Sunday, July 27, 2014

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
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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
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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
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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


2013-181
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NASA Radar Reveals Asteroid Has Its Own Moon

NASA Radar Reveals Asteroid Has Its Own Moon:

First radar images of asteroid 1998 QE2 were obtained when the asteroid was about 3.75 million miles
First radar images of asteroid 1998 QE2 were obtained when the asteroid was about 3.75 million miles (6 million kilometers) from Earth. The small white dot at lower right is the moon, or satellite, orbiting asteroid 1998 QE2.
Image credit: NASA/JPL-Caltech/GSSR

› Larger image

May 30, 2013

PASADENA, Calif. -- A sequence of radar images of asteroid 1998 QE2 was obtained on the evening of May 29, 2013, by NASA scientists using the 230-foot (70-meter) Deep Space Network antenna at Goldstone, Calif., when the asteroid was about 3.75 million miles (6 million kilometers) from Earth, which is 15.6 lunar distances.


The radar imagery revealed that 1998 QE2 is a binary asteroid. In the near-Earth population, about 16 percent of asteroids that are about 655 feet (200 meters) or larger are binary or triple systems. Radar images suggest that the main body, or primary, is approximately 1.7 miles (2.7 kilometers) in diameter and has a rotation period of less than four hours. Also revealed in the radar imagery of 1998 QE2 are several dark surface features that suggest large concavities. The preliminary estimate for the size of the asteroid's satellite, or moon, is approximately 2,000 feet (600 meters) wide. The radar collage covers a little bit more than two hours.


The radar observations were led by scientist Marina Brozovic of NASA's Jet Propulsion Laboratory, Pasadena, Calif.


The closest approach of the asteroid occurs on May 31 at 1:59 p.m. Pacific (4:59 p.m. Eastern / 20:59 UTC), when the asteroid will get no closer than about 3.6 million miles (5.8 million kilometers), or about 15 times the distance between Earth and the moon. 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, N.M.


The resolution of these initial images of 1998 QE2 is approximately 250 feet (75 meters) per pixel. Resolution is expected to increase in the coming days as more data become available. 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, will perform an extensive campaign of observations on asteroid 1998 QE2. 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.


Radar is a powerful technique for studying an asteroid's size, shape, rotation state, surface features and surface roughness, and for improving the calculation of asteroid orbits. Radar measurements of asteroid distances and velocities often enable computation of asteroid orbits much further into the future than if radar observations weren't available.


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


In 2012, the Near-Earth Object budget was increased from $6 million to $20 million. Literally dozens of people are involved with some aspect of near-Earth object 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 objects that come close to 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 Near-Earth Objects. 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 development of a first-ever mission to identify, capture and relocate an asteroid for human exploration. Using game-changing technologies 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


2013-182
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NASA's GRAIL Mission Solves Mystery of Moon's Surface Gravity

NASA's GRAIL Mission Solves Mystery of Moon's Surface Gravity:

Using a precision formation-flying technique, the twin GRAIL spacecraft will map the moon's gravity field, as depicted in this artist's rendering.
Using a precision formation-flying technique, the twin GRAIL spacecraft mapped the moon's gravity field, as depicted in this artist's rendering. Image credit: NASA/JPL-Caltech
› Full image and caption

May 30, 2013

PASADENA, Calif. -- NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission has uncovered the origin of massive invisible regions that make the moon's gravity uneven, a phenomenon that affects the operations of lunar-orbiting spacecraft.


Because of GRAIL's findings, spacecraft on missions to other celestial bodies can navigate with greater precision in the future.


GRAIL's twin spacecraft studied the internal structure and composition of the moon in unprecedented detail for nine months. They pinpointed the locations of large, dense regions called mass concentrations, or mascons, which are characterized by strong gravitational pull. Mascons lurk beneath the lunar surface and cannot be seen by normal optical cameras.


GRAIL scientists found the mascons by combining the gravity data from GRAIL with sophisticated computer models of large asteroid impacts and known detail about the geologic evolution of the impact craters. The findings are published in the May 30 edition of the journal Science.


"GRAIL data confirm that lunar mascons were generated when large asteroids or comets impacted the ancient moon, when its interior was much hotter than it is now," said Jay Melosh, a GRAIL co-investigator at Purdue University in West Lafayette, Ind., and lead author of the paper. "We believe the data from GRAIL show how the moon's light crust and dense mantle combined with the shock of a large impact to create the distinctive pattern of density anomalies that we recognize as mascons."


