Cassini Finishes Sleigh Ride by Icy Moons

On the heels of a successful close flyby of Saturn's moon Enceladus, NASA's Cassini spacecraft is returning images of Enceladus and the nearby moon Dione.

Several pictures show Enceladus backlit, with the dark outline of the moon crowned by glowing jets from the south polar region. The images show several separate jets, or sets of jets, emanating from the fissures known as "tiger stripes." Scientists will use the images to pinpoint the jet source locations on the surface and learn more about their shape and variability.

The Enceladus flyby took Cassini within about 48 kilometers (30 miles) of the moon's northern hemisphere. Cassini's fields and particles instruments worked on searching for particles that may form a tenuous atmosphere around Enceladus. They also hope to learn whether those particles may be similar to the faint oxygen- and carbon-dioxide atmosphere detected recently around Rhea, another Saturnian moon.

The scientists were particularly interested in the Enceladus environment away from the jets emanating from the south polar region. Scientists also hope this flyby will help them understand the rate of micrometeoroid bombardment in the Saturn system and get at the age of Saturn's main rings.

This flyby of Enceladus, the 13th in Cassini's mission, took a similar path to the last Enceladus flyby on Nov. 30.

About eight hours before the Enceladus flyby, Cassini also swung past Dione at a distance of about 100,000 kilometers (62,000 miles). During that flyby, the spacecraft snapped clear, intriguing images of the bright, fractured region known as the "wispy terrain." These features are tectonic ridges and faults formed by geologic activity on the moon sometime in the past. Scientists will now be able to measure the depth and extent of them more accurately.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C.

For more information about the Cassini-Huygens mission, visit
http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini .

A Galaxy for Everyone

This collage of galaxies from NASA's Wide-Field Infrared Survey Explorer, or WISE, showcases the many "flavors" that galaxies come in, from star-studded spirals to bulging ellipticals to those paired with other companion galaxies. The WISE team put this collage together to celebrate the anniversary of the mission's launch on Dec. 14, 2009.

After launch and a one-month checkout period, WISE began mapping the sky in infrared light. By July of this year, the entire sky had been surveyed, detecting hundreds of millions of objects, including the galaxies pictured here. In October of this year, after scanning the sky about one-and–a-half times, the spacecraft ran out of its frozen coolant, as planned. With its two shortest-wavelength infrared detectors still operational, the mission continues to survey the sky, focusing primarily on asteroids and comets.

NGC 300 is seen in the image in the upper left panel. This is a textbook spiral galaxy. In fact, it is such a good representation of a spiral galaxy that astronomers have studied it in great detail to learn about the structure of all spirals in general. Infrared images like this one from WISE show astronomers where areas of gas and warm dust are concentrated -- features that cannot be seen in visible light. At about 39,000 light-years across, NGC 300 is only about 40 percent the size of the Milky Way galaxy.

The upper right image shows Messier 104, or M104, also known as the Sombrero galaxy. Although M104 is also classified as a spiral galaxy, it has a very different appearance than NGC 300. In part, this is because the dusty, star-forming spiral disk in M104 is seen nearly edge-on from our point of view. M104 also has a large, ball-shaped bulge component of older stars, seen here in blue.

The large, fuzzy grouping of stars at the center of the lower left panel is the galaxy Messier 60, or M60. This galaxy does not have a spiral disk, just a bulge, making it a massive elliptical galaxy. M60 is about 20 percent larger than our Milky Way galaxy, and lies in the Virgo cluster of galaxies.

The brighter, dense spot inside but off-center from the blue core of M60 is a separate spiral galaxy called NGC 4647. In addition, two different asteroids were caught crossing the field of view when WISE imaged this portion of the sky (seen as dotted green lines extending out from M60 at about the 2 o'clock and 8 o'clock positions).

The galaxy in the lower right panel is Messier 51, or NGC 5194, also frequently referred to as the Whirlpool galaxy. The Whirlpool is a "grand design" spiral galaxy. It is interacting with its smaller companion -- NGC 5195, a dwarf galaxy, which can be seen as a bright spot near the tip of the spiral arm extending up and to the right of the Whirlpool galaxy.

JPL manages and operates the Wide-field Infrared Survey Explorer for NASA's Science Mission Directorate, Washington. The principal investigator, Edward Wright, is at UCLA. 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 the California Institute of Technology in Pasadena. Caltech manages JPL for NASA. More information is online at http://www.nasa.gov/wise and http://wise.astro.ucla.edu and http://www.jpl.nasa.gov/wise .

Hot Plasma Explosions Inflate Saturn's Magnetic Field

A new analysis based on data from NASA's Cassini spacecraft finds a causal link between mysterious, periodic signals from Saturn's magnetic field and explosions of hot ionized gas, known as plasma, around the planet.

Scientists have found that enormous clouds of plasma periodically bloom around Saturn and move around the planet like an unbalanced load of laundry on spin cycle. The movement of this hot plasma produces a repeating signature "thump" in measurements of Saturn's rotating magnetic environment and helps to illustrate why scientists have had such a difficult time measuring the length of a day on Saturn.

"This is a breakthrough that may point us to the origin of the mysteriously changing periodicities that cloud the true rotation period of Saturn," said Pontus Brandt, the lead author on the paper and a Cassini team scientist based at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "The big question now is why these explosions occur periodically."
The data show how plasma injections, electrical currents and Saturn's magnetic field -- phenomena that are invisible to the human eye -- are partners in an intricate choreography. Periodic plasma explosions form islands of pressure that rotate around Saturn. The islands of pressure "inflate" the magnetic field.

A new animation showing the linked behavior is available at http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov .

The visualization shows how invisible hot plasma in Saturn's magnetosphere – the magnetic bubble around the planet -- explodes and distorts magnetic field lines in response to the pressure. Saturn's magnetosphere is not a perfect bubble because it is blown back by the force of the solar wind, which contains charged particles streaming off the sun.

The force of the solar wind stretches the magnetic field of the side of Saturn facing away from the sun into a so-called magnetotail. The collapse of the magnetotail appears to kick off a process that causes the hot plasma bursts, which in turn inflate the magnetic field in the inner magnetosphere.

Scientists are still investigating what causes Saturn's magnetotail to collapse, but there are strong indications that cold, dense plasma originally from Saturn's moon Enceladus rotates with Saturn. Centrifugal forces stretch the magnetic field until part of the tail snaps back.

The snapping back heats plasma around Saturn and the heated plasma becomes trapped in the magnetic field. It rotates around the planet in islands at the speed of about 100 kilometers per second (200,000 mph). In the same way that high and low pressure systems on Earth cause winds, the high pressures of space cause electrical currents. Currents cause magnetic field distortions.

A radio signal known as Saturn Kilometric Radiation, which scientists have used to estimate the length of a day on Saturn, is intimately linked to the behavior of Saturn's magnetic field. Because Saturn has no surface or fixed point to clock its rotation rate, scientists inferred the rotation rate from timing the peaks in this type of radio emission, which is assumed to surge with each rotation of a planet. This method has worked for Jupiter, but the Saturn signals have varied. Measurements from the early 1980s taken by NASA's Voyager spacecraft, data obtained in 2000 by the ESA/NASA Ulysses mission, and Cassini data from about 2003 to the present differ by a small, but significant degree. As a result, scientists are not sure how long a Saturn day is.

"What's important about this new work is that scientists are beginning to describe the global, causal relationships between some of the complex, invisible forces that shape the Saturn environment," said Marcia Burton, the Cassini fields and particles investigation scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "The new results still don't give us the length of a Saturn day, but they do give us important clues to begin figuring it out. The Saturn day length, or Saturn's rotation rate, is important for determining fundamental properties of Saturn, like the structure of its interior and the speed of its winds."

Plasma is invisible to the human eye. But the ion and neutral camera on Cassini's magnetospheric imaging instrument provides a three-dimensional view by detecting energetic neutral atoms emitted from the plasma clouds around Saturn. Energetic neutral atoms form when cold, neutral gas collides with electrically-charged particles in a cloud of plasma. The resulting particles are neutrally charged, so they are able to escape magnetic fields and zoom off into space. The emission of these particles often occurs in the magnetic fields surrounding planets.

