Sunday, July 27, 2014

Milky Way Black Hole Snacks on Hot Gas

Milky Way Black Hole Snacks on Hot Gas:

This artist's concept illustrates the frenzied activity at the core of our Milky Way galaxy.
This artist's concept illustrates the frenzied activity at the core of our Milky Way galaxy. The galactic center hosts a supermassive black hole in the region known as Sagittarius A*, or Sgr A*, with a mass of about four million times that of our sun. The Herschel space observatory has made detailed observations of surprisingly hot gas that may be orbiting or falling toward the supermassive black hole. Image credits: ESA-C. Carreau
› Full image and caption

May 07, 2013

The Herschel space observatory has made detailed observations of surprisingly hot gas that may be orbiting or falling towards the supermassive black hole lurking at the center of our Milky Way galaxy. Herschel is a European Space Agency mission with important NASA participation.


"The black hole appears to be devouring the gas," said Paul Goldsmith, the U.S. project scientist for Herschel at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "This will teach us about how supermassive black holes grow."


Our galaxy's black hole is located in a region known as Sagittarius A* -- or Sgr A* for short -- which is a nearby source of radio waves. The black hole has a mass about four million times that of our sun and lies roughly 26,000 light-years away from our solar system.


Even at that distance, it is a few hundred times closer to us than any other galaxy with an active black hole at its center, making it the ideal natural laboratory to study the environment around these enigmatic objects. At Herschel's far-infrared wavelengths, scientists can peer through the dust in our galaxy and study the turbulent innermost region of the galaxy in great detail.


The biggest surprise was the hot gas in the innermost central region of the galaxy. At least some of it is 1,832 degrees Fahrenheit (around 1,000 degrees Celsius), much hotter than typical interstellar clouds, which are usually only a few tens of degrees above absolute zero, or minus 460 degrees Fahrenheit (minus 273 degrees Celsius).


The team hypothesizes that emissions from strong shocks in highly magnetized gas in the region may be a significant contributor to the high temperatures. Such shocks can be generated in collisions between gas clouds, or in material flowing at high speeds.


Using near-infrared observations, other astronomers have spotted a separate, compact cloud of gas amounting to just a few Earth masses spiralling toward the black hole. Located much closer to the black hole than the reservoir of material studied by Herschel in this work, it may finally be gobbled up later this year.


Spacecraft, including NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and the Chandra X-ray Observatory, will be waiting to spot any X-ray burps as the black hole enjoys its feast.


Read the full ESA news release at http://www.esa.int/Our_Activities/Space_Science/Herschel/Herschel_finds_hot_gas_on_the_menu_for_Milky_Way_s_black_hole .


Herschel is a European Space Agency mission, with science instruments provided by consortia of European institutes and with important participation by NASA. NASA's Herschel Project Office is based at NASA's Jet Propulsion Laboratory, Pasadena, Calif. JPL contributed mission-enabling technology for two of Herschel's three science instruments. The NASA Herschel Science Center, part of the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, supports the United States astronomical community. Caltech manages JPL for NASA.


More information is online at http://www.herschel.caltech.edu , http://www.nasa.gov/herschel and http://www.esa.int/SPECIALS/Herschel .

Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov


2013-156
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Sifting Through the Atmospheres of Far-off Worlds

Sifting Through the Atmospheres of Far-off Worlds:

Planetary Family Portrait
This image shows the HR 8799 planets with starlight optically suppressed and data processing conducted to remove residual starlight. The star is at the center of the blackened circle in the image. The four spots indicated with the letters b through e are the planets. This is a composite image using 30 wavelengths of light and was obtained over a period of 1.25 hours on June 14 and 15, 2012. Image courtesy of Project 1640
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May 09, 2013

Gone are the days of being able to count the number of known planets on your fingers. Today, there are more than 800 confirmed exoplanets -- planets that orbit stars beyond our sun -- and more than 2,700 other candidates. What are these exotic planets made of? Unfortunately, you cannot stack them in a jar like marbles and take a closer look. Instead, researchers are coming up with advanced techniques for probing the planets' makeup.


One breakthrough to come in recent years is direct imaging of exoplanets. Ground-based telescopes have begun taking infrared pictures of the planets posing near their stars in family portraits. But to astronomers, a picture is worth even more than a thousand words if its light can be broken apart into a rainbow of different wavelengths.


Those wishes are coming true as researchers are beginning to install infrared cameras on ground-based telescopes equipped with spectrographs. Spectrographs are instruments that spread an object's light apart, revealing signatures of molecules. Project 1640, partly funded by NASA's Jet Propulsion Laboratory, Pasadena, Calif., recently accomplished this goal using the Palomar Observatory near San Diego.


"In just one hour, we were able to get precise composition information about four planets around one overwhelmingly bright star," said Gautam Vasisht of JPL, co-author of the new study appearing in the Astrophysical Journal. "The star is a hundred thousand times as bright as the planets, so we've developed ways to remove that starlight and isolate the extremely faint light of the planets."


Along with ground-based infrared imaging, other strategies for combing through the atmospheres of giant planets are being actively pursued as well. For example, NASA's Spitzer and Hubble space telescopes monitor planets as they cross in front of their stars, and then disappear behind. NASA's upcoming James Webb Space Telescope will use a comparable strategy to study the atmospheres of planets only slightly larger than Earth.


In the new study, the researchers examined HR 8799, a large star orbited by at least four known giant, red planets. Three of the planets were among the first ever directly imaged around a star, thanks to observations from the Gemini and Keck telescopes on Mauna Kea, Hawaii, in 2008. The fourth planet, the closest to the star and the hardest to see, was revealed in images taken by the Keck telescope in 2010.


That alone was a tremendous feat considering that all planet discoveries up until then had been made through indirect means, for example by looking for the wobble of a star induced by the tug of planets.


Those images weren't enough, however, to reveal any information about the planets' chemical composition. That's where spectrographs are needed -- to expose the "fingerprints" of molecules in a planet's atmosphere. Capturing a distant world's spectrum requires gathering even more planet light, and that means further blocking the glare of the star.


Project 1640 accomplished this with a collection of instruments, which the team installs on the ground-based telescopes each time they go on "observing runs." The instrument suite includes a coronagraph to mask out the starlight; an advanced adaptive optics system, which removes the blur of our moving atmosphere by making millions of tiny adjustments to two deformable telescope mirrors; an imaging spectrograph that records 30 images in a rainbow of infrared colors simultaneously; and a state-of-the-art wave front sensor that further adjusts the mirrors to compensate for scattered starlight.


"It's like taking a single picture of the Empire State Building from an airplane that reveals a bump on the sidewalk next to it that is as high as an ant," said Ben R. Oppenheimer, lead author of the new study and associate curator and chair of the Astrophysics Department at the American Museum of Natural History, N.Y., N.Y.


Their results revealed that all four planets, though nearly the same in temperature, have different compositions. Some, unexpectedly, do not have methane in them, and there may be hints of ammonia or other compounds that would also be surprising. Further theoretical modeling will help to understand the chemistry of these planets.