The origin of lunar mascons has been a mystery in planetary science since their discovery in 1968 by a team at NASA's Jet Propulsion Laboratory in Pasadena, Calif. Researchers generally agree mascons resulted from ancient impacts billions of years ago. It was not clear until now how much of the unseen excess mass resulted from lava filling the crater or iron-rich mantle upwelling to the crust.


On a map of the moon's gravity field, a mascon appears in a target pattern. The bulls-eye has a gravity surplus. It is surrounded by a ring with a gravity deficit. A ring with a gravity surplus surrounds the bulls-eye and the inner ring. This pattern arises as a natural consequence of crater excavation, collapse and cooling following an impact. The increase in density and gravitational pull at a mascon's bulls-eye is caused by lunar material melted from the heat of a long-ago asteroid impact.


"Knowing about mascons means we finally are beginning to understand the geologic consequences of large impacts," Melosh said. "Our planet suffered similar impacts in its distant past, and understanding mascons may teach us more about the ancient Earth, perhaps about how plate tectonics got started and what created the first ore deposits."


This new understanding of lunar mascons also is expected to influence knowledge of planetary geology well beyond that of Earth and our nearest celestial neighbor.


"Mascons also have been identified in association with impact basins on Mars and Mercury," said GRAIL principal investigator Maria Zuber of the Massachusetts Institute of Technology in Cambridge. "Understanding them on the moon tells us how the largest impacts modified early planetary crusts."


Launched as GRAIL A and GRAIL B in September 2011, the probes, renamed Ebb and Flow, operated in a nearly circular orbit near the poles of the moon at an altitude of about 34 miles (55 kilometers) until their mission ended in December 2012. The distance between the twin probes changed slightly as they flew over areas of greater and lesser gravity caused by visible features, such as mountains and craters, and by masses hidden beneath the lunar surface.


JPL, a division of the California Institute of Technology in Pasadena, Calif. managed GRAIL for NASA's Science Mission Directorate in Washington. The mission was part of the Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. NASA's Goddard Space Flight Center, in Greenbelt, Md., manages the Lunar Reconnaissance Orbiter. Operations of the spacecraft's laser altimeter, which provided supporting data used in this investigation, is led by the Massachusetts Institute of Technology in Cambridge. Lockheed Martin Space Systems in Denver built GRAIL.


For more information about GRAIL, visit http://www.nasa.gov/grail and http://grail.nasa.gov .

DC Agle 818-393-9011

Jet Propulsion Laboratory, Pasadena, Calif.

818-393-9011

agle@jpl.nasa.gov


Dwayne Brown 202-358-1726

Headquarters, Washington

dwayne.c.brown@nasa.gov


Elizabeth Gardner 765-494-2081

Purdue University, West Lafayette, Ind.

ekgardner@purdue.edu


Jennifer Chu 617-715-4531

Massachusetts Institute of Technology, Cambridge, Mass.

j_chu@mit.edu


2013-184
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NASA Spacecraft Sees Tornado's Destructive Swath

NASA Spacecraft Sees Tornado's Destructive Swath:

The Newcastle-Moore EF-5 tornado ripped through central Oklahoma on May 20, 2013, killing 24 people
The Newcastle-Moore EF-5 tornado ripped through central Oklahoma on May 20, 2013, killing 24 people and leaving behind more than $2 billion in damage. Image Credit:
NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team
› Full image and caption

June 05, 2013

A new image from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra spacecraft shows the extent of destruction from the deadly Newcastle-Moore tornado that ripped through central Oklahoma on May 20, 2013.


The Newcastle-Moore tornado was rated at EF-5 on the Enhanced Fujita scale. An EF-5 is the most powerful category of tornado.


ASTER acquired this false-color image of the scar left on the landscape by the tornado's track on June 2, 2013. In the image, vegetation appears red, water is dark blue, roads and buildings are gray, and white and bare fields are tan. The tornado's track crosses the image from left to right, as indicated by the arrows. The image covers an area of 6 by 8.6 miles (9.6 by 13.8 kilometers), and is located at 35.3 degrees north latitude, 97.5 degrees west longitude.


The Newcastle-Moore tornado had peak winds estimated at 210 mph (340 kilometers per hour). It remained on the ground for 39 minutes over a 17-mile-long path (27 kilometers). As of June 5, the storm is known to be responsible for 24 deaths and more than $2 billion in damage.