By stringing together images obtained every half hour, scientists produced movies of plasma as it drifted around the planet. Scientists used these images to reconstruct the 3-D pressure produced by the plasma clouds, and supplemented those results with plasma pressures derived from the Cassini plasma spectrometer. Once scientists understood the pressure and its evolution, they could calculate the associated magnetic field perturbations along the Cassini flight path. The calculated field perturbation matched the observed magnetic field "thumps" perfectly, confirming the source of the field oscillations.

"We all know that changing rotation periods have been observed at pulsars, millions of light years from our solar system, and now we find that a similar phenomenon is observed right here at Saturn," said Tom Krimigis, principal investigator of the magnetospheric imaging instrument, also based at the Applied Physics Laboratory and the Academy of Athens, Greece. "With instruments right at the spot where it's happening, we can tell that plasma flows and complex current systems can mask the real rotation period of the central body. That's how observations in our solar system help us understand what is seen in distant astrophysical objects."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif. manages the mission for NASA's Science Mission Directorate, Washington, D.C. The magnetic imaging instrument team is based at the Johns Hopkins University Applied Physics Laboratory, Laurel, Md.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini .

Cassini Spots Potential Ice Volcano on Saturn Moon

NASA's Cassini spacecraft has found possible ice volcanoes on Saturn's moon Titan that are similar in shape to those on Earth that spew molten rock.

Topography and surface composition data have enabled scientists to make the best case yet in the outer solar system for an Earth-like volcano landform that erupts in ice. The results were presented today at the American Geophysical Union meeting in San Francisco.

"When we look at our new 3-D map of Sotra Facula on Titan, we are struck by its resemblance to volcanoes like Mt. Etna in Italy, Laki in Iceland and even some small volcanic cones and flows near my hometown of Flagstaff," said Randolph Kirk, who led the 3-D mapping work, and is a Cassini radar team member and geophysicist at the U.S. Geological Survey (USGS) Astrogeology Science Center in Flagstaff, Ariz.

Scientists have been debating for years whether ice volcanoes, also called cryovolcanoes, exist on ice-rich moons, and if they do, what their characteristics are. The working definition assumes some kind of subterranean geological activity warms the cold environment enough to melt part of the satellite's interior and sends slushy ice or other materials through an opening in the surface. Volcanoes on Jupiter's moon Io and Earth spew silicate lava.

Some cryovolcanoes bear little resemblance to terrestrial volcanoes, such as the tiger stripes at Saturn's moon Enceladus, where long fissures spray jets of water and icy particles that leave little trace on the surface. At other sites, eruption of denser materials might build up volcanic peaks or finger-like flows. But when such flows were spotted on Titan in the past, theories explained them as non-volcanic processes, such as rivers depositing sediment. At Sotra, however, cryovolcanism is the best explanation for two peaks more than 1,000 meters (3,000 feet) high with deep volcanic craters and finger-like flows.
"This is the very best evidence, by far, for volcanic topography anywhere documented on an icy satellite," said Jeffrey Kargel, a planetary scientist at the University of Arizona, Tucson. "It's possible the mountains are tectonic in origin, but the interpretation of cryovolcano is a much simpler, more consistent explanation."

Kirk and colleagues analyzed new Cassini radar images. His USGS group created the topographic map and 3-D flyover images of Sotra Facula. Data from Cassini's visual and infrared mapping spectrometer revealed the lobed flows had a composition different from the surrounding surface. Scientists have no evidence of current activity at Sotra, but they plan to monitor the area.

"Cryovolcanoes help explain the geological forces sculpting some of these exotic places in our solar system," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "At Titan, for instance, they explain how methane can be continually replenished in the atmosphere when the sun is constantly breaking that molecule down."

Cassini launched Oct. 15, 1997, and began orbiting Saturn in 2004. Saturn has more than 60 known moons, with Titan being the largest. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency (ASI). JPL manages the mission for NASA's Science Mission Directorate at the agency's Headquarters in Washington.

The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and ASI, working with team members from the U.S. and several European countries. The visual and infrared mapping spectrometer was built by JPL, with a major contribution by ASI. The visual and infrared mapping spectrometer science team is based at the University of Arizona, Tucson. JPL is a division of the California Institute of Technology in Pasadena.

For more information about the Cassini mission, visit: http://www.nasa.gov/cassini

Mexico Quake Studies Uncover Surprises for California

New technologies developed by NASA and other agencies are revealing surprising insights into a major earthquake that rocked parts of the American Southwest and Mexico in April, including increased potential for more large earthquakes in Southern California.

At the fall meeting of the American Geophysical Union in San Francisco, scientists from NASA and other agencies presented the latest research on the magnitude 7.2 El Mayor-Cucapah earthquake, that region's largest in nearly 120 years. Scientists have studied the earthquake's effects in unprecedented detail using data from GPS, advanced simulation tools and new remote sensing and image analysis techniques, including airborne light detection and ranging (LiDAR), satellite synthetic aperture radar and NASA's airborne Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR).

Among their findings:

-- The earthquake is among the most complex ever documented along the Pacific/North American tectonic plate boundary. The main shock activated segments of at least six faults, some unnamed or previously unrecognized. It triggered slip along faults north of the border as far as 165 kilometers (about 100 miles) away, including the San Andreas, San Jacinto, Imperial and Superstition Hills Faults, and many faults in California's Yuha Desert, some not previously mapped. Some of this slip was quiet, without detectable earthquakes. Activity was observed on several northwest-trending faults due for potentially large earthquakes.
-- The rupture's northern end in Southern California resembles the frayed end of a rope. The complex, 32-kilometer (20-mile) network of faults that slipped there during and after the earthquake-- many unnamed or previously unrecognized--reveals how the earthquake distributed strain.
-- Satellite radar, UAVSAR and GPS station data show additional slip along some of the Yuha Desert faults in the months after the main earthquake. Recent data from UAVSAR and satellite radar show this slip slowed and probably stopped in late summer or early fall.
-- Mexico's Sierra Cucapah mountains were, surprisingly, lowered, not raised, by the earthquake.
-- The main rupture jumped an 11-kilometer (7-mile) fault gap-more than twice that ever observed before.
-- UAVSAR and satellite radar reveal deep faulting that may be a buried continuation of Mexico's Laguna Salada Fault that largely fills the gap to California's Elsinore Fault. This could mean the fault system is capable of larger earthquakes. A connection had only been inferred before.
-- Analyses show a northward advance of strain after the main shock, including a pattern of triggered fault slip and increased seismicity. The July 7, 2010 magnitude 5.4 Collins Valley earthquake on the San Jacinto Fault may have been triggered by the main earthquake.
-- Forecasting methods in development suggest earthquakes triggered by the main shock changed hazard patterns, while experimental virtual reality scenarios show a substantial chance of a damaging earthquake north of Baja within three to 30 years of a Baja quake like the one in April.

"This earthquake is changing our understanding of earthquake processes along the Pacific/North American plate boundary, including earthquake physics, forecast modeling and regional faulting processes," said Professor John Fletcher of the Center for Scientific Research and Higher Education at Ensenada (CICESE), Baja Calif., Mexico. Fletcher led a multi-agency Mexico fault mapping effort that included the U.S. Geological Survey and California Geological Survey, among others.

UAVSAR, developed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., uses a technique called interferometric synthetic aperture radar to measure ground deformation over large areas to a precision of 0.1 to 0.5 centimeters (0.04 to 0.2 inches). A NASA Gulfstream III aircraft carrying the radar flew repeat GPS-guided passes over the California border region twice in 2009 and four times since the April earthquake, imaging it and continuing deformation since. Field mapping since April has demonstrated its ability to show remarkable surface rupture detail.

"UAVSAR is blanketing California's seismic danger zones about every six months to detect changes such as earthquakes or creeping faults," said JPL Geophysicist Eric Fielding. "The major earthquake in Baja last April is providing direct evidence that time-critical monitoring of hazardous faults is possible through NASA-funded technology."

"The accurate and detailed imagery derived from synthetic aperture radar, and in particular UAVSAR, produced a more complete picture of fault patterns, precisely guiding field geologists to remote areas of fault rupture and saving significant mapping time," said geologist Jerry Treiman of the California Geological Survey, Los Angeles.

JPL geophysicist Jay Parker said UAVSAR's precise images are adding realism to NASA's QuakeSim crustal models and forecasts. "Once we have these precise measurements of the changing landscape, we use them to deduce changes in stress that accelerate or delay the next major earthquakes, with the help of structural models and forecasting tools," he said.

