November 1, 2004. Copyright, 2004, Graphic News. All rights reserved

Space probe to explore mysterious cosmic blasts
By Mark Rutter

LONDON, November 1, Graphic News: It was the late 1960s at the height of the Cold War. U.S. military satellites were orbiting the earth actively checking for explosions of atomic bombs. When mysterious gamma-ray bursts (GRBs) started being detected at a rate of around one every day, it was reasonable to assume that they were a product of Soviet Union nuclear tests in space.

Lasting from fractions of a second to a few hundred seconds, these brief intense flashes of gamma radiation were confirmed as natural phenomena in 1973. Today they are the subject of much research although we still know relatively little about their cause. All that could change with the launch of the U.S. Swift probe. Costing around $260 million (£140 million, 200 million euros) and involving British and Italian collaboration, it is scheduled to take off in Florida on Thursday, November 11. Scientists hope that it will finally solve the puzzle of the origin of gamma ray bursts in outer space.

Astrophysicists suggest that GRBs result from the formation of black holes, either by the hypernova scenario, when a massive star collapses in upon itself; or the compact object scenario, the collision of two ultra-dense neutron stars.

Whatever the explanation, bursts are associated with the generation of huge amounts of energy giving rise to the very high-energy gamma rays, a well as lower energy electromagnetic radiation, X-rays and visible light. These intense bursts are among the most violent explosions in the universe, giving out as much energy in a few minutes as the Sun in its lifetime. 

The effect is similar to the detonation of a nuclear bomb, leading some astrophysicists to speculate that explosions nearer to Earth, even those 30,000 light years away, might be powerful enough to have brought about mass extinctions in the past and to present a risk to life on Earth in the future. 

Up until now, the short-lived nature of gamma ray bursts has made their study difficult. Swift is designed to overcome this problem by orbiting the Earth and using a ÒBurst Alert TelescopeÓ to monitor a section of the sky for flashes from explosions. When an explosion is detected, Swift will be able to respond rapidly by aligning its two other onboard telescopes with the burst to allow detailed observations. This ÒswiftÓ response, reminiscent of the small, nimble bird that quickly darts from one direction to another, and catches its prey on the wing, gives the spacecraft its name.

Also, by relaying information on the location of a burst to the ground within a few seconds, it will allow telescopes around the world to observe the afterglow. Some observatories will follow-up bursts for weeks and months afterwards. Studying a distant burst in a far-flung galaxy would also provide a snapshot back into time when the universe was much younger. It is hoped that Swift will detect up to two or three bursts a week.
/ENDS