Dec 5 2012
From The Space Library
RELEASE: 12-417 NASA TWIN SPACECRAFT CREATE MOST ACCURATE GRAVITY MAP OF MOON
WASHINGTON -- Twin NASA probes orbiting the moon have generated the highest resolution gravity field map of any celestial body. The new map, created by the Gravity Recovery and Interior Laboratory (GRAIL) mission, is allowing scientists to learn about the moon's internal structure and composition in unprecedented detail. Data from the two washing machine-sized spacecraft also will provide a better understanding of how Earth and other rocky planets in the solar system formed and evolved. The gravity field map reveals an abundance of features never before seen in detail, such as tectonic structures, volcanic landforms, basin rings, crater central peaks, and numerous simple, bowl-shaped craters. Data also show the moon's gravity field is unlike that of any terrestrial planet in our solar system. These are the first scientific results from the prime phase of the mission, and they are published in three papers in the journal Science. "What this map tells us is that more than any other celestial body we know of, the moon wears its gravity field on its sleeve," said GRAIL principal investigator Maria Zuber of the Massachusetts Institute of Technology in Cambridge. "When we see a notable change in the gravity field, we can sync up this change with surface topography features such as craters, rilles or mountains." According to Zuber, the moon's gravity field preserves the record of impact bombardment that characterized all terrestrial planetary bodies and reveals evidence for fracturing of the interior extending to the deep crust and possibly the mantle. This impact record is preserved, and now precisely measured, on the moon. The probes revealed the bulk density of the moon's highland crust is substantially lower than generally assumed. This low bulk crustal density agrees well with data obtained during the final Apollo lunar missions in early 1970s, indicating that local samples returned by astronauts are indicative of global processes. "With our new crustal bulk density determination, we find that the average thickness of the moon's crust is between 21 and 27 miles (34 and 43 kilometers), which is about 6 to 12 miles (10 to 20 kilometers) thinner than previously thought." said GRAIL co-investigator Mark Wieczorek of the Institut de Physique du Globe de Paris. "With this crustal thickness, the bulk composition of the moon is similar to that of Earth. This supports models where the moon is derived from Earth materials that were ejected during a giant impact event early in solar system history." The map was created by the spacecraft transmitting radio signals to define precisely the distance between them as they orbit the moon in formation. As they fly over areas of greater and lesser gravity caused by both visible features, such as mountains and craters, and masses hidden beneath the lunar surface, the distance between the two spacecraft will change slightly. "We used gradients of the gravity field in order to highlight smaller and narrower structures than could be seen in previous datasets," said Jeff Andrews-Hanna, a GRAIL guest scientist with the Colorado School of Mines in Golden. "This data revealed a population of long, linear, gravity anomalies, with lengths of hundreds of kilometers, crisscrossing the surface. These linear gravity anomalies indicate the presence of dikes, or long, thin, vertical bodies of solidified magma in the subsurface. The dikes are among the oldest features on the moon, and understanding them will tell us about its early history." While results from the primary science mission are just beginning to be released, the collection of gravity science by the lunar twins continues. GRAIL's extended mission science phase began Aug. 30 and will conclude Dec. 17. As the end of mission nears, the spacecraft will operate at lower orbital altitudes above the moon. When launched in September 2011, the probes were named GRAIL A and B. They were renamed Ebb and Flow in January by elementary students in Bozeman, Mont., in a nationwide contest. Ebb and Flow were placed in a near-polar, near-circular orbit at an altitude of approximately 34 miles (55 kilometers) on Dec. 31, 2011, and Jan. 1, 2012. NASA's Jet Propulsion Laboratory in Pasadena, Calif., manages the mission for NASA's Science Mission Directorate in Washington. GRAIL is part of the Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems of Denver built the spacecraft.
RELEASE: 12-421 SOCIAL MEDIA ACCREDITATION OPENS FOR NASA AIRBORNE EARTH SCIENCE EVENT
WASHINGTON -- NASA is inviting social media followers for a behind-the-scenes look at several airborne Earth science missions during an event Jan. 25 at NASA's Dryden Flight Research Center in Edwards, Calif. Social media users may apply for credentials to meet scientists and learn how they study the Earth using specialized science instruments on a unique fleet of aircraft. Three major Earth science missions that will be airborne studying air pollution and climate change next month will be featured. -- NASA's high-altitude unmanned Global Hawk aircraft will fly six miles above the surface to a region of the atmosphere that controls the entry of pollutants and other gases into the stratosphere. NASA's Airborne Tropical Tropopause Experiment (ATTREX) will look at how these gases influence Earth's climate, ozone layer and energy budget. -- Two NASA planes will fly over the San Joaquin Valley to measure air pollution this winter. They are part of a five-year NASA science campaign called DISCOVER-AQ, which is working to improve the ability of satellites to observe air quality in the lowest part of the atmosphere. The goal is to better monitor pollution from satellites, so scientists can make better air quality forecasts and more accurately determine the source of pollution. -- NASA's high-altitude ER-2 will fly three state-of-the-art instruments to develop new orbiting sensors to better measure aerosol and cloud physical properties around the world. These new instruments, part of the Polar Definition Experiment, show great promise for advancing aerosol measurements from space. Tiny aerosol particles can be found over oceans, deserts, mountains and forests. Despite their small size, aerosols have major impacts on our climate and our health. Social media users selected to attend the event will be given the same access as news media. Individuals who actively collect, report, analyze and disseminate news on social networking platforms are encouraged to apply for credentials. Selection is not random. Those chosen must demonstrate through the registration process they meet specific engagement criteria.
