Karen O'Neil, Frank Drake, and Jay Lockman at the GBT controls. Image Credit: John Stoke and NRAO.
Fifty years ago, Philip Morrison and Giuseppe Cocconi proposed that extraterrestrial civilizations could be communicating via radio waves and that we could eavesdrop on the conversation. At the same time, Frank Drake was planning a search for such signals, using the 85-foot radio telescope in Green Bank, West Virginia, for the first SETI project, or the Search for Extraterrestrial Intelligence. Fifty years later, no such signal has been detected, but you can't keep a dreamer down. Frank Drake returned to Green Bank last week to recreate his famous observations with one of the largest radio telescopes in the world.
The original Project Ozma surveyed the nearby, Sun-like stars Tau Ceti and Epsilon Eridani at 1420 MHz for a total of 150 hours over four months. With an entire spectrum to chose from, 1420 MHz (in the L-band, if you speak that lingo) is at the spin-flip transition of hydrogen. Since hydrogen is everywhere, you can imagine that any civilization conducting astronomy would be paying attention to that frequency.
Last Tuesday, with the incredibly powerful Green Bank Telescope, Frank Drake re-observed Tau Ceti and Epsilon Eridani at 1420 MHz with Green Bank astronomers Jay Lockman and Karen O'Neil over the course of an hour. I hung back, watching along with other scientists and staff as a BBC film crew recorded the event. A bottle of champagne sat next to the observers' computer, just in case...
No extraterrestrials were discovered on that rainy afternoon, or else you would have heard about it by now. I did watch a man-made signal come and go on the spectrum analyzer, so strongly that it could be seen outside of the frequency range that the telescopes was observing. It was there no matter where the telescope pointed, which is often your first clue that it is a local signal. Good to know that there is still intelligent life somewhere!
SETI efforts roll on in a larger capacity with the Allen Telescope Array, jointly run by the SETI Institute, of which Frank Drake is an important part, and the Radio Astronomy Laboratory at Berkeley. Though we've been searching here and there in space (and frequency) for a signal, systematic searches have only probed so far into the galaxy. The ATA is needed to expand our search capabilities, and do radio astronomy along the way.
A comparison of the distances probed by a previous SETI project and the ATA, based on sensitivities. Image Credit: SETI Institute.
As we constantly improve our instruments and techniques, I think it is still worth it to take this gamble, to spend a little bit of time and money, in the grand scheme of things, with the chance that the greatest discovery in human history can be made. We know now that there are countless planets in our galaxy, so it's not such a stretch to imagine that we have neighbors. I held just a little bit of breathless hope as I watched the radio astronomers work away at the telescope that maybe, just maybe, this would be it.
Many thanks to John Stoke for letting me use one of his photographs of the event, to the BBC film crew for letting us spectate and for giving me the thumbs up to post this while they are in production, and to Sue Ann Heatherly for giving me the heads up about this event!
Tags: Alien Life, SETI, Telescopes
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