For more on UAVSAR, see: http://uavsar.jpl.nasa.gov/ . For more on QuakeSim, see: http://quakesim.jpl.nasa.gov/ .

Cassini Spots Potential Ice Volcano on Saturn Moon

NASA's Cassini spacecraft has found possible ice volcanoes on Saturn's moon Titan that are similar in shape to those on Earth that spew molten rock.

Topography and surface composition data have enabled scientists to make the best case yet in the outer solar system for an Earth-like volcano landform that erupts in ice. The results were presented today at the American Geophysical Union meeting in San Francisco.

"When we look at our new 3-D map of Sotra Facula on Titan, we are struck by its resemblance to volcanoes like Mt. Etna in Italy, Laki in Iceland and even some small volcanic cones and flows near my hometown of Flagstaff," said Randolph Kirk, who led the 3-D mapping work, and is a Cassini radar team member and geophysicist at the U.S. Geological Survey (USGS) Astrogeology Science Center in Flagstaff, Ariz.

Scientists have been debating for years whether ice volcanoes, also called cryovolcanoes, exist on ice-rich moons, and if they do, what their characteristics are. The working definition assumes some kind of subterranean geological activity warms the cold environment enough to melt part of the satellite's interior and sends slushy ice or other materials through an opening in the surface. Volcanoes on Jupiter's moon Io and Earth spew silicate lava.

Some cryovolcanoes bear little resemblance to terrestrial volcanoes, such as the tiger stripes at Saturn's moon Enceladus, where long fissures spray jets of water and icy particles that leave little trace on the surface. At other sites, eruption of denser materials might build up volcanic peaks or finger-like flows. But when such flows were spotted on Titan in the past, theories explained them as non-volcanic processes, such as rivers depositing sediment. At Sotra, however, cryovolcanism is the best explanation for two peaks more than 1,000 meters (3,000 feet) high with deep volcanic craters and finger-like flows.

"This is the very best evidence, by far, for volcanic topography anywhere documented on an icy satellite," said Jeffrey Kargel, a planetary scientist at the University of Arizona, Tucson. "It's possible the mountains are tectonic in origin, but the interpretation of cryovolcano is a much simpler, more consistent explanation."

Kirk and colleagues analyzed new Cassini radar images. His USGS group created the topographic map and 3-D flyover images of Sotra Facula. Data from Cassini's visual and infrared mapping spectrometer revealed the lobed flows had a composition different from the surrounding surface. Scientists have no evidence of current activity at Sotra, but they plan to monitor the area.

"Cryovolcanoes help explain the geological forces sculpting some of these exotic places in our solar system," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "At Titan, for instance, they explain how methane can be continually replenished in the atmosphere when the sun is constantly breaking that molecule down."

Cassini launched Oct. 15, 1997, and began orbiting Saturn in 2004. Saturn has more than 60 known moons, with Titan being the largest. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency (ASI). JPL manages the mission for NASA's Science Mission Directorate at the agency's Headquarters in Washington.

The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and ASI, working with team members from the U.S. and several European countries. The visual and infrared mapping spectrometer was built by JPL, with a major contribution by ASI. The visual and infrared mapping spectrometer science team is based at the University of Arizona, Tucson. JPL is a division of the California Institute of Technology in Pasadena.

For more information about the Cassini mission, visit: http://www.nasa.gov/cassini

Students Bounce to the Top at JPL Competition

Magnolia Science Academy, Carson, Calif., led by mentor Yunis Karaca and student captain Robert Butler, picked up top honors at the annual Invention Challenge, held today, Dec. 10, at JPL. The winning device was appropriately named "Catapult. "

The event drew more than 260 students and teachers representing 16 schools from throughout Southern California. This year's challenge was to build a unique device capable of lifting an officially supplied ping-pong ball and cause the ball to touch and hold against a ceiling located 2 meters (about 6.6 feet) above ground. The winner completed this task in the fastest time.

A total of 19 student teams competed side-by-side with 15 teams that included JPL engineers. There was a tie for the winning JPL team between P.C. Chen and David Van Buren, while second place went to Richard Goldstein and third place to Bob Krylo.

The requirements this year: The devices had to be initiated by a single operation (cut a string, flick a switch, etc.), use safe energy sources, and could be no larger, prior to the start of the task than 50 centimeters (19.7 inches) high by 1.2 meters (about 3.9 feet) wide by 1.2 meters (about 3.9 feet) long. The devices had to be made from non-toxic and safe materials.

The rules change each year, but the results remain consistent: Students challenge themselves, solve problems and appreciate that math, science and engineering can be fun.

When asked for the key to their success, Yunis Karaca, the team's mentor replied, "We first brainstormed and then I let the kids use their imagination."

NASA's Spitzer Reveals First Carbon-Rich Planet

Astronomers have discovered that a huge, searing-hot planet orbiting another star is loaded with an unusual amount of carbon. The planet, a gas giant named WASP-12b, is the first carbon-rich world ever observed. The discovery was made using NASA's Spitzer Space Telescope, along with previously published ground-based observations.

"This planet reveals the astounding diversity of worlds out there," said Nikku Madhusudhan of the Massachusetts Institute of Technology, Cambridge, lead author of a report in the Dec. 9 issue of the journal Nature. "Carbon-rich planets would be exotic in every way -- formation, interiors and atmospheres."

It's possible that WASP-12b might harbor graphite, diamond, or even a more exotic form of carbon in its interior, beneath its gaseous layers. Astronomers don't currently have the technology to observe the cores of exoplanets, or planets orbiting stars beyond our sun, but their theories hint at these intriguing possibilities.

The research also supports theories that carbon-rich rocky planets much less massive than WASP-12b could exist around other stars. Our Earth has rocks like quartz and feldspar, which are made of silicon and oxygen plus other elements. A carbon-rich rocky planet could be a very different place.

"A carbon-dominated terrestrial world could have lots of pure carbon rocks, like diamond or graphite, as well as carbon compounds like tar," said Joseph Harrington of the University of Central Florida, in Orlando, who is the principal investigator of the research.

Carbon is a common component of planetary systems and a key ingredient of life on Earth. Astronomers often measure carbon-to-oxygen ratios to get an idea of a star's chemistry. Our sun has a carbon-to-oxygen ratio of about one to two, which means it has about half as much carbon as oxygen. None of the planets in our solar system is known to have more carbon than oxygen, or a ratio of one or greater. However, this ratio is unknown for Jupiter, Saturn, Uranus, and Neptune. Unlike WASP-12b, these planets harbor water -- the main oxygen carrier -- deep inside their atmospheres, making it hard to detect.


WASP-12b is the first planet ever to have its carbon-to-oxygen ratio measured at greater than one (the actual ratio is most likely between one and two). This means the planet has excess carbon, some of which is in the form of atmospheric methane.

"When the relative amount of carbon gets that high, it's as though you flip a switch, and everything changes," said Marc Kuchner, an astronomer at NASA Goddard Space Flight Center, Greenbelt, Md., who helped develop the theory of carbon-rich rocky planets but is not associated with the study. "If something like this had happened on Earth, your expensive engagement ring would be made of glass, which would be rare, and the mountains would all be made of diamonds."

Madhusudhan, Harrington and colleagues used Spitzer to observe WASP-12b as it slipped behind its star, in a technique known as secondary eclipse, which was pioneered for exoplanets by Spitzer. These data were combined with previously published observations taken from the ground with the Canada-France-Hawaii Telescope at Mauna Kea, Hawaii. Madhusudhan used the data to conduct a detailed atmospheric analysis, revealing chemicals such as methane and carbon monoxide in the planet's atmosphere.

WASP-12b derives its name from the consortium that found it, the Wide Angle Search for Planets. It is 1.4 times as massive as Jupiter and located roughly 1,200 light-years away from Earth. This blistering world whips around its star in a little over a day, with one side always facing the star. It is so close to its star that the star's gravity stretches the planet into an egg-like shape. What's more, the star's gravity is siphoning mass off the planet into a thin disk that orbits around with it.

The Spitzer data also reveal more information about WASP-12b's temperature. The world was already known to be one of the hottest exoplanets found so far; the new observations indicate that the side that faces the star is 2,600 Kelvin, or 4,200 degrees Fahrenheit. That's more than hot enough to melt steel.

