent into Jupiter's atmosphere in 2003.

"During the final phase of the Galileo mission, models of the interaction between Io and Jupiter's immense magnetic field, which bathes the moon in charged particles, were not yet sophisticated enough for us to understand what was going on in Io's interior," said Xianzhe Jia, a co-author of the study at the University of Michigan.

Recent work in mineral physics showed that a group of rocks known as "ultramafic" rocks become capable of carrying substantial electrical current when melted. Ultramafic rocks are igneous in origin, or form through the cooling of magma. On Earth, they are believed to originate from the mantle. The finding led Khurana and colleagues to test the hypothesis that the strange signature was produced by current flowing in a molten or partially molten layer of this kind of rock.

Tests showed that the signatures detected by Galileo were consistent with a rock such as lherzolite, an igneous rock rich in silicates of magnesium and iron found in Spitzbergen, Norway. The magma ocean layer on Io appears to be more than 50 kilometers (30 miles thick), making up at least 10 percent of the moon's mantle by volume. The blistering temperature of the magma ocean probably exceeds 1,200 degrees Celsius (2,200 degrees Fahrenheit).

The Galileo mission was managed by JPL for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena.

NASA's Jet Propulsion Laboratory invites the public to its annual Open House on Saturday, May 14, and Sunday, May 15, from 9 a.m. to 5 p.m.

The event, themed "The Excitement in Explorations," invites visitors to share in the wonders of space through high-definition and 3-D videos, live demonstrations, interactions with scientists and engineers, and a first look at JPL's new Earth Science Center.

The Earth Science Center showcases our home planet and JPL's Earth science missions. Visitors will pass by two touchscreens located on opposite walls of the facility that control real-time views of "Eyes on the Earth," an interactive 3-D visualization website. Visitors will also have the opportunity to watch a movie in the 3-D theater, which seats up to 40 people.

Other Open House highlights include:

- A chance to see the most unique car in this world before it leaves Earth: The next rover bound for Mars, Mars Science Laboratory/Curiosity, in the "clean room" before it is shipped to Florida for a November 2011 launch. Curiosity also stars in its own "reality TV show" via live-streaming webcam: http://www.ustream.tv/nasajpl .
- Life-size rover models in a "Mars" test bed.
- A perennial crowd-pleaser, the Robo-Dome, where a pair of 700-pound robots glide in a high-tech arena under artificial stars. The Robo-Dome is used to simulate complex maneuvers that could be used for future space missions.
- JPL's Microdevices Lab, where engineers and scientists use tiny technology to revolutionize space exploration.
- Solar-safe telescopes that allow visitors to see the sun.

Selected locations at Open House will be featured live online, with a live chat available, on Ustream TV at: http://www.ustream.tv/nasajpl2 on Sat., May 14, from 9 a.m. to noon PDT (noon to 3 p.m. EDT).

JPL is located at 4800 Oak Grove Drive, Pasadena, Calif., 91109. Admission to Open House is free. Parking is also free, but is limited. To get to JPL, take the Berkshire Avenue/Oak Grove Drive exit from the 210 Freeway in La Canada/Flintridge. All visitors should wear comfortable shoes -- no buses will be provided from JPL parking lots. JPL will provide vans for mobility-challenged guests.

Vehicles entering NASA/JPL property are subject to inspection. Visitors cannot bring these items to NASA/JPL: weapons, explosives, incendiary devices, dangerous instruments, alcohol, illegal drugs, pets, all types of skates including skateboards, Segways and bicycles. No bags, backpacks or ice chests are allowed, except small purses and diaper bags.

More information about JPL is online at: http://www.jpl.nasa.gov . Follow us via social media, including Facebook and Twitter . A full list, with links, is at: http://www.jpl.nasa.gov/social/ .

Two NASA websites have been recognized in the 15th Annual Webby Awards -- the leading international honor for the world's best Internet sites.

NASA's main website, www.NASA.gov, received its third consecutive People's Voice Award for best government site. NASA's Global Climate Change site at http://climate.nasa.gov/, which won last year's People's Voice Award for science, won the 2011 judges' award for best science site.

