Science Interviews


Sun, 21st Nov 2004



Part of the show Cloud-dwelling Bacteria, & Ozone Holes

The Swift mission launched this week. Space scientist Julian Osbourne, from the University of Leicester, joins to explain its purpose.

Chris - What are we hoping to learn from the Swift? And why are Gamma Ray Bursts important?

Julian - The Swift is dedicated to gamma ray bursts. Gamma rays are a very energetic ray of light, about 100 thousand times more energetic than a typical packet of life from a light bulb. Bursts were first seen in 1969 by the Bealer satellite. They found bursts that could be a signature of a nuclear explosion, but were coming from space and not from earth. In1997, the first precise position of the burst was found coming from distant galaxies. Gamma ray bursts are significant because they represent very extreme physics. The energy of a gamma ray burst -which might last between 0.1 and 100 seconds - is equivalent to the energy given off in the same duration by a billion billion suns or 10 million galaxies

Chris - What do gamma ray bursts tell us about our history and our place in the universe?

Julian - We might learn about first generation of stars. We have never seen these stars, but we think the first generation of stars were more massive than our present-day stars. It takes a massive star that collapses in a supernova explosion to make one of these gamma way bursts.

Chris - So why was this satellite called Swift?

Julian - It is named after the fast moving bird. After the Swift detects a gamma ray burst, it immediately and very rapidly re-orientates itself to point that direction. It is predicted to re-point about 3 times a week. All satellites move by a magnetic brake on a reaction wheel - basically, a spinning gyroscope. Swift has 6 of these whereas most spacecrafts only have 4, and the ones on Swift are 2-3 times more massive than those used normally. By suddenly grabbing hold of this spinning thing when it detects a gamma ray burst, the satellite can whiz around very quickly.


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