Jun 11 2012
From The Space Library
RELEASE: 12-191 BLACK HOLE GROWTH FOUND TO BE OUT OF SYNC
WASHINGTON -- New evidence from NASA's Chandra X-ray Observatory challenges prevailing ideas about how black holes grow in the centers of galaxies. Astronomers long have thought that a supermassive black hole and the bulge of stars at the center of its host galaxy grow at the same rate -- the bigger the bulge, the bigger the black hole. However, a new study of Chandra data has revealed two nearby galaxies with supermassive black holes that are growing faster than the galaxies themselves. The mass of a giant black hole at the center of a galaxy typically is a tiny fraction -- about 0.2 percent -- of the mass contained in the bulge, or region of densely packed stars, surrounding it. The targets of the latest Chandra study, galaxies NGC 4342 and NGC 4291, have black holes 10 times to 35 times more massive than they should be compared to their bulges. The new observations with Chandra show the halos, or massive envelopes of dark matter in which these galaxies reside, also are overweight. This study suggests the two supermassive black holes and their evolution are tied to their dark matter halos and did not grow in tandem with the galactic bulges. In this view, the black holes and dark matter halos are not overweight, but the total mass in the galaxies is too low. "This gives us more evidence of a link between two of the most mysterious and darkest phenomena in astrophysics -- black holes and dark matter -- in these galaxies," said Akos Bogdan of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., who led the new study. NGC 4342 and NGC 4291 are close to Earth in cosmic terms, at distances of 75 million and 85 million light years. Astronomers had known from previous observations that these galaxies host black holes with relatively large masses, but are not certain what is responsible for the disparity. Based on the new Chandra observations, however, they are able to rule out a phenomenon known as tidal stripping. Tidal stripping occurs when some of a galaxy's stars are stripped away by gravity during a close encounter with another galaxy. If such tidal stripping had taken place, the halos mostly would have been missing. Because dark matter extends farther away from the galaxies, it is more loosely tied to them than the stars and more likely to be pulled away. To rule out tidal stripping, astronomers used Chandra to look for evidence of hot, X-ray-emitting gas around the two galaxies. Because the pressure of hot gas -- estimated from X-ray images -- balances the gravitational pull of all the matter in the galaxy, the new Chandra data can provide information about the dark matter halos. The hot gas was found to be distributed widely around NGC 4342 and NGC 4291, implying that each galaxy has an unusually massive dark matter halo and that tidal stripping is unlikely. "This is the clearest evidence we have, in the nearby universe, for black holes growing faster than their host galaxy," said co-author Bill Forman, also of CfA. "It's not that the galaxies have been compromised by close encounters, but instead they had some sort of arrested development." How can the mass of a black hole grow faster than the stellar mass of its host galaxy? The study's authors suggest a large concentration of gas spinning slowly in the galactic center is what the black hole consumes very early in its history. It grows quickly, and as it grows, the amount of gas it can accrete, or swallow, increases along with the energy output from the accretion. After the black hole reaches a critical mass, outbursts powered by the continued consumption of gas prevent cooling and limit the production of new stars. "It's possible that the supermassive black hole reached a hefty size before there were many stars at all in the galaxy," said Bogdan. "That is a significant change in our way of thinking about how galaxies and black holes evolve together." The results were presented June 11 at the 220th meeting of the American Astronomical Society in Anchorage, Alaska. The study also has been accepted for publication in The Astrophysical Journal. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for the agency's NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Mass., controls Chandra's science and flight operations.