With its 14 spectral bands from the visible to the thermal infrared wavelength region and its high spatial resolution of about 50 to 300 feet (15 to 90 meters), ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched Dec. 18, 1999, on NASA's Terra spacecraft. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and data products. The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate, Washington, D.C. The California Institute of Technology in Pasadena manages JPL for NASA.


The image is online at: http://photojournal.jpl.nasa.gov/catalog/PIA16488 . More information about ASTER is available at http://asterweb.jpl.nasa.gov/ .

Alan Buis 818-354-0474

Jet Propulsion Laboratory, Pasadena, Calif.

alan.buis@jpl.nasa.gov

2013-189
Posted by Nelio Inacio at 5:28 PM 0 comments
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Cassini Sees Precursors to Aerosol Haze on Titan

Cassini Sees Precursors to Aerosol Haze on Titan:

A Ring of Color
NASA's Cassini spacecraft looks toward the night side of Saturn's largest moon and sees sunlight scattering through the periphery of Titan's atmosphere and forming a ring of color. Image credit:
NASA/JPL-Caltech/Space Science Institute
› Full image and caption

June 05, 2013

Scientists working with data from NASA's Cassini mission have confirmed the presence of a population of complex hydrocarbons in the upper atmosphere of Saturn's largest moon, Titan, that later evolve into the components that give the moon a distinctive orange-brown haze. The presence of these complex, ringed hydrocarbons, known as polycyclic aromatic hydrocarbons (PAHs), explains the origin of the aerosol particles found in the lowest haze layer that blankets Titan's surface. Scientists think these PAH compounds aggregate into larger particles as they drift downward.


"With the huge amount of methane in its atmosphere, Titan smog is like L.A. smog on steroids," said Scott Edgington, Cassini deputy project scientist based at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "These new papers using Cassini data shed light on how the heavy, complex hydrocarbon molecules that make up Titan's smog came to form out of the simpler molecules in the atmosphere. Now that they have been identified, the longevity of Cassini's mission will make it possible to study their variation with Titan seasons."


Of all the bodies in the solar system, Saturn's largest moon, Titan, has the atmosphere most resembling that of Earth. Like that of our planet, Titan's atmosphere is largely composed of molecular nitrogen. Unlike Earth's atmosphere, however, Titan's contains only small traces of oxygen and water. Another molecule, methane, plays a similar role to that of water in Earth's atmosphere, and makes up about 2 percent of Titan's atmosphere. Scientists have speculated that the atmosphere of this moon may resemble that of our planet in its early days, before primitive living organisms enriched it with oxygen via photosynthesis.


When sunlight or highly energetic particles from Saturn's magnetic bubble hit the layers of Titan's atmosphere above about 600 miles (1,000 kilometers), the nitrogen and methane molecules there are broken up. This results in the formation of massive positive ions and electrons, which trigger a chain of chemical reactions, producing a variety of hydrocarbons -- a wide range of which have been detected in Titan's atmosphere. These reactions eventually lead to the production of carbon-based aerosols, large aggregates of atoms and molecules that are found in the lower layers of the haze that enshrouds Titan, well below 300 miles (500 kilometers). The process is similar to Earth, where smog starts with sunlight breaking up hydrocarbons that are emitted into the air. The resulting pieces recombine to form more complex molecules.


Aerosols in Titan's lower haze have been studied using data from the descent of the European Space Agency's Huygens probe, which reached the surface in 2005, but their origin remained unclear. New studies analyzing data from Cassini's visual and infrared mapping spectrometer (VIMS) gathered in July and August 2007 might solve the problem. One new study of Titan's upper atmosphere in the Astrophysical Journal describes the detection of the PAHs, which are large carbon-based molecules that form from the aggregation of smaller hydrocarbons.


"We can finally confirm that PAHs play a major role in the production of Titan's lower haze, and that the chemical reactions leading to the formation of the haze start high up in the atmosphere," said this paper's lead author Manuel López-Puertas from the Astrophysics Institute of Andalucia in Granada, Spain. "This finding is surprising: we had long suspected that PAHs and aerosols were linked in Titan's atmosphere, but didn't expect we could prove this with current instruments."


The team of scientists had been studying the emission from various molecules in Titan's atmosphere when they stumbled upon a peculiar feature in the data. One of the characteristic lines in the spectrum -- from methane emissions -- had a slightly anomalous shape, and the scientists suspected it was hiding something.


