Bird's eye. NASA's Swift satellite swivels quickly in orbit to view the fleeting flashes of gamma ray bursts.

A Swift Eye

A satellite dedicated to hunting gamma ray bursts, the most powerful explosions in space, has turned on with a bang. NASA's Swift satellite caught a burst in the act on 17 January, quickly pivoting in orbit to provide the first x-ray pictures of a burst as it flares into life. The satellite is likely to repeat its debut performance hundreds of times, helping reveal what happens in the chaotic moments after huge stars collapse to form new black holes.

NASA launched the $250-million Swift on 20 November to probe mysteries surrounding the origins of gamma ray bursts. Most bursts likely happen after the cores of massive stars run out of nuclear fuel and collapse, forming black holes. Torrents of energy from hot matter plunging into these holes are thought to then create bursts of gamma rays and x-rays. But to find out exactly what drives the explosions, astronomers must study them as soon as they erupt. Swift is able to spot the flare of a new burst anywhere in a wide swath of the sky; then, the satellite rapidly trains two telescopes on the explosion before it fades away.

Swift lived up to its name on 17 January, when it detected a bright and relatively long-lasting gamma ray burst. Within 200 seconds, the satellite began collecting the first x-ray images of a burst's early stages, says mission director Neil Gehrels of NASA's Goddard Space Flight Center in Greenbelt, Maryland. X-rays stream from the hottest, most violent parts of the blast wave, so astrophysicists expect that analysis will yield insights into the physics of how new black holes spew titanic jets of energy into space. A second telescope on Swift will study bursts in ultraviolet and optical light, but it was not quite ready to take data last week.

Other astrophysicists are thrilled with Swift's success. "They're doing fantastically well," says Jonathan Grindlay of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. Grindlay expects Swift to shed light on whether "short" gamma ray bursts, lasting just a second or so, arise from different events--such as the violent collisions of neutron stars. Swift also may see faint bursts from the first stars in the universe: giant objects that probably created large black holes more than 13 billion years ago, Grindlay predicts.

Related sites
Swift mission
Real-time gamma ray burst alert network
Background on gamma ray bursts

Posted in Space