Cassini Finds Warm Cracks on Enceladus

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New images and data from NASA's Cassini spacecraft give scientists a unique Saturn-lit view of active fissures through the south polar region of Saturn's moon Enceladus. They reveal a more complicated web of warm fractures than previously thought.

Scientists working jointly with Cassini's composite infrared spectrometer and its high-resolution imaging camera have constructed the highest-resolution heat intensity maps yet of the hottest part of a region of long fissures spraying water vapor and icy particles from Enceladus. These fissures have been nicknamed "tiger stripes." Additional high-resolution spectrometer maps of one end of the tiger stripes Alexandria Sulcus and Cairo Sulcus reveal never-before-seen warm fractures that branch off like split ends from the main tiger stripe trenches. They also show an intriguing warm spot isolated from other active surface fissures.

"The ends of the tiger stripes may be the places where the activity is just getting started, or is winding down, so the complex patterns of heat we see there may give us clues to the life cycle of tiger stripes," said John Spencer, a Cassini team scientist based at Southwest Research Institute in Boulder, Colo.

The images and maps come from the Aug. 13, 2010, Enceladus flyby, Cassini's last remote sensing flyby of the moon until 2015. The geometry of the many flybys between now and 2015 will not allow Cassini to do thermal scans like these, because the spacecraft will be too close to scan the surface and will not view the south pole. This Enceladus flyby, the 11th of Cassini's tour, also gave Cassini its last look at any part of the active south polar region in sunlight.

The highest-resolution spectrometer scan examined the hottest part of the entire tiger stripe system, part of the fracture called Damascus Sulcus. Scientists used the scan to measure fracture temperatures up to190 Kelvin (minus 120 degrees Fahrenheit). This temperature appears slightly higher than previously measured temperatures at Damascus, which were around 170 Kelvin (minus 150 degrees Fahrenheit).

Spencer said he isn't sure if this tiger stripe is just more active than it was the last time Cassini's spectrometer scanned it, in 2008, or if the hottest part of the tiger stripe is so narrow that previous scans averaged its temperature out over a larger area. In any case, the new scan had such good resolution, showing details as small as 800 meters (2,600 feet), that scientists could see for the first time warm material flanking the central trench of Damascus, cooling off quickly away from the trench. The Damascus thermal scan also shows large variations in heat output within a few kilometers along the length of the fracture. This unprecedented resolution will help scientists understand how the tiger stripes deliver heat to the surface of Enceladus.

Cassini acquired the thermal map of Damascus simultaneously with a visible-light image where the tiger stripe is lit by sunlight reflecting off Saturn. The visible-light and thermal data were merged to help scientists understand the relationships between physical heat processes and surface geology.

"Our high-resolution images show that this section of Damascus Sulcus is among the most structurally complex and tectonically dynamic of the tiger stripes," said imaging science team associate Paul Helfenstein of Cornell University, Ithaca, N.Y. Some details in the appearance of the landforms, such as a peculiar pattern of curving striations along the flanks of Damascus, had not previously been noticed in ordinary sunlit images.

The day after the Enceladus flyby, Cassini swooped by the icy moon Tethys, collecting images that helped fill in gaps in the Tethys global map. Cassini's new views of the heavily cratered moon will help scientists understand how tectonic forces, impact cratering, and perhaps even ancient resurfacing events have shaped the moon's appearance.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo. The composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md., where the instrument was built.

For more information visit http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20101130.html

Dark Dune Fields of Proctor Crater, Mars

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The dark rippled dunes of Mars' Proctor Crater likely formed more recently than the lighter rock forms they appear to cover, and are thought to slowly shift in response to pervasive winds. The dunes arise from a complex relationship between the sandy surface and high winds on Mars. Similar dunes were first seen in Proctor Crater by Mariner 9 more than 35 years ago.

This image was taken by HiRISE camera on board the Mars Reconnaissance Orbiter, currently in orbit around Mars.

For more information visit http://www.nasa.gov/multimedia/imagegallery/image_feature_1810.html

Thin Air - Cassini Finds Ethereal Atmosphere at Rhea

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NASA's Cassini spacecraft has detected a very tenuous atmosphere known as an exosphere, infused with oxygen and carbon dioxide around Saturn's icy moon Rhea. This is the first time a spacecraft has directly captured molecules of an oxygen atmosphere – albeit a very thin one -- at a world other than Earth.

The oxygen appears to arise when Saturn's magnetic field rotates over Rhea. Energetic particles trapped in the planet's magnetic field pepper the moon’s water-ice surface. They cause chemical reactions that decompose the surface and release oxygen. The source of the carbon dioxide is less certain.

Oxygen at Rhea's surface is estimated to be about 5 trillion times less dense than what we have at Earth. But the new results show that surface decomposition could contribute abundant molecules of oxygen, leading to surface densities roughly 100 times greater than the exospheres of either Earth's moon or Mercury. The formation of oxygen and carbon dioxide could possibly drive complex chemistry on the surfaces of many icy bodies in the universe.

"The new results suggest that active, complex chemistry involving oxygen may be quite common throughout the solar system and even our universe," said lead author Ben Teolis, a Cassini team scientist based at Southwest Research Institute in San Antonio. "Such chemistry could be a prerequisite for life. All evidence from Cassini indicates that Rhea is too cold and devoid of the liquid water necessary for life as we know it."

Releasing oxygen through surface irradiation could help generate conditions favorable for life at an icy body other than Rhea that has liquid water under the surface, Teolis said. If the oxygen and carbon dioxide from the surface could somehow get transported down to a sub-surface ocean, that would provide a much more hospitable environment for more complex compounds and life to form. Scientists are keen to investigate whether life on icy moons with an ocean is possible, though they have not yet detected it.

The tenuous atmosphere with oxygen and carbon dioxide makes Rhea, Saturn's second largest moon, unique in the Saturnian system. Titan has a thick nitrogen-methane atmosphere, but very little carbon dioxide and oxygen.

"Rhea is turning out to be much more interesting than we had imagined," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "The Cassini finding highlights the rich diversity of Saturn’s moons and gives us clues on how they formed and evolved."

Scientists had suspected Rhea could have a thin atmosphere with oxygen and carbon dioxide, based on remote observations of Jupiter's icy moons by NASA's Galileo spacecraft and Hubble Space Telescope. Other Cassini observations detected oxygen escaping from icy Saturn ring particles after ultraviolet bombardment. But Cassini was able to detect oxygen and carbon dioxide in the exosphere directly because of how close it flew to Rhea – 101 kilometers, or 63 miles – and its special suite of instruments.

In the new study, scientists combined data from Cassini's ion and neutral mass spectrometer and the Cassini plasma spectrometer during flybys on Nov. 26, 2005, Aug. 30, 2007, and March 2, 2010. The ion and neutral mass spectrometer "tasted" peak densities of oxygen of around 50 billion molecules per cubic meter (1 billion molecules per cubic foot). It detected peak densities of carbon dioxide of around 20 billion molecules per cubic meter (about 600 million molecules per cubic foot).

The plasma spectrometer saw clear signatures of flowing streams of positive and negative ions, with masses that corresponded to ions of oxygen and carbon dioxide.

"How exactly the carbon dioxide is released is still a puzzle," said co-author Geraint Jones, a Cassini team scientist based at University College London in the U.K. "But with Cassini's diverse suite of instruments observing Rhea from afar, as well as sniffing the gas surrounding it, we hope to solve the puzzle."

The carbon dioxide may be the result of “dry ice” trapped from the primordial solar nebula, as is the case with comets, or it may be due to similar irradiation processes operating on the organic molecules trapped in the water ice of Rhea. The carbon dioxide could also come from carbon-rich materials deposited by tiny meteors that bombarded Rhea's surface.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency, and the Italian Space Agency. NASA's Jet Propulsion Laboratory, Pasadena, Calif., a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The ion and neutral mass spectrometer team and the Cassini plasma spectrometer team are based at Southwest Research Institute, San Antonio.

For more information visit http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20101126.html

Harrat Khaybar

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Harrat Khaybar, Saudi Arabia lies in the western half of the Arabian peninsula and contains not only large expanses of sand and gravel, but also extensive lava fields known as haraat (harrat for a named field). According to scientists, the volcanic field was formed by eruptions along a long north-south linear vent system over the past 5 million years; the most recent recorded eruption took place between 600-700 A.D.