Other authors of the paper are Kevin Stevenson, Sarah Nymeyer, Christopher Campo, Jasmina Blecic, Ryan Hardy, Nate Lust, Christopher Britt and William Bowman of University of Central Florida, Orlando; Peter Wheatley of the University of Warwick, United Kingdom; Drake Deming of NASA Goddard Space Flight Center, Greenbelt, Md.; David Anderson, Coel Hellier and Pierre Maxted of Keele University, United Kingdom; Andrew Collier-Cameron of the University of St. Andrews, United Kingdom; Leslie Hebb of Vanderbilt University, Nashville, Tenn.; Don Pollacco of Queen's University, United Kingdom; and Richard West of the University of Leicester, United Kingdom.

The Spitzer observations were made before it ran out of its liquid coolant in May 2009 and began its warm mission. NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA. For more information about Spitzer, visit http://spitzer.caltech.edu/ and http://www.nasa.gov/spitzer . More information about NASA’s search for exoplanets is at: http://planetquest.jpl.nasa.gov/ .

NASA Scientists Theorize Final Growth Spurt for Planets

A team of NASA-funded researchers has unveiled a new theory that contends planets gained the final portions of their mass from a limited number of large comet or asteroid impacts more than 4.5 billion years ago. These impacts added less than one percent of the planets' mass.

Scientists hope the research not only will provide a better historical picture of the birth and evolution of Earth, the moon and Mars, but also allow researchers to better explore what happened in our solar system's beginning and middle stages of planet formation.

“No one has a model of precisely what happened at the end of planet formation—we’ve had a broad idea—but variables such as impactor size, the approximate timing of the impacts, and how they affect the evolution of the planets are unknown,” said William Bottke, principal investigator from the Southwest Research Institute (SWRI) in Boulder, Colo. “This research hopefully provides better insights into the early stages of planet formation.”

The team used numerical models, lunar samples returned by Apollo astronauts and meteorites believed to be from Mars to develop its findings. The scientists examined the abundances of elements such as gold and platinum in the mantles, or layers beneath the crust, of Earth, the moon and Mars. Consistent with previous studies, they concluded the elements were added by a process called late accretion during a planet's final growth spurt.

"These impactors probably represent the largest objects to hit Earth since the giant impact that formed our moon," Bottke said. “They also may be responsible for the accessible abundance of gold, platinum, palladium, and other important metals used by our society today in items ranging from jewelry to our cars’ catalytic convertors.”

The results indicate the largest Earth impactor was between 1,500 - 2,000 miles in diameter, roughly the size of Pluto. Because it is smaller than Earth, the moon avoided such enormous projectiles and was only hit by impactors 150 - 200 miles wide. These impacts may have played important roles in the evolution of both worlds. For example, the projectiles that struck Earth may have modified the orientation of its spin axis by 10 degrees, while those that hit the moon may have delivered water to its mantle.

"Keep in mind that while the idea the Earth-moon system owes its existence to a single, random event was initially viewed as radical, it is now believed that large impacts were commonplace during the final stages of planet formation,’ Bottke said. “Our new results provide additional evidence that the effects of large impacts did not end with the moon-forming event."

The paper, "Stochastic Late Accretion to the Earth, Moon, and Mars," was published in the Dec. 9 issue of Science. It was written by Bottke and David Nesvorny of SWRI; Richard J. Walker of the University of Maryland; James Day of the University of Maryland and Scripps Institution of Oceanography, University of California, San Diego; and Linda Elkins-Tanton of the Massachusetts Institute of Technology. The research is funded by the NASA Lunar Science Institute (NLSI) at the agency's Ames Research Center in Moffett Field, Calif.

The NLSI is a virtual organization that enables collaborative, interdisciplinary research in support of NASA lunar science programs. The institute uses technology to bring scientists together around the world and comprises competitively selected U.S. teams and several international partners. NASA's Science Mission Directorate and the Exploration Systems Mission Directorate at the agency's Headquarters in Washington, funds the institute, which is managed by a central office at Ames.

For more information on NLSI, visit:

http://lunarscience.nasa.gov

Site List Narrows For NASA's Next Mars Landing

Four intriguing places on Mars have risen to the final round as NASA selects a landing site for its next Mars mission, the Mars Science Laboratory.

The agency had a wider range of possible landing sites to choose from than for any previous mission, thanks to the Mars Science Laboratory's advanced technologies, and the highly capable orbiters helping this mission identify scientifically compelling places to explore.

Mars Science Laboratory project leaders at NASA's Jet Propulsion Laboratory, Pasadena, Calif., chose the four this month, after seeking input from international Mars experts and from engineers working on the landing system and rover capabilities.

The sites, alphabetically, are: Eberswalde, where an ancient river deposited a delta in a possible lake; Gale, with a mountain of stacked layers including clays and sulfates; Holden, a crater containing alluvial fans, flood deposits, possible lake beds and clay-rich deposits; and Mawrth, which shows exposed layers containing at least two types of clay.

"All four of these sites would be great places to use our roving laboratory to study the processes and history of early Martian environments and whether any of these environments were capable of supporting microbial life and its preservation as biosignatures," said John Grotzinger of the California Institute of Technology, Pasadena. He is the project scientist for the Mars Science Laboratory.

The mission's capabilities for landing more precisely than ever before and for generating electricity without reliance on sunshine have made landing sites eligible that would not have been acceptable for past Mars missions. During the past two years, multiple observations of dozens of candidate sites by NASA's Mars Reconnaissance Orbiter have augmented data from earlier orbiters for evaluating sites' scientific attractions and engineering risks.

JPL is assembling and testing the Mars Science Laboratory spacecraft for launch in fall 2009. Paring the landing-site list to four finalists allows the team to focus further on evaluating the sites and planning the navigation. The mission plan calls for the rover to spend a full Mars year (23 months) examining the environment with a diverse payload of tools.

After evaluating additional Mars orbiter observations of the four sites, NASA will hold a fourth science workshop about the candidates in the spring and plans to choose a final site next summer. Three previous landing-site science workshops for Mars Science Laboratory, in 2006, 2007 and two months ago, drew participation of more than 100 Mars scientists and presentations about more than 30 sites. The four sites rated highest by participants in the latest workshop were the same ones chosen by mission leaders after a subsequent round of safety evaluations and analysis of terrain for rover driving. One site, Gale, had been a favorite of scientists considering 2004 landing sites for NASA's Spirit and Opportunity rovers, but was ruled out as too hazardous for the capabilities of those spacecraft.

"Landing on Mars always is a risky balance between science and engineering. The safest sites are flat, but the spectacular geology is generally where there are ups and downs, such as hills and canyons. That's why we have engineered this spacecraft to make more sites qualify as safe," said JPL's Michael Watkins, mission manager for the Mars Science Laboratory. "This will be the first spacecraft that can adjust its course as it descends through the Martian atmosphere, responding to variability in the atmosphere. This ability to land in much smaller areas than previous missions, plus capabilities to land at higher elevations and drive farther, allows us consider more places the scientists want to explore."

For their Mars landings in 2004, Spirit and Opportunity needed safe target areas about 70 kilometers (about 40 miles) long. Mars Science Laboratory is designed to hit a target area roughly 20 kilometers (12 miles) in diameter. Also, a new "skycrane" technology to lower the rover on a tether for the final touchdown can accommodate more slope than the airbag method used for Spirit and Opportunity. In addition, a radioisotope power supply, like that used by Mars Viking landers in the 1970s, will enable year-round operation farther from the equator than the solar power systems of more recent missions.

Gale is near the equator, Eberswalde and Holden are farther south, and Mawrth is in the north.

As a clay-bearing site where a river once flowed into a lake, Eberswalde Crater offers a chance to use knowledge that oil industry geologists have accumulated about locations of the most promising parts of a delta to look for any concentrations of carbon chemistry that is crucial to life.

The mountain inside Gale Crater could provide a route for the rover to drive up a 5-kilometer (3-mile) sequence of layers, studying a transition from environments that produced clay deposits near the bottom to later environments that produced sulfate deposits partway up.

Running water once carved gullies and deposited sediments as alluvial fans and catastrophic flood deposits in Holden Crater, a site that may also present the chance to evaluate layers deposited in a lake. Exploration of key features within this target area would require drives to the edge of a broad valley, and then down into the valley.

