NASA's Chandra Reveals Origin of Key Cosmic Explosions

New findings from NASA's Chandra X-ray Observatory have provided a major advance in understanding a type of supernova critical for studying the dark energy that astronomers think pervades the universe. The results show mergers of two dense stellar remnants are the likely cause of many of the supernovae that have been used to measure the accelerated expansion of the universe.

These supernovae, called Type 1a, serve as cosmic mile markers to measure expansion of the universe because they can be seen at large distances, and they follow a reliable pattern of brightness. However, until now, scientists have been unsure what actually causes the explosions.

"These are such critical objects in understanding the universe," said Marat Gilfanov of the Max PlanckInstitute for Astrophysics in Germany and lead author of the study that appears in the Feb. 18 edition of the journal Nature. "It was a major embarrassment that we did not know how they worked. Now we are beginning to understand what lights the fuse of these explosions."

Perspective View of Layered Mound in Gale Crater, Mars

This oblique view shows geological layers of rock exposed on a mound inside Gale Crater on Mars. This is a lower portion of the mound, with the crater floor at the left (and lowest) edge of the image. Layers near the bottom of the mound contain clay and sulfate minerals that indicate wet conditions. Overlying rock layers contain sulfates with little or no clay, consistent with these layers forming in an environment in which water was evaporating and Mars was drying out.

This view was created from a three-dimensional topographic model of the mound. The U.S. Geological Survey generated the model from a stereo pair of images taken by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. Observations of the site by the Compact Reconnaissance Imaging Spectrometer for Mars, on the same orbiter, yielded information about composition. The vertical dimension is exaggerated three-fold relative to the horizontal dimensions. The view is toward the southeast. The width of the area included in the image is about 1.5 kilometers (about 5,000 feet). The scale bar in the labeled version is 200 meters (656 feet).

Radar Studies Continue in Hispaniola

NASA radar imaging flights over Central America, Haiti and the Dominican Republic are in the second week of a three-week campaign.

The JPL-developed Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) is currently in the second week of a three-week campaign in Central America, Haiti and the Dominican Republic. Flying beneath the belly of a modified Gulfstream III aircraft from NASA’s Dryden Flight Research Center, the sophisticated radar can spot minute changes in Earth's surface by flying precise repeat passes over targeted areas.

The Central American survey flights are focusing on measuring biomass in Central American rain forests, imaging volcanoes from Guatemala to Costa Rica, and imaging Mayan ruins. The flights over Haiti and the Dominican Republic are targeting earthquake faults on the island of Hispaniola. Scientists collected data over Central American nations again on Feb. 2, and then flew a second set of data tracks over Haiti on Feb. 3 before returning to Costa Rica on Feb. 4.

Envisioning Future Flight

Today's students will be designing tomorrow's aircraft, and NASA's Fundamental Aeronautics Student Competition gives them a head start.

Each year, the competition challenges students to research a particular real-world issue in aeronautics and to develop their own solutions to the problem.

Past participants in NASA's Fundamental Aeronautics Student Competition said the experience was a rewarding one that helped them learn more about aeronautics and encouraged them to improve their approaches to research and creative problem-solving.

In the 2008-2009 competition, students were challenged to develop ideas for making commercial supersonic air transportation available by 2020. Contest participants did so by examining obstacles to supersonic transportation and proposing solutions. In an additional challenge, some students submitted designs for a small supersonic airliner.