Bianca Maria Dinelli from the Institute of Atmospheric Sciences and Climate (part of the National Research Council) in Bologna, Italy, was the lead author of a related paper in the journal Geophysical Research Letters. She and her colleagues conducted a painstaking investigation to identify the chemical species responsible for the anomaly. The additional signal was found only during daytime, so it clearly had something to do with solar irradiation.


"The central wavelength of this signal, about 3.28 microns, is typical for aromatic compounds -- hydrocarbon molecules in which the carbon atoms are bound in ring-like structures," said Dinelli.


The scientists tested whether the unidentified emission could be produced by benzene, the simplest aromatic compound consisting of one ring only, which had been detected earlier in Titan's atmosphere. However, the relatively low abundances of benzene are not sufficient to explain the emission that had been observed.


After they ruled out benzene, the scientists tried to reproduce the observed emission with the more complex PAHs. They checked their data against the NASA Ames PAH Infrared Spectral Data Base. And they were successful: the data can be explained as emission by a mixture of many different PAHs, which contain an average of 34 carbon atoms and about 10 rings each.


"PAHs are very efficient in absorbing ultraviolet radiation from the sun, redistributing the energy within the molecule and finally emitting it at infrared wavelengths," said co-author Alberto Adriani from the Institute for Space Astrophysics and Planetology at Italy's National Institute for Astrophysics (INAF) in Rome. He is part of the Cassini-VIMS co-investigators team and started this investigation. He manages the team that collected and processed VIMS data.


These hydrocarbons also are peculiarly capable of sending out profuse amounts of infrared radiation even in the rarefied environment of Titan's upper atmosphere, where the collisions between molecules are not very frequent. The molecules are themselves an intermediate product, generated when radiation from the sun ionizes smaller molecules in the upper atmosphere of Titan that then coagulate and sink.


The Cassini-Huygens mission is a cooperative project of NASA, ESA and Italy's ASI space agency. The Jet Propulsion Laboratory manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington DC, USA. The visual and infrared mapping spectrometer team is based at the University of Arizona, Tucson. The California Institute of Technology in Pasadena manages JPL for NASA.

Jia-Rui C. Cook 818-354-0850

Jet Propulsion Laboratory, Pasadena, Calif.

jccook@jpl.nasa.gov


Markus Bauer 011-31-71-565-6799

European Space Agency, Noordwijk, the Netherlands

markus.bauer@esa.int


2013-188
Posted by Nelio Inacio at 5:27 PM 0 comments
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Stars Don't Obliterate Their Planets (Very Often)

Stars Don't Obliterate Their Planets (Very Often):

On the Road Toward a Star, Planets Halt Their Migration
Researchers using data from NASA's Kepler space telescope have shown that migrating planets stop their inward journey before reaching their stars, as illustrated in this artist's concept. Jupiter-like planets, called "hot Jupiters" are known to migrate from their star's frigid outer reaches in toward the star and its blistering heat. Dozens of hot Jupiters have been discovered orbiting closely to their stars, whipping around in just days. Image credit: NASA/JPL-Caltech
› Full image and caption

June 06, 2013

Stars have an alluring pull on planets, especially those in a class called hot Jupiters, which are gas giants that form farther from their stars before migrating inward and heating up.


Now, a new study using data from NASA's Kepler Space Telescope shows that hot Jupiters, despite their close-in orbits, are not regularly consumed by their stars. Instead, the planets remain in fairly stable orbits for billions of years, until the day comes when they may ultimately get eaten.


"Eventually, all hot Jupiters get closer and closer to their stars, but in this study we are showing that this process stops before the stars get too close," said Peter Plavchan of NASA's Exoplanet Science Institute at the California Institute of Technology, Pasadena, Calif. "The planets mostly stabilize once their orbits become circular, whipping around their stars every few days."


The study, published recently in the Astrophysical Journal, is the first to demonstrate how the hot Jupiter planets halt their inward march on stars. Gravitational, or tidal, forces of a star circularize and stabilize a planet's orbit; when its orbit finally become circular, the migration ceases.


"When only a few hot Jupiters were known, several models could explain the observations," said Jack Lissauer, a Kepler scientist at NASA's Ames Research Center, Moffet Field, Calif., not affiliated with the study. "But finding trends in populations of these planets shows that tides, in combination with gravitational forces by often unseen planetary and stellar companions, can bring these giant planets close to their host stars."