The presence of tuff cones -- formed by eruption of lava in the presence of water together with other volcanic features indicative of water -- in the Harrat Khaybar suggest that the local climate was much wetter during some periods of volcanic activity. Today, however, the regional climate is hyperarid -- little to no yearly precipitation -- leading to an almost total lack of vegetation.

The image was taken by the Expedition 16 crew aboard the Inernational Space Station in March 2008.

For more information visit http://www.nasa.gov/multimedia/imagegallery/image_feature_1808.html

Astronomers Probe 'Sandbar' Between Islands of Galaxies

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Astronomers have caught sight of an unusual galaxy that has illuminated new details about a celestial "sandbar" connecting two massive islands of galaxies. The research was conducted in part with NASA's Spitzer Space Telescope.

These "sandbars," or filaments, are known to span vast distances between galaxy clusters and form a lattice-like structure known as the cosmic web. Though immense, these filaments are difficult to see and study in detail. Two years ago, Spitzer's infrared eyes revealed that one such intergalactic filament containing star-forming galaxies ran between the galaxy clusters called Abell 1763 and Abell 1770.

Now these observations have been bolstered by the discovery, inside this same filament, of a galaxy that has a rare boomerang shape and unusual light emissions. Hot gas is sweeping the wandering galaxy into this shape as it passes through the filament, presenting a new way to gauge the filament's particle density. Researchers hope that other such galaxies with oddly curved profiles could serve as signposts for the faint threads, which in turn signify regions ripe for forming stars.

"These filaments are integral to the evolution of galaxy clusters -- among the biggest gravitationally bound objects in the universe -- as well as the creation of new generations of stars," said Louise Edwards, a postdoctoral researcher at the California Institute of Technology in Pasadena, and lead author of a study detailing the findings in the Dec. 1 issue of the Astrophysical Journal Letters. Her collaborators are Dario Fadda, also at Caltech, and Dave Frayer from the National Science Foundation's National Radio Astronomy Observatory, based in Charlottesville, Virginia.

Blowing in the cosmic breeze

Astronomers spotted the bent galaxy about 11 million light-years away from the center of the galaxy cluster Abell 1763 during follow-up observations with the WIYN Observatory near Tucson, Ariz., and radio-wave observations by the Very Large Array near Socorro, N.M. The WIYN Observatory is named after the consortium that owns and operates it, which includes the University of Wisconsin, Indiana University, Yale University, and the National Optical Astronomy Observatories.

The galaxy has an unusual ratio of radio to infrared light, as measured by the Very Large Array and Spitzer, making it stand out like a beacon. This is due in part to the galaxy having twin jets of material spewing in opposite directions from a supermassive black hole at its center. These jets have puffed out into giant lobes of material that emit a tremendous amount of radio waves.

Edwards and her colleagues noticed that these lobes appear to be bent back and away from the galaxy's trajectory through the filament. This bow shape, the astronomers reasoned, is due to particles in the filament pushing on the gas and dust in the lobes.

By measuring the angle of the arced lobes, Edwards' team calculated the pressure exerted by the filaments' particles and then determined the density of the medium. The method is somewhat like looking at streamers on a kite soaring overhead to judge the wind strength and the thickness of the air.

According to the data, the density inside this filament is indeed about 100 times the average density of the universe. This value agrees with that obtained in a previous X-ray study of filaments and also nicely matches predictions of supercomputer simulations.

Interconnected superclusters

Galaxies tend to bunch together as great islands in the void of space, called galaxy clusters. These galaxy groupings themselves often keep company with other clusters in "superclusters" that loom as gargantuan, gravitationally associated walls of galaxies. These structures evolved from denser patches of material as the universe rapidly expanded after the Big Bang, some 13.7 billion years ago.

The clumps and threads of this primordial matter eventually cooled, and some of it has condensed into the galaxies we see today. The leftover gas is strewn in filaments between galaxy clusters. Much of it is still quite hot -- about one million degrees Celsius (1.8 million degrees Fahrenheit) -- and blazes in high-energy X-rays that permeate galaxy clusters. Filaments are therefore best detected in X-ray light, and one direct density reading of the strands has previously been obtained in this band of frequencies.

But the X-ray-emitting gas in filaments is much more diffuse and weak than in clusters, just as submerged sandbars are extremely hard to spot at sea compared to islands poking above the water. Therefore, obtaining quality observations of filaments is time-consuming with current space observatories.

The technique by Edwards and her colleagues, which uses radio frequencies that can reach a host of ground-based telescopes, points to an easier way to probe the interiors of galaxy-cluster filaments. Instead of laboring to find subtle X-rays clues, astronomers could trust these arced "lighthouse" galaxies to indicate just where cosmic filaments lie.

Knowing how much material these filaments contain and how they interact with galaxy clusters will be very important for understanding the overall evolution of the universe, Edwards said.

The Spitzer observations were made before it ran out of its liquid coolant in May 2009 and began its warm mission.

For more information visit http://www.nasa.gov/mission_pages/spitzer/news/spitzer20101124.html

Earth Observing-1: Ten Years of Innovation

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Scheduled to fly for a year, designed to last a year and a half, EO-1 celebrated its tenth anniversary on November 21, 2010. During its decade in space, the satellite has accomplished far more than anyone dreamed.

"Earth-Observing-1 has had three missions," says mission manager Dan Mandl of NASA’s Goddard Space Flight Center in Greenbelt, Md. Its original mission was to test new technologies, a mission completed in the first year. Its second mission was to provide images and data. Its third mission was to test new cost-saving software that operates the satellite semi-autonomously and allows users to target the sensors.

All of the missions come down to one thing: "We're the satellite people can try things on." Mandl calls EO-1 NASA's on-orbit test bed, and the name rings true.

Testing New Technology: Faster, Better, Cheaper

EO-1 was commissioned as part of NASA's New Millennium Program, set up to develop and fly technology that would reduce the risk and cost of future science missions. In short, NASA told its engineers: find a way to fly faster, better, and cheaper.

"EO-1's primary purpose was to demonstrate that the Advanced Land Imager (ALI) was a suitable follow-on instrument for Landsat," says Bryant Cramer, the program manager at Goddard during EO-1's development and launch. Like Landsat-7, ALI records seven wavelengths of light reflected from Earth's surface. ALI also records an additional two wavelengths to improve measurements of forests and crops, coastal waters, and aerosols.

Later, an innovative new instrument, the Hyperion imaging spectrometer, was added to the mission. Hyperion records more than 200 adjacent wavelengths of light to even better understand the makeup of Earth's surface.

"EO-1 succeeded beyond anyone's expectations," says former project scientist Steve Ungar of NASA Goddard. He credits the mission's success to EO-1's "crackerjack team" of engineers and scientists, who were drawn to the mission because they recognized that they could have a stake in the future of satellite technology.

Hyperion

"Hyperion is probably the future of remote sensing," says Cramer. Hyperion is a hyperspectral instrument, a change in technology that is like going from black-and-white to color television, Mandl adds.

Other remote sensing instruments—multispectrometers—measure discreet wavelengths of light. It is as if your eyes could only see red and blue light; you could tell much about the world based on how much red and how much blue you saw, but your vision would have gaps in the green tones. A hyperspectral instrument corrects this color blindness by measuring many more wavelengths of light.

The science behind the hyperspectral instrument is spectroscopy, says current EO-1 project scientist, Elizabeth Middleton of NASA Goddard. "Spectroscopy is the study of constituents of materials using specific wavelengths," she notes. "Hyperion measures the chemical constituents of Earth's surface."

Space-based imaging spectroscopy enables a wide range of science, including tracking the amount of carbon plants take out of the atmosphere everywhere from the Amazon Rainforest to the Alaskan tundra. It also has been used to find evidence of microbial life in the Arctic and to monitor volcanic activity.

Perhaps the most important thing Hyperion has done, says Middleton, is teach the community how to work with complex hyperspectral data. Germany will soon launch the next hyperspectral instrument, EnMap, followed by NASA's HyspIRI satellite, which is still in the planning stage. Both missions build on lessons learned from Hyperion.

Advanced Land Imager

The Advanced Land Imager (ALI) was built, says Cramer, to test new technology and to provide a safe technology shift for future Landsat missions. The Landsat series of satellites has provided a continuous record of changes in Earth's landscape from 1972 to the present.