RELEASE: 12-192 NASA MARS ROVER TEAM AIMS FOR LANDING CLOSER TO PRIME SCIENCE SITE
WASHINGTON -- NASA has narrowed the target for its most advanced Mars rover, Curiosity, which will land on the Red Planet in August. The car-sized rover will arrive closer to its ultimate destination for science operations, but also closer to the foot of a mountain slope that poses a landing hazard. "We're trimming the distance we'll have to drive after landing by almost half," said Pete Theisinger, Mars Science Laboratory (MSL) project manager at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. "That could get us to the mountain months earlier." It was possible to adjust landing plans because of increased confidence in precision landing technology aboard the MSL spacecraft, which is carrying the rover. That spacecraft can aim closer without hitting Mount Sharp at the center of Gale crater. Rock layers located in the mountain are the prime location for research with the rover. Curiosity is scheduled to land at approximately 10:31 p.m. PDT Aug. 5 (1:31 a.m. EDT, Aug. 6). Following checkout operations, Curiosity will begin a 2-year study of whether the landing vicinity ever offered an environment favorable for microbial life. Theisinger and other mission leaders described the target adjustment during a June 11 update to reporters Monday about preparations for landing and for operating Curiosity on Mars. The landing target ellipse had been an ellipse approximately 12 miles wide and 16 miles long (20 kilometers by 25 kilometers). Continuing analysis of the new landing system's capabilities has allowed mission planners to shrink the area to approximately 4 miles wide and 12 miles long (7 kilometers by 20 kilometers), assuming winds and other atmospheric conditions as predicted. Even with the smaller ellipse, Curiosity will be able to touch down at a safe distance from steep slopes at the edge of Mount Sharp. "We have been preparing for years for a successful landing by Curiosity, and all signs are good," said Dave Lavery, MSL program executive. "However, landing on Mars always carries risks, so success is not guaranteed. Once on the ground we'll proceed carefully. We have plenty of time since Curiosity is not as life-limited as the approximate 90-day missions like NASA's Mars Exploration Rovers and the Phoenix lander. Since the spacecraft was launched in November 2011, engineers have continued testing and improving its landing software. MSL will use an upgraded version of flight software installed on its computers during the past two weeks. Additional upgrades for Mars surface operations will be sent to the rover about a week after landing. Other preparations include upgrades to the rover's software and understanding effects of debris coming from the drill the rover will use to collect samples from rocks on Mars. Experiments at JPL indicate that Teflon from the drill could mix with the powdered samples. Testing will continue past landing with copies of the drill. The rover will deliver the samples to onboard instruments that can identify mineral and chemical ingredients. "The material from the drill could complicate, but will not prevent analysis of carbon content in rocks by one of the rover's 10 instruments. There are workarounds," said John Grotzinger, MSL project scientist at the California Institute of Technology in Pasadena. "Organic carbon compounds in an environment are one prerequisite for life. We know meteorites deliver non-biological organic carbon to Mars, but not whether it persists near the surface. We will be checking for that and for other chemical and mineral clues about habitability." Curiosity will be in good company as it nears landing. Two NASA Mars orbiters along with a European Space Agency orbiter will be in position to listen to radio transmissions as MSL descends through Mars' atmosphere. The mission is managed by JPL for NASA's Science Mission Directorate in Washington. Curiosity was designed, developed and assembled at JPL.
RELEASE: 12-194 NASA'S UNDERSEA MISSION SUBMERGES IN THE ATLANTIC
HOUSTON -- An international crew of aquanauts is settling into its home on the ocean floor, where the team will spend 12 days testing concepts for a potential asteroid mission. The expedition is the 16th excursion of the NASA Extreme Environment Mission Operations (NEEMO). The crew of four began its mission in the National Oceanic and Atmospheric Administration's Aquarius Reef Base undersea research habitat off the coast of Key Largo, Fla., at 11:04 a.m. EDT Monday. NEEMO sends groups of astronauts, engineers and scientists to live in the Aquarius lab, 63 feet below the surface of the Atlantic Ocean. The laboratory is located in the Florida Keys National Marine Sanctuary. For NASA, Aquarius provides a convincing simulation to space exploration, and NEEMO crew members experience some of the same tasks and challenges under water that they would in space. The NEEMO 16 mission will focus on three areas related to asteroid missions. The crew of aquanauts will investigate communication delays, restraint and translation techniques, and optimum crew size. The isolation and microgravity environment of the ocean floor allows the NEEMO 16 crew to study and test concepts for how future exploration of asteroids might be conducted. NASA's Orion spacecraft and the Space Launch System rocket, which currently are in development, will allow people to begin exploring beyond the boundaries of Earth's orbit. The first human mission to an asteroid is planned for 2025. NEEMO 16 Commander Dottie Metcalf-Lindenburger of NASA will be joined by European Space Agency astronaut Timothy Peake; Japan Aerospace Exploration Agency astronaut Kimiya Yui; and Steven W. Squyres, Goldwin Smith professor of astronomy at Cornell University and chairman of the NASA Advisory Council. Squyres also was a member of NEEMO 15.
