Extreme Storms on Uranus Puzzle Astronomers

These infrared images of the planet Uranus show a white spot that is actually a massive storm on the planet. This image was recorded by the Keck II telescope atop Mauna Kea in Hawaii on Aug. 6, 2014 in the 2.2-micron wavelength.


Uranus is finally having some summer storms, seven years after the planet reached its closest approach to the sun, leaving scientists wondering why the massive storms are so late.

The usually quiet gas giant now has such "incredibly active" weather that some of the features are even visible to amateurs, said Imke de Pater, the project's lead researcher and an astronomer at the University of California, Berkeley. Astronomers first announced the extreme storms on Uranus in August, and have been trying to understand them ever since.

This is by far the most active weather de Pater's team has seen on Uranus in the past decade, examining its storms and northern convective features. It also paints a different picture of the quiet planet Voyager 2 saw when the NASA spacecraft flew by in 1986.

"This type of activity would have been expected in 2007, when Uranus' once-every-42-year equinox occurred and the sun shined directly on the equator," research co-investigator Heidi Hammel, of the Association of Universities for Research in Astronomy, said in a statement. "But we predicted that such activity would have died down by now. Why we see these incredible storms now is beyond anybody's guess."

But here's where the mystery comes in: As far as anyone can tell, Uranus has no source of internal heat. Sunlight is thought to be responsible for changes in its atmosphere, such as storms. But the sun's light is currently weak in Uranus' northern hemisphere, so scientists are puzzled as to why that area is so active today.

Huge storms on Uranus

De Pater's team tracked eight large storms in Uranus' northern hemisphere when observing the planet with the Keck II telescope between Aug. 5 and 6. One storm stood out from the rest: Shining in 2.2 microns, a wavelength sensitive to clouds in the tropopause (just below the stratosphere), it made up 30 percent of all of the light reflected from Uranus.
Another storm, visible at 1.6 microns, could even be seen by amateur astronomers. One observer, Marc Delcroix from France, photographed it with his 1-meter telescope.

"I was thrilled to see such activity on Uranus," Delcroix said in a Keck Observatory statement. "Getting details on Mars, Jupiter or Saturn is now routine. But seeing details on Uranus and Neptune are the new frontiers for us amateurs, and I did not want to miss that."

Uranus' extreme weather
Based on the colors and structure of the storm spotted by amateurs, professional astronomers believe it could hint at a vortex deeper in the atmosphere — similar to phenomena spotted on Jupiter, such as the Great Red Spot.

Follow-up observations with the Keck II telescope revealed that the storm was still raging, although it had changed its shape, and possibly its intensity.

Also contributing to the effort was the Hubble Space Telescope, which examined the entire planet of Uranus Oct. 14 in several wavelengths. The observations revealed storms spanning several altitudes, over a distance of about 5,592 miles (9,000 kilometers).

"If, indeed, these features are high-altitude clouds generated by flow perturbations associated with a deeper vortex system, such drastic fluctuations in intensity would indeed be possible," said Larry Sromovsky, a planetary scientist at the University of Wisconsin-Madison who performed the newer work.

New Map Shows Frequency of Small Asteroid Impacts, Provides Clues on Larger Asteroid Population

A map released today by NASA's Near Earth Object (NEO) Program reveals that small asteroids frequently enter and disintegrate in the Earth's atmosphere with random distribution around the globe. Released to the scientific community, the map visualizes data gathered by U.S. government sensors from 1994 to 2013. The data indicate that Earth's atmosphere was impacted by small asteroids, resulting in a bolide (or fireball), on 556 separate occasions in a 20-year period. Almost all asteroids of this size disintegrate in the atmosphere and are usually harmless. The notable exception was the Chelyabinsk event which was the largest asteroid to hit Earth in this period. The new data could help scientists better refine estimates of the distribution of the sizes of NEOs including larger ones that could pose a danger to Earth.
Finding and characterizing hazardous asteroids to protect our home planet is a high priority for NASA. It is one of the reasons NASA has increased by a factor of 10 investments in asteroid detection, characterization and mitigation activities over the last five years. In addition, NASA has aggressively developed strategies and plans with its partners in the U.S. and abroad to detect, track and characterize NEOs. These activities also will help identify NEOs that might pose a risk of Earth impact, and further help inform developing options for planetary defense.
The public can help participate in the hunt for potentially hazardous Near Earth Objects through the Asteroid Grand Challenge, which aims to create a plan to find all asteroid threats to human populations and know what to do about them. NASA is also pursuing an Asteroid Redirect Mission (ARM) which will identify, redirect and send astronauts to explore an asteroid. Among its many exploration goals, the mission could demonstrate basic planetary defense techniques for asteroid deflection.
For more information about the map and data, go to:
http://neo.jpl.nasa.gov
For details about ARM, and the Asteroid Grand Challenge, visit:
http://www.nasa.gov/asteroidinitiative

Jupiter's Red Spot is Likely a Sunburn, Not a Blush

Research suggests effects of sunlight produce the color of Jupiter's Great Red Spot. The feature's clouds are much higher than those elsewhere on the planet, and its vortex nature confines the reddish particles once they form. Image credit: NASA/JPL-Caltech/ Space Science Institute

The ruddy color of Jupiter's Great Red Spot is likely a product of simple chemicals being broken apart by sunlight in the planet's upper atmosphere, according to a new analysis of data from NASA's Cassini mission. The results contradict the other leading theory for the origin of the spot's striking color -- that the reddish chemicals come from beneath Jupiter's clouds.
The results are being presented this week by Kevin Baines, a Cassini team scientist based at NASA's Jet Propulsion Laboratory, Pasadena, California, at the American Astronomical Society's Division for Planetary Science Meeting in Tucson, Arizona.
Baines and JPL colleagues Bob Carlson and Tom Momary arrived at their conclusions using a combination of data from Cassini's December 2000 Jupiter flyby and laboratory experiments.
In the lab, the researchers blasted ammonia and acetylene gases -- chemicals known to exist on Jupiter -- with ultraviolet light, to simulate the sun's effects on these materials at the extreme heights of clouds in the Great Red Spot. This produced a reddish material, which the team compared to the Great Red Spot as observed by Cassini's Visible and Infrared Mapping Spectrometer (VIMS). They found that the light-scattering properties of their red concoction nicely matched a model of the Great Red Spot in which the red-colored material is confined to the uppermost reaches of the giant cyclone-like feature.
"Our models suggest most of the Great Red Spot is actually pretty bland in color, beneath the upper cloud layer of reddish material," said Baines. "Under the reddish 'sunburn' the clouds are probably whitish or grayish." A coloring agent confined to the top of the clouds would be inconsistent with the competing theory, which posits that the spot's red color is due to upwelling chemicals formed deep beneath the visible cloud layers, he said. If red material were being transported from below, it should be present at other altitudes as well, which would make the red spot redder still.
Jupiter is composed almost entirely of hydrogen and helium, with just a sprinkling of other elements. Scientists are interested in understanding what combinations of elements are responsible for the hues seen in Jupiter's clouds, as this would provide insights into the giant planet's make-up.
Baines and colleagues initially set out to determine if the Great Red Spot's color might derive from sun-induced breakdown of a more complex molecule, ammonium hydrosulfide, which makes up one of Jupiter's main cloud layers. They quickly found that instead of a red color, the products their experiment produced were a brilliant shade of green. This surprising negative result prompted the researchers to try simple combinations of ammonia with hydrocarbons that are common at Jupiter's high altitudes. Breaking down ammonia and acetylene with ultraviolet light turned out to best fit the data collected by Cassini.
The Great Red Spot is a long-lived feature in Jupiter's atmosphere that is as wide as two earths. Jupiter possesses three main cloud layers, which occupy specific altitudes in its skies; from highest to lowest they are: ammonia, ammonium hydrosulfide and water clouds.
As for why the intense red color is seen only in the Great Red Spot and a few much smaller spots on the planet, the researchers think altitude plays a key role. "The Great Red Spot is extremely tall," Baines said. "It reaches much higher altitudes than clouds elsewhere on Jupiter."
The team thinks the spot's great heights both enable and enhance the reddening. Its winds transport ammonia ice particles higher into the atmosphere than usual, where they are exposed to much more of the sun's ultraviolet light. In addition, the vortex nature of the spot confines particles, preventing them from escaping. This causes the redness of the spot's cloud tops to increase beyond what might otherwise be expected.
Other areas of Jupiter display a mixed palette of oranges, browns and even shades of red. Baines says these are places where high, bright clouds are known to be much thinner, allowing views to depths in the atmosphere where more colorful substances exist.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology, Pasadena, manages the mission for NASA's Science Mission Directorate in Washington. The VIMS team is based at the University of Arizona in Tucson.
More information about Cassini is available at the following sites:
http://www.nasa.gov/cassini
http://saturn.jpl.nasa.gov