ALI differs from previous Landsat sensors because of how it takes images. Previous Landsat instruments scanned from side to side, like a whiskbroom. The image is built from horizontal strips of information. ALI, on the other hand, is more like a push broom. It has detectors arranged parallel to one another and facing forward, and they collect information in vertical strips. This arrangement eliminates the need for the sensor optics to move from side to side, and fewer moving parts means less chance of failure, says EO-1 engineer Stuart Frye of NASA Goddard.

After ten years of operation, ALI has proven that the push-broom technology is stable and reliable enough that the next Landsat satellite uses the same design. "The Landsat community is treating push-broom sensors like we've been building them for years," says Cramer. "That's a tribute to EO-1."

NASA's On-orbit test bed

As the EO-1 mission has aged, perhaps the most critical innovation has come from the onboard computer. "EO-1 has two separate computer processors with 256 megabytes of extra memory each," says Mandl. "It meant we had excess capacity to try new things."

The first new software loaded onto EO-1 was the Autonomous Science Experiment, an onboard intelligent scheduling tool that allows the satellite to decide for itself which images Hyperion and ALI should take. The on-board scheduler prioritizes requests based on what they are for (ranked by theme) and the weather.

"It's a customer-driven method of running a mission," says Mandl. Anyone from an archeologist to a disaster response agency can request images. "Flying a mission with a customizable user experience is one of EO-1's greatest achievement."

Sometimes the "customers" targeting EO-1 are other satellites. As part of SensorWeb, EO-1 automatically acquires images that are triggered by other satellites. For example, EO-1 monitors 100 volcanoes. When another satellite detects a hot spot at any of them, EO-1 automatically acquires an image on its next overpass. Hyperion records the temperature and position of lava flows, while ALI tracks ash plumes.

SensorWeb and the scheduling tool have saved money. "Initially, we were spending about $7,500 per image to acquire them. Now the cost is less than $600 a scene," says Cramer.

"EO-1 is one of the cheapest of NASA's Earth missions," confirms Middleton. These cost savings mean that anyone can now target EO-1 and access all data free of charge, making it useful to a growing range of people.

"EO-1 has done so many different things, NASA got three or four missions for the price of one," says Cramer. "We achieved all of the things that we hoped for and then some."

For more information visit http://www.nasa.gov/topics/earth/features/eo1-10th.html

Spitzer Sees Shrouded Burst of Stars

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Astronomers using NASA's Spitzer Space Telescope have found a stunning burst of star formation that beams out as much infrared light as an entire galaxy.

The "starburst" stands as the most luminous ever seen taking place away from the centers, or nuclei, of merging parent galaxies. The new findings show that galaxy mergers can pack a real star-making wallop far from their respective galactic centers, where star-forming dust and gases typically pool.

For more information visit http://www.jpl.nasa.gov/news/news.cfm?release=2010-391

Scientists Chosen to Help on Venus Climate Orbiter

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NASA has established a Venus Climate Orbiter Participating Scientist Program to complement scientific return of the Japan Aerospace Exploration Agency (JAXA)-led Venus Climate Orbiter, or "Akatsuki" mission. The Participating Scientist Program will fund two scientists in residence to live in Japan and five Participating Scientists to conduct joint research with the Venus Climate Orbiter science team.

Based on peer-reviewed proposals submitted to NASA, NASA and JAXA are pleased to announce the following joint selections of U.S. Participating Scientists:

Participating Scientist in Residence
Name: Sanjay S. Limaye
Affiliation: University of Wisconsin, Madison
Proposal Title: Investigation of the Venus weather as a Participating Scientist in
Residence

Name: Kevin McGouldrick
Affiliation: University of Colorado, Boulder
Proposal Title: Combined theoretical and observational multi-disciplinary analysis
of the structure and evolution of the clouds and hazes of Venus

Participating Scientist
Name: Charles H. Acton
Affiliation: Jet Propulsion Laboratory, Pasadena, Calif.
Proposal Title: SPICE for Venus Climate Orbiter

Name: Ralph D. Lorenz
Affiliation: Johns Hopkins University Applied Physics Laboratory, Laurel, Md.
Proposal Title: Combined theoretical and observational multi-disciplinary analysis of the structure and evolution of the clouds and hazes of Venus

Name: Gerald Schubert
Affiliation: University of California, Los Angeles
Proposal Title: Modeling Venus atmospheric dynamics with data from the
Venus Climate Orbiter (Akatsuki)

Name: Eliot F. Young
Affiliation: University of California, Los Angeles
Proposal Title: Identifying cloud properties and altitude: spectral image cubes to
accompany Akatsuki image data

Name: Mark A. Bullock
Affiliation: Southwest Research Institute, San Antonio
Proposal Title: Observational and theoretical constraints on current Venus
volcanism from Akatsuki UV and IR imaging

Akatsuki was launched on May 21, 2010 (Japan Standard Time, JST) and is Japan's first mission to Venus. The spacecraft will arrive at Venus on Dec. 7, 2010, and will follow the Venus westward rotation of the atmosphere, mapping the circulation, evolution and vertical structure of the planet's thick clouds.

The three-dimensional structure of the Venusian atmosphere and its temporal variation will be observed by using the Akatsuki spacecraft's imaging cameras (from the ultraviolet to thermal infrared wavelengths), a high-speed lightning detector and radio occultation techniques that will penetrate the thick Venusian atmosphere. Akatsuki's systematic and continuous observations from a quasi-equatorial orbit will provide a complete dataset of atmospheric dynamics.

Mitsubishi Heavy Industries, Ltd. and JAXA launched Akasutki aboard H-IIA Launch Vehicle No. 17 (H-IIA F17) at 6:58:22 a.m. on May 21, 2010 (JST) from the Tanegashima Space Center. The mission lifespan in Venus orbit is approximately two Earth years.

For more information visit http://www.nasa.gov/topics/solarsystem/features/venus20101119.html

Hubble Captures New 'Life' in an Ancient Galaxy

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Elliptical galaxies were once thought to be aging star cities whose star-making heyday was billions of years ago.

But new observations with NASA's Hubble Space Telescope are helping to show that elliptical galaxies still have some youthful vigor left, thanks to encounters with smaller galaxies.

Images of the core of NGC 4150, taken in near-ultraviolet light with the sharp-eyed Wide Field Camera 3 (WFC3), reveal streamers of dust and gas and clumps of young, blue stars that are significantly less than a billion years old. Evidence shows that the star birth was sparked by a merger with a dwarf galaxy.

The new study helps bolster the emerging view that most elliptical galaxies have young stars, bringing new life to old galaxies.

"Elliptical galaxies were thought to have made all of their stars billions of years ago," says astronomer Mark Crockett of the University of Oxford, leader of the Hubble observations. "They had consumed all their gas to make new stars. Now we are finding evidence of star birth in many elliptical galaxies, fueled mostly by cannibalizing smaller galaxies.

"These observations support the theory that galaxies built themselves up over billions of years by collisions with dwarf galaxies," Crockett continues. "NGC 4150 is a dramatic example in our galactic back yard of a common occurrence in the early universe."

The Hubble images reveal turbulent activity deep inside the galaxy's core. Clusters of young, blue stars trace a ring around the center that is rotating with the galaxy. The stellar breeding ground is about 1,300 light-years across. Long strands of dust are silhouetted against the yellowish core, which is composed of populations of older stars.

From a Hubble analysis of the stars' colors, Crockett and his team calculated that the star-formation boom started about a billion years ago, a comparatively recent event in cosmological history. The galaxy's star-making factory has slowed down since then.

"We are seeing this galaxy after the major starburst has occurred," explains team member Joseph Silk of the University of Oxford. "The most massive stars are already gone. The youngest stars are between 50 million and 300 to 400 million years old. By comparison, most of the stars in the galaxy are around 10 billion years old."

The encounter that triggered the star birth would have been similar to our Milky Way swallowing the nearby Large Magellanic Cloud.

"We believe that a merger with a small, gas-rich galaxy around one billion years ago supplied NGC 4150 with the fuel necessary to form new stars," says team member Sugata Kaviraj of the Imperial College London and the University of Oxford. "The abundance of 'metals' -- elements heavier than hydrogen and helium—in the young stars is very low, suggesting the galaxy that merged with NGC 4150 was also metal-poor. This points towards a small, dwarf galaxy, around one-twentieth the mass of NGC 4150."

