Astronomers are to build the ultimate alien-hunting telescope — a machine so powerful it could detect transmissions equivalent to a mobile phone network from a planet up to 50 light years from Earth.
The square kilometre array (SKA), as the giant radio-telescope is known, will be the world’s largest astronomical instrument with 3,000 separate radio dishes and other antennae all linked together into one huge machine.
British astronomers have been appointed to oversee its design and construction, and it will be thousands of times more sensitive than anything already built, including the iconic Lovell telescope at Jodrell Bank at Manchester University.
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“We know that the universe is incredibly vast, containing hundreds of billions of stars,” said Richard Schilizzi, director of the SKA project, which is based at Jodrell Bank. “However, at present we can only see a fraction of what is out there. The SKA will enable us to explore some of its furthest reaches.”
More than 20 countries, including Britain, will share the estimated £1.4 billion cost of the project for the telescope. Two potential sites have been chosen, one in Western Australia and the other in South Africa. Both are in the southern hemisphere because this will give the instrument a direct line of sight into the heart of the Milky Way, our home galaxy.
This week more than 150 astronomers and science ministers will meet in Banff, Canada, to start the final site selection.
The telescope will give humanity its best chance of detecting any alien civilisation advanced enough to have invented radio.
It will potentially be able to detect the equivalent of a mobile phone system within 50 light years of Earth, but will probably be able to scan much more remote star systems, since any advanced civilisation would have powerful radio emitters such as radar and radio stations. About 8,500 stars are thought to lie within 150 light years of Earth, and around 250,000 lie within 250 light years.
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“We want to watch for signals that could suggest signs of intelligent alien life,” said Schilizzi, “but hunting for extraterrestrial civilisations is just one of several key tasks for the SKA.”
The telescope will also seek to map the entire known universe, showing the locations of more than a billion galaxies — and the way they are moving relative to us.
Astronomers hope that such a map will help them understand “dark energy”, the force that makes the universe expand at an ever-increasing rate but whose true nature and origins remain a mystery.
A third task will be to pick up the faint radiation left over from the formation of the first stars, galaxies and black holes, more than 13 billion years ago.
This era, known as “first light”, saw the huge clouds of swirling hydrogen created in the Big Bang coalesce into clumps big enough to form stars and ignite, lighting up the universe for the first time.
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Astronomers want to find out what shaped those clouds — because those forces led directly to the structure of the universe as we see it today.
“The SKA is a bit like a time machine,” said Phil Diamond, head of the astronomy and space science division of CSIRO, the Australian government’s research arm, where he heads a team overseeing Australia’s bid for the telescope.
“It will gather radiation emitted more than 13 billion years ago, allowing us to get a picture of what the universe looked like then. By choosing the type of radiation we look at, we can get similar pictures of the universe from any other era we choose — so we can watch how it evolved.”
It may even solve a mystery that baffled Einstein: how to reconcile the force of gravity, which controls the workings of the universe at the scale of stars and galaxies, with quantum mechanics, which describes interactions between sub-atomic particles.
The SKA must be built on a site completely free of radio interference — with the host country pledging it will prevent the construction of any mobile phone, radio or TV masts for up to 50 years. This means it will have to be built mainly in a desert — either in the outback of Western Australia or the Karoo of South Africa.
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It is expected to generate 100 times more data than all the traffic currently flowing around the internet, and will need the world’s most powerful supercomputer to analyse the information.