Meanwhile, the quest to obtain more and better spectra of exoplanets continues. Other researchers have used the Keck telescope and the Large Binocular Telescope near Tucson, Ariz., to study the emission of individual planets in the HR8799 system. In addition to the HR 8799 system, only two others have yielded images of exoplanets. The next step is to find more planets ripe for giving up their chemical secrets. Several ground-based telescopes are being prepared for the hunt, including Keck, Gemini, Palomar and Japan's Subaru Telescope on Mauna Kea, Hawaii.


Ideally, the researchers want to find young planets that still have enough heat left over from their formation, and thus more infrared light for the spectrographs to see. They also want to find planets located far from their stars, and out of the blinding starlight. NASA's infrared Spitzer and Wide-field Infrared Survey Explorer (WISE) missions, and its ultraviolet Galaxy Evolution Explorer, now led by the California Institute of Technology, Pasadena, have helped identify candidate young stars that may host planets meeting these criteria.


"We're looking for super-Jupiter planets located faraway from their star," said Vasisht. "As our technique develops, we hope to be able to acquire molecular compositions of smaller, and slightly older, gas planets."


Still lower-mass planets, down to the size of Saturn, will be targets for imaging studies by the James Webb Space Telescope.


"Rocky Earth-like planets are too small and close to their stars for the current technology, or even for James Webb to detect. The feat of cracking the chemical compositions of true Earth analogs will come from a future space mission such as the proposed Terrestrial Planet Finder," said Charles Beichman, a co-author of the P1640 result and executive director of NASA's Exoplanet Science Institute at Caltech.


Though the larger, gas planets are not hospitable to life, the current studies are teaching astronomers how the smaller, rocky ones form.


"The outer giant planets dictate the fate of rocky ones like Earth. Giant planets can migrate in toward a star, and in the process, tug the smaller, rocky planets around or even kick them out of the system. We're looking at hot Jupiters before they migrate in, and hope to understand more about how and when they might influence the destiny of the rocky, inner planets," said Vasisht.


NASA's Exoplanet Science Institute manages time allocation on the Keck telescope for NASA. JPL manages NASA's Exoplanet Exploration program office. Caltech manages JPL for NASA.


A visualization from the American Museum of Natural History showing where the HR 8799 system is in relation to our solar system is online at http://www.youtube.com/watch?v=yDNAk0bwLrU .


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

Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov


2013-057
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Cassini Shapes First Global Topographic Map of Titan

Cassini Shapes First Global Topographic Map of Titan:

Global Topographic Map of Titan
These polar maps show the first global, topographic mapping of Saturn's moon Titan, using data from NASA's Cassini mission. To create these maps, scientists employed a mathematical process called splining, which uses smooth curved surfaces to "join" the areas between grids of existing topography profiles obtained by Cassini's radar instrument.Image credit: NASA/JPL-Caltech/ASI/JHUAPL/Cornell/Weizmann
› Full image and caption

May 15, 2013

Scientists have created the first global topographic map of Saturn's moon Titan, giving researchers a valuable tool for learning more about one of the most Earth-like and interesting worlds in the solar system. The map was just published as part of a paper in the journal Icarus.


Titan is Saturn's largest moon - with a radius of about 1,600 miles (2,574 kilometers), it's bigger than planet Mercury - and is the second-largest moon in the solar system. Scientists care about Titan because it's the only moon in the solar system known to have clouds, surface liquids and a mysterious, thick atmosphere. The cold atmosphere is mostly nitrogen, like Earth's, but the organic compound methane on Titan acts the way water vapor does on Earth, forming clouds and falling as rain and carving the surface with rivers. Organic chemicals, derived from methane, are present in Titan's atmosphere, lakes and rivers and may offer clues about the origins of life.


"Titan has so much interesting activity - like flowing liquids and moving sand dunes - but to understand these processes it's useful to know how the terrain slopes," said Ralph Lorenz, a member of the Cassini radar team based at the Johns Hopkins University Applied Physics Laboratory, Laurel, Md., who led the map-design team. "It's especially helpful to those studying hydrology and modeling Titan's climate and weather, who need to know whether there is high ground or low ground driving their models."


Titan's thick haze scatters light in ways that make it very hard for remote cameras to "see" landscape shapes and shadows, the usual approach to measuring topography on planetary bodies. Virtually all the data we have on Titan comes from NASA's Saturn-orbiting Cassini spacecraft, which has flown past the moon nearly 100 times over the past decade. On many of those flybys, Cassini has used a radar imager, which can peer through the haze, and the radar data can be used to estimate the surface height.


"With this new topographic map, one of the most fascinating and dynamic worlds in our solar system now pops out in 3-D," said Steve Wall, the deputy team lead of Cassini's radar team, based at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "On Earth, rivers, volcanoes and even weather are closely related to heights of surfaces - we're now eager to see what we can learn from them on Titan."


There are challenges, however. "Cassini isn't orbiting Titan," Lorenz said. "We have only imaged about half of Titan's surface, and multiple 'looks' or special observations are needed to estimate the surface heights. If you divided Titan into 1-degree by 1-degree [latitude and longitude] squares, only 11 percent of those squares have topography data in them."


Lorenz's team used a mathematical process called splining - effectively using smooth, curved surfaces to "join" the areas between grids of existing data. "You can take a spot where there is no data, look how close it is to the nearest data, and use various approaches of averaging and estimating to calculate your best guess," he said. "If you pick a point, and all the nearby points are high altitude, you'd need a special reason for thinking that point would be lower. We're mathematically papering over the gaps in our coverage."


The estimations fit with current knowledge of the moon - that its polar regions are "lower" than areas around the equator, for example - but connecting those points allows scientists to add new layers to their studies of Titan's surface, especially those modeling how and where Titan's rivers flow, and the seasonal distribution of its methane rainfall. "The movement of sands and the flow of liquids are influenced by slopes, and mountains can trigger cloud formation and therefore rainfall. This global product now gives modelers a convenient description of this key factor in Titan's dynamic climate system," Lorenz said.


The most recent data used to compile the map is from 2012; Lorenz says it could be worth revising when the Cassini mission ends in 2017, when more data will have accumulated, filling some of the gaps in present coverage. "We felt we couldn't wait and should release an interim product," he says. "The community has been hoping to get this for a while. I think it will stimulate a lot of interesting work."


The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and ASI, the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

Jia-Rui Cook 818-354-0850

Jet Propulsion Laboratory, Pasadena, Calif.

jccook@jpl.nasa.gov


Michael Buckley 240-228-7536

Johns Hopkins Applied Physics Laboratory, Laurel, Md.

Michael.buckley@jhuapl.edu


2013-161
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Asteroid 1998 QE2 to Sail Past Earth Nine Times Larger Than Cruise Ship

Asteroid 1998 QE2 to Sail Past Earth Nine Times Larger Than Cruise Ship:

The orbit of asteroid 1998 QE2.
The orbit of asteroid 1998 QE2.
Image credit:
NASA/JPL-Caltech
› Larger image

May 15, 2013

On May 31, 2013, asteroid 1998 QE2 will sail serenely past Earth, getting no closer than about 3.6 million miles (5.8 million kilometers), or about 15 times the distance between Earth and the moon. And while QE2 is not of much interest to those astronomers and scientists on the lookout for hazardous asteroids, it is of interest to those who dabble in radar astronomy and have a 230-foot (70-meter) -- or larger -- radar telescope at their disposal.