Minor mergers such as this one are more ubiquitous than interactions between hefty galaxies, the astronomers say. For every major encounter, there are probably up to 10 times more frequent clashes between a large and a small galaxy. Major collisions are easier to see because they create incredible fireworks: distorted galaxies, long streamers of gas, and dozens of young star clusters. Smaller interactions are harder to detect because they leave relatively little trace.

Over the past five years, however, ground- and space-based telescopes have offered hints of fresh star formation in elliptical galaxies. Ground-based observatories captured the blue glow of stars in elliptical galaxies, and satellites such as the Galaxy Evolution Explorer (GALEX), which looks in far- and near-ultraviolet light, confirmed that the blue glow came from fledgling stars much less than a billion years old. Ultraviolet light traces the glow of hot, young stars.

Crockett and his team selected NGC 4150 for their Hubble study because a ground-based spectroscopic analysis gave tantalizing hints that the galaxy's core was not a quiet place. The ground-based survey, called the Spectrographic Areal Unit for Research on Optical Nebulae (SAURON), revealed the presence of young stars and dynamic activity that was out of sync with the galaxy.

"In visible light, elliptical galaxies such as NGC 4150 look like normal elliptical galaxies," Silk says. "But the picture changes when we look in ultraviolet light. At least a third of all elliptical galaxies glow with the blue light of young stars."

Adds Crockett: "Ellipticals are the perfect laboratory for studying minor mergers in ultraviolet light because they are dominated by old red stars, allowing astronomers to see the faint blue glow of young stars."

The astronomers hope to study other elliptical galaxies in the SAURON survey to look for the signposts of new star birth. The team's results have been accepted for publication in The Astrophysical Journal.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

For more information visit http://www.nasa.gov/mission_pages/hubble/science/ancient-galaxy.html

WISE Image Reveals Strange Specimen in Starry Sea

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A new image from NASA's Wide-field Infrared Survey Explorer shows what looks like a glowing jellyfish floating at the bottom of a dark, speckled sea. In reality, this critter belongs to the cosmos -- it's a dying star surrounded by fluorescing gas and two very unusual rings.

"I am reminded of the jellyfish exhibition at the Monterey Bay Aquarium -- beautiful things floating in water, except this one is in space," said Edward (Ned) Wright, the principal investigator of the WISE mission at UCLA, and a co-author of a paper on the findings, reported in the Astronomical Journal.

The object, known as NGC 1514 and sometimes the "Crystal Ball" nebula, belongs to a class of objects called planetary nebulae, which form when dying stars toss off their outer layers of material. Ultraviolet light from a central star, or in this case a pair of stars, causes the gas to fluoresce with colorful light. The result is often beautiful -- these objects have been referred to as the butterflies of space.

NGC 1514 was discovered in 1790 by Sir William Herschel, who noted that its "shining fluid" meant that it could not be a faint cluster of stars, as originally suspected. Herschel had previously coined the term planetary nebulae to describe similar objects with circular, planet-like shapes.

Planetary nebulae with asymmetrical wings of nebulosity are common. But nothing like the newfound rings around NGC 1514 had been seen before. Astronomers say the rings are made of dust ejected by the dying pair of stars at the center of NGC 1514. This burst of dust collided with the walls of a cavity that was already cleared out by stellar winds, forming the rings.

"I just happened to look up one of my favorite objects in our WISE catalogue and was shocked to see these odd rings," said Michael Ressler, a member of the WISE science team at NASA's Jet Propulsion Laboratory in Pasadena, Calif., and lead author of the Astronomical Journal paper. Ressler first became acquainted with the object years ago while playing around with his amateur telescope on a desert camping trip. "It's funny how things come around full circle like this."

WISE was able to spot the rings for the first time because their dust is being heated and glows with the infrared light that WISE can detect. In visible-light images, the rings are hidden from view, overwhelmed by the brightly fluorescing clouds of gas.

"This object has been studied for more than 200 years, but WISE shows us it still has surprises," said Ressler.

Infrared light has been color-coded in the new WISE picture, such that blue represents light with a wavelength of 3.4 microns; turquoise is 4.6-micron light; green is 12-micron light; and red is 22-micron light. The dust rings stand out in orange. The greenish glow at the center is an inner shell of material, blown out more recently than an outer shell that is too faint to be seen in WISE's infrared view. The white dot in the middle is the central pair of stars, which are too close together for WISE to see separately.

Ressler says NGC 1514's structure, though it looks unique, is probably similar in overall geometry to other hour-glass nebulae, such as the Engraved Hourglass Nebula (http://hubblesite.org/newscenter/archive/releases/1996/07). The structure looks different in WISE's view because the rings are detectable only by their heat; they do not fluoresce at visible wavelengths, as do the rings in the other objects.

Serendipitous findings like this one are common in survey missions like WISE, which comb through the whole sky. WISE has been surveying the sky in infrared light since January 2010, cataloguing hundreds of millions of asteroids, stars and galaxies. In late September, after covering the sky about one-and-a-half times, it ran out of the frozen coolant needed to chill its longest-wavelength detectors. The mission, now called NEOWISE, is still scanning the skies with two of its infrared detectors, focusing primarily on comets and asteroids, including near-Earth objects, which are bodies whose orbits pass relatively close to Earth's orbit around the sun.

The WISE science team says that more oddballs like NGC 1514 are sure to turn up in the plethora of WISE data -- the first batch of which will be released to the astronomical community in spring 2011.

Other study authors are Martin Cohen of the Monterey Institute for Research in Astronomy, Marina, Calif.; Stefanie Wachter and Don Hoard of NASA's Spitzer Science Center at the California Institute of Technology in Pasadena; and Amy Mainzer of JPL.

JPL manages and operates the Wide-field Infrared Survey Explorer for NASA's Science Mission Directorate, Washington. The mission was competitively selected under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at Caltech.

For more information visit http://www.nasa.gov/mission_pages/WISE/news/wise20101117.html
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NASA's Chandra Finds Youngest Nearby Black Hole

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Astronomers using NASA's Chandra X-ray Observatory have found evidence of the youngest black hole known to exist in our cosmic neighborhood. The 30-year-old black hole provides a unique opportunity to watch this type of object develop from infancy.

The black hole could help scientists better understand how massive stars explode, which ones leave behind black holes or neutron stars, and the number of black holes in our galaxy and others.

The 30-year-old object is a remnant of SN 1979C, a supernova in the galaxy M100 approximately 50 million light years from Earth. Data from Chandra, NASA's Swift satellite, the European Space Agency's XMM-Newton and the German ROSAT observatory revealed a bright source of X-rays that has remained steady during observation from 1995 to 2007. This suggests the object is a black hole being fed either by material falling into it from the supernova or a binary companion.

"If our interpretation is correct, this is the nearest example where the birth of a black hole has been observed," said Daniel Patnaude of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. who led the study.

The scientists think SN 1979C, first discovered by an amateur astronomer in 1979, formed when a star about 20 times more massive than the sun collapsed. Many new black holes in the distant universe previously have been detected in the form of gamma-ray bursts (GRBs). However, SN 1979C is different because it is much closer and belongs to a class of supernovas unlikely to be associated with a GRB. Theory predicts most black holes in the universe should form when the core of a star collapses and a GRB is not produced.

"This may be the first time the common way of making a black hole has been observed," said co-author Abraham Loeb, also of the Harvard-Smithsonian Center for Astrophysics. "However, it is very difficult to detect this type of black hole birth because decades of X-ray observations are needed to make the case."

The idea of a black hole with an observed age of only about 30 years is consistent with recent theoretical work. In 2005, a theory was presented that the bright optical light of this supernova was powered by a jet from a black hole that was unable to penetrate the hydrogen envelope of the star to form a GRB. The results seen in the observations of SN 1979C fit this theory very well.

Although the evidence points to a newly formed black hole in SN 1979C, another intriguing possibility is that a young, rapidly spinning neutron star with a powerful wind of high energy particles could be responsible for the X-ray emission. This would make the object in SN 1979C the youngest and brightest example of such a "pulsar wind nebula" and the youngest known neutron star. The Crab pulsar, the best-known example of a bright pulsar wind nebula, is about 950 years old.

"It's very rewarding to see how the commitment of some of the most advanced telescopes in space, like Chandra, can help complete the story," said Jon Morse, head of the Astrophysics Division at NASA's Science Mission Directorate.