MEDIA ADVISORY: M12-110 GARVER TO ATTEND NASA $1.5 MILLION ROBOT COMPETITION JUNE 16
WASHINGTON -- NASA Deputy Administrator Lori Garver and NASA Chief Technologist Mason Peck will be on hand Saturday, June 16, at the Worcester Polytechnic Institute (WPI) as six teams of engineers from across the country compete for agency-funded prize of $1.5 million. Garver will join congressional and local officials during opening ceremonies at 10 a.m. EDT on the campus of WPI in Worcester, Mass. Part of NASA's Centennial Challenges prize competitions, the Sample Return Robot challenge, is to design and develop the next generation of autonomous robots to explore the landscapes of other worlds. Competing teams are required to build an autonomous robotic system that will locate and collect a set of specific objects from a large area and return the "planetary samples" to the starting zone. During the first phase of the competition, a robot must autonomously navigate and retrieve a pre-cached sample within 15 minutes. Teams will compete for portions of a $50,000 total prize purse, with a maximum winning value of $5,000 per team. In the second phase, a robot must autonomously navigate and retrieve pre-cached samples, as well as other, more difficult samples distributed over the roving area within two hours. Teams will compete for as much as $1.5 million during this phase, with awards depending on the amount of points scored and number of successful competing finalists. NASA uses prize competitions to establish important technical challenges without having to specify the approach that is most likely to succeed, while only paying for successful results. These competitions increase the number and diversity of individuals, organizations and teams that are addressing a particular problem or challenge of national or international significance. These challenges stimulate private sector investment many times greater than the cash value of the prize. The Centennial Challenges are part of NASA's Space Technology Program.
MEDIA ADVISORY: M12-111 MEDIA INVITED TO NASA'S NEWEST COMMUNICATIONS-DELAY TESTS
HOUSTON -- NASA is preparing to move exploration beyond Earth's orbit, but communication delays will change how the agency conducts its missions. Reporters can see for themselves how NASA is planning for that change through NASA's newest test project, the Autonomous Mission Operations (AMO). Journalists are invited to watch the simulations at 3 p.m. CDT Thursday, June 14 at NASA's Johnson Space Center in Houston. NASA's Orion spacecraft and Space Launch System rocket, which currently are in development, will move humans farther away from low Earth orbit than ever before. These greater distances will cause communications delays to increase. Tasks that once were the responsibility of flight controllers in mission control will shift to the crews aboard Orion. AMO will investigate various ways astronauts and flight controllers can work through this challenge. Reporters will meet members of one of the crews involved in the test and their support team. They also will tour the Deep Space Habitat, which is being used for the simulation, and the supporting control room. The tests will simulate the return from a 30-day exploration of a near-Earth asteroid, which is part of a larger 386-day mission. Crews consisting of one astronaut and three flight controllers will perform simulated tasks under varying time delays -- 1.2 seconds, 50 seconds and 5 minutes, one way -- that impede to differing degrees real-time conversations with mission control. They will communicate through and evaluate the effectiveness of voice, text and video messages; written questionnaires; and computer timeline tools. The results should help identify the best communications tools for future exploration missions. The AMO project is part of NASA's Advanced Exploration Systems Program consisting of small projects aimed at rapidly developing and demonstrating prototype systems for future human spaceflight missions. Projects in the program will help reduce risk, lower cost and test concepts for future human missions beyond Earth orbit.