"Asteroid 1998 QE2 will be an outstanding radar imaging target at Goldstone and Arecibo and we expect to obtain a series of high-resolution images that could reveal a wealth of surface features," said radar astronomer Lance Benner, the principal investigator for the Goldstone radar observations from NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Whenever an asteroid approaches this closely, it provides an important scientific opportunity to study it in detail to understand its size, shape, rotation, surface features, and what they can tell us about its origin. We will also use new radar measurements of the asteroid's distance and velocity to improve our calculation of its orbit and compute its motion farther into the future than we could otherwise."


The closest approach of the asteroid occurs on May 31 at 1:59 p.m. Pacific (4:59 p.m. Eastern / 20:59 UTC). This is the closest approach the asteroid will make to Earth for at least the next two centuries. Asteroid 1998 QE2 was discovered on Aug. 19, 1998, by the Massachusetts Institute of Technology Lincoln Near Earth Asteroid Research (LINEAR) program near Socorro, New Mexico.


The asteroid, which is believed to be about 1.7 miles (2.7 kilometers) or nine Queen Elizabeth 2 ship-lengths in size, is not named after that 12-decked, transatlantic-crossing flagship for the Cunard Line. Instead, the name is assigned by the NASA-supported Minor Planet Center in Cambridge, Mass., which gives each newly discovered asteroid a provisional designation starting with the year of first detection, along with an alphanumeric code indicating the half-month it was discovered, and the sequence within that half-month.


Radar images from the Goldstone antenna could resolve features on the asteroid as small as 12 feet (3.75 meters) across, even from 4 million miles away.


"It is tremendously exciting to see detailed images of this asteroid for the first time," said Benner. "With radar we can transform an object from a point of light into a small world with its own unique set of characteristics. In a real sense, radar imaging of near-Earth asteroids is a fundamental form of exploring a whole class of solar system objects."


Asteroids, which are always exposed to the sun, can be shaped like almost anything under it. Those previously imaged by radar and spacecraft have looked like dog bones, bowling pins, spheroids, diamonds, muffins, and potatoes. To find out what 1998 QE2 looks like, stay tuned. Between May 30 and June 9, radar astronomers using NASA's 230-foot-wide (70 meter) Deep Space Network antenna at Goldstone, Calif., and the Arecibo Observatory in Puerto Rico, are planning an extensive campaign of observations. The two telescopes have complementary imaging capabilities that will enable astronomers to learn as much as possible about the asteroid during its brief visit near Earth.


NASA places a high priority on tracking asteroids and protecting our home planet from them. In fact, the U.S. has the most robust and productive survey and detection program for discovering near-Earth objects. To date, U.S. assets have discovered over 98 percent of the known NEOs.


In 2012, the NEO budget was increased from $6 million to $20 million. Literally dozens of people are involved with some aspect of near-Earth object (NEO) research across NASA and its centers. Moreover, there are many more people involved in researching and understanding the nature of asteroids and comets, including those that come close to the Earth, plus those who are trying to find and track them in the first place.


In addition to the resources NASA puts into understanding asteroids, it also partners with other U.S. government agencies, university-based astronomers, and space science institutes across the country that are working to track and better understand these objects, often with grants, interagency transfers and other contracts from NASA.


NASA's Near-Earth Object Program at NASA Headquarters, Washington, manages and funds the search, study, and monitoring of asteroids and comets whose orbits periodically bring them close to Earth. JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena.


In 2016, NASA will launch a robotic probe to one of the most potentially hazardous of the known NEOs. The OSIRIS-REx mission to asteroid (101955) Bennu will be a pathfinder for future spacecraft designed to perform reconnaissance on any newly-discovered threatening objects. Aside from monitoring potential threats, the study of asteroids and comets enables a valuable opportunity to learn more about the origins of our solar system, the source of water on Earth, and even the origin of organic molecules that lead to the development of life.


NASA recently announced developing a first-ever mission to identify, capture and relocate an asteroid for human exploration. Using game-changing technologies advanced by the Administration, this mission would mark an unprecedented technological achievement that raises the bar of what humans can do in space. Capturing and redirecting an asteroid will integrate the best of NASA's science, technology and human exploration capabilities and draw on the innovation of America's brightest scientists and engineers.


More information about asteroids and near-Earth objects is available at:
http://neo.jpl.nasa.gov/ ,
http://www.jpl.nasa.gov/asteroidwatch and via Twitter at http://www.twitter.com/asteroidwatch .


More information about asteroid radar research is at: http://echo.jpl.nasa.gov/


More information about the Deep Space Network is at: http://deepspace.jpl.nasa.gov/dsn .

DC Agle 818-393-9011
Jet Propulsion Laboratory, Pasadena, Calif.
agle@jpl.nasa.gov


2013-163
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Galaxy's Ring of Fire

Galaxy's Ring of Fire:

Galactic Wheels within Wheels
How many rings do you see in this new image of the galaxy Messier 94, also known as NGC 4736? While at first glance one might see a number of them, astronomers believe there is just one. This image was captured in infrared light by NASA's Spitzer Space Telescope. Image credit: NASA/JPL-Caltech
› Full image and caption

May 16, 2013

Johnny Cash may have preferred this galaxy's burning ring of fire to the one he sang about falling into in his popular song. The "starburst ring" seen at center in red and yellow hues is not the product of love, as in the song, but is instead a frenetic region of star formation.


The galaxy, a spiral beauty called Messier 94, is located about 17 million light-years away. In this image from NASA's Spitzer Space Telescope, infrared light is represented in different colors, with blue having the shortest wavelengths and red, the longest.


Starburst rings like this can often be triggered by gravitational encounters with other galaxies but, in this case, may have instead been caused by the galaxy's oval shape. Gas in the ring is being converted into hot, young stars, which then warm the dust, causing it to glow with infrared light.


The outer, faint blue ring around the galaxy might be an optical illusion. Astronomers think that two separate spiral arms appear as a single unbroken ring when viewed from our position in space.


NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA. For more information about Spitzer, visit http://spitzer.caltech.edu and http://www.nasa.gov/spitzer .

Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

Whitney.Clavin@jpl.nasa.gov


2013-165
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Herschel Space Observatory Finds Galaxy Mega Merger

Herschel Space Observatory Finds Galaxy Mega Merger:

The Making of a Giant Galaxy
Several telescopes have teamed up to discover a rare and massive merging of two galaxies that took place when the universe was just 3 billion years old (its current age is about 14 billion years). The galaxies, collectively called HXMM01, are churning out the equivalent of 2,000 suns a year. By comparison, our Milky Way hatches about two to three suns a year. The total number of stars in both colliding galaxies averages out to about 400 billion suns. Image credit: ESA/NASA/JPL-Caltech/UC Irvine/STScI/Keck/NRAO/SAO
› Full image and caption

May 22, 2013

PASADENA, Calif. - A massive and rare merging of two galaxies has been spotted in images taken by the Herschel space observatory, a European Space Agency mission with important NASA participation.


Follow-up studies by several telescopes on the ground and in space, including NASA's Hubble Space Telescope and Spitzer Space Telescope, tell a tale of two faraway galaxies intertwined and furiously making stars. Eventually, the duo will settle down to form one super-giant elliptical galaxy.