The results will appear in the New Astronomy journal in a paper by Patnaude, Loeb, and Christine Jones of the Harvard-Smithsonian Center for Astrophysics. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge.

For more information visit http://www.nasa.gov/mission_pages/chandra/news/H-10-299.html
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Oh Snap, NASA and LEGO Join Forces

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LEGO bricks aren't just for kids, and they aren't just for Earth, either.

Astronauts on board the International Space Station will build small model spacecraft and working objects in orbit and share the experience with schoolchildren watching on Earth.

The students will build some of the same things in their own classrooms and see firsthand how differently objects behave in space, where there is practically no gravity, compared to the familiar world of Earth.

The project is one of the first steps in a three-year partnership between NASA and the Denmark-based The LEGO Group , maker of the ubiquitous plastic bricks that have been covering children's playroom floors for decades.

"We're going to use the classroom of space, the International Space Station, to inspire the next generation," said Leland Melvin, associate administrator for NASA Education and a former astronaut. Melvin flew two shuttle flights, spending time at the station during both missions. He joined LEGO officials Nov. 1 at NASA's Kennedy Space Center in Florida to announce the partnership.

Two small LEGO shuttles are packed inside Discovery for the STS-133 launch to promote the new partnership. They are expected to stay in their lockers, but astronauts may pull them out during the mission if they have time, said Debbie Biggs, an education specialist for International Space Station National Lab Education Projects.

NASA's fundamental goal is to use the partnership to inspire children to learn about science, technical fields, engineering and math. Known as STEM education, the focus has been a priority for the agency throughout this year's "Summer of Innovation."

Stephan Turnipseed, president of LEGO Education North America, said LEGO is the right partner because the bricks encourage kids to develop their inner engineer.

"Children think with their hands," Turnipseed said.

Astronaut Dan Tani, a veteran shuttle flier and station resident, agreed.

"LEGO taught me a lot of things about how things are built, what makes sense in terms of structure," said Tani, who brought his daughter to the LEGO activity tent. "I don't think I'd have been as good an engineer if it had not been for things like LEGO and construction kinds of toys."

There were plenty of children who thought so, too. Visiting LEGO's activity tent at one of the launch viewing sites at Kennedy on Wednesday, kids took to 1 ton of bricks and specialized pieces with barely any instructions. They quickly constructed spacecraft of all shapes, some small with launch facilities, others large replicas of the space shuttle. Some made a run at imagining colonies on the moon or Mars.

"You can make anything you want," said Tanner, a nine-year-old who has been building LEGO sets for years.

Melvin and Turnipseed were delighted with the kids' enthusiasm. They even joined in the building.

"This is showing what happens when we give kids a challenge, give them a tool that allows them to express their response to that challenge, their ideas," Turnipseed said.

LEGO and NASA still are working on lesson plans for students that will coincide with the work the astronauts perform in space, Biggs said. Some of the plans may even have the students challenge the astronaut to see who can build something quicker.

Astronaut Cady Coleman, in training for a mission to the International Space Station later this year, is slated to be the first astronaut enlisted to build LEGO objects in space.

Space shuttle Endeavour will carry nine specialized kits to the station in February during the STS-134 mission. Working with them inside a see-through glove box so the small pieces don't get lost in the station, Coleman will assemble LEGO blocks into models and working machines.

She already is practicing with some of the kits with her son and even picking up tips from other kids.

Melvin said the LEGO partnership is crucial for NASA's education mission because the blocks invite children to think, basically, like engineers. After all, building with the toys means deciding what kind of shape to make, what combination of blocks together make that shape the best and what can the thing do when it's finished. They also come up with designs that will be stronger depending on how the bricks are aligned with each other.

LEGO also is releasing four kits to the public based on NASA spacecraft and missions. Rather than being a part of a line of science fiction or fantasy toy kits, though, the NASA sets are being marketed as part of the company's "CITY" line, which calls on kids to build things that are part of everyday life.

"We believe that space, that space exploration, the fact that we have satellites in the air, it is a part of everyday life," Turnipseed said. "The children get it, they understand the importance of what we're doing."

"Space is permeated into everything we do," Melvin said.

For more information visit http://www.nasa.gov/mission_pages/shuttle/behindscenes/lego.html
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Detailed Dark Matter Map Yields Clues to Galaxy Cluster Growth

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Astronomers using NASA's Hubble Space Telescope took advantage of a giant cosmic magnifying glass to create one of the sharpest and most detailed maps of dark matter in the universe. Dark matter is an invisible and unknown substance that makes up the bulk of the universe's mass.

The new dark matter observations may yield new insights into the role of dark energy in the universe's early formative years. The result suggests that galaxy clusters may have formed earlier than expected, before the push of dark energy inhibited their growth. A mysterious property of space, dark energy fights against the gravitational pull of dark matter. Dark energy pushes galaxies apart from one another by stretching the space between them, thereby suppressing the formation of giant structures called galaxy clusters. One way astronomers can probe this primeval tug-of-war is through mapping the distribution of dark matter in clusters.

A team led by Dan Coe at NASA's Jet Propulsion Laboratory in Pasadena, Calif., used Hubble's Advanced Camera for Surveys to chart the invisible matter in the massive galaxy cluster Abell 1689, located 2.2 billion light-years away. The cluster's gravity, the majority of which comes from dark matter, acts like a cosmic magnifying glass, bending and amplifying the light from distant galaxies behind it. This effect, called gravitational lensing, produces multiple, warped, and greatly magnified images of those galaxies, like the view in a funhouse mirror. By studying the distorted images, astronomers estimated the amount of dark matter within the cluster. If the cluster's gravity only came from the visible galaxies, the lensing distortions would be much weaker.

Based on their higher-resolution mass map, Coe and his collaborators confirm previous results showing that the core of Abell 1689 is much denser in dark matter than expected for a cluster of its size, based on computer simulations of structure growth. Abell 1689 joins a handful of other well-studied clusters found to have similarly dense cores. The finding is surprising, because the push of dark energy early in the universe's history would have stunted the growth of all galaxy clusters.

"Galaxy clusters, therefore, would had to have started forming billions of years earlier in order to build up to the numbers we see today," Coe explains. "At earlier times, the universe was smaller and more densely packed with dark matter. Abell 1689 appears to have been well fed at birth by the dense matter surrounding it in the early universe. The cluster has carried this bulk with it through its adult life to appear as we observe it today."

Mapping the Invisible

Abell 1689 is among the most powerful gravitational lensing clusters ever observed. Coe's observations, combined with previous studies, yielded 135 multiple images of 42 background galaxies.

"The lensed images are like a big puzzle," Coe says. "Here we have figured out, for the first time, a way to arrange the mass of Abell 1689 such that it lenses all of these background galaxies to their observed positions." Coe used this information to produce a higher-resolution map of the cluster's dark matter distribution than was possible before.

Coe teamed with mathematician Edward Fuselier, who, at the time, was at the United States Military Academy at West Point, to devise a new technique to calculate the new map. "Thanks, in large part, to Eddie's contributions, we have finally `cracked the code' of gravitational lensing. Other methods are based on making a series of guesses as to what the mass map is, and then astronomers find the one that best fits the data. Using our method, we can obtain, directly from the data, a mass map that gives a perfect fit."

Astronomers are planning to study more clusters to confirm the possible influence of dark energy. A major Hubble program that will analyze dark matter in gigantic galaxy clusters is the Cluster Lensing and Supernova survey with Hubble (CLASH). In this survey, the telescope will study 25 clusters for a total of one month over the next three years. The CLASH clusters were selected because of their strong X-ray emission, indicating they contain large quantities of hot gas. This abundance means the clusters are extremely massive. By observing these clusters, astronomers will map the dark matter distributions and look for more conclusive evidence of early cluster formation, and possibly early dark energy.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

For more information visit http://www.nasa.gov/mission_pages/hubble/science/dark-matter-map.html
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Saturn Then and Now: 30 Years Since Voyager Visit

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Ed Stone, project scientist for NASA's Voyager mission, remembers the first time he saw the kinks in one of Saturn's narrowest rings. It was the day the Voyager 1 spacecraft made its closest approach to the giant ringed planet, 30 years ago. Scientists were gathering in front of television monitors and in one another's offices every day during this heady period to pore over the bewildering images and other data streaming down to NASA's Jet Propulsion Laboratory in Pasadena, Calif.

