Jan 10 2013

From The Space Library

RELEASE: 13-014 - NASA'S GALEX REVEALS THE LARGEST-KNOWN SPIRAL GALAXY --WASHINGTON -- The spectacular barred spiral galaxy NGC 6872 has ranked among the biggest stellar systems for decades. Now a team of astronomers from the United States, Chile and Brazil has crowned it the largest-known spiral, based on archival data from NASA's Galaxy Evolution Explorer (GALEX) mission. GALEX has since been loaned to the California Institute of Technology in Pasadena, Calif. Measuring tip-to-tip across its two outsized spiral arms, NGC 6872 spans more than 522,000 light-years, making it more than five times the size of our Milky Way galaxy. Without GALEX's ability to detect the ultraviolet light of the youngest, hottest stars, we would never have recognized the full extent of this intriguing system, said lead scientist Rafael Eufrasio, a research assistant at NASA's Goddard Space Flight Center in Greenbelt, Md., and a doctoral student at Catholic University of America in Washington. He presented the findings Thursday at the American Astronomical Society meeting in Long Beach, Calif. The galaxy's unusual size and appearance stem from its interaction with a much smaller disk galaxy named IC 4970, which has only about one-fifth the mass of NGC 6872. The odd couple is located 212 million light-years from Earth in the southern constellation Pavo. Astronomers think large galaxies, including our own, grew through mergers and acquisitions -- assembling over billions of years by absorbing numerous smaller systems. Intriguingly, the gravitational interaction of NGC 6872 and IC 4970 may have done the opposite, spawning what may develop into a new small galaxy. The northeastern arm of NGC 6872 is the most disturbed and is rippling with star formation, but at its far end, visible only in the ultraviolet, is an object that appears to be a tidal dwarf galaxy similar to those seen in other interacting systems, said team member Duilia de Mello, a professor of astronomy at Catholic University. The tidal dwarf candidate is brighter in the ultraviolet than other regions of the galaxy, a sign it bears a rich supply of hot young stars less than 200 million years old. The researchers studied the galaxy across the spectrum using archival data from the European Southern Observatory's Very Large Telescope, the Two Micron All Sky Survey, and NASA's Spitzer Space Telescope, as well as GALEX. By analyzing the distribution of energy by wavelength, the team uncovered a distinct pattern of stellar age along the galaxy's two prominent spiral arms. The youngest stars appear in the far end of the northwestern arm, within the tidal dwarf candidate, and stellar ages skew progressively older toward the galaxy's center. The southwestern arm displays the same pattern, which is likely connected to waves of star formation triggered by the galactic encounter. A 2007 study by Cathy Horellou at Onsala Space Observatory in Sweden and Baerbel Koribalski of the Australia National Telescope Facility developed computer simulations of the collision that reproduced the overall appearance of the system as we see it today. According to the closest match, IC 4970 made its closest approach about 130 million years ago and followed a path that took it nearly along the plane of the spiral's disk in the same direction it rotates. The current study is consistent with this picture. As in all barred spirals, NGC 6872 contains a stellar bar component that transitions between the spiral arms and the galaxy's central regions. Measuring about 26,000 light-years in radius, or about twice the average length found in nearby barred spirals, it is a bar that befits a giant galaxy. The team found no sign of recent star formation along the bar, which indicates it formed at least a few billion years ago. Its aged stars provide a fossil record of the galaxy's stellar population before the encounter with IC 4970 stirred things up. Understanding the structure and dynamics of nearby interacting systems like this one brings us a step closer to placing these events into their proper cosmological context, paving the way to decoding what we find in younger, more distant systems, said team member and Goddard astrophysicist Eli Dwek. The study also included Fernanda Urrutia-Viscarra and Claudia Mendes de Oliveira at the University of Sao Paulo in Brazil and Dimitri Gadotti at the European Southern Observatory in Santiago, Chile. The GALEX mission is led by the California Institute of Technology in Pasadena, which is responsible for science operations and data analysis. NASA's Jet Propulsion Laboratory, also in Pasadena, manages the mission and built the science instrument. GALEX was developed under NASA's Explorers Program managed by NASA's Goddard Space Flight Center. In May 2012, In May 2012, NASA announced it was loaning GALEX to Caltech, which continues spacecraft operations and data management using private funds.