Cassini Sails into New Ocean Adventures on Titan

Cassini's radar instrument images show that a bright feature appeared in Kraken Mare, Titan's largest sea. Image Credit: NASA/JPL-Caltech/ASI/Cornell

NASA's Cassini mission continues its adventures in extraterrestrial oceanography with new findings about the hydrocarbon seas on Saturn's moon Titan. During a flyby in August, the spacecraft sounded the depths near the mouth of a flooded river valley and observed new, bright features in the seas that might be related to the mysterious feature that researchers dubbed the "magic island."
The findings are being presented this week at the Division for Planetary Sciences Meeting of the American Astronomical Society held in Tucson, Arizona.
To the delight of Cassini scientists, two new bright features appeared in Titan's largest sea, Kraken Mare, during the August 21 flyby. In contrast to a previously reported bright, mystery feature in another of Titan's large seas, Ligeia Mare, the new features in Kraken Mare were observed in both radar data and images from Cassini's Visible and Infrared Mapping Spectrometer (VIMS). Having observations at two different wavelengths provides researchers with important clues to the nature of these enigmatic objects.
The VIMS data suggest the new features might have similarities to places in and around the seas that the Cassini team has interpreted as waves or wet ground. The observations support two of the possible explanations the team thinks are most likely -- that the features might be waves or floating debris.
Unfortunately for mystery lovers, the August Titan flyby marked the final opportunity for Cassini's radar to observe Kraken Mare. However, the spacecraft is scheduled to observe the original "magic island" feature in Ligeia Mare once more, in January 2015.
The August Titan flyby also included a segment designed to collect altimetry (or height) data, using the spacecraft's radar instrument along a 120-mile (200-kilometer) shore-to-shore track of Kraken Mare. For a 25-mile (40-kilometer) segment of this data along the sea's eastern shoreline, Cassini's radar beam bounced off the sea bottom and back to the spacecraft, revealing the sea's depth in that area. This region, which is near the mouth of a large, flooded river valley, showed depths of 66 to 115 feet (20 to 35 meters). Cassini will perform this experiment one last time in January 2015, to try to measure the depth of Punga Mare. Punga Mare is the smallest of three large seas in Titan's far north, and the only sea whose depth has not been observed by Cassini.
Scientists think that, for the areas in which Cassini did not observe a radar echo from the seafloor, Kraken Mare might be too deep for the radar beam to penetrate. Alternatively, the signal over this region might simply have been absorbed by the liquid, which is mostly methane and ethane. The altimetry data for the area in and around Kraken Mare also showed relatively steep slopes leading down to the sea, which also suggests the Kraken Mare might indeed be quite deep.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology, Pasadena, manages the mission for NASA's Science Mission Directorate in Washington. The VIMS team is based at the University of Arizona in Tucson. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the US and several European countries.
More information about Cassini is available at the following sites:
http://www.nasa.gov/cassini
http://saturn.jpl.nasa.gov

Follow the Dust to Find Planets

This diagram illustrates two similar star systems, HD 95086 and HR 8799. Evidence from NASA's Spitzer Space Telescope has pointed to the presence of two dust belts in each system: warm, inner belts similar to our solar system's asteroid belt, and cool, outer belts like our Kuiper belt of icy comets. Image credit: NASA/JPL-Caltech

Researchers studying what appears to be a beefed-up version of our solar system have discovered that it is encased in a halo of fine dust. The findings are based on infrared data from NASA's Spitzer Space Telescope and the European Space Agency's Herschel Space Observatory, in which NASA is a partner.
The dusty star system, called HD 95086, is located 295 light-years from Earth in the constellation Carina. It is thought to include two belts of dust, which lie within the newfound outer dust halo. One of these belts is warm and closer to its star, as is the case with our solar system's asteroid belt, while the second belt is cooler and farther out, similar to our own Kuiper belt of icy comets.
"By looking at other star systems like these, we can piece together how our own solar system came to be," said Kate Su, an associate astronomer at the University of Arizona, Tucson, and lead author of the paper.
Within our solar system, the planets Jupiter, Saturn, Uranus and Neptune are sandwiched between the two dust belts. Scientists think something similar is happening in the star system HD 95086, only on larger scales. One planet, about five times the mass of Jupiter, is already known to sit right inside HD 95086's cooler belt. Other massive planets may be lurking between the two dust belts, waiting to be discovered.
Studies like this from Spitzer and Herschel point the way for ground-based telescopes to snap pictures of such planets in hiding, a technique referred to as direct imaging. The one planet known to exist in HD 95086 was, in fact, discovered and imaged using this technique in 2013. The images aren't sharp because the planets are so faint and far away, but they reveal new information about the global architecture of a planetary system.
"By knowing where the debris is, plus the properties of the known planet in the system, we can get an idea of what other kinds of planets can be there," said Sarah Morrison, a co-author of the paper and a PhD student at the University of Arizona. She ran computer models to constrain the possibilities of how many planets are likely to inhabit the system. "We know that we should be looking for multiple planets instead of a single giant planet."
To learn what HD 95086 looks like, the astronomers turned to a similar star system called HR 8799. It too has an inner and outer belt of debris surrounded by a large halo of fine dust, and four known planets between the belts -- among the first exoplanets, or planets beyond our solar system, to be directly imaged.
Comparing data from the two star systems hints that HD95086, like its cousin HR 8799, is a possible home to multiple planets that have yet to be seen. Ground-based telescopes might be able to take pictures of the family of planets.
Both HD 95086 and HR 8799 are much younger and dustier than our solar system. When planetary systems are young and still forming, collisions between growing planetary bodies, asteroids and comets kick up dust. Some of the dust coagulates into planets, some winds up in the belts, and the rest is either blown out into a halo, or funneled onto the star.
Herschel and Spitzer are ideally suited to study the dust structures in these systems, which glow at the infrared wavelengths the telescopes detect.
The researchers will present the findings at the Division for Planetary Science Meeting of the American Astronomical Society held in Tucson, Arizona from Nov. 8 to 15.
Read more about the research at:
http://uanews.org/story/baby-photos-of-a-scaled-up-solar-system
Other coauthors of the paper include Zoltan Balog at the Max-Planck Institute of Astronomy, Heidelberg, Germany, and Renu Malhotra, Paul Smith and George Rieke of the University of Arizona.
NASA's Jet Propulsion Laboratory, Pasadena, California, 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. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. 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://www.nasa.gov/spitzer
Herschel is a European Space Agency mission, with science instruments provided by consortia of European institutes and with important participation by NASA. While the observatory stopped making science observations in April 2013, after running out of liquid coolant as expected, scientists continue to analyze its data. NASA's Herschel Project Office is based at JPL. 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, supports the U.S. astronomical community. More information is online at:
http://www.nasa.gov/herschel

Violent Asteroid Collision Recreated with High-Speed Cannon (Video)

esta, the solar system's brightest asteroid, used to be round until it got pounded by another space rock. The collision not only carved out a huge crater and left Vesta somewhat flattened, but it also cracked opened deep rifts around the asteroid's equator, some of them wider than the Grand Canyon.

To understand how Vesta's belt of fractures formed, scientists tried to recreate this violent impact in a lab and watch it slow motion, by shooting beads at softball-sized spheres with a high-speed cannon.

Scientists recently got a close look at the craggy surface of Vesta, the second most massive body in the asteroid belt, thanks to NASA's Dawn probe. Between 2011 and 2012, the spacecraft orbited the 330-mile-wide (530 kilometers) protoplanet.

"Vesta got hammered," Peter Schultz, a professor of earth, environmental, and planetary sciences at Brown University in Rhode Island, said in a statement. "The whole interior was reverberating, and what we see on the surface is the manifestation of what happened in the interior."

To get a better idea of how that reverberation played out, Schultz and colleagues turned to a massive cannon at the NASA's Ames Research Center in Moffett Field, California.

Dubbed the Ames Vertical Gun Range, the cannon has 14-foot (4.2 meters) barrel that's used to mimic celestial collisions, launching projectiles up to 16,000 mph (25,750 km/h) in vacuum chamber. For these experiments, Schultz's team shot tiny Pyrex beads at larger spheres that were about 4 inches (10 centimeters) in diameter and made of PMMA, a brittle, transparent acrylic material. PMMA is a good substitute for rock because it has mechanical properties similar to that of Earth's upper crust and it becomes opaque under stress, which allows researchers to track the damage.
Images taken with superfast cameras that capture a million shots per second show that the damage starts at the impact point. But then cracks start to form in the sphere's interior, opposite the impact point, the researchers said. These cracks extend to the sphere's center and grow outward toward the sphere's surface, in a pattern that looks like a blooming "rosette," according to the study. The edges of these "petals" are responsible for Vesta's deep canyons.