Hot Jupiters are giant balls of gas that resemble Jupiter in mass and composition. They don't begin life under the glare of a sun, but form in the chilly outer reaches, as Jupiter did in our solar system. Ultimately, the hot Jupiter planets head in toward their stars, a relatively rare process still poorly understood.


The new study answers questions about the end of the hot Jupiters' travels, revealing what put the brakes on their migration. Previously, there were a handful of theories explaining how this might occur. One theory proposed that the star's magnetic field prevented the planets from going any farther. When a star is young, a planet-forming disk of material surrounds it. The material falls into the star -- a process astronomers call accretion -- but when it hits the magnetic bubble around it, called the magnetosphere, the material travels up and around the bubble, landing on the star from the top and bottom. This bubble could be halting migrating planets, so the theory went.


Another theory held that the planets stopped marching forward when they hit the end of the dusty portion of the planet-forming disk.


"This theory basically said that the dust road a planet travels on ends before the planet falls all the way into the star," said co-author Chris Bilinski of the University of Arizona, Tucson. "A gap forms between the star and the inner edge of its dusty disk where the planets are thought to stop their migration."


And yet a third theory, the one the researchers found to be correct, proposed that a migrating planet stops once the star's tidal forces have completed their job of circularizing its orbit.


To test these and other scenarios, the scientists looked at 126 confirmed planets and more than 2,300 candidates. The majority of the candidates and some of the known planets were identified via NASA's Kepler mission. Kepler has found planets of all sizes and types, including rocky ones that orbit where temperatures are warm enough for liquid water.


The scientists looked at how the planets' distance from their stars varied depending on the mass of the star. It turns out that the various theories explaining what stops migrating planets differ in their predictions of how the mass of a star affects the orbit of the planet. The "tidal forces" theory predicted that the hot Jupiters of more massive stars would orbit farther out, on average.


The survey results matched the "tidal forces" theory and even showed more of a correlation between massive stars and farther-out orbits than predicted.


This may be the end of the road for the mystery of what halts migrating planets, but the journey itself still poses many questions. As gas giants voyage inward, it is thought that they sometimes kick smaller, rocky planets out of the way, and with them any chance of life evolving. Lucky for us, our Jupiter did not voyage toward the sun, and our Earth was left in peace. More studies like this one will help explain these and other secrets of planetary migration.


The technical paper is online at http://iopscience.iop.org/0004-637X/769/2/86/ .


NASA Ames manages Kepler's ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed Kepler mission development. Ball Aerospace & Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with JPL at the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. The Space Telescope Science Institute in Baltimore archives, hosts and distributes the Kepler science data. Kepler is NASA's 10th Discovery Mission and is funded by NASA's Science Mission Directorate at the agency's headquarters in Washington.


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


More information about the Kepler mission is at http://www.nasa.gov/kepler .


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


Michele Johnson 650-604-4789

Ames Research Center, Moffett Field, Calif.

michele.johnson@nasa.gov

2013-190
Posted by Nelio Inacio at 5:26 PM 0 comments
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Radar Movies Highlight Asteroid 1998 QE2 and Its Moon

Radar Movies Highlight Asteroid 1998 QE2 and Its Moon:

This image of asteroid 1998 QE2 was obtained on June 1, 2013
This image of asteroid 1998 QE2 was obtained on June 1, 2013, when the asteroid was about 3.75 million miles (6 million kilometers) from Earth. The small white dot at upper left is the moon, or satellite, orbiting asteroid 1998 QE2. Image credit: NASA/JPL-Caltech/GSSR. Image credit: NASA/JPL-Caltech/GSSR

› Larger image

June 06, 2013

PASADENA, Calif. - Scientists working with NASA's 230-foot-wide (70-meter) Deep Space Network antenna at Goldstone, Calif., have released a second, longer, more refined movie clip of asteroid 1998 QE2 and its moon. The 55 individual images used in the movie were generated from data collected at Goldstone on June 1, 2013.


Each of the individual images obtained on June 1, 2013, required about five minutes of data collection by the Goldstone radar. At the time of the observations that day, asteroid 1998 QE2 was about 3.75 million miles (6 million kilometers) from Earth. The resolution is about 125 feet (38 meters) per pixel.


With additional radar images and time for analysis, NASA scientists have been able to refine their estimates of the asteroid's size and rotation. The data indicate the main, or primary body, is approximately 1.9 miles (3 kilometers) in diameter and has a rotation period of about five hours.


