Nasa hunts black holes
2004-11-22 12:45
Florida - A new space observatory was rocketing into orbit on Sunday preparing to scan the universe for the most violent celestial explosions since the Big Bang.
The $250m Nasa probe - named Swift for its speedy pivoting and pointing - will detect and analyse gamma ray bursts, which astronomers believe represent the birth screams of black holes.
Lasting just a few seconds on average, the bursts appear out of nowhere like flashlight beams and are thought to signal the formation of black holes.
The observatory, which was launched from Cape Canaveral in Florida on Saturday, carries three telescopes that work together: The Burst Alert telescope built by the US space agency's Goddard research centre; an X-ray telescope built by Penn State University, the University of Leicester and the Osservatorio Astronomico di Brera; and an ultraviolet optical telescope, made by Penn State and University College London's Mullard Space Science Laboratory.
Swift should begin its hunt for gamma ray bursts by January and erase some of the mystery surrounding these explosions and black holes.
Astronomers believe the collapse or collision of massive stars is what produces black holes - so dense not even light can escape - and that the resulting gravitational energy sends gamma rays shooting out across time and space.
Neil Gehrels, Nasa's principal scientist, said: "We think that, perhaps, bursts are the birth cries of black holes and we're seeing these throughout the universe."
'Swift will lead to a windfall of discovery'
A single gamma ray burst releases more energy than the sun will emit in its entire lifetime at all wavelengths, Gehrels said.
So far, astronomers have managed to identify only a few dozen gamma ray bursts, as close as a few million light years and as far as 12 billion light years. Swift should zero in on two gamma ray bursts a week as far away as 15 billion light years, representing the first generation of stars, during the planned two-year mission.
The spacecraft will scan one-sixth of the sky at any one time and thus see one-sixth of all gamma ray bursts.
Gehrels said: "We expect to detect and analyse over 100 gamma-ray bursts a year. Swift will lead to a windfall of discovery on these most powerful explosions in the universe."
The Hubble space telescope, by contrast, takes hours if not an entire day or two to swivel into an impromptu viewing position.
After chasing gamma ray bursts for a year or two, Swift will expand its repertoire to other rapidly occurring cosmic events.
Gamma ray bursts were first observed during the Cold War, when Western researchers thought that they might be the product of Soviet nuclear tests on the moon or other planets.
Four other satellites will work in tandem with the probe and alerts on gamma ray bursts will be relayed to scientists worldwide.
- AP