The experiments also shed light on the orientation of those canyons, which circle Vesta like a belt.

"The belt is askew, as if Vesta were making a fashion statement," Schultz said. That flashy placement suggests the impact object struck at an angle less than 40 degrees, at about 11,000 mph (17,700 km/h).

"Vesta was lucky," Schultz added. "If this collision had been straight on, there would have been one less large asteroid and only a family of fragments left behind."

The study was led Angela Stickle, a former graduate student at Brown, who is now a researcher at the Johns Hopkins University Applied Physics Laboratory. The results have already been published online and will appear in the February 2015 issue of the journal Icarus.

Cassini Sees Sunny Seas on Titan

As it soared past Saturn's large moon Titan recently, NASA's Cassini spacecraft caught a glimpse of bright sunlight reflecting off hydrocarbon seas.
In the past, Cassini had captured, separately, views of the polar seas and the sun glinting off them, but this is the first time both have been seen together in the same view.
The image is available at:
http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA18432
Also in the image:
-- An arrow-shaped complex of bright methane clouds hovers near Titan's north pole. The clouds could be actively refilling the lakes with rainfall.
-- A "bathtub ring," or bright margin, around Kraken Mare -- the sea containing the reflected sunglint -- indicates that the sea was larger at some point, but evaporation has decreased its size.
Titan's seas are mostly liquid methane and ethane. Before Cassini's arrival at Saturn, scientists suspected that Titan might have bodies of open liquid on its surface. Cassini found only great fields of sand dunes near the equator and lower latitudes, but located lakes and seas near the poles, particularly in the north.
The new view shows Titan in infrared light. It was obtained by Cassini's Visible and Infrared Mapping Spectrometer (VIMS) on Aug. 21.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology, Pasadena, manages the mission for NASA's Science Mission Directorate in Washington. The VIMS team is based at the University of Arizona in Tucson.
More information about Cassini is available at the following sites:
http://www.nasa.gov/cassini
http://saturn.jpl.nasa.gov

NASA Mission Provides Its First Look at Martian Upper Atmosphere

NASA's Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft has provided scientists their first look at a storm of energetic solar particles at Mars, produced unprecedented ultraviolet images of the tenuous oxygen, hydrogen, and carbon coronas surrounding the Red Planet, and yielded a comprehensive map of highly variable ozone in the atmosphere underlying the coronas.
The spacecraft, which entered Mars' orbit Sept. 21, now is lowering its orbit and testing its instruments. MAVEN was launched to Mars in November 2013, to help solve the mystery of how the Red Planet lost most of its atmosphere.
"All the instruments are showing data quality that is better than anticipated at this early stage of the mission," said Bruce Jakosky, MAVEN principal investigator at the University of Colorado, Boulder. "All instruments have now been turned on -- although not yet fully checked out -- and are functioning nominally. It's turning out to be an easy and straightforward spacecraft to fly, at least so far. It really looks as if we're headed for an exciting science mission."
Solar energetic particles (SEPs) are streams of high-speed particles blasted from the sun during explosive solar activity like flares or coronal mass ejections (CMEs). Around Earth, SEP storms can damage the sensitive electronics on satellites. At Mars, they are thought to be one possible mechanism for driving atmospheric loss.
A solar flare on Sept. 26 produced a CME that was observed by NASA satellites on both sides of the sun. Computer models of the CME propagation predicted the disturbance and the accompanying SEPs would reach Mars on Sept. 29. MAVEN's Solar Energetic Particle instrument was able to observe the onset of the event that day.
"After traveling through interplanetary space, these energetic particles of mostly protons deposit their energy in the upper atmosphere of Mars," said SEP instrument lead Davin Larson of the Space Sciences Laboratory at the University of California, Berkeley. "A SEP event like this typically occurs every couple weeks. Once all the instruments are turned on, we expect to also be able to track the response of the upper atmosphere to them."
The hydrogen and oxygen coronas of Mars are the tenuous outer fringe of the planet's upper atmosphere, where the edge of the atmosphere meets space. In this region, atoms that were once a part of carbon dioxide or water molecules near the surface can escape to space. These molecules control the climate, so following them allows us to understand the history of Mars over the last four billion years and to track the change from a warm and wet climate to the cold, dry climate we see today. MAVEN observed the edges of the Martian atmosphere using the Imaging Ultraviolet Spectrograph (IUVS), which is sensitive to the sunlight reflected by these atoms.
"With these observations, MAVEN's IUVS has obtained the most complete picture of the extended Martian upper atmosphere ever made," said MAVEN remote sensing team member Mike Chaffin of the University of Colorado, Boulder. "By measuring the extended upper atmosphere of the planet, MAVEN directly probes how these atoms escape to space. The observations support our current understanding that the upper atmosphere of Mars, when compared to Venus and Earth, is only tenuously bound by the Red Planet's weak gravity."
IUVS also created a map of the atmospheric ozone on Mars by detecting the absorption of ultraviolet sunlight by the molecule.
"With these maps we have the kind of complete and simultaneous coverage of Mars that is usually only possible for Earth," said MAVEN remote sensing team member Justin Deighan of the University of Colorado, Boulder. "On Earth, ozone destruction by refrigerator CFCs is the cause of the polar ozone hole. On Mars, ozone is just as easily destroyed by the byproducts of water vapor breakdown by ultraviolet sunlight. Tracking the ozone lets us track the photochemical processes taking place in the Martian atmosphere. We'll be exploring this in more complete detail during MAVEN's primary science mission."
There will be about two weeks of additional instrument calibration and testing before MAVEN starts its primary science mission. This includes an end-to-end test to transmit data between NASA's Curiosity rover on the surface of Mars and Earth using the MAVEN mission's Electra telecommunications relay. The mission aims to start full science gathering in early to mid-November.
MAVEN's principal investigator is based at the University of Colorado's Laboratory for Atmospheric and Space Physics. The university provided two science instruments and leads science operations, as well as education and public outreach, for the mission. The University of California at Berkeley's Space Sciences Laboratory also provided four science instruments for the mission. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the MAVEN project and provided two science instruments for the mission. Lockheed Martin built the spacecraft and is responsible for mission operations. NASA's Jet Propulsion Laboratory in Pasadena, California, provides navigation and Deep Space Network support, as well as the Electra telecommunications relay hardware and operations.
For more about MAVEN, visit:
http://www.nasa.gov/maven

Saturn's Weird Hexagon Vortex Stuns in NASA Photo

What looks like a weird hexagon on Saturn is actually a long-lived jet stream that has swirled around the ringed planet's north pole for more than 30 years. This NASA image, released on Oct. 7, 2014, was actually captured in July 2013 by NASA's Cassini spacecraft.

Forget Saturn's rings. The jewel of the solar system has another stunning feature that only faraway spacecraft can see clearly: a weird hexagon-shaped vortex that's been swirling above Saturn's north pole for at least 30 years.

NASA's Cassini spacecraft captured this dramatic portrait of Saturn's geometric jet stream in July 2013 from about 605,000 miles (973,000 kilometers) away from the planet. The image — which NASA released this week — has a scale of 36 miles (58 km) per pixel and faces the sunlit side of the rings, from about 33 degrees above the ringplane.

The puzzling, hexagonal cloud pattern was first spotted by NASA's Voyager mission in the early 1980s. It was still there after Cassini arrived in orbit around Saturn in 2004 after a long journey from Earth than began in 1997.

Cassini started getting its best views of the six-sided jet stream in August 2009, when sunlight finally began shining on Saturn's northern hemisphere at the start of the planet's northern spring. (Saturn takes 29 years to complete one orbit around the sun and its seasons last roughly seven years.)

The vortex over Saturn spans about 20,000 miles (30,000 km) across, with air currents racing 200 mph (about 322 km/h), according to NASA. Other planets have jet streams but astronomers haven't seen anything like this weather pattern anywhere else. Scientists think the vortex has been able to persist for so long because Saturn, a gas giant, has no landforms to help break up storms like mountains and icecaps do on Earth.

Last year, when NASA released their highest resolution movie of Saturn's wavy jet stream, space agency officials said that there are actually smaller vortices within the main hexagon, some spinning in the opposite direction. "Small" is relative. The biggest of these small storms stretches about 2,200 miles (3,500 km) across — double the size of the biggest hurricane recorded on Earth.