Mawrth Valley is an apparent flood channel near the edge of vast Martian highlands. It holds different types of clays in clearly layered context, offering an opportunity for studying the changes in wet conditions that produced or altered the clays. The clay signatures are stronger than at the other sites, and this is the only one of the four for which the science target is within the landing area, not nearby.

JPL, a division of the California Institute of Technology, Pasadena, manages the Mars Science Laboratory for the NASA Science Mission Directorate, Washington. For additional information about the mission, see http://mars.jpl.nasa.gov/msl.

Mars Rover Construction Webcam Tops Million Viewers

More than one million people have watched assembly and testing of NASA's next Mars rover via a live webcam since it went online in October.

NASA's Mars Science Laboratory, also known as the Curiosity rover, is being tested and assembled in a clean room at the agency's Jet Propulsion Laboratory in Pasadena, Calif. The webcam, affectionately dubbed "Curiosity Cam," shows engineers and technicians clad in head-to-toe white smocks working on the rover.

Metrics from the webcam's hosting platform, Ustream, showed more than one million unique viewers spent more than 400,000 hours watching Curiosity Cam between Oct. 21 and Nov. 23. There have been more than 2.3 million viewer sessions.

The camera is mounted in the viewing gallery of the Spacecraft Assembly Facility at JPL. While the gallery is a regular stop on JPL's public tour, Curiosity Cam allows visitors from around the world to see NASA engineers at work without traveling to Pasadena.

Viewers from Chile, Japan, Turkey, Spain, Mexico and the United Kingdom have sent good wishes and asked questions in the chat box that accompanies the Curiosity Cam webstream. At scheduled times, viewers can interact with each other and JPL staff. The chat schedule is updated weekdays at http://www.ustream.tv/nasajpl.

Months of assembly and testing remain before the car-sized rover is ready for launch from Cape Canaveral, Fla. The rover and spacecraft components will ship to NASA's Kennedy Space Center in Florida next spring. The launch will occur between Nov. 25 and Dec. 18, 2011. Curiosity will arrive on Mars in August 2012.

The rover is one of the most technologically challenging interplanetary missions ever designed. Curiosity is engineered to drive longer distances over rougher terrain than previous Mars rovers. It will carry a science payload 10 times the mass of instruments on NASA's Spirit and Opportunity rovers. Curiosity will investigate whether the landing region had environments favorable for supporting microbial life. It will also look for environments that have been favorable for preserving evidence about whether life existed

NASA Aids in Characterizing Super-Earth Atmosphere

A team of astronomers, including two NASA Sagan Fellows, has made the first characterizations of a super-Earth's atmosphere, by using a ground-based telescope.

A super-Earth is a planet up to three times the size of Earth and weighing up to 10 times as much. The findings, reported in the Dec. 2 issue of the journal Nature, are a significant milestone toward eventually being able to probe the atmospheres of Earth-like planets for signs of life.

The team determined the planet, GJ 1214b, is either blanketed with a thin layer of water steam or surrounded by a thick layer of high clouds. If the former, the planet itself would have an icy composition. If the latter, the planet would be rocky or similar to the composition of Neptune, though much smaller.

"This is the first super-Earth known to have an atmosphere," said Jacob Bean, a NASA Sagan Fellow and astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. "But even with these new measurements, we can't say yet what that atmosphere is made of. This world is being very shy and veiling its true nature from us."

GJ 1214b, first discovered in December 2009, is 2.7 times the size of Earth and 6.5 times as massive. Previous observations of the planet's size and mass demonstrated it has a low density for its size, leading astronomers to conclude the planet is some kind of solid body with an atmosphere.

The planet orbits close to its dim star, at a distance of 0.014 astronomical units. An astronomical unit is the distance between Earth and the sun, approximately 93 million miles. GJ 1214b circles too close to its star to be habitable by any life forms.

Bean and his team observed infrared light as the planet crossed in front of its star. During such transits, the star's light filters through the atmosphere. Gases absorb the starlight at particular wavelengths, leaving behind chemical fingerprints detectable from Earth. This same type of technique has been used to study the atmospheres of distant "hot Jupiters," or Jupiter-like planets orbiting close to their stars, and found gases like hydrogen, methane and sodium vapor.

In the case of the super-Earth, no chemical fingerprints were detected; however, this doesn't mean there are no chemicals present. Instead, this information ruled out some possibilities for GJ 1214b's atmosphere, and narrowed the scope to either an atmosphere of water steam or high clouds. Astronomers believe it's more likely the atmosphere is too thin around the planet to let enough light filter through and reveal chemical fingerprints.

"A steamy atmosphere would have to be very dense – about one-fifth water vapor by volume -- compared to our Earth, with an atmosphere that's four-fifths nitrogen and one-fifth oxygen with only a touch of water vapor," Bean said. "During the next year, we should have some solid answers about what this planet is truly like."

The team, which included Bean's co-authors -- Eliza Miller-Ricci Kempton, a NASA Sagan Fellow at the University of California in Santa Cruz, and Derek Homeier of the Institute for Astrophysics in Gottingen, Germany -- examined GJ 1214b using the ground-based Very Large Telescope at Paranal Observatory in Chile.

"This is an important step forward, narrowing our understanding of the atmosphere of this planet," said NASA Exoplanet Exploration Program Scientist Douglas Hudgins at NASA Headquarters in Washington. "Bizarre worlds like this make exoplanet science one of the most compelling areas in astrophysics today."

The Sagan Fellowship Program is administered by the NASA Exoplanet Science Institute at the California Institute of Technology in Pasadena. Its purpose is to advance the scientific and technical goals of NASA's Exoplanet Exploration Program. The program is managed for NASA by the Jet Propulsion Laboratory in Pasadena, Calif. Caltech manages JPL for NASA.

Cassini Finds Warm Cracks on Enceladus

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.

The new images are available at: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov.

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.

Cassini Returns Images of Bright Jets at Enceladus

NASA's Cassini spacecraft successfully dipped near the surface of Saturn's moon Enceladus on Nov. 30.

NASA's Cassini spacecraft successfully dipped near the surface of Saturn's moon Enceladus on Nov. 30. Though Cassini's closest approach took it to within about 48 kilometers (30 miles) of the moon's northern hemisphere, the spacecraft also captured shadowy images of the tortured south polar terrain and the brilliant jets that spray out from it.

Many of the raw images feature darkened terrain because winter has descended upon the southern hemisphere of Enceladus. But sunlight behind the moon backlights the jets of water vapor and icy particles. In some images, the jets line up in rows, forming curtains of spray.

The new raw images can be seen at http://saturn.jpl.nasa.gov/photos/raw/ .

The Enceladus flyby was the 12th of Cassini's mission, with the spacecraft swooping down around 61 degrees north latitude. This encounter and its twin three weeks later at the same altitude and latitude, are the closest Cassini will come to the northern hemisphere surface of Enceladus during the extended Solstice mission. (Cassini's closest-ever approach to Enceladus occurred in October 2008, when the spacecraft dipped to an altitude of 25 kilometers, or 16 miles.)

Among the observations Cassini made during this Enceladus flyby, the radio science subsystem collected gravity measurements to understand the moon's interior structure, and the fields and particles instruments sampled the charged particle environment around the moon.

About two days before the Enceladus flyby, Cassini also passed the sponge-like moon Hyperion, beaming back intriguing images of the craters on its surface. The flyby, at 72,000 kilometers (45,000 miles) in altitude, was one of the closest approaches to Hyperion that Cassini has made.

Scientists are still working to analyze the data and images collected during the flybys.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory manages the project for NASA's Science Mission Directorate in Washington. The Cassini orbiter was designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

NASA Aids in Characterizing Super-Earth Atmosphere

A team of astronomers, including two NASA Sagan Fellows, has made the first characterizations of a super-Earth's atmosphere, by using a ground-based telescope. A super-Earth is a planet up to three times the size of Earth and weighing up to 10 times as much. The findings, reported in the Dec. 2 issue of the journal Nature, are a significant milestone toward eventually being able to probe the atmospheres of Earth-like planets for signs of life.

The team determined the planet, GJ 1214b, is either blanketed with a thin layer of water steam or surrounded by a thick layer of high clouds. If the former, the planet itself would have an icy composition. If the latter, the planet would be rocky or similar to the composition of Neptune, though much smaller.

"This is the first super-Earth known to have an atmosphere," said Jacob Bean, a NASA Sagan Fellow and astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. "But even with these new measurements, we can't say yet what that atmosphere is made of. This world is being very shy and veiling its true nature from us."