The findings help explain a mystery in astronomy. Back when our universe was 3 billion to 4 billion years old, it was populated with large reddish elliptical-shaped galaxies made up of old stars. Scientists have wondered whether those galaxies built up slowly over time through the acquisitions of smaller galaxies, or formed more rapidly through powerful collisions between two large galaxies.


The new findings suggest massive mergers are responsible for the giant elliptical galaxies.


"We're looking at a younger phase in the life of these galaxies -- an adolescent burst of activity that won't last very long," said Hai Fu of the University of California at Irvine, who is lead author of a new study describing the results. The study is published in the May 22 online issue of Nature.


"These merging galaxies are bursting with new stars and completely hidden by dust," said co-author Asantha Cooray, also of the University of California at Irvine. "Without Herschel's far-infrared detectors, we wouldn't have been able to see through the dust to the action taking place behind."


Herschel, which operated for almost four years, was designed to see the longest-wavelength infrared light. As expected, it recently ran out of the liquid coolant needed to chill its delicate infrared instruments. While its mission in space is over, astronomers still are scrutinizing the data, and further discoveries are expected.


In the new study, Herschel was used to spot the colliding galaxies, called HXMM01, located about 11 billion light-years from Earth, during a time when our universe was about 3 billion years old. At first, astronomers thought the two galaxies were just warped, mirror images of one galaxy. Such lensed galaxies are fairly common in astronomy and occur when the gravity from a foreground galaxy bends the light from a more distant object. After a thorough investigation, the team realized they were actually looking at a massive galaxy merger.


Follow-up characterization revealed the merging galaxies are churning out the equivalent of 2,000 stars a year. By comparison, our Milky Way hatches about two to three stars a year. The total number of stars in both colliding galaxies averages out to about 400 billion.


Mergers are fairly common in the cosmos, but this particular event is unusual because of the prolific amounts of gas and star formation, and the sheer size of the merger at such a distant epoch.


The results go against the more popular model explaining how the biggest galaxies arise: through minor acquisitions of small galaxies. Instead, mega smash-ups may be doing the job.


NASA's Herschel Project Office is based at the agency's Jet Propulsion Laboratory in Pasadena, Calif., which contributed mission-enabling technology for two of Herschel's three science instruments. JPL is a division of the California Institute of Technology, Pasadena.


For more information about Herschel, visit: http://www.nasa.gov/herschel and http://www.esa.int/SPECIALS/Herschel .

Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov


J.D. Harrington 202-358-5241

NASA Headquarters, Washington

j.d.harrington@nasa.gov


2013-171
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Galaxies Fed by Funnels of Fuel

Galaxies Fed by Funnels of Fuel:

simulation shows the formation of a massive galaxy
Created with the help of supercomputers, this still from a simulation shows the formation of a massive galaxy during the first 2 billion years of the universe. Hydrogen gas is gray, young stars appear blue, and older stars are red. The simulation reveals that gas flows into galaxies along filaments akin to cosmic bendy, or swirly, straws. Image credit: Video courtesy of the N-Body Shop at University of Washington
› Full image and caption

May 23, 2013

Computer simulations of galaxies growing over billions of years have revealed a likely scenario for how they feed: a cosmic version of swirly straws.


The results show that cold gas -- fuel for stars -- spirals into the cores of galaxies along filaments, rapidly making its way to their "guts." Once there, the gas is converted into new stars, and the galaxies bulk up in mass.


"Galaxy formation is really chaotic," said Kyle Stewart, lead author of the new study appearing in the May 20th issue of the Astrophysical Journal. "It took us several hundred computer processors, over months of time, to simulate and learn more about how this process works." Stewart, who is now at the California Baptist University in Riverside, Calif., completed the majority of this work while at NASA's Jet Propulsion Laboratory in Pasadena, Calif.


In the early universe, galaxies formed out of clumps of matter, connected by filaments in a giant cosmic web. Within the galaxies, nuggets of gas cooled and condensed, becoming dense enough to trigger the birth of stars. Our Milky Way spiral galaxy and its billions of stars took shape in this way.


The previous, standard model of galaxy formation held that hot gas sank into the centers of burgeoning galaxies from all directions. Gas clouds were thought to collide into each other, sending out shock waves, which then heated up the gas. The process is similar to jets creating sonic booms, only in the case of galaxies, the in-falling gas travels faster than the speed of sound, piling up into waves. Eventually, the gas cools and sinks to the galactic center. This process was theorized to be slow, taking up to 8 billion years.


Recent research has contradicted this scenario in smaller galaxies, showing that the gas is not heated. An alternate "cold-mode" theory of galaxy formation was proposed instead, suggesting the cold gas might funnel along filaments into galaxy centers. Stewart and his colleagues set out to test this theory and address the mysteries about how the cold gas gets into galaxies, as well as the rate at which it spirals in.


Since it would take billions of years to watch a galaxy grow, the team simulated the process using supercomputers at JPL; NASA's Ames Research Center, Moffett Field, Calif.; and the University of California, Irvine. They ran four different simulations of the formation of a galaxy like our Milky Way, starting from just 57 million years after the big bang until present day.


The simulations began with the starting ingredients for galaxies -- hydrogen, helium and dark matter -- and then let the laws of physics take over to create their galactic masterpieces. Supercomputers are needed due to the enormous number of interactions.


"The simulations are like a gigantic game of chess," said Alyson Brooks, a co-author of the paper and expert in galaxy simulations at the University of Wisconsin, Madison. "For each point in time, we have to figure out how a given particle -- our chess piece -- should move based on the positions of all of the other particles. There are tens of millions of particles in the simulation, so figuring out how the gravitational forces affect each particle is time-consuming."


When the galaxy concoctions were ready, the researchers inspected the data, finding new clues about how cold gas sinks into the galaxy centers. The new results confirm that cold gas flows along filaments and show, for the first time, that the gas is spinning around faster than previously believed. The simulations also revealed that the gas is making its way down to the centers of galaxies more quickly than what occurs in the "hot-mode" of galaxy formation, in about 1 billion years.


"We have found that the filamentary structures that galaxies are built on are key to how they build up over time, by threading gas into them efficiently," said Leonidas Moustakas, a co-author at JPL.


The researchers looked at dark matter too -- an invisible substance making up about 85 percent of matter in the universe. Galaxies form out of lumps of regular matter, so-called baryonic matter that is composed of atoms, and dark matter. The simulations showed that dark matter is also spinning at a faster rate along the filaments, spiraling into the galaxy centers.


The results help answer a riddle in astronomy about galaxies with large extended disks of material spinning around them, far from their centers. Researchers didn't understand how the outer material could be spinning so fast. The cold-mode allows for this rapid spinning, fitting another jigsaw piece into the puzzle of how galaxies grow.


"The goal of simulating galaxies is to compare them to what telescopes observe and see if we really understand how to build a galaxy," said Stewart. "It helps us makes sense of the real universe."


Other authors of the paper are: James Bullock of the University of California, Irvine; Ariyeh Maller of the New York City College of Technology, Brooklyn, N.Y., Jürg Diemand of the University of Zurich, Switzerland; and James Wadsley of the McMaster University, Hamilton, Ontario, Canada.


