Close encounters

Is there life on HD164595b?

The news that Russian scientists observed an unexplained ‘strong signal’ from a star just 95 light years away has piqued the interest of scientists and would-be alien hunters worldwide. Dr Alan Penny, an Honorary Reader at the School of Physics and Astronomy and Co-ordinator of the UK’s Search for Extraterrestrial Intelligence Research Network, investigates.

“Those of us who are in the business of SETI – the Search for Extraterrestrial Intelligence – have many problems, but a major one is how to distinguish a radio signal originating from a natural source in the sky, for example a quasar or a pulsar, from one originating from an extraterrestrial civilisation. Ever since the first modern SETI search with a radio telescope in 1960 up to the modern searches which are a trillion times more sensitive, much effort has been put into solving this problem.

“Just last week, we were made yet again aware of this, with a report from a Russian radio telescope that last year they had found radiation coming from the direction of a nearby star with the name HD164595, which might be such an artificial signal. This caused much excitement in the very small international SETI community, and two radio telescopes in America are now trained on this object to see if they can detect anything. And once the media found out about this, there was a bit of a media storm, and this morning I found myself quoted on the front page of The Times, and interviewed on BBC Radio 4’s Today programme.

“I wish I could say that the UK is taking part in this follow-up checking, but unfortunately there is no UK funding for SETI. A group of about 15 UK academics have indeed set up the UK SETI Research Network, but we (I am the UKSRN Co-ordinator) merely write papers on theoretical aspects of SETI, such as where to look, what an ET signal might look like, etc. We have tried to get funding to use one of the UK radio telescopes for a SETI search, but so far with no luck.

“Let’s go into more detail on what the Russians found. They were using the RATAN-600 large radio telescope in Zelenchukskaya, near the Caucasus mountains, to survey 31 nearby stars, much like the Sun, on the basis that one place that ET might be is on a planet orbiting such a star. The telescope is of the transit type, in that it looks due south or north and waits until the rotation of the Earth each day brings the target into its field of view for a short time. They looked at each star some thirty times, and found nothing, which is what you would expect as stars like the Sun are, astrophysically speaking, very weak radio sources.

“Except for one star – HD164595 – from which on one transit pass there was a clear signal. This is not what you would expect from a ‘normal’ radio source – they don’t pop into existence and then disappear again. So what was the evidence that it was ET? Well, it was an unusual source, which seemed to be associated with a Sun-like star. In the two months the Russians surveyed, they did not see any similar signal, so this seems to point away from a problem with the telescope.

“But as Carl Sagan once said ‘extraordinary claims need extraordinary evidence’, and that evidence doesn’t at the moment meet that criterion. What we would really need is observations from other telescopes to rule out local radio sources or things like passing aeroplanes. And the Russians only saw it once. Now the news is out, there are two American telescopes working on it; in the first few days of searching, they haven’t seen anything.

“One tell-tale sign of artificiality would be that the signal was limited to a very narrow frequency bandwidth, say 1 Hz wide as our own radio and analogue TV stations are. It is very difficult to think of a natural source which could do that. Unfortunately the RATAN-600 telescope was being used with a 1 GHz bandwidth, so that test is not available. Unless the American telescopes find that the source has switched on again, and shows these distinct artificiality signs, we will be left with the ‘I wonder what that was’ situation, and the international SETI searches will continue as before, without, as I said, the UK. It is really a shame that the various UK funding agencies are not eager to support us.

“On a personal note, I am actually involved in one follow-up search. METI International, of which I am Vice-President and which is a mainly American organisation, is planning a search using a small optical telescope to look for nanosecond visible flashes from HD164595, flashes so short that again they couldn’t be from a natural source. Stay tuned for news from us.

“Wouldn’t it be great if here in the UK we could afford the relatively small amount of money to equip the University’s James Gregory Telescope with the instrumentation to enable us to take part in such a search?”

Issued by the University of St Andrews Communications Office, contactable on 01334 462530 or [email protected].