NASA's NuSTAR Telescope Discovers Shockingly Bright Dead Star

High-energy X-rays streaming from a rare and mighty pulsar (magenta), the brightest found to date, can be seen in this new image combining multi-wavelength data from three telescopes. Image credit: NASA/JPL-Caltech/SAO/NOAO



Astronomers have found a pulsating, dead star beaming with the energy of about 10 million suns. This is the brightest pulsar - a dense stellar remnant left over from a supernova explosion - ever recorded. The discovery was made with NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR.
"You might think of this pulsar as the 'Mighty Mouse' of stellar remnants," said Fiona Harrison, the NuSTAR principal investigator at the California Institute of Technology in Pasadena. "It has all the power of a black hole, but with much less mass."
The discovery appears in a new report in the Thursday, Oct. 9, issue of the journal Nature.
The surprising find is helping astronomers better understand mysterious sources of blinding X-rays, called ultraluminous X-ray sources (ULXs). Until now, all ULXs were thought to be black holes. The new data from NuSTAR show at least one ULX, about 12 million light-years away in the galaxy Messier 82 (M82), is actually a pulsar.
"The pulsar appears to be eating the equivalent of a black hole diet," said Harrison. "This result will help us understand how black holes gorge and grow so quickly, which is an important event in the formation of galaxies and structures in the universe."
ULXs are generally thought to be black holes feeding off companion stars -- a process called accretion. They also are suspected to be the long-sought-after "medium-size" black holes - missing links between smaller, stellar-size black holes and the gargantuan ones that dominate the hearts of most galaxies. But research into the true nature of ULXs continues toward more definitive answers.
NuSTAR did not initially set out to study the two ULXs in M82. Astronomers had been observing a recent supernova in the galaxy when they serendipitously noticed pulses of bright X-rays coming from the ULX known as M82 X-2. Black holes do not pulse, but pulsars do.
Pulsars belong to a class of stars called neutron stars. Like black holes, neutron stars are the burnt-out cores of exploded stars, but puny in mass by comparison. Pulsars send out beams of radiation ranging from radio waves to ultra-high-energy gamma rays. As the star spins, these beams intercept Earth like lighthouse beacons, producing a pulsed signal.
"We took it for granted that the powerful ULXs must be massive black holes," said lead study author Matteo Bachetti, of the University of Toulouse in France. "When we first saw the pulsations in the data, we thought they must be from another source."
NASA's Chandra X-ray Observatory and Swift satellite also have monitored M82 to study the same supernova, and confirmed the intense X-rays of M82 X-2 were coming from a pulsar.
"Having a diverse array of telescopes in space means that they can help each other out," said Paul Hertz, director of NASA's astrophysics division in Washington. "When one telescope makes a discovery, others with complementary capabilities can be called in to investigate it at different wavelengths."
The key to NuSTAR's discovery was its sensitivity to high-energy X-rays, as well as its ability to precisely measure the timing of the signals, which allowed astronomers to measure a pulse rate of 1.37 seconds. They also measured its energy output at the equivalent of 10 million suns, or 10 times more than that observed from other X-ray pulsars. This is a big punch for something about the mass of our sun and the size of Pasadena.
How is this puny, dead star radiating so fiercely? Astronomers are not sure, but they say it is likely due to a lavish feast of the cosmic kind. As is the case with black holes, the gravity of a neutron star can pull matter off companion stars. As the matter is dragged onto the neutron star, it heats up and glows with X-rays. If the pulsar is indeed feeding off surrounding matter, it is doing so at such an extreme rate as to have theorists scratching their heads.
Astronomers are planning follow-up observations with NASA's NuSTAR, Swift and Chandra spacecraft to find an explanation for the pulsar's bizarre behavior. The NuSTAR team also will look at more ULXs, meaning they could turn up more pulsars. At this point, it is not clear whether M82 X-2 is an oddball or whether more ULXs beat with the pulse of dead stars. NuSTAR, a relatively small telescope, has thrown a big loop into the mystery of black holes.
"In the news recently, we have seen that another source of unusually bright X-rays in the M82 galaxy seems to be a medium-sized black hole," said astronomer Jeanette Gladstone of the University of Alberta, Canada, who is not affiliated with the study. "Now, we find that the second source of bright X-rays in M82 isn't a black hole at all. This is going to challenge theorists and pave the way for a new understanding of the diversity of these fascinating objects."
More information about NuSTAR is online at: http://www.nasa.gov/nustar

Swirling Cloud at Titan's Pole is Cold and Toxic

Scientists analyzing data from NASA's Cassini mission have discovered that a giant, toxic cloud is hovering over the south pole of Saturn's largest moon, Titan, after the atmosphere there cooled dramatically.
The scientists found that this giant polar vortex contains frozen particles of the toxic compound hydrogen cyanide, or HCN.
"The discovery suggests that the atmosphere of Titan's southern hemisphere is cooling much faster than we expected," said Remco de Kok of Leiden Observatory and SRON Netherlands Institute for Space Research, lead author of the study published today in the journal Nature.
Titan is the only moon in the solar system that is cloaked in a dense atmosphere. Like our home planet, Earth, Titan experiences seasons. As it makes its 29-year orbit around the sun along with Saturn, each season lasts about seven Earth years. The most recent seasonal switch occurred in 2009, when winter gave way to spring in the northern hemisphere, and summer transitioned to autumn in the southern hemisphere.
In May 2012, while Titan's southern hemisphere was experiencing autumn, images from Cassini revealed a huge swirling cloud, several hundred miles across, taking shape above Titan's south pole. This polar vortex appears to be an effect of the change of season.
A puzzling detail about the swirling cloud is its altitude, some 200 miles (about 300 kilometers) above Titan's surface, where scientists thought the temperature was too warm for clouds to form. "We really didn't expect to see such a massive cloud so high in the atmosphere," said de Kok.
Keen to understand what could give rise to this mysterious cloud, the scientists dove into Cassini's observations and found an important clue in the spectrum of sunlight reflected by Titan's atmosphere.
A spectrum splits the light from a celestial body into its constituent colors, revealing signatures of the elements and molecules present. Cassini's visual and infrared mapping spectrometer (VIMS) maps the distribution of chemical compounds in Titan's atmosphere and on its surface.
"The light coming from the polar vortex showed a remarkable difference with respect to other portions of Titan's atmosphere," says de Kok. "We could clearly see a signature of frozen HCN molecules."
As a gas, HCN is present in small amounts in the nitrogen-rich atmosphere of Titan. Finding these molecules in the form of ice was surprising, as HCN can condense to form frozen particles only if the atmospheric temperature is as cold as minus 234 degrees Farenheit (minus 148 degrees Celsius). This is about 200 degrees Fahrenheit (about 100 degrees Celsius) colder than predictions from current theoretical models of Titan's upper atmosphere.
To check whether such low temperatures were actually possible, the team looked at observations from Cassini's composite infrared spectrometer (CIRS), which measures atmospheric temperature at different altitudes. Those data showed that the southern hemisphere of Titan has been cooling rapidly, making it possible to reach the cold temperature needed to form the giant toxic cloud seen on the south pole.
Atmospheric circulation has been drawing large masses of gas towards the south since the change of season in 2009. As HCN gas becomes more concentrated there, its molecules shine brightly at infrared wavelengths, cooling the surrounding air in the process. Another factor contributing to this cooling is the reduced exposure to sunlight in Titan's southern hemisphere as winter approaches there.
"These fascinating results from a body whose seasons are measured in years rather than months provide yet another example of the longevity of the remarkable Cassini spacecraft and its instruments," said Earl Maize, Cassini project manager at NASA's Jet Propulsion Laboratory in Pasadena, California. "We look forward to further revelations as we approach summer solstice for the Saturn system in 2017."

Cassini Watches Mysterious Feature Evolve in Titan Sea

NASA's Cassini spacecraft is monitoring the evolution of a mysterious feature in a large hydrocarbon sea on Saturn's moon Titan. The feature covers an area of about 100 square miles (260 square kilometers) in Ligeia Mare, one of the largest seas on Titan. It has now been observed twice by Cassini's radar experiment, but its appearance changed between the two apparitions.
Images of the feature taken during the Cassini flybys are available at:
http://photojournal.jpl.nasa.gov/catalog/PIA18430
The mysterious feature, which appears bright in radar images against the dark background of the liquid sea, was first spotted during Cassini's July 2013 Titan flyby. Previous observations showed no sign of bright features in that part of Ligeia Mare. Scientists were perplexed to find the feature had vanished when they looked again, over several months, with low-resolution radar and Cassini's infrared imager. This led some team members to suggest it might have been a transient feature. But during Cassini's flyby on August 21, 2014, the feature was again visible, and its appearance had changed during the 11 months since it was last seen.
Scientists on the radar team are confident that the feature is not an artifact, or flaw, in their data, which would have been one of the simplest explanations. They also do not see evidence that its appearance results from evaporation in the sea, as the overall shoreline of Ligeia Mare has not changed noticeably.
The team has suggested the feature could be surface waves, rising bubbles, floating solids, solids suspended just below the surface, or perhaps something more exotic.
The researchers suspect that the appearance of this feature could be related to changing seasons on Titan, as summer draws near in the moon's northern hemisphere. Monitoring such changes is a major goal for Cassini's current extended mission.
"Science loves a mystery, and with this enigmatic feature, we have a thrilling example of ongoing change on Titan," said Stephen Wall, the deputy team lead of Cassini's radar team, based at NASA's Jet Propulsion Laboratory in Pasadena, California. "We're hopeful that we'll be able to continue watching the changes unfold and gain insights about what's going on in that alien sea."