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

Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov


2013-174
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NASA to Discuss Mars Curiosity Radiation Findings

NASA to Discuss Mars Curiosity Radiation Findings:

This artist's concept features NASA's Mars Science Laboratory Curiosity rover
This artist's concept features NASA's Mars Science Laboratory Curiosity rover, a mobile robot for investigating Mars' past or present ability to sustain microbial life. Image credit: NASA/JPL-Caltech
› Full image and caption

May 28, 2013

PASADENA, Calif. - NASA will host a media teleconference at 11:30 a.m. PDT (2:30 p.m. EDT) Thursday, May 30, to present new findings from the Mars Science Laboratory Radiation Assessment Detector (RAD) aboard the rover Curiosity.


The briefing participants are:
-- Donald M. Hassler, RAD principal investigator and program director, Southwest Research Institute, San Antonio

-- Cary Zeitlin, principal scientist, Southwest Research Institute

-- Eddie Semones, spaceflight radiation health officer, NASA's Johnson Space Center, Houston

-- Chris Moore, deputy director of advanced exploration systems, NASA Headquarters, Washington


The Southwest Research Institute and Christian Albrechts University in Kiel, Germany, built RAD with funding from NASA's Human Exploration and Operations Mission Directorate and Germany's national aerospace research center, Deutsches Zentrum fur Luft- und Raumfahrt. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Science Laboratory Project. NASA's Science Mission Directorate in Washington manages the Mars Exploration Program.


Audio and visuals of the event will be streamed live online at: http://www.nasa.gov/newsaudio and http://www.ustream.tv/nasajpl .


Visuals will be posted at the start of the teleconference on NASA's Mars Science Laboratory website at: http://go.nasa.gov/curiositytelecon .


For information about NASA's Curiosity mission, visit: http://www.jpl.nasa.gov/msl , http://www.nasa.gov/msl and http://mars.jpl.nasa.gov/msl .
-end-

Guy Webster/Elena Mejia 818-354-5011

Jet Propulsion Laboratory, Pasadena, Calif.

guy.webster@jpl.nasa.gov / elena.mejia@jpl.nasa.gov


Trent Perrotto 202-358-1100

NASA Headquarters, Washington

trent.j.perrotto@nasa.gov


2013-176
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NASA's WISE Mission Finds Lost Asteroid Family Members

NASA's WISE Mission Finds Lost Asteroid Family Members:

Asteroid Family's Shattered Past
This artist's conception shows how families of asteroids are created. Over the history of our solar system, catastrophic collisions between asteroids located in the belt between Mars and Jupiter have formed families of objects on similar orbits around the sun. Image credit: NASA/JPL-Caltech
› Full image and caption

May 29, 2013

PASADENA, Calif. -- Data from NASA's Wide-field Infrared Survey Explorer (WISE) have led to a new and improved family tree for asteroids in the main belt between Mars and Jupiter.


Astronomers used millions of infrared snapshots from the asteroid-hunting portion of the WISE all-sky survey, called NEOWISE, to identify 28 new asteroid families. The snapshots also helped place thousands of previously hidden and uncategorized asteroids into families for the first time. The findings are a critical step in understanding the origins of asteroid families, and the collisions thought to have created these rocky clans.


"NEOWISE has given us the data for a much more detailed look at the evolution of asteroids throughout the solar system," said Lindley Johnson, the program executive for the Near-Earth Object Observation Program at NASA Headquarters in Washington. "This will help us trace the NEOs back to their sources and understand how some of them have migrated to orbits hazardous to the Earth."


The main asteroid belt is a major source of near-Earth objects (NEOs), which are those asteroids and comets that come within 28 million miles (45 million kilometers) of Earth's path around the sun. Some near-Earth objects start out in stable orbits in the main asteroid belt, until a collision or gravitational disturbance flings them inward like flippers in a game of pinball.


The NEOWISE team looked at about 120,000 main belt asteroids out of the approximately 600,000 known. They found that about 38,000 of these objects, roughly one third of the observed population, could be assigned to 76 families, 28 of which are new. In addition, some asteroids thought to belong to a particular family were reclassified.


An asteroid family is formed when a collision breaks apart a large parent body into fragments of various sizes. Some collisions leave giant craters. For example, the asteroid Vesta's southern hemisphere was excavated by two large impacts. Other smash-ups are catastrophic, shattering an object into numerous fragments, as was the case with the Eos asteroid family. The cast-off pieces move together in packs, traveling on the same path around the sun, but over time the pieces become more and more spread out.


Previous knowledge of asteroid family lineages comes from observations of their orbits. NEOWISE also looked at the asteroids' reflectivity to identify family members.


Asteroids in the same family generally have similar mineral composition and reflect similar amounts of light. Some families consist of darker-colored, or duller, asteroids, while others are made up of lighter-colored, or shinier, rocks. It is difficult to distinguish between dark and light asteroids in visible light. A large, dull asteroid can appear the same as a small, shiny one. The dark asteroid reflects less light but has more total surface area, so it appears brighter.


NEOWISE could distinguish between the dark and light asteroids because it could detct infrared light, which reveals the heat of an object. The larger the object, the more heat it gives off. When the size of an asteroid can be measured, its true reflective properties can be determined, and a group of asteroids once thought to belong to a single family circling the sun in a similar orbit can be sorted into distinct families.


"We're separating zebras from the gazelles," said Joseph Masiero of NASA's Jet Propulsion Laboratory in Pasadena, Calif., who is lead author of a report on the new study that appears in the Astrophysical Journal. "Before, family members were harder to tell apart because they were traveling in nearby packs. But now we have a better idea of which asteroid belongs to which family."


The next step for the team is to learn more about the original parent bodies that spawned the families.


"It's as if you have shards from a broken vase, and you want to put it back together to find out what happened," said Amy Mainzer, the NEOWISE principal investigator at JPL. "Why did the asteroid belt form in the first place and fail to become a planet? We are piecing together our asteroids' history."


JPL, a division of the California Institute of Technology in Pasadena, managed and operated WISE for NASA's Science Mission Directorate. The spacecraft was put into hibernation mode in 2011, after completing its main objectives of scanning the entire sky twice.


More information about the mission is online at: http://www.nasa.gov/wise .

Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov


J.D. Harrington 202-358-5241

NASA Headquarters, Washington

j.d.harrington@nasa.gov


2013-179
Posted by Nelio Inacio at 5:33 PM 0 comments
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Cassini Finds Hints of Activity at Saturn Moon Dione

Cassini Finds Hints of Activity at Saturn Moon Dione:

North Polar View
The Cassini spacecraft looks down, almost directly at the north pole of Dione. The feature just left of the terminator at bottom is Janiculum Dorsa, a long, roughly north-south trending ridge. Image credit:
NASA/JPL/Space Science Institute
› Full image and caption

May 29, 2013

From a distance, most of the Saturnian moon Dione resembles a bland cueball. Thanks to close-up images of a 500-mile-long (800-kilometer-long) mountain on the moon from NASA's Cassini spacecraft, scientists have found more evidence for the idea that Dione was likely active in the past. It could still be active now.


"A picture is emerging that suggests Dione could be a fossil of the wondrous activity Cassini discovered spraying from Saturn's geyser moon Enceladus or perhaps a weaker copycat Enceladus," said Bonnie Buratti of NASA's Jet Propulsion Laboratory in Pasadena, Calif., who leads the Cassini science team that studies icy satellites. "There may turn out to be many more active worlds with water out there than we previously thought."


