Swift blasts off on dying star mission

Spot the gamma ray burst

By Lucy Sherriff, 22nd November 2004

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Swift, a satellite space lab that will hunt and study the most violent explosions ever seen in the universe, has finally launched from Cape Canaveral. It was originally schedule to launch on 8 November, but various set-backs meant that it wasn't until 12:16 (EST) on 20 November, that Swift finally got off the ground.

The craft separated from the Delta second stage about 80 minutes after launch, NASA said, and has sent back signals confirming that its solar arrays are properly deployed.

"It's a thrill that Swift is in orbit. We expect to detect and analyse more than 100 gamma-ray bursts a year. These are the most powerful explosions in the universe, and I can't wait to learn more about them," said Swift principal investigator Dr. Neil Gehrels. The satellite is charged with spotting gamma ray bursts. These are very short lived, but massively powerful signals, thought to be produced when very massive stars go supernova and leave a black hole behind. They might also be the evidence of a collision between two neutron stars. One of Swift's tasks is to gather enough data that scientists can work out exactly what does cause these huge explosions.

Swift gets off the ground (Image: NASA)

One of the reasons GRBs are important is that they tell us so much about the early universe. The explosions are so bright that they could be detected as far back as the earliest five percent of the universe's life time. A star must collapse, or two stars must collide to produce one, their presence is conclusive proof of star formation. This gives us an insight into when stars began forming, and what the universe must have been like, billions of years ago.

NASA describes catching Gamma Ray Bursts (GRBs) as being harder than bottling light. The bursts are very short lived: lasting from less than a second to just a few minutes. Catching one in the act, then, is a difficult task, especially when getting ground based telescopes pointing the right way can even take a number of days.

Swift has been designed to detect the gamma ray burst, and respond within 20-70 seconds. It will swing around to face the direction of the signal and will pinpoint the source. It carries three instruments: the Burst Alert Telescope (BAT), the X-Ray telescope, and the Optical and UV telescope. Each one in turn will give astronomers more accurate data about where to look in the sky, and ground based telescopes can join the hunt too.

The satellite will now begin a month-long calibration period. It will check that all its instruments work, and that it can swivel around in its orbit without pointing its cameras at the sun.

Scientists expect the satellite will make many discoveries once it become fully operation in March or April next year, because it can respond to any astronomical phenomenon. While Swift is not actively tracking a GRB, it will conduct the largest ever X-Ray survey of the sky.

The NASA site following Swift's progress can be found here. ®