Birth, growth, decay and death in outer space: Scientists celebrate satellite's 10th birthday

By Ben Miller | 18 November 2014

Scientists will mark the tenth birthday of a busy bee in outer space this Wednesday - and it shows no signs of slowing down

A photo of a group of scientists standing inside an office smiling
Professor Julian Osbourne, of the X-ray and Observational Astrophysics Group, and his team in the Department of Physics and Astronomy at the University of Leicester© University of Leicester
For the past ten years, a satellite has hurtled around the Earth every 96 minutes at a height of 375 miles.

Eyeing up black holes, quasars, neutron stars and the explosive cosmic events which outshine everything else in the universe during incredibly brief bursts, Swift has been providing scientists with around 100 alerts of new bangs every year. And it regularly wakes its monitoring team up or gets them out of the shower.

A photo of a man sitting beneath a recreation of a satellite smiling
© University of Leicester
“They are some of the most energetic events that have occurred in the universe since the Big Bang, the very beginning of the universe,” explains Professor Alan Wells, of the Leicester-based UK Swift Science Data Centre, where scientists receive direct calls from orbit.

“They’re very difficult to locate and they have been a mystery for many years, since they were first discovered in the 1970s.

“What Swift is able to do is to study gamma ray bursts through their life cycle of birth, growth, decay and death – and that, I think, has been a scientific voyage of discovery, these last ten years.”

NASA-built and weighing a ton and a half, the satellite spins around the sky, finding these elusive rays. Although Professor Wells admits its estimates are “very crude”, its x-ray telescope and optical ultraviolet telescope can hint at the possible location of the burst.

Maintaining such a unique and versatile satellite has not been without its challenges. “The instrument had to be kept cool – particularly the detector.

A photo of two people looking at data from outer space on a computer monitor
© University of Leicester
“But quite early in the project we encountered a solar storm and it is likely that a solar proton impacted part of the electronics and killed the power supply that was keeping the detector cool.

“We had to completely redefine the pointing strategy of the satellite to be able to make sure that the telescopes didn’t look at the sun, the radiator that we were using to cool the detector didn’t look at the earth and we could actually look at the x-ray source that we were trying to find the gamma ray burst in.

“That was really like juggling – we had to learn how to combine all of these restraints and still carry out the mission. I think it was a remarkable achievement.”

Another minor problem arrived when a micro-meteorite hit the detector, producing a massive signal and swamping the imagery in an unwanted addition to the kit which meant the software had to be altered to bypass it.

“Now we have a satellite that is in late middle age, but it’s been taking the tablets and is in good shape,” says Professor Wells, praising Swift’s “very big” contribution to astrophysics.

“Swift has been able to measure the properties of many long bursts and their afterglows, which have given big clues as to their behaviour and decay processes.

“It is like a lighthouse in the middle of these early decaying, exploding, dying stars. We have been able to follow the short bursts, which last only for a few milliseconds in their decay.

“They point to neutron stars emerging with black holes. Swift actually witnessed that event for the first time.”

The satellite might be able to detect another mystery, predicted in Albert Einstein’s general theory of relativity.

“Gamma ray detection has the potential to find candidates which may be emitting gravity waves,” believes Professor Wells.

“If you have a merger of two neutron stars or a neutron star with a black hole there should, in theory, be emissions of gravity waves. And that would be pretty exciting.”

One black hole, known as Sagittarius A*, is close to swallowing up a cloud of gas, spewing out “enormous amounts” of high energy radiation and flickering the hole back into life for the first time in a million years. Swift will be waiting should that happen.

“Swift is such a flexible satellite, designed to re-point quickly and access a lot of the sky,” says Professor Julian Osborne, of the X-ray and Observational Astrophysics Group at the University of Leicester’s Department of Physics and Astronomy.

“Other X-ray telescopes can take many days to respond to a reposition request.

“But with Swift we can ask for an observation and take a look at data within a few hours, and then immediately ask for a new observation if we need it.

“The autonomy and agility of Swift was something radically new in our field – and it is still unique in that respect.”

What do you think? Leave a comment below.

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