Other bodies in the solar system thought to have a subsurface ocean - including Saturn's moons Enceladus and Titan and Jupiter's moon Europa - are among the most geologically active worlds in our solar system. They have been intriguing targets for geologists and scientists looking for the building blocks of life elsewhere in the solar system. The presence of a subsurface ocean at Dione would boost the astrobiological potential of this once-boring iceball.


Hints of Dione's activity have recently come from Cassini, which has been exploring the Saturn system since 2004. The spacecraft's magnetometer has detected a faint particle stream coming from the moon, and images showed evidence for a possible liquid or slushy layer under its rock-hard ice crust. Other Cassini images have also revealed ancient, inactive fractures at Dione similar to those seen at Enceladus that currently spray water ice and organic particles.


The mountain examined in the latest paper -- published in March in the journal Icarus -- is called Janiculum Dorsa and ranges in height from about 0.6 to 1.2 miles (1 to 2 kilometers). The moon's crust appears to pucker under this mountain as much as about 0.3 mile (0.5 kilometer).


"The bending of the crust under Janiculum Dorsa suggests the icy crust was warm, and the best way to get that heat is if Dione had a subsurface ocean when the ridge formed," said Noah Hammond, the paper's lead author, who is based at Brown University, Providence, R.I.


Dione gets heated up by being stretched and squeezed as it gets closer to and farther from Saturn in its orbit. With an icy crust that can slide around independently of the moon's core, the gravitational pulls of Saturn get exaggerated and create 10 times more heat, Hammond explained. Other possible explanations, such as a local hotspot or a wild orbit, seemed unlikely.


Scientists are still trying to figure out why Enceladus became so active while Dione just seems to have sputtered along. Perhaps the tidal forces were stronger on Enceladus, or maybe the larger fraction of rock in the core of Enceladus provided more radioactive heating from heavy elements. In any case, liquid subsurface oceans seem to be common on these once-boring icy satellites, fueling the hope that other icy worlds soon to be explored - like the dwarf planets Ceres and Pluto - could have oceans underneath their crusts. NASA's Dawn and New Horizons missions reach those dwarf planets in 2015.


The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, Pasadena, Calif., a division of the California Institute of Technology, Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate in Washington. JPL designed, developed and assembled the Cassini orbiter and its two onboard cameras. The imaging team consists of scientists from the United States, England, France and Germany. The imaging operations center is based at the Space Science Institute in Boulder, Colo.


Hammond's work was funded through a NASA Outer Planets Research grant.


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

Jia-Rui Cook 818-354-0850

Jet Propulsion Laboratory, Pasadena, Calif.

jccook@jpl.nasa.gov


2013-178
Posted by Nelio Inacio at 5:33 PM 0 comments
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NASA Hosts News and Social Media Events Around this Week's Asteroid Pass

NASA Hosts News and Social Media Events Around this Week's Asteroid Pass:

The orbit of asteroid 1998 QE2. Image credit: NASA/JPL-Caltech
The orbit of asteroid 1998 QE2. Image credit: NASA/JPL-Caltech
› Larger image

May 29, 2013

PASADENA, Calif. -- NASA is inviting members of the media and public to participate in online and televised events May 30 to 31 with NASA officials and experts discussing the agency's asteroid initiative and the Earth flyby of the 1.7-mile-long (2.7-kilometer-long) asteroid 1998 QE2.


At 1:59 p.m. PDT (4:59 p.m. EDT), Friday, May 31, the 1998 QE2 asteroid will pass by Earth at a safe distance of about 3.6 million miles (5.8 million kilometers) -- its closest approach for at least the next two centuries. The asteroid was discovered Aug. 19, 1998, by the Massachusetts Institute of Technology's Lincoln Near Earth Asteroid Research Program near Socorro, N.M.


The schedule of events is:


Thursday, May 30


-- 10:30 to 11:30 a.m. PDT (1:30 to 2:30 p.m. EDT): NASA's Jet Propulsion Laboratory in Pasadena, Calif., will show on NASA Television live telescope images of the asteroid and host a discussion with NASA Administrator Charles Bolden and experts from JPL and the Goldstone Deep Space Communications Complex. Scientists at Goldstone will be using radar to track and image the asteroid.


The event also will be streamed live on the agency's website at: http://www.nasa.gov/ntv . It will also be available on Ustream.tv with live chat capability at: http://www.ustream.tv/nasajpl2 .


Viewers may submit questions in advance to @AsteroidWatch on Twitter with the hashtag #asteroidQE2.


-- 5 to 7 p.m. PDT (8 to 10 p.m. EDT): Bill Cooke of the Meteoroid Environment Office at NASA's Marshall Space Flight Center in Huntsville, Ala., will host an online chat at:
http://www.nasa.gov/chat .


Friday, May 31


-- 11 a.m. to 12 p.m. PDT (2 to 3 p.m. EDT), NASA Deputy Administrator Lori Garver will participate in a White House "We the Geeks" Google+ Hangout. Participants will discuss asteroid identification, characterization, resource utilization and hazard mitigation. The hangout can be viewed at the White House website at:
https://plus.google.com/+whitehouse/posts .


NASA recently announced plans to find, study, capture and relocate an asteroid for exploration by astronauts. The asteroid initiative is a strategy to leverage human and robotic activities for the first human mission while accelerating efforts to improve detection and characterization of asteroids.


For more about NASA's asteroid activities, visit: http://www.nasa.gov/asteroid .


More information about asteroids and near-Earth objects is available at: http://neo.jpl.nasa.gov/ , http://www.jpl.nasa.gov/asteroidwatch and via Twitter at http://www.twitter.com/asteroidwatch .


More information about asteroid radar research is at: http://echo.jpl.nasa.gov/ .

D.C. Agle 818-393-9011

Jet Propulsion Laboratory, Pasadena, Calif.

agle@jpl.nasa.gov


Sarah Ramsey 202-358-1694

NASA Headquarters, Washington

sarah.ramsey@nasa.gov


2013-177
Posted by Nelio Inacio at 5:32 PM 0 comments
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NASA's WISE Mission Finds Lost Asteroid Family Members

NASA's WISE Mission Finds Lost Asteroid Family Members:

Asteroid Family's Shattered Past
This artist's conception shows how families of asteroids are created. Over the history of our solar system, catastrophic collisions between asteroids located in the belt between Mars and Jupiter have formed families of objects on similar orbits around the sun. Image credit: NASA/JPL-Caltech
› Full image and caption

May 29, 2013

PASADENA, Calif. -- Data from NASA's Wide-field Infrared Survey Explorer (WISE) have led to a new and improved family tree for asteroids in the main belt between Mars and Jupiter.


Astronomers used millions of infrared snapshots from the asteroid-hunting portion of the WISE all-sky survey, called NEOWISE, to identify 28 new asteroid families. The snapshots also helped place thousands of previously hidden and uncategorized asteroids into families for the first time. The findings are a critical step in understanding the origins of asteroid families, and the collisions thought to have created these rocky clans.


"NEOWISE has given us the data for a much more detailed look at the evolution of asteroids throughout the solar system," said Lindley Johnson, the program executive for the Near-Earth Object Observation Program at NASA Headquarters in Washington. "This will help us trace the NEOs back to their sources and understand how some of them have migrated to orbits hazardous to the Earth."