NASA Telescopes Find Clear Skies and Water Vapor on Exoplanet

Astronomers using data from three of NASA's space telescopes -- Hubble, Spitzer and Kepler -- have discovered clear skies and steamy water vapor on a gaseous planet outside our solar system. The planet is about the size of Neptune, making it the smallest planet from which molecules of any kind have been detected.
"This discovery is a significant milepost on the road to eventually analyzing the atmospheric composition of smaller, rocky planets more like Earth," said John Grunsfeld, assistant administrator of NASA's Science Mission Directorate. "Such achievements are only possible today with the combined capabilities of these unique and powerful observatories."
Clouds in a planet's atmosphere can block the view to underlying molecules that reveal information about the planet's composition and history. Finding clear skies on a Neptune-size planet is a good sign that smaller planets might have similarly good visibility.
"When astronomers go observing at night with telescopes, they say 'clear skies' to mean good luck," said Jonathan Fraine of the University of Maryland, College Park, lead author of a new study appearing in Nature. "In this case, we found clear skies on a distant planet. That's lucky for us because it means clouds didn't block our view of water molecules."

The planet, HAT-P-11b, is categorized as an exo-Neptune -- a Neptune-sized planet that orbits the star HAT-P-11. It is located 120 light-years away in the constellation Cygnus. This planet orbits closer to its star than does our Neptune to our sun, making one lap roughly every five days. It is a warm world thought to have a rocky core and gaseous atmosphere. Not much else was known about the composition of the planet, or other exo-Neptunes like it, until now.
Part of the challenge in analyzing the atmospheres of planets like this is their size. Larger Jupiter-like planets are easier to see because of their impressive girth and relatively inflated atmospheres. In fact, researchers already have detected water vapor in the atmospheres of those planets. The handful of smaller planets observed previously had proved more difficult to probe, partly because they all appeared to be cloudy.
In the new study, astronomers set out to look at the atmosphere of HAT-P-11b, not knowing if its weather would call for clouds. They used Hubble's Wide Field Camera 3 and a technique called transmission spectroscopy, in which a planet is observed as it crosses in front of its parent star. Starlight filters through the rim of the planet's atmosphere. If molecules like water vapor are present, they absorb some of the starlight, leaving distinct signatures in the light that reaches our telescopes.
Using this strategy, Hubble was able to detect water vapor in HAT-P-11b. But before the team could celebrate clear skies on the exo-Neptune, they had to show that starspots -- cooler "freckles" on the face of stars -- were not the real sources of water vapor. Cool starspots on the parent star can contain water vapor that might erroneously appear to be from the planet.
The team turned to Kepler and Spitzer. Kepler had been observing one patch of sky for years, and HAT-P-11b happens to lie in the field. Those visible-light data were combined with targeted Spitzer observations taken at infrared wavelengths. By comparing these observations, the astronomers figured out that the starspots were too hot to have any steam. It was at that point the team could celebrate detecting water vapor on a world unlike any in our solar system. This discovery indicates the planet did not have clouds blocking the view, a hopeful sign that more cloudless planets can be located and analyzed in the future.
"We think that exo-Neptunes may have diverse compositions, which reflect their formation histories," said study co-author Heather Knutson of the California Institute of Technology in Pasadena. "Now with data like these, we can begin to piece together a narrative for the origin of these distant worlds."
The results from all three telescopes demonstrate that HAT-P-11b is blanketed in water vapor, hydrogen gas and likely other yet-to-be-identified molecules. Theorists will be drawing up new models to explain the planet's makeup and origins.
"We are working our way down the line, from hot Jupiters to exo-Neptunes," said Drake Deming, a co-author of the study who is also from the University of Maryland. "We want to expand our knowledge to a diverse range of exoplanets."
The astronomers plan to examine more exo-Neptunes in the future, and hope to apply the same method to super-Earths -- massive, rocky cousins to our home world with up to 10 times the mass. Although our solar system doesn't have a super-Earth, NASA's Kepler mission is finding them in droves around other stars. NASA's James Webb Space Telescope, scheduled to launch in 2018, will search super-Earths for signs of water vapor and other molecules; however, finding signs of oceans and potentially habitable worlds is likely a ways off.
"The work we are doing now is important for future studies of super-Earths and even smaller planets, because we want to be able to pick out in advance the planets with clear atmospheres that will let us detect molecules," said Knutson.
Once again, astronomers will be crossing their fingers for clear skies.

NASA Pluto-Bound Spacecraft Crosses Neptune's Orbit

NASA's Pluto-bound New Horizons spacecraft has traversed the orbit of Neptune. This is its last major crossing en route to becoming the first probe to make a close encounter with distant Pluto on July 14, 2015.
The sophisticated piano-sized spacecraft, which launched in January 2006, reached Neptune's orbit -- nearly 2.75 billion miles (4.4. billion kilometers) from Earth -- in a record eight years and eight months. New Horizons' milestone matches precisely the 25th anniversary of the historic encounter of NASA's Voyager 2 spacecraft with Neptune on Aug. 25, 1989.
"It's a cosmic coincidence that connects one of NASA's iconic past outer solar system explorers, with our next outer solar system explorer," said Jim Green, director of NASA's Planetary Science Division, NASA Headquarters in Washington. "Exactly 25 years ago at Neptune, Voyager 2 delivered our 'first' look at an unexplored planet. Now it will be New Horizons' turn to reveal the unexplored Pluto and its moons in stunning detail next summer on its way into the vast outer reaches of the solar system."
New Horizons now is about 2.48 billion miles (nearly 4 billion kilometers) from Neptune -- nearly 27 times the distance between Earth and our sun -- as it crosses the giant planet's orbit at 7:04 p.m. PDT (10:04 p.m. EDT) Monday. Although the spacecraft will be much farther from the planet than Voyager 2's closest approach, New Horizons' telescopic camera was able to obtain several long-distance "approach" shots of Neptune on July 10.
"NASA's Voyager 1 and 2 explored the entire middle zone of the solar system where the giant planets orbit," said Alan Stern, New Horizons principal investigator at the Southwest Research Institute in Boulder, Colorado. "Now we stand on Voyager's broad shoulders to explore the even more distant and mysterious Pluto system."
Several senior members of the New Horizons science team were young members of Voyager's science team in 1989. Many remember how Voyager 2's approach images of Neptune and its planet-sized moon Triton fueled anticipation of the discoveries to come. They share a similar, growing excitement as New Horizons begins its approach to Pluto.
"The feeling 25 years ago was that this was really cool, because we're going to see Neptune and Triton up-close for the first time," said Ralph McNutt of the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, who leads the New Horizons energetic-particle investigation and served on the Voyager plasma-analysis team. "The same is happening for New Horizons. Even this summer, when we're still a year out and our cameras can only spot Pluto and its largest moon as dots, we know we're in for something incredible ahead."
Voyager's visit to the Neptune system revealed previously unseen features of Neptune itself, such as the Great Dark Spot, a massive storm similar to, but not as long-lived, as Jupiter's Great Red Spot. Voyager also, for the first time, captured clear images of the ice giant's ring system, too faint to be clearly viewed from Earth. "There were surprises at Neptune and there were surprises at Triton," said Ed Stone, Voyager's long-standing project scientist from the California Institute of Technology in Pasadena. "I'm sure that will continue at Pluto."
Many researchers feel the 1989 Neptune flyby -- Voyager's final planetary encounter -- might have offered a preview of what's to come next summer. Scientists suggest that Triton, with its icy surface, bright poles, varied terrain and cryovolcanoes, is a Pluto-like object that Neptune pulled into orbit. Scientists recently restored Voyager's footage of Triton and used it to construct the best global color map of that strange moon yet -- further whetting appetites for a Pluto close-up.
"There is a lot of speculation over whether Pluto will look like Triton, and how well they'll match up," McNutt said. "That's the great thing about first-time encounters like this -- we don't know exactly what we'll see, but we know from decades of experience in first-time exploration of new planets that we will be very surprised."
Similar to Voyager 1 and 2's historic observations, New Horizons also is on a path toward potential discoveries in the Kuiper Belt, which is a disc-shaped region of icy objects past the orbit of Neptune, and other unexplored realms of the outer solar system and beyond.
"No country except the United States has the demonstrated capability to explore so far away," said Stern. "The U.S. has led the exploration of the planets and space to a degree no other nation has, and continues to do so with New Horizons. We're incredibly proud that New Horizons represents the nation again as NASA breaks records with its newest, farthest and very capable planetary exploration spacecraft."
Voyager 1 and 2 were launched 16 days apart in 1977, and one of the spacecraft visited Jupiter, Saturn, Uranus and Neptune. Voyager 1 now is the most distant human-made object, about 12 billion miles (19 billion kilometers) away from the sun. In 2012, it became the first human-made object to venture into interstellar space. Voyager 2, the longest continuously operated spacecraft, is about 9 billion miles (15 billion kilometers) away from our sun.