RELEASE: 13-015 - NASA PREPARES FOR LAUNCH OF NEXT EARTH OBSERVATION SATELLITE --WASHINGTON -- NASA's Landsat Data Continuity Mission (LDCM) is scheduled to launch Feb. 11 from Vandenberg Air Force Base in California. A joint NASA and U.S. Geological Survey (USGS) mission, LDCM will add to the longest continuous data record of Earth's surface as viewed from space. LDCM is the eighth satellite in the Landsat series, which began in 1972. The mission will extend more than 40 years of global land observations that are critical in many areas, such as energy and water management, forest monitoring, human and environmental health, urban planning, disaster recovery and agriculture. NASA and the USGS jointly manage the Landsat Program. For decades, Landsat has played an important part in NASA's mission to advance Earth system science. LDCM promises to extend and expand that capability, said Michael Freilich, director of the Earth Science Division in the Science Mission Directorate at NASA Headquarters in Washington. "USGS's policy of offering free and open access to the phenomenal 40-year Landsat data record will continue to give the United States and global research community a better understanding of the changes occurring on our planet." After launch, LDCM will enter a polar orbit, circling the Earth about 14 times daily from an altitude of 438 miles (705 kilometers), returning over each location on Earth every 16 days. After launch and the initial checkout phase, the USGS will take operational control of the satellite, and LDCM will be renamed Landsat 8. Data will be downlinked to three ground stations in Gilmore Creek, Alaska; Svalbard, Norway; and Sioux Falls, S.D. The data will be archived and distributed at no cost to users from the USGS's Earth Resources Observation and Science Center in Sioux Falls. The Landsat program provides the nation with crucial, impartial data about its natural resources, said Matthew Larsen, USGS associate director for climate and land use change in Reston, Va. "Forest managers, for instance, use Landsat's recurring imagery to monitor the status of woodlands in near real-time. Landsat-based approaches also now are being used in most western states for cost-effective allocation of water for irrigation. This mission will continue that vital role." LDCM carries two instruments, the Operational Land Imager (OLI), built by Ball Aerospace & Technologies Corp. in Boulder, Colo., and the Thermal Infrared Sensor (TIRS), built by NASA's Goddard Space Flight Center in Greenbelt, Md. These instruments are designed to improve performance and reliability over previous Landsat sensors. LDCM will be the best Landsat satellite yet launched in terms of the quality and quantity of the data collected by the LDCM sensors, said Jim Irons, LDCM project scientist at Goddard. "OLI and TIRS both employ technological advances that will make the observations more sensitive to the variation across the landscape and to changes in the land surface over time." OLI will continue observations currently made by Landsat 7 in the visible, near infrared, and shortwave infrared portions of the electromagnetic spectrum. It also will take measurements in two new bands, one to observe high altitude cirrus clouds and one to observe water quality in lakes and shallow coastal oceans as well as aerosols. OLI's new design has fewer moving parts than previous versions. TIRS will collect data on heat emitted from Earth's surface in two thermal bands, as opposed to the single thermal band on previous Landsat satellites. Observations in the thermal bands are vital to monitoring water consumption, especially in the arid western United States. The LDCM spacecraft, built by Orbital Sciences Corp. in Gilbert, Ariz., will launch from Vandenberg's Space Complex 3 aboard an Atlas V rocket provided by United Launch Alliance. NASA's Launch Services Program at Kennedy Space Center is responsible for launch management.