"NASA is committed to sharing its compelling story with people everywhere and with every communication tool," said David Weaver, NASA's associate administrator for communications. "We are very grateful to the online community for its continued support of what we are doing, and are excited about our future."

NASA recently posted new interactive pieces on the 30th anniversary of the Space Shuttle Program and the 50th anniversary of the first U.S. spaceflight. And in the last year, the agency has streamlined its online video presentation into a single player and deployed a version of the site optimized for mobile devices.

"NASA has a very broad-based Web team that can take content, literally the best raw material in the universe, and create compelling imagery, video and multimedia pieces to tell the agency's story," said Internet Services Manager Brian Dunbar in the Office of Communications at NASA Headquarters in Washington.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Global Climate Change site for the agency's Science Mission Directorate.

"NASA satellites take key measurements of our climate, and the Global Climate Change site gives the public access to that data as a visual, immersive experience," said Randal Jackson, JPL's Internet communications manager for the Global Climate Change site. "We're grateful for the high degree of interest the public has shown in Earth's vital signs."

NASA has had a Web presence almost since HTML was invented in the early 1990's, but the site's popularity skyrocketed after a 2003 redesign and relaunch focused on making it more usable and understandable for the general public. Since then, there have been more than 1.5 billion visits to the site, and its customer-satisfaction ratings are among the highest in government and comparable to popular commercial sites.

Reaching beyond the agency's website, NASA's online communications include a Facebook page with more than 368,000 "likes"; a Twitter feed with more than a million followers; and more than 160 accounts across a variety of social media platforms. Last fall, NASA placed first by a wide margin in the L2 Digital IQ Index for the Public Sector study that ranks 100 public sector organizations in the effectiveness of their websites, digital outreach, social media use and mobile sites.

The Office of Communications and the Office of the Chief Information Officer, both at NASA Headquarters, manage the agency's website.

Presented by the International Academy of Digital Arts and Sciences, the Webby Award recognizes excellence in technology and creativity. The academy created the awards in 1996 to help drive the creative, technical, and professional progress of the Internet and evolving forms of interactive media. While members of the International Academy of Digital Arts and Sciences select the Webby award winners, the online community determines the winners of the People's Voice Awards.

To find all the ways you can connect and collaborate with NASA, visit: http://www.nasa.gov/connect.

The California Institute of Technology in Pasadena manages JPL for NASA.

Design techniques honed at NASA's Jet Propulsion Laboratory in Pasadena, Calif., for Mars rovers were used to create the rover currently examining the inside of Japan's nuclear reactors, in areas not yet deemed safe for human crews.

The iRobot PackBot employs technologies used previously in the design of "Rocky-7," which served as a terrestrial test bed at JPL for the current twin Mars rovers, Spirit and Opportunity. PackBot's structural features are modeled after Rocky-7, including the lightweight, high-torque actuators that control the rover; and its strong, lightweight frame structure and sheet-metal chassis.

PackBot's other "ancestor," called Urbie, was an urban reconnaissance robot with military and disaster response applications. Urbie's lightweight structure and rugged features also made it useful in emergency response situations; for example, at sites contaminated with radiation and chemical spills, and at buildings damaged by earthquakes. Urbie's physical structure was designed by iRobot Corp., Bedford, Mass., while JPL was responsible for the intelligent robot's onboard sensors and vision algorithms, which helped the robot factor in obstacles and determine an appropriate driving path. Following the success of Urbie's milestones, the team at iRobot created its successor: PackBot.

Since 2002, iRobot has delivered variations of the PackBot model to the U.S. Army, U.S. Air Force and U.S. Navy. The tactical robot's first military deployment was to Afghanistan in July 2002, to assist soldiers by providing "eyes and ears" in the most dangerous or inaccessible areas. It was also used to search through debris at Ground Zero after the Sept. 11, 2001 attacks in New York.

Recently, iRobot provided two PackBots to help after the devastating March 11, 2011, earthquake and tsunami in Japan. The PackBot models, currently taking radioactivity readings in the damaged Fukushima Daiichi nuclear power plant buildings, are equipped with multiple cameras and hazard material sensors. The images and readings provided by the PackBots indicated radiation levels are still too high to allow human repair crews to safely enter the buildings.

