Answering ET’s call

  • The Allen Telescope Array in California listens for signals from extraterrestrial civilisations. To volunteer online: Photograph by AP/wide world photos
  • SETILive volunteers categorise the signals they see online. The angle of the image is important; it can help indicate whether a transmission comes from an object in orbit or from deep space. Photocredit: SETILive
  • This is the erratic signal from a wobbly satellite. The SETI Institute needs human observers to help screen out near-Earth signals such as this. Photocredit: SETILive
  • A “broken” or pulsed pattern normally indicates ground-based radio interference. Photocredit: SETILive
Date:5 January 2013 Tags:, ,

Tapping into SETI’s 42-dish telescope array to search for aliens.
By Madeline Bodin

Through a radio telescope, a signal from an alien 
civilisation would probably look a lot like a signal from a satellite orbiting Earth, only fainter. At least that’s what scientists engaged in the search for extraterrestrial intelligence (SETI) suspect.

After a brief shutdown for budgetary reasons, the SETI Institute is using California’s 42-dish Allen Telescope Array to investigate the 2 321 exoplanets turned up 
by Nasa’s Kepler space-based observatory, which is searching for Earth-like planets.

Jill Tarter, the Bernard M Oliver chair at the SETI Institute – and the model for Jodie Foster’s character in Contact – says the most promising window for signals is from 1 GHz to 10 GHz. Unfortunately, that range is noisy with everything from GPS satellite signals to Wi-Fi communications. And computer algorithms can only do so much.

Since February 2012, SETILive has been receiving help from volunteers who review the data online, 
categorising white lines that appear against a background of radio static that looks eerily like a starry sky. Depending on which frequencies the array is searching, as many as half the views or as few as one in 10 will show some kind of line. After watching for several hours, I saw live signals only once, but you can also examine archived data. Assessments that a signal might be ET send the telescope back for a second (and even 
a third) look at about 10 per cent of the signals.

SETILive is the fruition of Tarter’s 2009 TED Prize wish: “to empower earthlings everywhere to become active participants in the ultimate search for cosmic company”. If that sounds like a message destined to attract people wearing tinfoil hats, Tarter is unconcerned. Even if all that’s found are GPS satellite signals, she believes the search itself has value. It “holds up a mirror to humanity”, she says. “We are all earthlings. That perspective may help trivialise the differences that we all struggle with today.”

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