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Lightpath illuminates the universe
JANET(UK) is helping UK scientists contribute towards an international astronomy project that will reveal how the first large-scale structures in the universe came into being, map the origin of high-energy cosmic rays, and even contribute to SETI – the search for extraterrestrial intelligence.
LOFAR – the Low Frequency Array – is a grid of radio telescopes that ultimately will consist of over 5,000 antennae spread across Europe, studying the lowest frequency radio waves that can be detected from Earth. With computing based at the University of Groningen in the Netherlands, stations are currently based at sites in the Netherlands, Germany, France, Sweden and the UK. The British component at Chilbolton in Hampshire is just nearing completion and will be plugged into the wider LOFAR array in the Netherlands via a 10Gbit/s JANET lightpath by the end of 2010. The Dutch endpoint of the lightpath will be configured by SURFnet.
LOFAR is a very cost-effective method of gathering vast amounts of data. A typical LOFAR station consists of around 100 antennae constructed from everyday mass-produced components with no moving parts. Unlike a conventional dish-shaped radio telescope, which rotates and can only look into one part of the sky at a time, LOFAR can be configured electronically to look into many parts of the sky simultaneously – or indeed all of it at once. As a result of the cheap construction, the entire project has so far cost in the region of €100 million, which is about the same as constructing a single 40m diameter radio dish. Most of the cost of the array lies in the data transport technology and vast amounts of computing power needed to keep the antennae synchronised to each other and to ensure the scientific information within the signals makes sense. The task is made more challenging by the sheer amounts of data: the Chilbolton site alone will be producing seven petabytes of raw data every year. (One petabyte is approximately 1 million gigabytes.) Real-time flows of data from the antennae are gathered on-site and then passed via the JANET lightpath to the data correlation centre in the Netherlands, to produce a detailed image of the sky.
As well as being a self-sufficient project in its own right, LOFAR is also an ideal testbed for methods of processing the vast amounts of data expected to flow from the even larger project SKA (Square Kilometre Array), which is scheduled for completion in about 2022. It is estimated SKA will produce 1 terabyte – 1000 gigabytes – of data every minute.