Urbie was a joint effort of the Defense Advanced Research Project's Agency's (DARPA) Tactical Mobile Robot program, JPL, iRobot Corp., the Robotics Institute of Carnegie Mellon University, and the University of Southern California's Robotics Research Laboratory. JPL is managed for NASA by the California Institute of Technology in Pasadena.

For more information on the history of the partnership between iRobot and JPL, visit: http://www.sti.nasa.gov/tto/Spinoff2005/ps_1.html .

NASA's Mars Reconnaissance Orbiter has discovered the total amount of atmosphere on Mars changes dramatically as the tilt of the planet's axis varies. This process can affect the stability of liquid water, if it exists on the Martian surface, and increase the frequency and severity of Martian dust storms.

Researchers using the orbiter's ground-penetrating radar identified a large, buried deposit of frozen carbon dioxide, or dry ice, at the Red Planet's south pole. The scientists suspect that much of this carbon dioxide enters the planet's atmosphere and swells the atmosphere's mass when Mars' tilt increases. The findings are published in this week's issue of the journal Science.

The newly found deposit has a volume similar to Lake Superior's nearly 3,000 cubic miles (about 12,000 cubic kilometers). The deposit holds up to 80 percent as much carbon dioxide as today's Martian atmosphere. Collapse pits caused by dry ice sublimation and other clues suggest the deposit is in a dissipating phase, adding gas to the atmosphere each year. Mars' atmosphere is about 95 percent carbon dioxide, in contrast to Earth's much thicker atmosphere, which is less than .04 percent carbon dioxide.

"We already knew there is a small perennial cap of carbon-dioxide ice on top of the water ice there, but this buried deposit has about 30 times more dry ice than previously estimated," said Roger Phillips of Southwest Research Institute in Boulder, Colo. Phillips is deputy team leader for the Mars Reconnaissance Orbiter's Shallow Radar instrument and lead author of the report.

"We identified the deposit as dry ice by determining the radar signature fit the radio-wave transmission characteristics of frozen carbon dioxide far better than the characteristics of frozen water," said Roberto Seu of Sapienza University of Rome, team leader for the Shallow Radar and a co-author of the new report. Additional evidence came from correlating the deposit to visible sublimation features typical of dry ice.

"When you include this buried deposit, Martian carbon dioxide right now is roughly half frozen and half in the atmosphere, but at other times it can be nearly all frozen or nearly all in the atmosphere," Phillips said.

An occasional increase in the atmosphere would strengthen winds, lofting more dust and leading to more frequent and more intense dust storms. Another result is an expanded area on the planet's surface where liquid water could persist without boiling. Modeling based on known variation in the tilt of Mars' axis suggests several-fold changes in the total mass of the planet's atmosphere can happen on time frames of 100,000 years or less.

The changes in atmospheric density caused by the carbon-dioxide increase also would amplify some effects of the changes caused by the tilt. Researchers plugged the mass of the buried carbon-dioxide deposit into climate models for the period when Mars' tilt and orbital properties maximize the amount of summer sunshine hitting the south pole. They found at such times, global, year-round average air pressure is approximately 75 percent greater than the current level.

"A tilted Mars with a thicker carbon-dioxide atmosphere causes a greenhouse effect that tries to warm the Martian surface, while thicker and longer-lived polar ice caps try to cool it," said co-author Robert Haberle, a planetary scientist at NASA's Ames Research Center in Moffett Field, Calif. "Our simulations show the polar caps cool more than the greenhouse warms. Unlike Earth, which has a thick, moist atmosphere that produces a strong greenhouse effect, Mars' atmosphere is too thin and dry to produce as strong a greenhouse effect as Earth's, even when you double its carbon-dioxide content."

The Shallow Radar, one of the Mars Reconnaissance Orbiter's six instruments, was provided by the Italian Space Agency, and its operations are led by the Department of Information Engineering, Electronics and Telecommunications at Sapienza University of Rome. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter project for NASA's Science Mission Directorate at the agency's headquarters in Washington. Lockheed Martin Space Systems in Denver built the spacecraft.