GJ 1214b, first discovered in December 2009, is 2.7 times the size of Earth and 6.5 times as massive. Previous observations of the planet's size and mass demonstrated it has a low density for its size, leading astronomers to conclude the planet is some kind of solid body with an atmosphere.

The planet orbits close to its dim star, at a distance of 0.014 astronomical units. An astronomical unit is the distance between Earth and the sun, approximately 93 million miles. GJ 1214b circles too close to its star to be habitable by any life forms.

Bean and his team observed infrared light as the planet crossed in front of its star. During such transits, the star's light filters through the atmosphere. Gases absorb the starlight at particular wavelengths, leaving behind chemical fingerprints detectable from Earth. This same type of technique has been used to study the atmospheres of distant "hot Jupiters," or Jupiter-like planets orbiting close to their stars, and found gases like hydrogen, methane and sodium vapor.

In the case of the super-Earth, no chemical fingerprints were detected; however, this doesn't mean there are no chemicals present. Instead, this information ruled out some possibilities for GJ 1214b's atmosphere, and narrowed the scope to either an atmosphere of water steam or high clouds. Astronomers believe it's more likely the atmosphere is too thin around the planet to let enough light filter through and reveal chemical fingerprints.

"A steamy atmosphere would have to be very dense – about one-fifth water vapor by volume -- compared to our Earth, with an atmosphere that's four-fifths nitrogen and one-fifth oxygen with only a touch of water vapor," Bean said. "During the next year, we should have some solid answers about what this planet is truly like."

The team, which included Bean's co-authors -- Eliza Miller-Ricci Kempton, a NASA Sagan Fellow at the University of California in Santa Cruz, and Derek Homeier of the Institute for Astrophysics in Gottingen, Germany -- examined GJ 1214b using the ground-based Very Large Telescope at Paranal Observatory in Chile.

"This is an important step forward, narrowing our understanding of the atmosphere of this planet," said NASA Exoplanet Exploration Program Scientist Douglas Hudgins at NASA Headquarters in Washington. "Bizarre worlds like this make exoplanet science one of the most compelling areas in astrophysics today."

The Sagan Fellowship Program is administered by the NASA Exoplanet Science Institute at the California Institute of Technology in Pasadena. Its purpose is to advance the scientific and technical goals of NASA's Exoplanet Exploration Program. The program is managed for NASA by the Jet Propulsion Laboratory in Pasadena, Calif. Caltech manages JPL for NASA.

Cassini Finds Warm Cracks on Enceladus

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.

The new images are available at: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov.

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

Spain Supplies Weather Station for Next Mars Rover

The first instrument from Spain for a mission to Mars will provide daily weather reports from the Red Planet. Expect extremes.

Major goals for NASA's Mars Science Laboratory include assessing the modern environment in its landing area, as well as clues to environments billions of years ago. The environment station from Spain will fill a central role in studying modern conditions by measuring daily and seasonal changes.

The Rover Environmental Monitoring Station, or REMS, is one of 10 instruments in the mission's science payload. REMS uses sensors on the mast, on the deck and inside the body of the mission's car-size rover, Curiosity. Spain's Ministry of Science and Innovation and Spain's Center for Industrial Technology Development supplied the instrument. Components were installed on Curiosity in September and are being tested at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

While most of Curiosity's electronics are sheltered for some protection from the Martian environment, the team that developed and built the environmental station needed to fashion external sensors that could tolerate the temperature extremes that some of them would be monitoring.

"That was our biggest engineering challenge," said REMS Principal Investigator Javier Gómez-Elvira, an aeronautical engineer with the Centro de Astrobiología, Madrid, Spain. "The sensors will get very cold and go through great changes in temperature every day." The Center for Astrobiology is affiliated with the Spanish National Research Council and the National Institute for Aerospace Technology.

The air temperature around the rover mast will likely drop to about minus 130 degrees Celsius (about minus 202 degrees Fahrenheit) some winter nights and climb to about minus 50 C (about minus 60 F) by 12 hours later. On warmer days, afternoon air temperatures could reach a balmy 10 to 30 C (50 to 86 F), depending on which landing site is selected.

Other challenges have included accounting for how the rover itself perturbs air movement, and keeping the entire weather station's mass to just 1.3 kilograms (2.9 pounds).

The instrument will record wind speed, wind direction, air pressure, relative humidity, air temperature and ground temperature, plus one variable that has not been measured by any previous weather station on the surface of Mars: ultraviolet radiation. Operational plans call for taking measurements for five minutes every hour of the 23-month-long mission. Twenty-three months is equal to approximately one Martian year.

Monitoring ground temperature and ultraviolet radiation along with other weather data will contribute to understanding the Martian climate and will aid the mission's assessment of whether the current environment around the rover has conditions favorable for microbial life.

"It is important to know the temperature and humidity right at ground level," said Gómez-Elvira. Humidity at the landing sites will be extremely low, but knowing daily humidity cycles at ground level could help researchers understand the interaction of water vapor between the soil and the atmosphere. If the environment supports, or ever supported, any underground microbes, that interaction could be key.

Ultraviolet radiation can also affect habitability. For example, germ-killing ultraviolet lamps are commonly used to help maintain sterile conditions for medical and research equipment. The ultraviolet sensor Curiosity's deck measures six different wavelength bands in the ultraviolet portion of the spectrum, including wavelengths also monitored from above by NASA's Mars Reconnaissance Orbiter.

The weather station will help extend years of synergy between missions that study Mars from orbit and missions on the surface.

"We will gain information about whether local conditions are favorable for habitability, and we will also contribute to understanding the global atmosphere of Mars," said Gómez-Elvira. "The circulation models of the Mars atmosphere are based mainly on observations by orbiters. Our measurements will provide a way to verify and improve the models."

For example, significant fractions of the Martian atmosphere freeze onto the ground as a south polar carbon-dioxide ice cap during southern winter and as a north polar carbon-dioxide ice cap in northern winter, returning to the atmosphere in each hemisphere's spring. At Curiosity's landing site far from either pole, REMS will check whether seasonal patterns of changing air pressure fit the existing models for effects of the coming and going of polar carbon-dioxide ice.

The sensor for air pressure, developed for REMS by the Finnish Meteorological Institute, uses a dust-shielded opening on Curiosity's deck. The most conspicuous components of the weather station are two fingers extending horizontally from partway up the rover's remote-sensing mast.

Each of these two REMS mini-booms holds three electronic sensors for detecting air movement in three dimensions. Placement of the booms at an angle of 120 degrees from each other enables calculating the velocity of wind without worrying about the main mast blocking the wind. One mini-boom also holds the humidity sensor; the other a set of directional infrared sensors for measuring ground temperature.

To develop REMS and prepare for analyzing the data it will provide, Spain has assembled a team of about 40 researchers -- engineers and scientists. The team plans to post daily Mars weather reports online.

Cassini Back to Normal, Ready for Enceladus

NASA's Cassini spacecraft resumed normal operations today, Nov. 24. All science instruments have been turned back on, the spacecraft is properly configured and Cassini is in good health. Mission managers expect to get a full stream of data during next week's flyby of the Saturnian moon Enceladus.

Cassini went into safe mode on Nov. 2, when one bit flipped in the onboard command and data subsystem computer. The bit flip prevented the computer from registering an important instruction, and the spacecraft, as programmed, went into the standby mode.

Engineers have traced the steps taken by the computer during that time and have determined that all spacecraft responses were proper, but still do not know why the bit flipped.

The flyby on Nov. 30 will bring Cassini to within about 48 kilometers (30 miles) of the surface of Enceladus. At 61 degrees north latitude, this encounter and its twin three weeks later at the same altitude and latitude, are the closest.

Cassini will come to the northern hemisphere surface of Enceladus during the extended Solstice mission. (Cassini's closest-ever approach to the surface occurred in October 2008, when it dipped to an altitude of 25 kilometers, or 16 miles.)

During the closest part of the Nov. 30 flyby, Cassini's radio science subsystem will make gravity measurements. The results will be compared with those from an earlier flyby of the Enceladus south pole to understand the moon's interior structure better.

Cassini's fields and particles instruments will sample the charged particle environment around Enceladus. Other instruments will capture images in visible light and other parts of the light spectrum after Cassini makes its closest approach.

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, D.C.

More Cassini information is available at http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov.