The asteroid's satellite, or moon, is approximately 2,000 feet (600 meters) wide, has an elongated appearance, and completes a revolution around its host body about once every 32 hours. At any point during its orbit, the maximum distance between the primary body and moon is about 4 miles (6.4 kilometers). Similar to our moon, which always points the same "face" at Earth, the asteroid's satellite appears to always show the same portion of its surface to the primary asteroid. This is called "synchronous rotation."


1998 QE2 is one of the slowest (with respect to its rotation) and largest binaries that have been observed by planetary radar. In the near-Earth population, about 16 percent of asteroids that are about 655 feet (200 meters) or larger are binary or triple systems.


The trajectory of asteroid 1998 QE2 is well understood. The closest approach of the asteroid occurred on May 31 at 1:59 p.m. PDT (4:59 p.m. EDT / 20:59 UTC), when the asteroid got no closer than about 3.6 million miles (5.8 million kilometers), or about 15 times the distance between Earth and the moon. This was 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, N.M.


Radar is a powerful technique for studying an asteroid's size, shape, rotation state, surface features and surface roughness, and for improving the calculation of asteroid orbits. Radar measurements of asteroid distances and velocities often enable computation of asteroid orbits much further into the future than if radar observations weren't available.


NASA places a high priority on tracking asteroids and protecting our home planet from them. In fact, the US has the most robust and productive survey and detection program for discovering near-Earth objects (NEOs). 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 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 objects that come close to 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 led to the development of life.


NASA recently announced development of a first-ever mission to identify, capture and relocate an asteroid for human exploration. Using game-changing technologies, 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


Dwayne Brown 202-358-1726

NASA Headquarters, Washington

Dwayne.c.brown@nasa.gov


2013-193
Posted by Nelio Inacio at 5:25 PM 0 comments
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Friday, July 25, 2014

Stars Don't Obliterate Their Planets (Very Often)

Stars Don't Obliterate Their Planets (Very Often):

On the Road Toward a Star, Planets Halt Their Migration
Researchers using data from NASA's Kepler space telescope have shown that migrating planets stop their inward journey before reaching their stars, as illustrated in this artist's concept. Jupiter-like planets, called "hot Jupiters" are known to migrate from their star's frigid outer reaches in toward the star and its blistering heat. Dozens of hot Jupiters have been discovered orbiting closely to their stars, whipping around in just days. Image credit: NASA/JPL-Caltech
› Full image and caption

June 06, 2013

Stars have an alluring pull on planets, especially those in a class called hot Jupiters, which are gas giants that form farther from their stars before migrating inward and heating up.


Now, a new study using data from NASA's Kepler Space Telescope shows that hot Jupiters, despite their close-in orbits, are not regularly consumed by their stars. Instead, the planets remain in fairly stable orbits for billions of years, until the day comes when they may ultimately get eaten.


"Eventually, all hot Jupiters get closer and closer to their stars, but in this study we are showing that this process stops before the stars get too close," said Peter Plavchan of NASA's Exoplanet Science Institute at the California Institute of Technology, Pasadena, Calif. "The planets mostly stabilize once their orbits become circular, whipping around their stars every few days."


The study, published recently in the Astrophysical Journal, is the first to demonstrate how the hot Jupiter planets halt their inward march on stars. Gravitational, or tidal, forces of a star circularize and stabilize a planet's orbit; when its orbit finally become circular, the migration ceases.


"When only a few hot Jupiters were known, several models could explain the observations," said Jack Lissauer, a Kepler scientist at NASA's Ames Research Center, Moffet Field, Calif., not affiliated with the study. "But finding trends in populations of these planets shows that tides, in combination with gravitational forces by often unseen planetary and stellar companions, can bring these giant planets close to their host stars."


Hot Jupiters are giant balls of gas that resemble Jupiter in mass and composition. They don't begin life under the glare of a sun, but form in the chilly outer reaches, as Jupiter did in our solar system. Ultimately, the hot Jupiter planets head in toward their stars, a relatively rare process still poorly understood.


The new study answers questions about the end of the hot Jupiters' travels, revealing what put the brakes on their migration. Previously, there were a handful of theories explaining how this might occur. One theory proposed that the star's magnetic field prevented the planets from going any farther. When a star is young, a planet-forming disk of material surrounds it. The material falls into the star -- a process astronomers call accretion -- but when it hits the magnetic bubble around it, called the magnetosphere, the material travels up and around the bubble, landing on the star from the top and bottom. This bubble could be halting migrating planets, so the theory went.


