European radio array launches SETI search
Posted: 20 April
A new SETI survey that will operate at frequencies lower than anyone has ever searched before will begin this spring using a new pan-European radio array, it was revealed at the Royal Astronomical Society’s National Astronomy Meeting at the University of Glasgow last week.One of the completed LOFAR stations that will soon be sweeping the skies for SETI signals. Image: ASTRON/MPIfR.
LOFAR – the Low Frequency Array – will conduct radio astronomy between 10–240MHz, and is built to primarily observe astrophysical phenomena such as galaxies and supermassive black holes. When all 44 stations are completed this summer (21 are operating so far), LOFAR will span the Netherlands, the UK, France, Germany and Sweden, with the majority of arrays in the Netherlands. The radio arrays will then be joined by interferometry, and such a large baseline is required because a wide area is needed to see detail with low radio frequencies.
Particularly intriguing is the SETI project, which will act as a pioneering survey not just because it will search uncharted radio frequencies, but also because European SETI programmes are almost as rare as the alien signals they are hunting seem to be.
“There have been few SETI programmes in Europe apart from early Russian work and an Italian team working with the SERENDIP group [a receiver piggybacking on the Arecibo radio telescope in Puerto Rico]. In the UK the only searching has been with the Lovell Telescope at Jodrell Bank by the SETI Institute as a check telescope in one of their programmes using Arecibo,” says Dr Alan Penny of the University of St Andrews, who is leading the LOFAR survey.
The survey is unique in the world because it is plumbing the depths of the radio spectrum, going as low as 20MHz. “On the Arecibo telescope there is a 400MHz radar that is also a receiver, and SERENDIP 3 used that to do a semi all-sky survey, but we’ll be working at shorter wavelengths and be able to look for a much narrower beam,” says Penny. “It makes sense to have a look and see if there is anything there.”
The initial LOFAR test survey will target perhaps a dozen stars, spending only a couple of hours listening to each, but the aim of this first phase is to figure out how to weed out terrestrial interference that interferes with the search. “Most of our radiation is across low frequency TV stations, or radar signals,” says Penny. “One of the reasons radio searches have been done in the gigahertz range is because the Galaxy is very quiet and very transparent at those frequencies. You do get terrestrial interference in the gigahertz range, but in the megahertz range there’s much more.”
Once it has been proven that Earthly interference can be eradicated sufficiently, Penny and his colleagues will return to the time allocation board that oversees LOFAR and request extra telescope time to conduct a much more thorough search, scanning hundreds of stars for many hours each. “If it works out we’ll probably ask for a 1,000 hours of telescope time,” says Penny. “From there the sky’s the limit.” Beyond that, further SETI work with piggyback LOFAR observations is a possibility.
For Alan Penny, SETI is not just a blue sky thinking, but has real worth. “Of course the payoff if you make a detection is unlimited, but it also helps with the public understanding of science; it’s a great tool for getting the public interested in science. But the main reason [to search] is, what kind of civilisation isn’t curious enough even to look? It would be wimpish not to.”
And how does he foresee SETI developing in Europe, and the UK in particular, in the future? Recognising that the European astronomy budget is quite large, but also that there are many science projects competing for public funding, Penny has a figure in mind that would allow a respectable SETI and outreach programme. “I’d like one in 200 of the astronomy budget to go to SETI,” he suggests with enthusiasm for a subject that is obviously a passion of his. “I think that would be a reasonable amount.”