NASA Funds High School Student Robotics Program

NASA is providing up to $20 million over the next five years to support a national program to inspire student interest in science, technology and mathematics with a focus on robotic technology.

The funding is part of a cooperative agreement with the Foundation for Inspiration and Recognition of Science and Technology (FIRST), a nonprofit organization in Manchester, N.H. FIRST provides students the opportunity to engage with government, industry and university experts, including those at NASA's Jet Propulsion Laboratory, Pasadena, Calif., for hands-on, realistic exposure to engineering and technical professions.

"This is the largest NASA-funded student program geared toward robotics activities," said NASA Administrator Charles Bolden. "For the next five years, approximately 25,000 students across the country will not only learn from our nation's best and brightest, but also compete and have fun at the same time."

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NASA Study Finds Earth's Lakes are Warming

In the first comprehensive global survey of temperature trends in major lakes, NASA researchers determined Earth's largest lakes have warmed during the past 25 years in response to climate change.

Researchers Philipp Schneider and Simon Hook of NASA's Jet Propulsion Laboratory in Pasadena, Calif., used satellite data to measure the surface temperatures of 167 large lakes worldwide.

They reported an average warming rate of 0.45 degrees Celsius (0.81 degrees Fahrenheit) per decade, with some lakes warming as much as 1 degree Celsius (1.8 degrees Fahrenheit) per decade. The warming trend was global, and the greatest increases were in the mid- to high-latitudes of the Northern Hemisphere.

"Our analysis provides a new, independent data source for assessing the impact of climate change over land around the world," said Schneider, lead author of the study published this week in the journal Geophysical Research Letters. "The results have implications for lake ecosystems, which can be adversely affected by even small water temperature changes."

Small changes in water temperature can result in algal blooms that can make a lake toxic to fish or result in the introduction of non-native species that change the lake's natural ecosystem.

Scientists have long used air temperature measurements taken near Earth's surface to compute warming trends. More recently, scientists have supplemented these measurements with thermal infrared satellite data that can be used to provide a comprehensive, accurate view of how surface temperatures are changing worldwide.

The NASA researchers used thermal infrared imagery from National Oceanic and Atmospheric Administration and European Space Agency satellites. They focused on summer temperatures (July to September in the Northern Hemisphere and January to March in the Southern Hemisphere) because of the difficulty in collecting data in seasons when lakes are ice-covered and/or often hidden by clouds. Only nighttime data were used in the study.

The bodies studied were selected from a global database of lakes and wetlands based on size (typically at least 500 square kilometers – 193 square miles – or larger) or other unique characteristics of scientific merit. The selected lakes also had to have large surface areas located away from shorelines, so land influences did not interfere with the measurements. Satellite lake data were collected from the point farthest from any shoreline.

The largest and most consistent area of warming was northern Europe. The warming trend was slightly weaker in southeastern Europe, around the Black and Caspian seas and Kazakhstan. The trends increased slightly farther east in Siberia, Mongolia and northern China.

In North America, trends were slightly higher in the southwest United States than in the Great Lakes region. Warming was weaker in the tropics and in the mid-latitudes of the Southern Hemisphere. The results were consistent with the expected changes associated with global warming.

The satellite temperature trends largely agreed with trends measured by nine buoys in the Great Lakes, Earth's largest group of freshwater lakes in terms of total surface area and volume.

The lake temperature trends were also in agreement with independent surface air temperature data from NASA's Goddard Institute for Space Studies in New York. In certain regions, such as the Great Lakes and northern Europe, water bodies appear to be warming more quickly than surrounding air temperature.

For more information about NASA and agency programs, visit: http://www.nasa.gov .

Spitzer Sees Shrouded Burst of Stars

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 collision of two spiral galaxies has triggered this explosion, which is cloaked by dust that renders its stars nearly invisible in other wavelengths of light.

The starburst newly revealed by Spitzer stands as the most luminous ever seen taking place away from the centers, or nuclei, of merging parent galaxies. It blazes ten times brighter than the nearby Universe's previous most famous "off-nuclear starburst" that gleams in another galactic smashup known as the Antennae Galaxy.

The new findings show that galaxy mergers can pack a real star-making wallop far from the respective galactic centers, where star-forming dust and gases typically pool.

"This discovery proves that merging galaxies can generate powerful starbursts outside of the centers of the parent galaxies," says Hanae Inami, first author of a paper detailing the results in the July issue of The Astronomical Journal. Inami is a graduate student at The Graduate University for Advanced Studies in Japan and the Spitzer Science Center at the California Institute of Technology. She adds: "The infrared light emission of the starburst dominates its host galaxy and rivals that of the most luminous galaxies we see that are relatively close to our home, the Milky Way."

"No matter how you slice it, this starburst is one of the most luminous objects in the local Universe," agrees Lee Armus, second author of the paper and a senior research astronomer also at the Spitzer Science Center.
A dazzling galactic dust-up

Inami, Armus and their colleagues spotted the buried starburst with Spitzer in the interacting galaxies known as II Zw 096. This galactic train wreck - located around 500 million light years away in the constellation Delphinus (the Dolphin) - will continue to unfold for a few hundred million years. Gravitational forces have already dissolved the once-pinwheel shape of one of II Zw 096's pair of merging galaxies.

The ultra-bright starburst region spans 700 light-years or so - just a tiny portion of II Zw 096, which streams across some 50,000 to 60,000 light-years - yet it blasts out 80 percent of the infrared light from this galactic tumult. Based on Spitzer data, researchers estimate the starburst is cranking out stars at the breakneck pace of around 100 solar masses, or masses of our Sun, per year.

The prodigious energy output of this starburst in a decentralized location as revealed in the infrared has surprised the Spitzer researchers. The new observations go to show how the notion of a cosmic object's nature can change tremendously when viewed at different wavelengths of light. In this way, the shapes and dynamics of distant, harder-to-study galactic mergers could turn out to be a good deal more complex than current observations over a narrow range of wavelengths imply.

"Most of the far-infrared emission in II Zw 096, and hence most of the power, is coming from a region that is not associated with the centers of the merging galaxies," Inami explains. "This suggests that the appearances and interactions of distant, early galaxies during epochs when mergers were much more common than today in the Universe might be more complicated than we think."
A fleeting, perhaps prophetic vista?

In galaxy mergers, individual stars rarely slam into one another because of the vast distances separating them; even in the comparatively crowded central hubs of spiral galaxies, trillions of kilometers still often yawn between the stars.

But giant, diffuse clouds of gas and dust in galaxies do crash together - passing through each other somewhat like ocean waves - and in turn spur the gravitational collapse of dense pockets of matter into new stars. These young, hot stars shine intensely in the energetic ultraviolet part of the spectrum. In the case of II Zw 096, however, a thick shroud of gas and dust still surrounds this stellar brood. The blanket of material absorbs the stars' light and re-radiates it in the lower-energy, infrared wavelengths that gleam clear through the dust to Spitzer's camera.

Astronomers were lucky to capture this transient phase in the evolution of the starburst and of the daughter galaxy that will eventually coalesce out of the collision. "Spitzer has allowed us to see the fireworks before all the gas and dust has cleared away, giving us a preview of the exciting new galaxy being built under the blanket," Inami says.

Merging galaxies such as II Zw 096 also offer a sneak peek at the fate of our Milky Way in some 4.5 billion years when it is expected to plow into its nearest large galactic neighbor, the Andromeda Galaxy. Off-nuclear starbursts such as that in II Zw 096 and the Antennae Galaxy could occur in the vicinity of our Solar System, perhaps, which is located about two-thirds of the way out from the Milky Way's glowing, bulging center.

"This kind of dramatic thing happening in II Zw 096 could happen to the Milky Way and Andromeda when they meet in the far future," says Inami.

NASA Mars Rover Images Honor Apollo 12

NASA's Mars Exploration Rover Opportunity has visited and photographed two craters informally named for the spacecraft that carried men to the moon 41 years ago this week.

Opportunity drove past "Yankee Clipper" crater on Nov. 4 and reached "Intrepid crater" on Nov. 9. For NASA's Apollo 12, the second mission to put humans onto the moon, the command and service module was called Yankee Clipper, piloted by Dick Gordon, and the lunar module was named Intrepid, piloted by Alan Bean and commanded by the late Pete Conrad. The Intrepid landed on the moon with Bean and Conrad on Nov. 19, 1969, while Yankee Clipper orbited overhead. Their landing came a mere four months after Apollo 11's first lunar landing.

