NASA's GRAIL Moon Twins Begin Extended Mission

   NASA's twin, lunar-orbiting Gravity Recovery and Interior Laboratory (GRAIL) spacecraft began data collection for the start of the mission's extended operations.
   "The data collected during GRAIL's primary mission team are currently being analyzed and hold the promise of producing a gravity field map of extraordinary quality and resolution," said Maria Zuber, principal investigator for GRAIL from the Massachusetts Institute of Technology in Cambridge. "Mapping at a substantially lower altitude during the extended mission, and getting an even more intimate glimpse of our nearest celestial neighbor, provides the unique opportunity to globally map the shallow crust of a planetary body beyond Earth."
   The science phase of GRAIL's extended mission runs from Aug. 30 to Dec. 3. Its goals are to take an even closer look at the moon's gravity field, deriving the gravitational influence of surface and subsurface features as small as simple craters, mountains and rilles. To achieve this unprecedented resolution, GRAIL mission planners are halving the operating altitude – flying at the lowest altitude that can be safely maintained.

NASA's Kepler Discovers Multiple Planets Orbiting a Pair of Stars

   Coming less than a year after the announcement of the first circumbinary planet, Kepler-16b, NASA's Kepler mission has discovered multiple transiting planets orbiting two suns for the first time. This system, known as a circumbinary planetary system, is 4,900 light-years from Earth in the constellation Cygnus.
   This discovery proves that more than one planet can form and persist in the stressful realm of a binary star and demonstrates the diversity of planetary systems in our galaxy.
   Astronomers detected two planets in the Kepler-47 system, a pair of orbiting stars that eclipse each other every 7.5 days from our vantage point on Earth. One star is similar to the sun in size, but only 84 percent as bright. The second star is diminutive, measuring only one-third the size of the sun and less than 1 percent as bright.
    In contrast to a single planet orbiting a single star, the planet in a circumbinary system must transit a 'moving target.' As a consequence, time intervals between the transits and their durations can vary substantially, sometimes short, other times long. The intervals were the telltale sign these planets are in circumbinary orbits.
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Arctic Sea Ice Shrinks To New Low In Satellite Era



Arctica as seen from Era satelite of NASA. The orange line the amount of ice that should normally exist by now. 



 The extent of the sea ice covering the Arctic Ocean has shrunk. According to scientists from NASA and the NASA-supported National Snow and Ice Data Center (NSIDC) in Boulder, Colo., the amount is the smallest size ever observed in the three decades since consistent satellite observations of the polar cap began.
The extent of Arctic sea ice on Aug. 26, as measured by the Special Sensor Microwave/Imager on the U.S. Defense Meteorological Satellite Program spacecraft and analyzed by NASA and NSIDC scientists, was 1.58 million square miles (4.1 million square kilometers), or 27,000 square miles (70,000 square kilometers) below the Sept. 18, 2007, daily extent of 1.61 million square miles (4.17 million square kilometers).
The sea ice cap naturally grows during the cold Arctic winters and shrinks when temperatures climb in the spring and summer. But over the last three decades, satellites have observed a 13 percent decline per decade in the minimum summertime extent of the sea ice. The thickness of the sea ice cover also continues to decline.
"The persistent loss of perennial ice cover -- ice that survives the melt season -- led to this year's record summertime retreat," said Joey Comiso, senior research scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "Unlike 2007, temperatures were not unusually warm in the Arctic this summer."

The new record was reached before the end of the melt season in the Arctic, which usually takes place in mid- to late-September. Scientists expect to see an even larger loss of sea ice in the coming weeks.
"In 2007, it was actually much warmer," Comiso said. "We are losing the thick component of the ice cover. And if you lose the thick component of the ice cover, the ice in the summer becomes very vulnerable."
"By itself it's just a number, and occasionally records are going to get set," NSIDC research scientist Walt Meier said about the new record. "But in the context of what's happened in the last several years and throughout the satellite record, it's an indication that the Arctic sea ice cover is fundamentally changing."