Another theory held that the planets stopped marching forward when they hit the end of the dusty portion of the planet-forming disk.


"This theory basically said that the dust road a planet travels on ends before the planet falls all the way into the star," said co-author Chris Bilinski of the University of Arizona, Tucson. "A gap forms between the star and the inner edge of its dusty disk where the planets are thought to stop their migration."


And yet a third theory, the one the researchers found to be correct, proposed that a migrating planet stops once the star's tidal forces have completed their job of circularizing its orbit.


To test these and other scenarios, the scientists looked at 126 confirmed planets and more than 2,300 candidates. The majority of the candidates and some of the known planets were identified via NASA's Kepler mission. Kepler has found planets of all sizes and types, including rocky ones that orbit where temperatures are warm enough for liquid water.


The scientists looked at how the planets' distance from their stars varied depending on the mass of the star. It turns out that the various theories explaining what stops migrating planets differ in their predictions of how the mass of a star affects the orbit of the planet. The "tidal forces" theory predicted that the hot Jupiters of more massive stars would orbit farther out, on average.


The survey results matched the "tidal forces" theory and even showed more of a correlation between massive stars and farther-out orbits than predicted.


This may be the end of the road for the mystery of what halts migrating planets, but the journey itself still poses many questions. As gas giants voyage inward, it is thought that they sometimes kick smaller, rocky planets out of the way, and with them any chance of life evolving. Lucky for us, our Jupiter did not voyage toward the sun, and our Earth was left in peace. More studies like this one will help explain these and other secrets of planetary migration.


The technical paper is online at http://iopscience.iop.org/0004-637X/769/2/86/ .


NASA Ames manages Kepler's ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed Kepler mission development. Ball Aerospace & Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with JPL at the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. The Space Telescope Science Institute in Baltimore archives, hosts and distributes the Kepler science data. Kepler is NASA's 10th Discovery Mission and is funded by NASA's Science Mission Directorate at the agency's headquarters in Washington.


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


More information about the Kepler mission is at http://www.nasa.gov/kepler .


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


Michele Johnson 650-604-4789

Ames Research Center, Moffett Field, Calif.

michele.johnson@nasa.gov

2013-190
Posted by Nelio Inacio at 8:08 AM 0 comments
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Small Asteroid Between Earth and Moon

Small Asteroid Between Earth and Moon:

This illustration shows the path of Asteroid 2013 LR6
This illustration shows the path of the small asteroid 2013 LR6, which will safely pass within 65,000 miles (105,000 kilometers) of Earth on June 7 at 9:42 p.m. PDT (June 8 at 12:42 a.m. EDT). Image credit: NASA/JPL-Caltech.
› Larger image

June 07, 2013

Small asteroid 2013 LR6 will safely fly past this evening at 9:42 p.m. PDT (which is June 8 at 12:42 a.m. EDT/June 8 at 04:42 UTC) at a distance of about 65,000 miles (105,000 kilometers) above Earth's surface. The space rock, which is about 30 feet (10 meters) in diameter, will be above the Southern Ocean, south of Tasmania, at the time of closest approach. Asteroid 2013 LR6 was discovered by the NASA-sponsored Catalina Sky Survey on June 6.


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.


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 .

DC Agle 818-393-9011

Jet Propulsion Laboratory, Pasadena, Calif.

agle@jpl.nasa.gov


Dwayne Brown 202-358-1726

NASA Headquarters, Washington

dwayne.c.brown@nasa.gov


2013-195
Posted by Nelio Inacio at 8:08 AM 0 comments
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Black Hole Naps Amidst Stellar Chaos

Black Hole Naps Amidst Stellar Chaos:

The Sculptor galaxy is seen in a new light, in this composite image from NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and the European Southern Observatory in Chile
The Sculptor galaxy is seen in a new light, in this composite image from NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and the European Southern Observatory in Chile. Image credit: NASA/JPL-Caltech/JHU

› Full image and caption   › NuSTAR view only

June 11, 2013

Nearly a decade ago, NASA's Chandra X-ray Observatory caught signs of what appeared to be a black hole snacking on gas at the middle of the nearby Sculptor galaxy. Now, NASA's Nuclear Spectroscopic Telescope Array (NuSTAR), which sees higher-energy X-ray light, has taken a peek and found the black hole asleep.