RELEASE: 13-016 - MAJOR NASA AIR POLLUTION STUDY TO FLY OVER CALIFORNIA --WASHINGTON -- A multi-year NASA airborne science mission is on its way to California to help scientists better understand how to measure and forecast air quality globally from space. Two NASA aircraft equipped with scientific instruments will fly over the San Joaquin Valley between Bakersfield and Fresno in January and February to measure air pollution. One aircraft will fly within 1,000 feet of the ground. The aircraft are part of NASA's five-year DISCOVER-AQ study, which stands for Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality. Its researchers are working to improve the ability of satellites to consistently observe air quality in the lowest part of the atmosphere. If scientists could better observe pollution from space, they would be able to make better air quality forecasts and more accurately determine where pollution is coming from and why emissions vary. A fundamental challenge for space-based instruments monitoring air quality is to distinguish between pollution high in the atmosphere and pollution near the surface where people live. DISCOVER-AQ will make measurements from aircraft in combination with ground-based monitoring sites to help scientists better understand how to observe ground-level pollution from space. DISCOVER-AQ is collecting data that will prepare us to make better observations from space, as well as determine the best mix of observations to have at the surface when we have new satellite instruments in orbit, said James Crawford, the mission's principal investigator at NASA's Langley Research Center in Hampton, Va. "NASA is planning to launch that satellite instrument, called TEMPO, in 2017." Because many countries, including the United States, have large gaps in ground-based networks of air pollution monitors, experts look to satellites to provide a more complete geographic perspective on the distribution of pollutants. A fleet of Earth-observing satellites, called the Afternoon Constellation or "A-train," will pass over the DISCOVER-AQ study area daily in the early afternoon. The satellites' data, especially from NASA's Aqua and Aura spacecraft, will give scientists the opportunity to compare the view from space with that from the ground and aircraft. The A-Train satellites have been useful in giving us a broader view of air pollution than we've ever had before, said Kenneth Pickering, DISCOVER-AQ's project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "DISCOVER-AQ will help scientists interpret that data to improve air-quality analysis and regional air quality models." Test flights are scheduled to start Jan. 16 with science flights continuing through mid-February. A four-engine P-3B turboprop plane from NASA's Wallops Flight Facility in Wallops Island, Va., will carry eight instruments. A two-engine B200 King Air aircraft from Langley will carry two instruments. Sampling will focus on agricultural and vehicle traffic areas extending from Bakersfield to Fresno. The flight path passes over six ground measurement sites operated by the California Air Resources Board and the San Joaquin Valley Air Pollution Control District. The117-foot-long P-3B will fly spiral flights over the ground stations. These flights will be from an altitude of 15,000 feet to as low as 1,000 feet. They will sample air along agricultural and traffic corridors at low altitudes between the ground stations. The smaller B200 King Air will collect data from as high as 26,000 feet. The plane's instruments will look down at the surface, much like a satellite, and measure particulate and gaseous air pollution. The two airplanes will fly from NASA's Dryden Aircraft Operations Facility in Palmdale, Calif. The DISCOVER-AQ mission is a partnership with the National Oceanic and Atmospheric Administration, the U.S. Environmental Protection Agency, and University of California campus branches in Berkeley, Davis, Irvine, and Santa Barbara. Other partners in the California campaign include the National Center for Atmospheric Research; the University of Maryland in College Park and Baltimore County; University of Colorado, Boulder; Pennsylvania State University, State College; University of Innsbruck in Austria; and Millersville University, Millersville, Penn. DISCOVER-AQ is an Earth Venture mission, part of the Earth System Science Pathfinder program managed at Langley for the Earth Science Division of NASA's Science Mission Directorate in Washington. DISCOVER-AQ is one of several active airborne science missions being featured during a media day Jan. 25 at Dryden. Reporters interested in attending must register by Jan. 11 with Dryden's Public Affairs Office by email at DrydenPAONASA.gov or phone at 661-276-3449.

MEDIA ADVISORY: M13-012 - NASA, MIT, DARPA HOST FOURTH ANNUAL STUDENT ROBOTIC CHALLENGE JAN. 11 --WASHINGTON -- NASA will join the Defense Advanced Research Projects Agency (DARPA), the Massachusetts Institute of Technology (MIT) and high school student teams from the United States and abroad for the fourth annual Zero Robotics SPHERES Challenge Friday, Jan. 11. The event will take place on the MIT campus in Cambridge, Mass., and be broadcast live on NASA Television beginning at 8:30 a.m. EST. For the competition, NASA will upload software developed by high school students onto Synchronized Position Hold, Engage, Reorient, Experimental Satellites (SPHERES), which are bowling ball-sized spherical satellites aboard the International Space Station. The top 45 teams from previous competitions had their code sent last week to the space station, where an astronaut will command the satellites to execute the teams' flight program. During a simulated mission, the teams will complete a special challenge inspired by future satellite technologies, such as formation flight and close proximity operations. Student finalists will be able to see their flight program live in the televised finals. The team with the highest software performance over several rounds of the competition will win the challenge. The winning team will receive certificates and a SPHERES flight patch that was flown aboard the space station. In addition to their use in this competition, the SPHERES satellites are used inside the space station to conduct formation flight maneuvers for spacecraft guidance navigation, control and docking. The three separate satellites that make up SPHERES fly in formation inside the space station's cabin. The satellites provide opportunities to test a wide range of hardware and software at an affordable cost. NASA's Ames Research Center in Moffett Field, Calif., operates and maintains the SPHERES National Laboratory Facility on the station.