RELEASE: 12-422 NASA-NOAA SATELLITE REVEALS NEW VIEWS OF EARTH AT NIGHT
WASHINGTON -- Scientists unveiled today an unprecedented new look at our planet at night. A global composite image, constructed using cloud-free night images from a new NASA and National Oceanic and Atmospheric Administration (NOAA) satellite, shows the glow of natural and human-built phenomena across the planet in greater detail than ever before. Many satellites are equipped to look at Earth during the day, when they can observe our planet fully illuminated by the sun. With a new sensor onboard the NASA-NOAA Suomi National Polar-orbiting Partnership (NPP) satellite launched last year, scientists now can observe Earth's atmosphere and surface during nighttime hours. The new sensor, the day-night band of the Visible Infrared Imaging Radiometer Suite (VIIRS), is sensitive enough to detect the nocturnal glow produced by Earth's atmosphere and the light from a single ship in the sea. Satellites in the U.S. Defense Meteorological Satellite Program have been making observations with low-light sensors for 40 years. But the VIIRS day-night band can better detect and resolve Earth's night lights. The new, higher resolution composite image of Earth at night was RELEASEd at a news conference at the American Geophysical Union meeting in San Francisco. This and other VIIRS day-night band images are providing researchers with valuable data for a wide variety of previously unseen or poorly seen events. "For all the reasons that we need to see Earth during the day, we also need to see Earth at night," said Steve Miller, a researcher at NOAA's Colorado State University Cooperative Institute for Research in the Atmosphere. "Unlike humans, the Earth never sleeps." The day-night band observed Hurricane Sandy, illuminated by moonlight, making landfall over New Jersey on the evening of Oct. 29. Night images showed the widespread power outages that left millions in darkness in the wake of the storm. With its night view, VIIRS is able to detect a more complete view of storms and other weather conditions, such as fog, that are difficult to discern with infrared, or thermal, sensors. Night is also when many types of clouds begin to form. "The use of the day-night band by the National Weather Service is growing," said Mitch Goldberg, program scientist for NOAA's Joint Polar Satellite System. For example, the NOAA Weather Service's forecast office in Monterey, Calif., is now using VIIRS day-night band images to improve monitoring and forecasting of fog and low clouds for high air traffic coastal airports like San Francisco. According to Goldberg, VIIRS images were used on Nov. 26, the Monday after Thanksgiving, to map the dense fog in the San Francisco Bay area that resulted in flight delays and cancellations. Unlike a camera that captures a picture in one exposure, the day-night band produces an image by repeatedly scanning a scene and resolving it as millions of individual pixels. Then, the day-night band reviews the amount of light in each pixel. If it is very bright, a low-gain mode prevents the pixel from oversaturating. If the pixel is very dark, the signal is amplified. "It's like having three simultaneous low-light cameras operating at once and we pick the best of various cameras, depending on where we're looking in the scene," Miller said. The instrument can capture images on nights with or without moonlight, producing crisp views of Earth's atmosphere, land and ocean surfaces. "The night is nowhere as dark as we might think," Miller said. And with the VIIRS day-night band helping scientists to tease out information from human and natural sources of nighttime light, "we don't have to be in the dark anymore, either." "The remarkable day-night band images from Suomi NPP have impressed the scientific community and exceeded our pre-launch expectations," said James Gleason, Suomi NPP project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.
RELEASE: 12-423 NASA OFFERS HIGH SCHOOL GIRLS A CHANCE TO JUMP-START THEIR FUTURE
WASHINGTON -- NASA is offering high school junior girls from across the United States an opportunity to jump-start their future by participating in the Women In STEM High School (WISH) Aerospace Scholars program for 2013. WISH participants will participate in online forums focusing on science, technology, engineering and mathematics (STEM) topics, and complete online activities to qualify for a six-day summer experience at NASA's Johnson Space Center in Houston. During the summer experience, they will work with mentors to design a mission to Mars, interact with NASA female role models, and mingle with scientists and engineers as they learn about careers in STEM. Applications are due Jan. 3. Applicants must be U.S. citizens, female high school juniors with a cumulative GPA of 3.25 or higher and interested in STEM. They must have access to the Internet and e-mail, be able to commit to the project for one year and participate in the Johnson summer program in 2013. WISH Aerospace Scholars is sponsored by NASA's Education Flights Project Office and offered at no cost to the participants