Sniffing Out Alien Life: Stinky Chemicals May Be Key

If Professor Hubert Farnsworth's "Smell-O-Scope" actually existed, astrobiologists would have pointed it at dozens of alien planets by now.
The Professor's odor-detecting invention, which was featured in several episodes of the animated sci-fi series "Futurama," would be a good life-hunting tool, researchers say, because alien organisms may betray their presence by pumping stinky chemicals into their home planets' skies.
"I joke often that maybe you want to smell for life on other planets instead of look for it with a telescope," Shawn Domagal-Goldman, a scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, said last month during a NASA panel discussion about ancient Earth and habitable exoplanets. [10 Exoplanets That Could Host Alien Life]

 

Hunting for biosignatures
Domagal-Goldman and other researchers spend a lot of time thinking about the best biosignatures, or signs of life, to look for in the atmospheres of faraway planets.
Two good candidates are oxygen and methane, both of which disappear from atmospheres without replenishment. While each substance can be created by geological as well as biological processes, detecting both oxygen and methane in an exoplanet's skies simultaneously would be strongly suggestive of alien life, many scientists say.
"They destroy each other," Domagal-Goldman said. "If they're both there together, you know someone is bringing the methane in an atmosphere rich in oxygen, so that's what you're looking for. The most likely explanation is, it's life that's bringing the methane and oxygen to the party."
The methane-oxygen strategy is informed by the biosignatures that currently swirl in Earth's skies: Plants and cyanobacteria generate oxygen, while many other types of bacteria, as well as animals, pump out methane.
But a comprehensive hunt for alien biosignatures should also look deeper into Earth's biological history, drawing further inspiration from the planet's pioneering first organisms, Domagal-Goldman stressed.

Different worlds
Life first appeared on Earth perhaps 3.7 billion years ago and had become indisputably established by 3.5 billion years ago, scientists say. It took a long, long time, however, for the biosphere we're familiar with today to take shape.
Simple microbial life dominated the planet for billions of years, with complex multicellular forms getting a firm foothold just 800 million years ago or so. And while oxygen-producing cyanobacteria may have evolved as early as 3 billion years ago, oxygen apparently didn’t start accumulating in the planet's atmosphere until 2.3 billion years ago or so, said Tim Lyons of the University of California-Riverside, who also participated in the NASA panel discussion last month.

So the oxygen-methane strategy would not have picked up signs of life on the early ("Archaean") Earth, even though the planet was teeming with organisms — just as it may result in false negatives when applied to exoplanets as well, researchers said.

But studying the microbes that thrive today in Earth's oxygen-free environments suggests a way to broaden the search for alien life. For example, Archaean life probably released some pretty stinky stuff into the ancient planet's air, such as sulfur-methyl gases, which Domagal-Goldman recalled smelling while walking past a colleague's lab.
"They don't last long in modern-day Earth's environment because they get oxidized," he said. "But if you went back to the Archaean, or any planet without oxygen, and you had life making these gases — which they clearly do; I detected them myself — then they might have built up enough for us to see with a telescope from far away."
Scientists have proposed looking for other biosignatures as well, including industrial pollutants such as cholorfluorocarbons that could be indicators of advanced alien civilizations.

Unfamiliar life
Of course, even looking back to the biosignatures of ancient Earth still involves a very large assumption — that alien life will probably resemble Earth life in important ways.
That would seem to suggest that it will be tough to detect lifeforms vastly different from those of Earth — organisms with exotic and undreamed of metabolic pathways. But Lyons thinks astrobiologists shouldn't view the challenge as insurmountable.
"We have chemical principles, and we hope that those are universal," Lyons said. "Life today is about the flow of electrons amongst bacteria, simple, single-celled organisms. And so if you had a sense for the chemistry on that [alien] planet that you're inferring from an atmosphere, you could start to envision reactions that could lead to that chemistry that could be a source of energy."

Hundreds of Methane Plumes Erupting Along East Coast

In an unexpected discovery, hundreds of gas plumes bubbling up from the seafloor were spotted during a sweeping survey of the U.S. Atlantic Coast.
Even though ocean explorers have yet to test the gas, the bubbles are almost certainly methane, researchers report today (Aug. 24) in the journal Nature Geoscience.
"We don't know of any explanation that fits as well as methane," said lead study author Adam Skarke, a geologist at Mississippi State University in Mississippi State.

Surprising seeps

Between North Carolina's Cape Hatteras and Massachusetts' Georges Bank, 570 methane seeps cluster in about eight regions, according to sonar and video gathered by the National Oceanographic and Atmospheric Administration ship Okeanos Explorer between 2011 and 2013. The vast majority of the seeps dot the continental slope break, where the seafloor topography swoops down toward the Atlantic Ocean basin. [Gallery: Amazing images of Atlantic Methane Seeps]
The Okeanos Explorer used sound waves to detect the methane bubbles and map the seafloor. The technique, called multibeam sonar, calculates the time and distance it takes for sound waves to travel from the ship to the seafloor and back. The sonar can also detect the density contrast between gas bubbles and seawater.
Huge canyons etched in the shallow continental shelf also hide bubble plumes, as well as diverse ecosystems that are based on methane-loving bacteria. In 2013, researchers explored a handful of these seeps with Jason, a remotely operated vehicle, finding them teeming with crabs, fish and mussel beds. In Norfolk canyon off the coast of Virginia, researchers from the University of North Carolina at Wilmington discovered the largest methane seep ever found in the Atlantic Ocean, and possibly all the world's oceans. [Photos: Unique Life Found at East Coast Gas Seep]
Most of the methane seeps are in water less than 1,640 feet (500 meters) deep. Most of these shallow methane seeps seem to arise from microbes blurping out methane, the researchers said. The researchers did find some deeper methane vents, at which the ROV Jason glimpsed patches of methane hydrate. This is the icy mix of methane and water that appears when deep ocean pressures and cold temperatures force methane to solidify. Any type of methane gas can form hydrates.

An illustration of the Atlantic margin showing the relationship between methane seeps and seafloor features.
Credit: A. Skarke and C. Ruppel/Nature Geoscience

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While methane vents are common around the world, only three natural gas seeps — where methane escapes from seafloor sediments — had been found off the East Coast before 2012.
"It was a surprise to find these features," Skarke said. "It was unexpected because many of the common things associated with methane gas do not exist on the Atlantic margin."
Gas, gas, gas?
The East Coast is a passive margin, and methane isn't expected to come out of this environment. The margin hasn't been squeezed or pulled by plate tectonic activity for tens of millions of years, and that means a lack of escape routes for methane. "I usually describe passive margins as cold, old and boring," said study co-author Carolyn Ruppel, chief of the U.S. Geological Survey gas hydrates project in Woods Hole, Massachusetts. [In Images: How North America Grew as a Continent]
Also missing from the Atlantic Coast are layers of salt, which are responsible for the Gulf of Mexico's oil and gas.

Without more exploring, the researchers can't say for sure why there are so many methane plumes along the Atlantic coastline. "It's a huge research area that needs to be pursued," Ruppel said.
If the East Coast could hide hundreds of bubbling methane pits, then it's likely there are nearly 30,000 more awaiting discovery in the world's oceans, the researchers said.
"These processes may be happening in places we didn't expect them," Skarke said.

Cup corals and bubblegum corals live on rock near the edge of the mussel bed.
Credit: NOAA Okeanos Explorer Program, 2013 Northeast U.S. Canyons Expedition

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There's also a good chance more methane vents will be found off the East Coast, but that doesn't mean one should expect new drilling platforms popping up offshore to extract the gas, the researchers said. "We have no evidence to suggest this material would be a recoverable resource," Skarke told Live Science. "There is no evidence whatsoever that there are conventional deep-seated oil and gas reservoirs underneath the Atlantic margin."
The more likely scenario: A fleet of research ships hurries to claim the seeps. The methane seeps are near ports where many of the U.S. research ships dock. The ease of access has set off an exploration stampede, with several new projects in planning stages or already funded.
"We're setting the stage for a decade of discovery," Ruppel said.
From the Arctic to Atlantic
Interest is running high because the seeps could be a laboratory for studying how methane hydrates respond to climate change.
Methane is a greenhouse gas that disappears more quickly than carbon dioxide in the atmosphere, but has more warming power than carbon dioxide. Millions of tons of methane are frozen in Arctic permafrost, both on land and in the seafloor. Recently, several studies have warned that rapid warming in the Arctic could upset these deposits, melting them and freeing the gas. This would boost the planet's greenhouse gas levels and could accelerate climate change.