RELEASE: 12-193 NASA'S FERMI DETECTS THE HIGHEST-ENERGY LIGHT FROM A SOLAR FLARE
WASHINGTON -- During a powerful solar blast on March 7, NASA's Fermi Gamma-ray Space Telescope detected the highest-energy light ever associated with an eruption on the sun. The discovery heralds Fermi's new role as a solar observatory, a powerful new tool for understanding solar outbursts during the sun's maximum period of activity. A solar flare is an explosive blast of light and charged particles. The powerful March 7 flare, which earned a classification of X5.4 based on the peak intensity of its X-rays, is the strongest eruption so far observed by Fermi's Large Area Telescope (LAT). The flare produced such an outpouring of gamma rays -- a form of light with even greater energy than X-rays -- that the sun briefly became the brightest object in the gamma-ray sky. "For most of Fermi's four years in orbit, its LAT saw the sun as a faint, steady gamma-ray source thanks to the impacts of high-speed particles called cosmic rays," said Nicola Omodei, an astrophysicist at Stanford University in California. "Now we're beginning to see what the sun itself can do." Omodei described Fermi's solar studies to journalists today at the 220th meeting of the American Astronomical Society in Anchorage, Alaska. At the flare's peak, the LAT detected gamma rays with two billion times the energy of visible light, or about four billion electron volts (GeV), easily setting a record for the highest-energy light ever detected during or immediately after a solar flare. The flux of high-energy gamma rays, defined as those with energies beyond 100 million electron volts (MeV), was 1,000 times greater than the sun's steady output. The March flare also is notable for the persistence of its gamma-ray emission. Fermi's LAT detected high-energy gamma rays for about 20 hours, two and a half times longer than any event on record. Additionally, the event marks the first time a greater-than-100-MeV gamma-ray source has been localized to the sun's disk, thanks to the LAT's keen angular resolution. Flares and other eruptive solar events produce gamma rays by accelerating charged particles, which then collide with matter in the sun's atmosphere and visible surface. For instance, interactions among protons result in short-lived subatomic particles called pions, which produce high-energy gamma rays when they decay. Nuclei excited by collisions with lower-energy ions give off characteristic gamma rays as they settle down. Accelerated electrons emit gamma rays as they collide with protons and atomic nuclei. Fermi's LAT scans the entire sky every 3 hours, looking for gamma rays with energies ranging from 20 MeV to more than 300 GeV. Its high sensitivity and wide field of view make the LAT an excellent tool for solar monitoring. Another Fermi instrument, the Gamma-ray Burst Monitor (GBM), observes the entire sky not blocked by the Earth at any given moment. Designed to detect light at energies from 8,000 eV to 40 MeV, the GBM's complementary capabilities give scientists access to a lower, but overlapping energy range where solar phenomena produce interesting features. Both instruments observed a strong, but less powerful solar flare on June 12, 2010. "Seeing the rise and fall of this brief flare in both instruments allowed us to determine that some of these particles were accelerated to two-thirds of the speed of light in as little as 3 seconds," said Michael Briggs, a member of GBM team at the University of Alabama in Huntsville. Solar eruptions are on the rise as the sun progresses toward the peak of its roughly 11-year-long activity cycle, now expected in mid-2013. "Merged with available theoretical models, Fermi observations will give us the ability to reconstruct the energies and types of particles that interact with the sun during flares, an understanding that will open up whole new avenues in solar research," said Gerald Share, an astrophysicist at the University of Maryland in College Park. NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership. Fermi is managed by NASA's Goddard Space Flight Center, Greenbelt, Md. It was developed in collaboration with the U.S. Department of Energy, with contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.