The main asteroid belt is a major source of near-Earth objects (NEOs), which are those asteroids and comets that come within 28 million miles (45 million kilometers) of Earth's path around the sun. Some near-Earth objects start out in stable orbits in the main asteroid belt, until a collision or gravitational disturbance flings them inward like flippers in a game of pinball.


The NEOWISE team looked at about 120,000 main belt asteroids out of the approximately 600,000 known. They found that about 38,000 of these objects, roughly one third of the observed population, could be assigned to 76 families, 28 of which are new. In addition, some asteroids thought to belong to a particular family were reclassified.


An asteroid family is formed when a collision breaks apart a large parent body into fragments of various sizes. Some collisions leave giant craters. For example, the asteroid Vesta's southern hemisphere was excavated by two large impacts. Other smash-ups are catastrophic, shattering an object into numerous fragments, as was the case with the Eos asteroid family. The cast-off pieces move together in packs, traveling on the same path around the sun, but over time the pieces become more and more spread out.


Previous knowledge of asteroid family lineages comes from observations of their orbits. NEOWISE also looked at the asteroids' reflectivity to identify family members.


Asteroids in the same family generally have similar mineral composition and reflect similar amounts of light. Some families consist of darker-colored, or duller, asteroids, while others are made up of lighter-colored, or shinier, rocks. It is difficult to distinguish between dark and light asteroids in visible light. A large, dull asteroid can appear the same as a small, shiny one. The dark asteroid reflects less light but has more total surface area, so it appears brighter.


NEOWISE could distinguish between the dark and light asteroids because it could detct infrared light, which reveals the heat of an object. The larger the object, the more heat it gives off. When the size of an asteroid can be measured, its true reflective properties can be determined, and a group of asteroids once thought to belong to a single family circling the sun in a similar orbit can be sorted into distinct families.


"We're separating zebras from the gazelles," said Joseph Masiero of NASA's Jet Propulsion Laboratory in Pasadena, Calif., who is lead author of a report on the new study that appears in the Astrophysical Journal. "Before, family members were harder to tell apart because they were traveling in nearby packs. But now we have a better idea of which asteroid belongs to which family."


The next step for the team is to learn more about the original parent bodies that spawned the families.


"It's as if you have shards from a broken vase, and you want to put it back together to find out what happened," said Amy Mainzer, the NEOWISE principal investigator at JPL. "Why did the asteroid belt form in the first place and fail to become a planet? We are piecing together our asteroids' history."


JPL, a division of the California Institute of Technology in Pasadena, managed and operated WISE for NASA's Science Mission Directorate. The spacecraft was put into hibernation mode in 2011, after completing its main objectives of scanning the entire sky twice.


More information about the mission is online at: http://www.nasa.gov/wise .

Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov


J.D. Harrington 202-358-5241

NASA Headquarters, Washington

j.d.harrington@nasa.gov


2013-179
Posted by Nelio Inacio at 5:31 PM 0 comments
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Cassini Finds Hints of Activity at Saturn Moon Dione

Cassini Finds Hints of Activity at Saturn Moon Dione:

North Polar View
The Cassini spacecraft looks down, almost directly at the north pole of Dione. The feature just left of the terminator at bottom is Janiculum Dorsa, a long, roughly north-south trending ridge. Image credit:
NASA/JPL/Space Science Institute
› Full image and caption

May 29, 2013

From a distance, most of the Saturnian moon Dione resembles a bland cueball. Thanks to close-up images of a 500-mile-long (800-kilometer-long) mountain on the moon from NASA's Cassini spacecraft, scientists have found more evidence for the idea that Dione was likely active in the past. It could still be active now.


"A picture is emerging that suggests Dione could be a fossil of the wondrous activity Cassini discovered spraying from Saturn's geyser moon Enceladus or perhaps a weaker copycat Enceladus," said Bonnie Buratti of NASA's Jet Propulsion Laboratory in Pasadena, Calif., who leads the Cassini science team that studies icy satellites. "There may turn out to be many more active worlds with water out there than we previously thought."


Other bodies in the solar system thought to have a subsurface ocean - including Saturn's moons Enceladus and Titan and Jupiter's moon Europa - are among the most geologically active worlds in our solar system. They have been intriguing targets for geologists and scientists looking for the building blocks of life elsewhere in the solar system. The presence of a subsurface ocean at Dione would boost the astrobiological potential of this once-boring iceball.


Hints of Dione's activity have recently come from Cassini, which has been exploring the Saturn system since 2004. The spacecraft's magnetometer has detected a faint particle stream coming from the moon, and images showed evidence for a possible liquid or slushy layer under its rock-hard ice crust. Other Cassini images have also revealed ancient, inactive fractures at Dione similar to those seen at Enceladus that currently spray water ice and organic particles.


The mountain examined in the latest paper -- published in March in the journal Icarus -- is called Janiculum Dorsa and ranges in height from about 0.6 to 1.2 miles (1 to 2 kilometers). The moon's crust appears to pucker under this mountain as much as about 0.3 mile (0.5 kilometer).


"The bending of the crust under Janiculum Dorsa suggests the icy crust was warm, and the best way to get that heat is if Dione had a subsurface ocean when the ridge formed," said Noah Hammond, the paper's lead author, who is based at Brown University, Providence, R.I.


Dione gets heated up by being stretched and squeezed as it gets closer to and farther from Saturn in its orbit. With an icy crust that can slide around independently of the moon's core, the gravitational pulls of Saturn get exaggerated and create 10 times more heat, Hammond explained. Other possible explanations, such as a local hotspot or a wild orbit, seemed unlikely.


Scientists are still trying to figure out why Enceladus became so active while Dione just seems to have sputtered along. Perhaps the tidal forces were stronger on Enceladus, or maybe the larger fraction of rock in the core of Enceladus provided more radioactive heating from heavy elements. In any case, liquid subsurface oceans seem to be common on these once-boring icy satellites, fueling the hope that other icy worlds soon to be explored - like the dwarf planets Ceres and Pluto - could have oceans underneath their crusts. NASA's Dawn and New Horizons missions reach those dwarf planets in 2015.


The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, Pasadena, Calif., a division of the California Institute of Technology, Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate in Washington. JPL designed, developed and assembled the Cassini orbiter and its two onboard cameras. The imaging team consists of scientists from the United States, England, France and Germany. The imaging operations center is based at the Space Science Institute in Boulder, Colo.


Hammond's work was funded through a NASA Outer Planets Research grant.


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

Jia-Rui Cook 818-354-0850

Jet Propulsion Laboratory, Pasadena, Calif.

jccook@jpl.nasa.gov


2013-178
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NASA Research Aircraft to Double-Team 2013 Hurricanes

NASA Research Aircraft to Double-Team 2013 Hurricanes:

The fifth science flight of NASA's Global Hawk (green line) concluded when the aircraft landed at NASA's Wallops Flight Facility
The fifth science flight of NASA's Global Hawk (green line) concluded when the aircraft landed at NASA's Wallops Flight Facility, Wallops Island, Va. on Sunday, Sept. 23, 2013 after flying over Tropical Storm Nadine in the Eastern Atlantic Ocean. The HS3 scientists changed the flight path (the original plan is in blue) during the GH flight to be able to overfly Nadine's center. Measurements from dropsondes found wind speeds greater than 60 knots at lower levels above the surface during that adjusted flight leg. Despite the large distance of Nadine from the U. S. East Coast, the Global Hawk was able to spend about 11 hours over the storm. The image shows the Global Hawk (red dot) returning to Wallops. Credit: NASA Wallops Technicians securing NASA's Global Hawk unmanned aircraft in the aircraft hangar of NASA's Wallops Flight Facility in Wallops Island, Va on Sept. 7, 2012. Credit: NASA Wallops
› Larger image

May 29, 2013

With the start of the 2013 Atlantic hurricane season less than a week away, NASA is preparing to send a pair of specially instrumented Global Hawk unmanned aircraft out over the Atlantic later this summer to investigate the processes that underlie hurricane formation and intensity.