A close-up of methane hydrate observed at a depth of 3,460 feet (1,055 meters) off the U.S. Atlantic Coast.
Credit: NOAA Okeanos Explorer Program/2013 Northeast U.S. Canyons Expedition

View full size image

"Now we have a study site where we can monitor these locations and see how they change," said David Valentine, a geochemist at the University of California, Santa Barbara, who was not involved in the study. "Finally we have a place where we can begin to address some of the questions about how water temperatures are influencing methane."
At present, scientists think the East Coast seeps don't contribute much methane to climate change.
Most of the methane gas dissolves in the ocean before reaching the surface, Ruppel said. The total amount of gas is also much smaller than sources on land, such as cows or gas drilling. "It's probably on the order of a feedlot of methane," Valentine said. However, some shallow-water seeps could vent methane to the surface, and researchers expect that future surveys will uncover even more shallow seeps. These regions only received a cursory look during the survey.
Even though the methane may not escape to the atmosphere, the gas still adds to the ocean's overall carbon budget — which is still a wildly uncertain number.
"It's not a huge number, but it's an important number for us to know," Ruppel said.

Voyager Map Details Neptune's Strange Moon Triton

NASA's Voyager 2 spacecraft gave humanity its first close-up look at Neptune and its moon Triton in the summer of 1989. Like an old film, Voyager's historic footage of Triton has been "restored" and used to construct the best-ever global color map of that strange moon. The map, produced by Paul Schenk, a scientist at the Lunar and Planetary Institute in Houston, has also been used to make a movie recreating that historic Voyager encounter, which took place 25 years ago, on August 25, 1989.
The new Triton map has a resolution of 1,970 feet (600 meters) per pixel. The colors have been enhanced to bring out contrast but are a close approximation to Triton's natural colors. Voyager's "eyes" saw in colors slightly different from human eyes, and this map was produced using orange, green and blue filter images.
In 1989, most of the northern hemisphere was in darkness and unseen by Voyager. Because of the speed of Voyager's visit and the slow rotation of Triton, only one hemisphere was seen clearly at close distance. The rest of the surface was either in darkness or seen as blurry markings.
The production of the new Triton map was inspired by anticipation of NASA's New Horizons encounter with Pluto, coming up a little under a year from now. Among the improvements on the map are updates to the accuracy of feature locations, sharpening of feature details by removing some of the blurring effects of the camera, and improved color processing.
Although Triton is a moon of a planet and Pluto is a dwarf planet, Triton serves as a preview of sorts for the upcoming Pluto encounter. Although both bodies originated in the outer solar system, Triton was captured by Neptune and has undergone a radically different thermal history than Pluto. Tidal heating has likely melted the interior of Triton, producing the volcanoes, fractures and other geological features that Voyager saw on that bitterly cold, icy surface.
Pluto is unlikely to be a copy of Triton, but some of the same types of features may be present. Triton is slightly larger than Pluto, has a very similar internal density and bulk composition, and has the same low-temperature volatiles frozen on its surface. The surface composition of both bodies includes carbon monoxide, carbon dioxide, methane and nitrogen ices.
Voyager also discovered atmospheric plumes on Triton, making it one of the known active bodies in the outer solar system, along with objects such as Jupiter's moon Io and Saturn's moon Enceladus. Scientists will be looking at Pluto next year to see if it will join this list. They will also be looking to see how Pluto and Triton compare and contrast, and how their different histories have shaped the surfaces we see.
Although a fast flyby, New Horizons' Pluto encounter on July 14, 2015, will not be a replay of Voyager but more of a sequel and a reboot, with a new and more technologically advanced spacecraft and, more importantly, a new cast of characters. Those characters are Pluto and its family of five known moons, all of which will be seen up close for the first time next summer.
Triton may not be a perfect preview of coming attractions, but it serves as a prequel to the cosmic blockbuster expected when New Horizons arrives at Pluto next year.
The new Triton map and movie can be found at:
http://www.lpi.usra.edu/icy_moons/

NASA's NuSTAR Sees Rare Blurring of Black Hole Light

NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) has captured an extreme and rare event in the regions immediately surrounding a supermassive black hole. A compact source of X-rays that sits near the black hole, called the corona, has moved closer to the black hole over a period of just days.
"The corona recently collapsed in toward the black hole, with the result that the black hole's intense gravity pulled all the light down onto its surrounding disk, where material is spiraling inward," said Michael Parker of the Institute of Astronomy in Cambridge, United Kingdom, lead author of a new paper on the findings appearing in the Monthly Notices of the Royal Astronomical Society.
As the corona shifted closer to the black hole, the gravity of the black hole exerted a stronger tug on the X-rays emitted by it. The result was an extreme blurring and stretching of the X-ray light. Such events had been observed previously, but never to this degree and in such detail.
Supermassive black holes are thought to reside in the centers of all galaxies. Some are more massive and rotate faster than others. The black hole in this new study, referred to as Markarian 335, or Mrk 335, is about 324 million light-years from Earth in the direction of the Pegasus constellation. It is one of the most extreme of the systems for which the mass and spin rate have ever been measured. The black hole squeezes about 10 million times the mass of our sun into a region only 30 times the diameter of the sun, and it spins so rapidly that space and time are dragged around with it.
Even though some light falls into a supermassive black hole never to be seen again, other high-energy light emanates from both the corona and the surrounding accretion disk of superheated material. Though astronomers are uncertain of the shape and temperature of coronas, they know that they contain particles that move close to the speed of light.
NASA's Swift satellite has monitored Mrk 335 for years, and recently noted a dramatic change in its X-ray brightness. In what is called a target-of-opportunity observation, NuSTAR was redirected to take a look at high-energy X-rays from this source in the range of 3 to 79 kiloelectron volts. This particular energy range offers astronomers a detailed look at what is happening near the event horizon, the region around a black hole from which light can no longer escape gravity's grasp.
Follow-up observations indicate that the corona is still in this close configuration, months after it moved. Researchers don't know whether and when the corona will shift back. What's more, the NuSTAR observations reveal that the grip of the black hole's gravity pulled the corona's light onto the inner portion of its superheated disk, better illuminating it. Almost as if somebody had shone a flashlight for the astronomers, the shifting corona lit up the precise region they wanted to study.
The new data could ultimately help determine more about the mysterious nature of black hole coronas. In addition, the observations have provided better measurements of Mrk 335's furious relativistic spin rate. Relativistic speeds are those approaching the speed of light, as described by Albert Einstein's theory of relativity.
"We still don't understand exactly how the corona is produced or why it changes its shape, but we see it lighting up material around the black hole, enabling us to study the regions so close in that effects described by Einstein's theory of general relativity become prominent," said NuSTAR Principal Investigator Fiona Harrison of the California Institute of Technology (Caltech) in Pasadena. "NuSTAR's unprecedented capability for observing this and similar events allows us to study the most extreme light-bending effects of general relativity."

Cassini Tracks Clouds Developing Over a Titan Sea

NASA's Cassini spacecraft recently captured images of clouds moving across the northern hydrocarbon seas of Saturn's moon Titan. This renewed weather activity, considered overdue by researchers, could finally signal the onset of summer storms that atmospheric models have long predicted.
A movie showing the clouds' movement is available at:
http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA18420
The Cassini spacecraft obtained the new views in late July, as it receded from Titan after a close flyby. Cassini tracked the system of clouds developing and dissipating over the large methane sea known as Ligeia Mare for more than two days. Measurements of cloud motions indicate wind speeds of around 7 to 10 mph (3 to 4.5 meters per second).
For several years after Cassini's 2004 arrival in the Saturn system, scientists frequently observed cloud activity near Titan's south pole, which was experiencing late summer at the time. Clouds continued to be observed as spring came to Titan's northern hemisphere. But since a huge storm swept across the icy moon's low latitudes in late 2010, only a few small clouds have been observed anywhere on the icy moon. The lack of cloud activity has surprised researchers, as computer simulations of Titan's atmospheric circulation predicted that clouds would increase in the north as summer approached, bringing increasingly warm temperatures to the atmosphere there.
"We're eager to find out if the clouds' appearance signals the beginning of summer weather patterns, or if it is an isolated occurrence," said Elizabeth Turtle, a Cassini imaging team associate at the Johns Hopkins University Applied Physics Lab in Laurel, Maryland. "Also, how are the clouds related to the seas? Did Cassini just happen catch them over the seas, or do they form there preferentially?"
A year on Titan lasts about 30 Earth years, with each season lasting about seven years. Observing seasonal changes on Titan will continue to be a major goal for the Cassini mission as summer comes to Titan's north and the southern latitudes fall into winter darkness.