Stone drew a crude sketch of this scalloped, multi-stranded ring, known as the F ring, in his notebook, but with no explanation next to it. The innumerable particles comprising the broad rings are in near-circular orbits about Saturn. So, it was a surprise to find that the F ring, discovered just a year before by NASA's Pioneer 11 spacecraft, had clumps and wayward kinks. What could have created such a pattern?

"It was clear Voyager was showing us something different at Saturn," said Stone, now based at the California Institute of Technology in Pasadena. "Over and over, the spacecraft revealed so many unexpected things that it often took days, months and even years to figure them out."

The F ring curiosity was only one of many strange phenomena discovered in the Voyager close encounters with Saturn, which occurred on Nov. 12, 1980, for Voyager 1, and Aug. 25, 1981, for Voyager 2. The Voyager encounters were responsible for finding six small moons and revealing the half-young, half-old terrain of Enceladus that had to point to some kind of geological activity.

Images from the two encounters also exposed individual storms roiling the planet's atmosphere, which did not show up at all in data from Earth-based telescopes. Scientists used Voyager data to resolve a debate about whether Titan had a thick or thin atmosphere, finding that Titan was shrouded in a thick haze of hydrocarbons in a nitrogen-rich atmosphere. The finding led scientists to predict there could be seas of liquid methane and ethane on Titan's surface.

"When I look back, I realize how little we actually knew about the solar system before Voyager," Stone added. "We discovered things we didn't know were there to be discovered, time after time."

In fact, the Voyager encounters sparked so many new questions that another spacecraft, NASA's Cassini, was sent to probe those mysteries. While Voyager 1 got to within about 126,000 kilometers (78,300 miles) above Saturn's cloud tops, and Voyager 2 approached as close as about 100,800 kilometers (62,600 miles), Cassini has dipped to this altitude and somewhat lower in its orbits around Saturn since 2004.

Because of Cassini's extended journey around Saturn, scientists have found explanations for many of the mysteries first seen by Voyager. Cassini has uncovered a mechanism to explain the new terrain on Enceladus – tiger stripe fissures with jets of water vapor and organic particles. It revealed that Titan indeed does have stable lakes of liquid hydrocarbons on its surface and showed just how similar to Earth that moon really is. Data from Cassini have also resolved how two small moons discovered by Voyager – Prometheus and Pandora – tug on the F ring to create its kinked shape and wakes that form snowballs.

"Cassini is indebted to Voyager for its many fascinating discoveries and for paving the way for Cassini," said Linda Spilker, Cassini project scientist at JPL, who started her career working on Voyager from 1977 to 1989. "On Cassini, we still compare our data to Voyager's and proudly build on Voyager's heritage."

But Voyager left a few mysteries that Cassini has not yet solved. For instance, scientists first spotted a hexagonal weather pattern when they stitched together Voyager images of Saturn's north pole. Cassini has obtained higher-resolution pictures of the hexagon – which tells scientists it's a remarkably stable wave in one of the jet streams that remains 30 years later – but scientists are still not sure what forces maintain the hexagon.

Even more perplexing are the somewhat wedge-shaped, transient clouds of tiny particles that Voyager discovered orbiting in Saturn's B ring. Scientists dubbed them "spokes" because they looked like bicycle spokes. Cassini scientists have been searching for them since the spacecraft first arrived. As Saturn approached equinox, and the sun's light hit the rings edge-on, the spokes did reappear in the outer part of Saturn's B ring. But Cassini scientists are still testing their theories of what might be causing these odd features.

"The fact that we still have mysteries today goes to show how much we still have to learn about our solar system," said Suzanne Dodd, Voyager's project manager, based at JPL. "Today, the Voyager spacecraft continue as pioneers traveling toward the edge of our solar system. We can't wait for the Voyager spacecraft to enter interstellar space – true outer space – and make more unexpected discoveries."

Voyager 1, which was launched on Sept. 5, 1977, is currently about 17 billion kilometers (11 billion miles) away from the sun. It is the most distant spacecraft. Voyager 2, which was launched on Aug. 20, 1977, is currently about 14 billion kilometers (9 billion miles) away from the sun.

The Voyagers were built by JPL, which continues to operate both spacecraft. Caltech manages JPL for NASA. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages Cassini for NASA. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL.

For more information visit http://www.nasa.gov/mission_pages/voyager/voyager20101111.html
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Cassini's CIRS Reveals Saturn Is on a Cosmic Dimmer Switch

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Like a cosmic light bulb on a dimmer switch, Saturn emitted gradually less energy each year from 2005 to 2009, according to observations by NASA’s Cassini spacecraft. But unlike an ordinary bulb, Saturn's southern hemisphere consistently emitted more energy than its northern one. On top of that, energy levels changed with the seasons and differed from the last time a spacecraft visited in the early 1980s. These never-before-seen trends came from an analysis of comprehensive data from the Composite Infrared Spectrometer (CIRS), an instrument built by NASA's Goddard Space Flight Center in Greenbelt, Md., as well as a comparison with earlier data from NASA's Voyager spacecraft. When combined with information about the energy coming to Saturn from the sun, the results could help scientists understand the nature of Saturn's internal heat source.

The findings were reported November 9 in the Journal of Geophysical Research-Planets by Liming Li of Cornell University in Ithaca, N.Y. (now at the University of Houston), and colleagues from several institutions, including Goddard and NASA's Jet Propulsion Laboratory in Pasadena Calif., which manages the Cassini mission. "The Cassini CIRS data are very valuable because they give us a nearly complete picture of Saturn," says Li. "This is the only single data set that provides so much information about this planet, and it's the first time that anybody has been able to study the power emitted by one of the giant planets in such detail."

The planets in our solar system lose energy in the form of heat radiation in wavelengths that are invisible to the human eye. The CIRS instrument picks up wavelengths in the thermal infrared region, which is beyond red light, where the wavelengths correspond to heat emission.

"In planetary science, we tend to think of planets as losing power evenly in all directions and at a steady rate," says Li. "Now we know Saturn is not doing that." (Power is the amount of energy emitted per unit of time.)

Instead, Saturn's flow of outgoing energy was lopsided, with its southern hemisphere giving off about one-sixth more energy than the northern one, Li explains. This effect matched Saturn's seasons: during those five Earth years, it was summer in the southern hemisphere and winter in the northern one. (A season on Saturn lasts about seven Earth years.) Like Earth, Saturn has these seasons because the planet is tilted on its axis, so one hemisphere receives more energy from the sun and experiences summer while the other receives less energy and is shrouded in winter. Saturn’s equinox, when the sun was directly over the equator, occurred in August 2009.

In the study, Saturn's seasons looked Earth-like in another way: in each hemisphere, its effective temperature, which characterizes its thermal emission to space, started to warm up or cool down as a change of season approached. Because Saturn's weather is variable and the atmosphere tends to retain heat (called heat inertia), the temperature changes in complicated ways throughout the atmosphere. "The effective temperature provides us a simple way to track the response of Saturn's atmosphere, as a system, to the seasonal changes," says Li. Cassini's observations in the northern hemisphere revealed that the effective temperature gradually dropped from 2005 to 2008 and then started to warm up again by 2009. In Saturn's southern hemisphere, the effective temperature cooled from 2005 to 2009, as the equinox started to approach.

The emitted energy for each hemisphere rose and fell along with the effective temperature. Even so, during this five-year period, the planet as a whole seemed to be slowly cooling down and emitting less energy.

To find out if similar changes were happening one Saturn year ago, the researchers looked at data collected by Voyager in 1980 and 1981. Like Cassini CIRS, Voyager recorded fluctuations in the energy emitted by the planet and in the effective temperature. But Voyager did not see the imbalance between the southern and northern hemispheres; instead, the two regions were much more consistent with each other.

Why wouldn't Voyager have seen the same summer-versus-winter difference between the two hemispheres? The amount of energy coming from the sun (called solar radiance), which drives weather and atmospheric temperatures, could have fluctuated from one Saturn year to the next. The patterns in Saturn's cloud cover and haze could have, too.

"It's reasonable to think that the changes in Saturn's emitted power are related to cloud cover," says Amy Simon-Miller, who heads the Planetary Systems Laboratory at Goddard and is a co-author on the paper. "As the amount of cloud cover changes, the amount of radiation escaping into space also changes. This might vary during a single season and from one Saturn year to another. But to fully understand what is happening on Saturn, we will need the other half of the picture: the amount of power being absorbed by the planet."