"Our results imply that the black hole went dormant in the past 10 years," said Bret Lehmer of the Johns Hopkins University, Baltimore, and NASA's Goddard Space Flight Center, Greenbelt, Md. "Periodic observations with both Chandra and NuSTAR should tell us unambiguously if the black hole wakes up again. If this happens in the next few years, we hope to be watching." Lehmer is lead author of a new study detailing the findings in the Astrophysical Journal.


The slumbering black hole is about 5 million times the mass of our sun. It lies at the center of the Sculptor galaxy, also known as NGC 253, a so-called starburst galaxy actively giving birth to new stars. At 13 million light-years away, this is one of the closest starbursts to our own galaxy, the Milky Way.


The Milky Way is all around more quiet than the Sculptor galaxy. It makes far fewer new stars, and its behemoth black hole, about 4 million times the mass of our sun, is also snoozing.


"Black holes feed off surrounding accretion disks of material. When they run out of this fuel, they go dormant," said co-author Ann Hornschemeier of Goddard. "NGC 253 is somewhat unusual because the giant black hole is asleep in the midst of tremendous star-forming activity all around it."


The findings are teaching astronomers how galaxies grow over time. Nearly all galaxies are suspected to harbor supermassive black holes at their hearts. In the most massive of these, the black holes are thought to grow at the same rate that new stars form, until blasting radiation from the black holes ultimately shuts down star formation. In the case of the Sculptor galaxy, astronomers do not know if star formation is winding down or ramping up.


"Black hole growth and star formation often go hand-in-hand in distant galaxies," said Daniel Stern, a co-author and NuSTAR project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "It's a bit surprising as to what's going on here, but we've got two powerful complementary X-ray telescopes on the case."


Chandra first observed signs of what appeared to be a feeding supermassive black hole at the heart of the Sculptor galaxy in 2003. As material spirals into a black hole, it heats up to tens of millions of degrees and glows in X-ray light that telescopes like Chandra and NuSTAR can see.


Then, in September and November of 2012, Chandra and NuSTAR observed the same region simultaneously. The NuSTAR observations -- the first-ever to detect focused, high-energy X-ray light from the region -- allowed the researchers to say conclusively that the black hole is not accreting material. NuSTAR launched into space in June of 2012.


In other words, the black hole seems to have fallen asleep. Another possibility is that the black hole was not actually awake 10 years ago, and Chandra observed a different source of X-rays. Future observations with both telescopes may solve the puzzle.


"The combination of coordinated Chandra and NuSTAR observations is extremely powerful for answering questions like this," said Lou Kaluzienski, NuSTAR Program Scientist at NASA Headquarters in Washington. "Now, we can get all sides of the story."


The observations also revealed a smaller, flaring object that the researchers were able to identify as an "ultraluminous X-ray source," or ULX. ULXs are black holes feeding off material from a partner star. They shine more brightly than typical stellar-mass black holes generated from dying stars, but are fainter and more randomly distributed than the supermassive black holes at the centers of massive galaxies. Astronomers are still working to understand the size, origins and physics of ULXs.


"These stellar-mass black holes are bumping along near the center of this galaxy," said Hornschemeier. "They tend to be more numerous in areas where there is more star-formation activity."


If and when the Sculptor's slumbering giant does wake up in the next few years amidst all the commotion, NuSTAR and Chandra will monitor the situation. The team plans to check back on the system periodically.


NuSTAR is a Small Explorer mission led by the California Institute of Technology in Pasadena and managed by NASA's Jet Propulsion Laboratory, also in Pasadena, for NASA's Science Mission Directorate in Washington. The spacecraft was built by Orbital Sciences Corporation, Dulles, Va. Its instrument was built by a consortium including Caltech; JPL; the University of California, Berkeley; Columbia University, New York; NASA's Goddard Space Flight Center, Greenbelt, Md.; the Danish Technical University in Denmark; Lawrence Livermore National Laboratory, Livermore, Calif.; ATK Aerospace Systems, Goleta, Calif., and with support from the Italian Space Agency (ASI) Science Data Center.


NuSTAR's mission operations center is at UC Berkeley, with the ASI providing its equatorial ground station located at Malindi, Kenya. The mission's outreach program is based at Sonoma State University, Rohnert Park, Calif. NASA's Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.


For more information, visit: http://www.nasa.gov/nustar and http://www.nustar.caltech.edu/ . Follow the mission on Twitter via http://www.twitter.com/NASANuSTAR .


Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov


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Posted by Nelio Inacio at 8:07 AM 0 comments
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