This week, Bean wrote to the Mars Exploration Rover team: "I just talked with Dick Gordon about the wonderful honor you have bestowed upon our Apollo 12 spacecraft. Forty-one years ago today, we were approaching the moon in Yankee Clipper with Intrepid in tow. We were excited to have the opportunity to perform some important exploration of a place in the universe other than planet Earth where humans had not gone before. We were anxious to give it our best effort. You and your team have that same opportunity. Give it your best effort."

Rover science team member James Rice, of NASA's Goddard Space Flight Center, Greenbelt, Md., suggested using the Apollo 12 names. He was applying the rover team's convention of using names of historic ships of exploration for the informal names of craters that Opportunity sees in the Meridian Planum region of Mars.

"The Apollo missions were so inspiring when I was young, I remember all the dates. When we were approaching these craters, I realized we were getting close to the Nov. 19 anniversary for Apollo 12," Rice said. He sent Bean and Gordon photographs that Opportunity took of the two craters.

The images are available online at http://photojournal.jpl.nasa.gov/catalog/PIA13593 and http://photojournal.jpl.nasa.gov/catalog/PIA13596. Intrepid crater is about 20 meters (66 feet) in diameter. Yankee Clipper crater is about half that width.

After a two-day stop to photograph the rocks exposed at Intrepid, Opportunity continued on a long-term trek toward Endeavour crater, a highly eroded crater about 1,000 times wider than Intrepid. Endeavour's name comes from the ship of James Cook's first Pacific voyage.

During a drive of 116.9 meters (383.5 feet) on Nov. 14, Opportunity's "odometer" passed 25 kilometers (15.53 miles). That is more than 40 times the driving-distance goal set for Opportunity to accomplish during its original three-month prime mission in 2004.

Mars Exploration Project Manager John Callas, of NASA's Jet Propulsion Laboratory, Pasadena, Calif., said, "Importantly, it's not how far the rovers have gone but how much exploration and science discovery they have accomplished on behalf of all humankind."

At the beginning of Opportunity's mission, the rover landed inside "Eagle crater," about the same size as Intrepid crater. The team's name for that landing-site crater paid tribute to the lunar module of Apollo 11, the first human landing on the moon. Opportunity spent two months inside Eagle crater, where it found multiple lines of evidence for a wet environment in the area's ancient past.

The rover team is checking regularly for Opportunity's twin, Spirit, in case the increasing daily solar energy available at Spirit's location enables the rover to reawaken and resume communication. No signal from Spirit has been received since March 22. Spring began last week in the southern hemisphere of Mars.

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

Camera on Curiosity's Arm will Magnify Clues in Rocks

NASA's next Mars rover, Curiosity, will wield an arm-mounted magnifying camera similar to one on the Mars Rover Opportunity, which promptly demonstrated its importance for reading environmental history from rocks at its landing site in 2004.

Within a few weeks after the landing, that camera at the end of Opportunity's arm revealed details of small spheres embedded in the rocks, hollows where crystals had dissolved, and fine layering shaped like smiles. These details all provided information about the site's wet past.

The camera installed on the end of Curiosity's arm this month is the Mars Hand Lens Imager, or MAHLI. Its work will include the same type of close-up inspections accomplished by the comparable camera on Opportunity, but MAHLI has significantly greater capabilities: full-color photography, adjustable focus, lights, and even video. Also, it sits on a longer arm, one that can hold MAHLI up higher than the cameras on the rover's mast. MAHLI will use those capabilities as one of 10 science instruments to study the area of Mars where NASA's Mars Science Laboratory mission lands Curiosity in August 2012.

The Mars Hand Lens Imager takes its name from the magnifying tool that every field geologist carries. Ken Edgett of Malin Space Science Systems, San Diego, is the principal investigator for the instrument. He said, "When you’re out in the field and you want to get a quick idea what minerals are in a rock, you pick up the rock in one hand and hold your hand lens in the other hand. You look through the lens at the colors, the crystals, the cleavage planes: features that help you diagnose what minerals you see.

"If it's a sedimentary rock, such as the sandstone you see at Arches National Park in Utah, or shale -- which is basically petrified mud -- like in the Painted Desert in Arizona, you use the hand lens not just to see what minerals are in it but also the sizes and shapes of the grains in the rock. You also look at the fine-scale layering in the rock to get an idea of the sequence of events. Sedimentary rocks record past events and environments."

While other instruments on Curiosity will provide more information about what minerals are in rocks, the Mars Hand Lens Imager will play an important role in reading the environmental history recorded in sedimentary rocks. The mission's science team will use the instruments to assess whether the selected landing area has had environmental conditions favorable for life and for preserving evidence about whether life existed.

The team currently assembling and testing Curiosity and other parts of the Mars Science Laboratory spacecraft at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is continuing tests of MAHLI this month, now that the camera is mounted beside other tools on the robotic arm. The spacecraft will launch from Florida between Nov. 25 and Dec. 18, 2011.

Edgett led the preparation in early 2004 of a proposal to include MAHLI in the Mars Science Laboratory's payload. During those same months, the camera on Opportunity's arm -- that mission's Microscopic Imager -- was demonstrating the potential value of a successor, and generating ideas for improvements. Opportunity's Microscopic Imager has a fixed focus. To get targets in focus, it always needs to be placed the same distance from the target, recording a view of an area 3 centimeters (1.2 inches) across. To view a larger area, the camera takes multiple images, sometimes more than a dozen, each requiring a repositioning of Opportunity's arm.

"When I was writing the proposal, the Microscopic Imager took about 40 images for a mosaic of one rock," Edgett said. "That's where the idea came from to make the focus adjustable. With adjustable focus, the science team has more flexibility for trade-offs among the rover's resources, such as power, time, data storage and data downlink. For example, the camera could take one or two images from farther away to cover a larger area, then go in and sample selected parts in higher resolution from closer up."

MAHLI can focus on targets as close as about 21 millimeters (0.8 inch) and as distant as the horizon or farther. JPL's Ashwin Vasavada, deputy project scientist for the Mars Science Laboratory, said, "MAHLI is really a fully functional camera that happens to be on the end of the arm. The close-up capability is its specialty, but it will also be able to take images or videos from many viewpoints inaccessible to the cameras on the mast, such as up high, down low, under the rover and on the rover deck. Think of it like a hand-held camera with a macro lens, one that you could use for taking pictures of the Grand Canyon, of yourself, or of a bumblebee on a flower."

Edgett is looking forward to what the camera will reveal in rock textures. "Just like larger rocks in a river, grains of sand carried in a stream get rounded from bouncing around and colliding with each other," he said. "If you look at a sandstone with a hand lens and see rounded grains, that tells you they came from a distance. If they are more angular, they didn't come as far before they were deposited in the sediment that became the rock. Where an impact excavated a crater, particles of the material ejected from the crater would be very angular.

"When you're talking about ancient rocks as clues for assessing habitability," he continued, "you're talking about the environments the sediments were deposited in -- whether a lake, a desert, an ice field. Also, what cemented the particles together to become rocks, and what changes have affected the rock after the sediments were deposited? All these things are relevant to whether an environment was favorable for life and also whether it was favorable for preserving the record of that life. Earth is a planet teeming with life, but most rocks have not preserved ancient organisms; Mars will be even more challenging than Earth in this sense."

Edgett says he is eager to see an additional image from this camera besides the details of rock textures. With the arm extended upwards, the camera can look down at the rover for a dramatic self-portrait on Mars. But as for the most important image the Mars Hand Lens Imager will take: "That will be something that surprises us, something we're not expecting."

Mars Science Laboratory is managed by NASA’s Jet Propulsion Laboratory, Pasadena, Calif. JPL also manages the Mars Exploration Rovers Spirit and Opportunity. JPL is a division of the California Institute of Technology in Pasadena.
More information about NASA's Mars Science Laboratory is at: http://www.nasa.gov/msl .

Shedding 'Bent' Light on Dark Matter

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. Astronomer Dan Coe led the research while working at NASA's Jet Propulsion Laboratory in Pasadena, Calif.; he is currently with the Space Telescope Science Institute in Baltimore, Md.

The astronomers used Hubble 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.

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

Read the full story at http://hubblesite.org/newscenter/archive/releases/2010/37/full/ .

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