Li is finishing an analysis of the solar energy that came to Saturn, based on data sets collected by two other Cassini instruments, the imaging science subsystem and the visual and infrared mapping spectrometer. He agrees that this information is crucial because Saturn, like its fellow giant planets Jupiter and Neptune, is thought to have its own source of internal energy. (The fourth giant planet, Uranus, does not seem to have an internal source.) By studying the changes in Saturn's outgoing energy along with the changes in incoming solar energy, scientists can learn about the nature of the planet's internal energy source and whether it, too, changes over time.

"The differences between Saturn's northern and southern hemisphere and that fact that Voyager did not see the same asymmetry raise a very important question: does Saturn's internal heat vary with time?" says Li. "The answer will significantly deepen our understanding of the weather, internal structure and evolution of Saturn and the other giant planets."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency, and the Italian Space Agency. NASA's Jet Propulsion Laboratory, Pasadena, Calif., a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The composite infrared spectrometer team is based at NASA Goddard, where the instrument was built.

For more information visit http://www.nasa.gov/mission_pages/cassini/whycassini/dimmer-switch.html
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NASA's Fermi Telescope Finds Giant Structure in our Galaxy

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NASA's Fermi Gamma-ray Space Telescope has unveiled a previously unseen structure centered in the Milky Way. The feature spans 50,000 light-years and may be the remnant of an eruption from a supersized black hole at the center of our galaxy.

"What we see are two gamma-ray-emitting bubbles that extend 25,000 light-years north and south of the galactic center," said Doug Finkbeiner, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., who first recognized the feature. "We don't fully understand their nature or origin."

The structure spans more than half of the visible sky, from the constellation Virgo to the constellation Grus, and it may be millions of years old. A paper about the findings has been accepted for publication in The Astrophysical Journal.

Finkbeiner and his team discovered the bubbles by processing publicly available data from Fermi's Large Area Telescope (LAT). The LAT is the most sensitive and highest-resolution gamma-ray detector ever launched. Gamma rays are the highest-energy form of light.



Other astronomers studying gamma rays hadn't detected the bubbles partly because of a fog of gamma rays that appears throughout the sky. The fog happens when particles moving near the speed of light interact with light and interstellar gas in the Milky Way. The LAT team constantly refines models to uncover new gamma-ray sources obscured by this so-called diffuse emission. By using various estimates of the fog, Finkbeiner and his colleagues were able to isolate it from the LAT data and unveil the giant bubbles.

Scientists now are conducting more analyses to better understand how the never-before-seen structure was formed. The bubble emissions are much more energetic than the gamma-ray fog seen elsewhere in the Milky Way. The bubbles also appear to have well-defined edges. The structure's shape and emissions suggest it was formed as a result of a large and relatively rapid energy release - the source of which remains a mystery.

One possibility includes a particle jet from the supermassive black hole at the galactic center. In many other galaxies, astronomers see fast particle jets powered by matter falling toward a central black hole. While there is no evidence the Milky Way's black hole has such a jet today, it may have in the past. The bubbles also may have formed as a result of gas outflows from a burst of star formation, perhaps the one that produced many massive star clusters in the Milky Way's center several million years ago.

"In other galaxies, we see that starbursts can drive enormous gas outflows," said David Spergel, a scientist at Princeton University in New Jersey. "Whatever the energy source behind these huge bubbles may be, it is connected to many deep questions in astrophysics."

Hints of the bubbles appear in earlier spacecraft data. X-ray observations from the German-led Roentgen Satellite suggested subtle evidence for bubble edges close to the galactic center, or in the same orientation as the Milky Way. NASA's Wilkinson Microwave Anisotropy Probe detected an excess of radio signals at the position of the gamma-ray bubbles.

The Fermi LAT team also revealed Tuesday the instrument's best picture of the gamma-ray sky, the result of two years of data collection.

"Fermi scans the entire sky every three hours, and as the mission continues and our exposure deepens, we see the extreme universe in progressively greater detail," said Julie McEnery, Fermi project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.

NASA's Fermi is an astrophysics and particle physics partnership, developed in collaboration with the U.S. Department of Energy, with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.

"Since its launch in June 2008, Fermi repeatedly has proven itself to be a frontier facility, giving us new insights ranging from the nature of space-time to the first observations of a gamma-ray nova," said Jon Morse, Astrophysics Division director at NASA Headquarters in Washington. “These latest discoveries continue to demonstrate Fermi's outstanding performance.”

For more information visit http://www.nasa.gov/mission_pages/GLAST/news/new-structure.html
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Sunspot 1121 Unleashes X-ray Flare

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Active sunspot 1121 has unleashed one of the brightest x-ray solar flares in years, an M5.4-class eruption at 15:36 UT on Nov. 6th.

Radiation from the flare created a wave of ionization in Earth's upper atmosphere that altered the propagation of low-frequency radio waves. There was, however, no bright CME (plasma cloud) hurled in our direction, so the event is unlikely to produce auroras in the nights ahead.

This is the third M-flare in as many days from this increasingly active sunspot. So far none of the eruptions has been squarely Earth-directed, but this could change in the days ahead as the sun's rotation turns the active region toward our planet.

For more information visit http://www.nasa.gov/topics/solarsystem/sunearthsystem/main/News110610-Mflare.html
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NASA Extends TIMED Mission for Fourth Time

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Nine years after beginning its unprecedented look at the gateway between Earth's environment and space, not to mention collecting more data on the upper atmosphere than any other satellite, NASA’s Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) mission has been extended again.

Before the launch of TIMED, the mesosphere and lower thermosphere/ionosphere -- which help protect us from harmful solar radiation -- had been one of the least explored and understood regions of our environment.

"The middle part of the atmosphere was the part we kind of ignored," says John Sigwarth, the deputy project scientist for TIMED at NASA's Goddard Space Flight Center in Greenbelt, MD. "It's too high for balloons and too low for spacecraft. So the understanding of this middle atmosphere and its impact on the upper atmosphere has been tremendously increased due to TIMED."

The mission will now continue to study the influences of the sun and humans on our upper atmosphere. TIMED began its extended mission on Oct. 1, 2010, and will collect data through 2014. This is its fourth extension since the original 2-year mission began in January 2002. TIMED will focus this time on a problem that has long puzzled scientists: differentiating between human-induced and naturally occurring changes in this atmospheric region. This extension also allows TIMED to continue collecting data for longer than a full 11-year solar cycle.

"The sun is a variable star with an 11 year cycle," says Sigwarth. "So, if things change in the mesosphere, you don't know if it's because the sun changed or because human activity has caused the change. By getting back to the same point in the cycle, we can compare what it was like then, and what it's like now, and see if there's a long term trend of changes that's not solar related."

The key instrument performing this work is known as SABER (or Sounding of the Atmosphere using Broadband Emission Radiometry), built by Hampton University in Hampton, Va. SABER can remotely sense composition and temperature in the mesosphere.

In addition to checking for effects from humans, TIMED scientists would like to understand how cooling temperatures in the middle atmosphere are causing the thermosphere to become less dense and its composition to change. With fewer particles in the thermosphere, there’s less drag on satellites in space, which affects how long spacecraft and space debris stay in orbit – information that must be integrated into calculations for orbit models.

Composition changes in the thermosphere can also alter ionospheric structures that affect radio wave propagation and communications. To help with this is an instrument called SEE (or the Solar EUV Experiment) built at the University of Colo., which looks at the sun's x-rays and extreme ultraviolet rays to see how they impact our atmosphere.

TIMED will also collaborate with NASA’s newest eye on the Sun, the Solar Dynamics Observatory, which provides continuing solar radiation measurements and new views of how solar activity is created.

NASA's Goddard Space Flight Center in Greenbelt, Md. manages the TIMED mission for the agency's Science Mission Directorate at NASA Headquarters in Washington. The spacecraft was built by the Johns Hopkins University Applied Physics Laboratory in Laurel, Md.

For more information visit http://www.nasa.gov/topics/solarsystem/sunearthsystem/main/timed-extended.html
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Mars Rovers Mission Using Cloud Computing

9:02 PM Gabriella Brianna , Posted in , 0 Comments


The project team that built and operates the Mars rovers Spirit and Opportunity has become the first NASA space mission to use cloud computing for daily mission operations.