Now in its second year, the NASA Hurricane and Severe Storm Sentinel, or HS3, airborne mission brings together several NASA centers, including NASA's Jet Propulsion Laboratory, Pasadena, Calif., with federal and university partners to study hurricane processes. Last year, just one Global Hawk flew during the campaign, focusing on the environment around tropical storms. This year, scientists will "double their fun" with a second aircraft and additional instruments focusing on the inner region of storms.


Global Hawk Two will include the JPL-developed High-Altitude Monolithic Microwave Integrated Circuit Sounding Radiometer, or HAMSR instrument, which uses microwave wavelengths to measure temperature, water vapor and precipitation from the top of storms to the surface. HAMSR has previously participated in NASA's Genesis and Rapid Intensification Processes (GRIP) experiment to study hurricanes in 2010. The instrument is demonstrating advanced technologies that are precursors to potential future satellite sensors.


"The advantage this year over 2012 is that the second aircraft will measure eyewall and rainband winds and precipitation, something we didn't get to do last year," said Scott Braun, HS3 mission principal investigator and research meteorologist at NASA's Goddard Space Flight Center in Greenbelt, Md. "In addition, just as we did in 2012, the first aircraft will examine the large-scale environment that tropical storms form in and move through and how that environment affects the inner workings of the storms."


The NASA Global Hawks will be piloted remotely from the HS3 mission base at NASA's Wallops Flight Facility in Wallops Island, Va. Global Hawk aircraft are well-suited for hurricane investigations because they can fly for as long as 28 hours and fly over hurricanes at altitudes greater than 60,000 feet (18,288 meters).


The mission will operate between Aug. 20 and Sept. 23. The Atlantic hurricane season runs from June 1 to November 30 and typically peaks in early to mid-September.


For more information, see: http://www.nasa.gov/mission_pages/hurricanes/missions/hs3/news/double-team.html . For more on HS3, visit: http://science.nasa.gov/missions/hs3/ . For more on NASA's hurricane research, visit: http://www.nasa.gov/hurricane . For more on HAMSR, visit: http://microwavescience.jpl.nasa.gov/instruments/hamsr/ . For more on NASA's Airborne Science Program, visit: http://airbornescience.nasa.gov .
The California Institute of Technology in Pasadena manages JPL for NASA.

Alan Buis 818-354-0474

Jet Propulsion Laboratory, Pasadena, Calif.

alan.buis@jpl.nasa.gov


2013-180
Posted by Nelio Inacio at 5:30 PM 0 comments
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Pebbly Rocks Testify to Old Streambed on Mars

Pebbly Rocks Testify to Old Streambed on Mars:

Remnants of Ancient Streambed on Mars (White-Balanced View)
NASA's Curiosity rover found evidence for an ancient, flowing stream on Mars at a few sites, including the rock outcrop pictured here, which the science team has named "Hottah" after Hottah Lake in Canada's Northwest Territories. It may look like a broken sidewalk, but this geological feature on Mars is actually exposed bedrock made up of smaller fragments cemented together, or what geologists call a sedimentary conglomerate. Scientists theorize that the bedrock was disrupted in the past, giving it the tilted angle, most likely via impacts from meteorites. Image credit: NASA/JPL-Caltech/MSSS
› Full image and caption

May 30, 2013

PASADENA, Calif. - Detailed analysis and review have borne out researchers' initial interpretation of pebble-containing slabs that NASA's Mars rover Curiosity investigated last year: They are part of an ancient streambed.


The rocks are the first ever found on Mars that contain streambed gravels. The sizes and shapes of the gravels embedded in these conglomerate rocks -- from the size of sand particles to the size of golf balls -- enabled researchers to calculate the depth and speed of the water that once flowed at this location.


"We completed more rigorous quantification of the outcrops to characterize the size distribution and roundness of the pebbles and sand that make up these conglomerates," said Rebecca Williams of the Planetary Science Institute, Tucson, Ariz., lead author of a report about them in the journal Science this week. "We ended up with a calculation in the same range as our initial estimate last fall. At a minimum, the stream was flowing at a speed equivalent to a walking pace -- a meter, or three feet, per second -- and it was ankle-deep to hip-deep."


Three pavement-like rocks examined with the telephoto capability of Curiosity's Mast Camera (Mastcam) during the rover's first 40 days on Mars are the basis for the new report. One, "Goulburn," is immediately adjacent to the rover's "Bradbury Landing" touchdown site. The other two, "Link" and "Hottah," are about 165 and 330 feet (50 and 100 meters) to the southeast. Researchers also used the rover's laser-shooting Chemistry and Camera (ChemCam) instrument to investigate the Link rock.


"These conglomerates look amazingly like streambed deposits on Earth," Williams said. "Most people are familiar with rounded river pebbles. Maybe you've picked up a smoothed, round rock to skip across the water. Seeing something so familiar on another world is exciting and also gratifying."


The larger pebbles are not distributed evenly in the conglomerate rocks. In Hottah, researchers detected alternating pebble-rich layers and sand layers. This is common in streambed deposits on Earth and provides additional evidence for stream flow on Mars. In addition, many of the pebbles are touching each other, a sign that they rolled along the bed of a stream.


"Our analysis of the amount of rounding of the pebbles provided further information," said Sanjeev Gupta of Imperial College, London, a co-author of the new report. "The rounding indicates sustained flow. It occurs as pebbles hit each other multiple times. This wasn't a one-off flow. It was sustained, certainly more than weeks or months, though we can't say exactly how long."


The stream carried the gravels at least a few miles, or kilometers, the researchers estimated.


The atmosphere of modern Mars is too thin to make a sustained stream flow of water possible, though the planet holds large quantities of water ice. Several types of evidence have indicated that ancient Mars had diverse environments with liquid water. However, none but these rocks found by Curiosity could provide the type of stream flow information published this week. Curiosity's images of conglomerate rocks indicate that atmospheric conditions at Gale Crater once enabled the flow of liquid water on the Martian surface.


During a two-year prime mission, researchers are using Curiosity's 10 science instruments to assess the environmental history in Gale Crater on Mars, where the rover has found evidence of ancient environmental conditions favorable for microbial life.


More information about Curiosity is online at: http://www.jpl.nasa.gov/msl , http://www.nasa.gov/msl and http://mars.jpl.nasa.gov/msl/ .


You can follow the mission on Facebook at: http://www.facebook.com/marscuriosity and on Twitter at http://www.twitter.com/marscuriosity .

Guy Webster 818-354-6278

Jet Propulsion Laboratory, Pasadena, Calif.

guy.webster@jpl.nasa.gov


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