In search of the meaning of celestial light

Irish-designed software will be used on a European satellite observatory to be launched later this year

Irish-designed software will be used on a European satellite observatory to be launched later this year. Declan Fahy talks to some of those behind the work

There are brilliant explosions occurring billions of light years away, briefly outshining all other light sources in the rest of the universe. These spectacular phenomena, gamma-ray bursts, occur several times a day, but remain one of the mysteries of the cosmos.

Scientists in three Irish institutions have developed technology that will help a European satellite observatory take accurate and high-resolution images of these celestial events.

The European Space Agency's (ESA) Integral satellite, an astronomical observatory with three different types of telescope, will search the far reaches of the universe for these little-understood gamma-ray bursts.

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Integral - or the International Gamma Ray Astrophysics Laboratory, to give it its full name - will be launched in October this year on a Russian Proton rocket from the Baikonour space centre in Kazakhstan.

The satellite will carry a high- resolution spectrograph, an X-ray measuring device and an Optical Monitoring Camera (OMC), a device developed by the Irish teams in collaboration with scientists from Spain, Belgium and Britain.

The OMC, the satellite's key device, has a complex series of lenses which will focus light on an array of sensitive devices that can capture data in space and relay it in picture form.

An enormous number of images will be continuously transmitted from the OMC. These will then be "cleaned up" and analysed, using software designed by Kevin Nolan, of IT Tallaght. The software system, which Nolan says is called "the standard pipeline", will be based on earth. The system "will receive the raw data from the space probe, clean it up, look for sources such as black holes, active galaxies and gamma-ray bursts and do an analysis on them".

"This is all done automatically and in real time," he says. "Time is important, as gamma-ray burst optical flashes might only linger for half an hour or so, so you have to do a preliminary analysis quickly."

Dr Lorraine Hanlon, lecturer in experimental physics at UCD, had a pivotal role in designing the OMC, says Nolan. The electronics on the camera were designed by Brendan Jordan, experimental officer at Dunsink Observatory and the Dublin Institute for Advanced Studies (DIAS).

Last week, Nolan says, he delivered a complete and working version of the software to the Integral Science Data Centre (ISDC) in Geneva, which he says is essentially "mission control" for the observatory.

The software will be sent to Madrid next month, where the space probe was built, and will be further tested on simulated test data.

The Republic has been a member of the ESA since 1980. Mr Nolan says "such projects are a source of national pride, in the same way that the new wing of the national art gallery is a great and proud addition to Irish culture".

Scientists are not sure how gamma-ray bursts originate, but Mr Nolan says that if their source is found, it will reveal much about the origin of the universe. "They are that fundamental," he says.

One theory says gamma-ray bursts are caused by the collapse of very large stars (dozens of times bigger than our sun), which then become black holes.

As a collapse begins, mass equivalent to that contained in our sun can condense into the black hole each second, reaching a peak of energy in the last few seconds of the star's death. This throws out twin jets of tremendously powerful gamma rays that cross the universe.

As well as pinpointing gamma-ray bursts, the observatory will bring much new information on stellar explosions, black holes and the formation of elements.