Cloud computing is a way to gain fast flexibility in computing ability by ordering capacity on demand -- as if from the clouds -- and paying only for what is used. NASA's Mars Exploration Rover Project moved to this strategy last week for the software and data that the rovers' flight team uses to develop daily plans for rover activities. NASA's Jet Propulsion Laboratory, Pasadena, Calif., which manages the project, gained confidence in cloud computing from experience with other uses of the technology, including public participation sites about Mars exploration.

"This is a change to thinking about computer capacity and data storage as a commodity like electricity, or even the money in your bank account," said JPL's John Callas, rover project manager. "You don't keep all your money in your wallet. Instead you go to a nearby ATM and get cash when you need it. Your money is safe, and the bank can hold as much or as little of the money as you want. Data is the same way: You don't need to have it on you all the time. It can be safely stored elsewhere and you can get it anytime via an Internet connection.

"When we need more computing capacity, we don't need to install more servers if we can rent more capacity from the cloud for just the time we need it. This way we don't waste electricity and air conditioning with servers idling waiting to be used, and we don't have to worry about hardware maintenance and operating system obsolescence."

Spirit and Opportunity landed on Mars in January 2004 for what were planned as three-month missions. Bonus, extended missions have continued for more than six years. Opportunity is currently active, requiring daily activity plans by a team of engineers at JPL, and scientists at many locations in North America and Europe. Spirit has been silent since March 2010 and is believed to be in a low-power hibernation mode for the Martian winter.

"The rover project is well suited for cloud computing," said Khawaja Shams, a JPL software engineer supporting the project. "It has a widespread user community acting collaboratively. Cloud enables us to deliver the data to each user from nearby locations for faster reaction time." Also, the unexpected longevity of the mission means the volume of data used has outgrown the systems originally planned for handling and sharing data, which makes the virtually limitless capacity of cloud computing attractive.

JPL collaborated with the cloud team of Amazon.com Inc., Seattle, to plan and implement the use of cloud computing in the Mars Exploration Rover Project's daily operations. JPL developed the rover project's activity-planning software, called Maestro.

"We have worked closely with multiple cloud vendors since 2007 to learn the best ways to gain the advantages of cloud computing," said Tomas Soderstrom, chief technology officer for the JPL Office of the Chief Information Officer. "To implement JPL CIO Jim Rinaldi's vision of renting instead of buying capacity, we pragmatically look past the hype about cloud computing to find the practical, cost-efficient real mission applications. The Mars Exploration Rover project's use of clouds is one example of this results-oriented partnership. More will follow."

In support of the federal Open Government Initiative, which increases public access to data collected by the federal government, JPL collaborated with the cloud team at Microsoft Corp., Redmond, Wash., to launch the "Be a Martian" website in November 2009. The site enables the public to participate as citizen scientists to improve Mars maps and take part in Mars research tasks.

For another early use of cloud computing, JPL worked with the cloud team at Google Inc., Mountain View, Calif. The Google cloud served a project in which JPL and computer science students at the University of California, San Diego, developed an educational application enabling fifth- and sixth-graders to tag labels onto images from Mars spacecraft.

In addition to establishing a private cloud and working with Amazon, Google and Microsoft, JPL has also collaborated with other vendors of public cloud computing. Soderstrom said, "We defined a 'cloud-oriented architecture' to use clouds as an extension of our own resources and to run the computing and storage where it is most appropriate for each application."

The extended missions of Spirit and Opportunity have provided a resource for testing innovations during an active space mission for possible use in future missions. New software uploads giving the rovers added autonomy have been one example, and cloud computing is another. JPL is currently building and testing NASA's next Mars rover, Curiosity, for launch in late 2011 in the Mars Science Laboratory mission. This rover will land on Mars in August 2012.

Shams said, "The experience we gain using cloud computing for planning Opportunity's activities may be valuable when Curiosity reaches Mars, too."

For more information visit http://www.nasa.gov/mission_pages/mer/news/mer20101102.html
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Using Planet Colors to Search for Alien Earths

9:11 PM Gabriella Brianna , Posted in , 0 Comments


Earth is invitingly blue. Mars is angry red. Venus is brilliant white. Astronomers have learned that a planet's "true colors" can reveal important details. For example, Mars is red because its soil contains rusty red stuff called iron oxide. And the famous tint of our planet, the "blue marble"? It's because the atmosphere scatters blue light rays more strongly than red ones. Therefore the atmosphere looks blue from above and below.

Planets around other stars probably exhibit a rainbow of colors every bit as diverse as those in our solar system. And astronomers would like to eventually harness color to learn more about exoplanets. Are they rocky or gaseous — or earthlike?

In a study recently accepted for publication in The Astrophysical Journal, a team led by NASA astronomer Lucy McFadden and UCLA graduate student Carolyn Crow describe a simple way to distinguish between the planets of our solar system based on color information. Earth, in particular, stands out clearly among the planets, like a blue jay in a flock of seagulls.

"The method we developed separates the planets out," Crow says. "It makes Earth look unique."

This suggests that someday, when we have the technology to gather light from individual exoplanets, astronomers could use color information to identify earthlike worlds. "Eventually, as telescopes get bigger, there will be the light-gathering power to look at the colors of planets around other stars," McFadden says. "Their colors will tell us which ones to study in more detail."

Earth the Exoplanet

The project began in 2008, when Crow teamed up with McFadden, her faculty mentor at the University of Maryland in College Park. McFadden currently heads university and post-doctoral programs at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

New color information about Earth, the moon, and Mars became available, thanks to NASA's Deep Impact spacecraft. En route to a planned encounter this November with Comet 103P/Hartley 2, Deep Impact observed Earth. The idea was to determine what our home looks like to alien astronomers and eventually use that insight to figure out how to spot earthlike worlds around other stars.

As Deep Impact cruised through space, its High Resolution Instrument (HRI) measured the intensity of Earth's light. HRI is an 11.8-inch (30 cm) telescope that feeds light through seven different color filters mounted on a revolving wheel. Each filter samples the incoming light at a different portion of the visible-light spectrum, from ultraviolet and blue to red and near-infrared. On May 28, 2008, Deep Impact even caught a glimpse of the moon's light as it crossed in front of Earth. Later, in 2009, HRI scoped Mars.

McFadden wondered what combination of color information from the filters would best distinguish Earth from the other planets and moons of the solar system. She recruited Crow to work on the project. Eight other researchers from NASA, the University of Maryland, the University of Washington (Seattle), and the Johns Hopkins University Applied Physics Lab also joined the team.

The Magic Mix

The Deep Impact color data covered Earth, the moon, and Mars. The relative amounts of light passing through the filters vary for each planet or moon, providing a kind of color fingerprint. To this the team added existing color information about Mercury, Venus, Jupiter, Saturn, Uranus, Neptune, and Saturn's moon Titan.

A simple side-by-side comparison of color data on all the major planets was a confusing mess. The team finally found a combination of three different filters — one in the blue, one in the green, and one in the red — that highlights the differences between the planets.

On a special "color-color" diagram the team created, the planets cluster into groups based on similarities in the wavelengths of sunlight that their surfaces and atmospheres reflect. The gas giants Jupiter and Saturn huddle in one corner, Uranus and Neptune in a different one. The rocky inner planets Mars, Venus, and Mercury cluster off in their own corner of "color space."

But Earth is the true loner in color space. Its uniqueness traces to two factors. One is the scattering of blue light by the atmosphere. This is called Rayleigh scattering, after the English scientist who discovered it.

The other reason Earth stands out in color space is because it does not absorb a lot of infrared light. That's because our atmosphere is low in infrared-absorbing gases like methane and ammonia, compared to the gas giant planets Jupiter and Saturn.

"It is Earth's atmosphere that dominates the colors of Earth," Crow says. "It's the scattering of light in the ultraviolet and the absence of absorption in the infrared."

Colorful Future

Someday, the three-filter approach may provide a rough "first cut" look at exoplanet surfaces and atmospheres. "There are some things we can tell from the colors but there are some things that we can't quite tell without additional information," Crow says.

For example, if an exoplanet shows a similar color fingerprint to Earth's, it would not necessarily mean that the planet has the blue skies and vast oceans of our home. But it would tell us to look at that planet more closely.

And that would be an important first step toward making sense of the colorful complexity of the 490 (and counting) alien planets already discovered, and the scores more on the way.

For more information visit http://www.nasa.gov/topics/universe/features/planet-colors.html
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