Aliens Could Live Like This! Life Found in Oily Goo

Extremely tiny newfound habitats hidden within oil could expand the potential for life in the universe, researchers say.
Scientists have discovered microbes living in microscopic droplets of water inside a giant asphalt lake on Earth, suggesting that alien life could perhaps exist within ponds of sludge on distant landscapes such as Saturn's largest moon Titan.
Researchers investigated the largest naturally occurring asphalt lake on Earth, Pitch Lake on the Caribbean island of Trinidad. Black goo there oozes across roughly 114 acres (0.46 square kilometers), an area equivalent to nearly 90 football fields. [See Photos of Pitch Lake and 'Alien Life' Oil Droplets]
 Prior studies had found that microbes could thrive at the boundary where oil and water meet in nature, helping to break down the oil. However, investigators had thought oil was too toxic for life, and that the levels of any water inside the oil were below the threshold for life on Earth. "Oil was considered to be dead,"said lead study author Rainer Meckenstock, an environmental microbiologist at Helmholtz Zentrum München, in Germany.
Now, scientists find microbes active within Pitch Lake, dwelling inside water droplets as small as 1 microliter, about one-fiftieth the size of an average drop of water.

 

"Each of these water droplets basically contains a little mini-ecosystem,"study co-author Dirk Schulze-Makuch, an astrobiologist at Washington State University in Pullman, told Live Science.

These droplets contain a diverse group of microbial species that are breaking the oil down into a variety of organic molecules. The chemistry of the droplets suggests this water does not come from rain, but from ancient seawater, or brine from deep underground.

"The microbes most likely were enclosed in droplets in the deep subsurface and ascended together with the oil," Meckenstock told Live Science.
These findings suggest microbes could play a greater role in breaking down oil than previously thought, Schulze-Makuch said.
"Even at the highest oil concentrations in, for example, an oil spill or contaminated groundwater, you can expect a vibrant microbial community eating the oil," Meckenstock said.
However, while microbes could break down oil more than previously suspected, this does not mean oil deposits will suddenly vanish, Meckenstock said. These processes are still "extremely slow and take geological time frames, say millions of years," Meckenstock said. "We have very little droplets and enormous amounts of oil."
The discovery of these new microscopic habitats for life may also have implications for Titan, which has hydrocarbon lakes on its surface, Schulze-Makuch said. Water-ammonia mixtures may rise up to Titan's surface from below, just as the water found in droplet form in Pitch Lake is thought to have.
The researchers plan to investigate "how life in the droplets works and how the ecology of these mini-ecosystems functions," Meckenstock said.

Understanding how life can survive in water droplets trapped within oil "would give us better ideas how organisms on Titan, if they exist, could adapt to live in those hydrocarbons," Schulze-Makuch said

Cassini Spacecraft Reveals 101 Geysers and More on Icy Saturn Moon

Scientists using mission data from NASA's Cassini spacecraft have identified 101 distinct geysers erupting on Saturn's icy moon Enceladus. Their analysis suggests it is possible for liquid water to reach from the moon's underground sea all the way to its surface.
These findings, and clues to what powers the geyser eruptions, are presented in two articles published in the current online edition of the Astronomical Journal.
Over a period of almost seven years, Cassini's cameras surveyed the south polar terrain of the small moon, a unique geological basin renowned for its four prominent "tiger stripe" fractures and the geysers of tiny icy particles and water vapor first sighted there nearly 10 years ago. The result of the survey is a map of 101 geysers, each erupting from one of the tiger stripe fractures, and the discovery that individual geysers are coincident with small hot spots. These relationships pointed the way to the geysers' origin.
After the first sighting of the geysers in 2005, scientists suspected that repeated flexing of Enceladus by Saturn's tides as the moon orbits the planet had something to do with their behavior. One suggestion included the back-and-forth rubbing of opposing walls of the fractures generating frictional heat that turned ice into geyser-forming vapor and liquid.
Alternate views held that the opening and closing of the fractures allowed water vapor from below to reach the surface. Before this new study, it was not clear which process was the dominating influence. Nor was it certain whether excess heat emitted by Enceladus was everywhere correlated with geyser activity.
To determine the surface locations of the geysers, researchers employed the same process of triangulation used historically to survey geological features on Earth, such as mountains. When the researchers compared the geysers' locations with low-resolution maps of thermal emission, it became apparent the greatest geyser activity coincided with the greatest thermal radiation. Comparisons between the geysers and tidal stresses revealed similar connections. However, these correlations alone were insufficient to answer the question, "What produces what?"
The answer to this mystery came from comparison of the survey results with high-resolution data collected in 2010 by Cassini's heat-sensing instruments. Individual geysers were found to coincide with small-scale hot spots, only a few dozen feet (or tens of meters) across, which were too small to be produced by frictional heating, but the right size to be the result of condensation of vapor on the near-surface walls of the fractures. This immediately implicated the hot spots as the signature of the geysering process.
"Once we had these results in hand, we knew right away heat was not causing the geysers, but vice versa," said Carolyn Porco, leader of the Cassini imaging team from the Space Science Institute in Boulder, Colorado, and lead author of the first paper. "It also told us the geysers are not a near-surface phenomenon, but have much deeper roots."
Thanks to recent analysis of Cassini gravity data, the researchers concluded the only plausible source of the material forming the geysers is the sea now known to exist beneath the ice shell. They also found that narrow pathways through the ice shell can remain open from the sea all the way to the surface, if filled with liquid water.
In the companion paper, the authors report the brightness of the plume formed by all the geysers, as seen with Cassini's high-resolution cameras, changes periodically as Enceladus orbits Saturn. Armed with the conclusion that the opening and closing of the fractures modulates the venting, the authors compared the observations with the expected venting schedule due to tides.
They found the simplest model of tidal flexing provides a good match for the brightness variations Cassini observes, but it does not predict the time when the plume begins to brighten. Some other important effect is present and the authors considered several in the course of their work.

NASA Long-Lived Mars Opportunity Rover Sets Off-World Driving Record

NASA's Opportunity Mars rover, which landed on the Red Planet in 2004, now holds the off-Earth roving distance record after accruing 25 miles (40 kilometers) of driving. The previous record was held by the Soviet Union's Lunokhod 2 rover.
"Opportunity has driven farther than any other wheeled vehicle on another world," said Mars Exploration Rover Project Manager John Callas, of NASA's Jet Propulsion Laboratory in Pasadena, California. "This is so remarkable considering Opportunity was intended to drive about one kilometer and was never designed for distance. But what is really important is not how many miles the rover has racked up, but how much exploration and discovery we have accomplished over that distance."
A drive of 157 feet (48 meters) on July 27 put Opportunity's total odometry at 25.01 miles (40.25 kilometers). This month's driving brought the rover southward along the western rim of Endeavour Crater. The rover had driven more than 20 miles (32 kilometers) before arriving at Endeavour Crater in 2011, where it has examined outcrops on the crater's rim containing clay and sulfate-bearing minerals. The sites are yielding evidence of ancient environments with less acidic water than those examined at Opportunity's landing site.
If the rover can continue to operate the distance of a marathon -- 26.2 miles (about 42.2 kilometers) -- it will approach the next major investigation site mission scientists have dubbed "Marathon Valley." Observations from spacecraft orbiting Mars suggest several clay minerals are exposed close together at this valley site, surrounded by steep slopes where the relationships among different layers may be evident.
The Russian Lunokhod 2 rover, a successor to the first Lunokhod mission in 1970, landed on Earth's moon on Jan. 15, 1973, where it drove about 24.2 miles (39 kilometers) in less than five months, according to calculations recently made using images from NASA's Lunar Reconnaissance Orbiter (LRO) cameras that reveal Lunokhod 2's tracks.
Irina Karachevtseva at Moscow State University of Geodesy and Cartography's Extraterrestrial Laboratory in Russia, Brad Jolliff of Washington University in St. Louis, Tim Parker of JPL, and others collaborated to verify the map-based methods for computing distances are comparable for Lunokhod-2 and Opportunity.
"The Lunokhod missions still stand as two signature accomplishments of what I think of as the first golden age of planetary exploration, the 1960s and '70s," said Steve Squyres of Cornell University in Ithaca, New York, and principal investigator for NASA's twin Mars rovers, Opportunity and Spirit. "We're in a second golden age now, and what we've tried to do on Mars with Spirit and Opportunity has been very much inspired by the accomplishments of the Lunokhod team on the moon so many years ago. It has been a real honor to follow in their historical wheel tracks."
As Opportunity neared the mileage record earlier this year, the rover team chose the name Lunokhod 2 for a crater about 20 feet (6 meters) in diameter on the outer slope of Endeavour's rim on Mars.