technosignatures Archives

Optical SETI searches for distant laser bursts as possible signs of technologial socieites in very far away solar systems. (SETI)

The Search for Extraterrestrial Intelligence (SETI) began decades ago as an effort to pick up radio signals from distant civilizations. The effort was centered at the Green Bank Observatory in West Virginia and was by today’s standards quite rudimentary.

A much broader search for distant radio signals remains very much at the core of SETI but the effort has also expanded to be an increasingly rigorous search for “technosignatures.”

These include radio signals, laser beams, the presence of chemical pollutants, unusual planetary heating and even the construction of massive structures around distant planets. All could potentially be signs of intelligent beings living and trying to communicate.

Laser SETI is one of the fastest growing branches of this search of technosignatures and a recent paper that will appear in The Astronomical Journal describes an intriguing technosignature collaboration.

It is a joint effort by The Breakthrough Listen effort, a very large and privately-fund search for evolved extraterrestrial life, and the operators of VERITAS, a ground-based gamma-ray instrument operating at the Fred Lawrence Whipple Observatory (FLWO) in southern Arizona.

The paper does not report any unexpected laser pulses. But as a proof of concept it shows that searching for laser pulses from many light years away is both possible and plausible.

“I would describe our current results as a very promising start,” Gregory Foote, a doctoral student at the University of Delaware and a co-author of the paper, said in an email. “The analysis and observation pipeline is built, so now we can scale up both within VERITAS and with any next generation telescopes which show interest in performing such searches.”

One of the four 12-meter telescopes comprising the VERITAS gamma-ray observatory. VERITAS (Very Energetic Radiation Imaging Telescope Array System) is located at the Fred Lawrence Whipple Observatory in southern Arizona. (CfA/Rick Peterson)

Optical SETI is the name of the overall search for optical technosignatures; signals based on optical light emitters such as lasers. There are two types of laser-based signals that astronomers are currently looking for — a continuous laser beam at a specific wavelength, and nanosecond time-scale pulse lasers. The VERITAS telescope can detect the nanosecond burst of lasers.

“Overall, if one wants to build an interstellar communication system, using pulsed lasers is a power-efficient way to do it,” Foote said. “The technology for both transmitting and receiving doesn’t require any sci-fi infrastructure: it exists today.… Read more

A rendering of a potential Dyson sphere, named after Freeman A. Dyson. As proposed by the physicist and astronomer decades ago, they would collect solar energy on a solar system wide scale for highly advanced civilizations. (SentientDevelopments.com)

The word “SETI” pretty much brings to mind the search for radio signals come from distant planets, the movie “Contact,” Jill Tarter, Frank Drake and perhaps the SETI Institute, where the effort lives and breathes.

But there was a time when SETI — the Search for Extraterrestrial Intelligence — was a significantly broader concept, that brought in other ways to look for intelligent life beyond Earth.

In the late 1950s and early 1960s — a time of great interest in UFOs, flying saucers and the like — scientists not only came up with the idea of searching for distant intelligent life via unnatural radio signals, but also by looking for signs of unexpectedly elevated heat signatures and for optical anomalies in the night sky.

The history of this search has seen many sharp turns, with radio SETI at one time embraced by NASA, subsequently de-funded because of congressional opposition, and then developed into a privately and philanthropically funded project of rigor and breadth at the SETI Institute. The other modes of SETI went pretty much underground and SETI became synonymous with radio searches for ET life.

But this history may be about to take another sharp turn as some in Congress and NASA have become increasingly interested in what are now called “technosignatures,” potentially detectable signatures and signals of the presence of distant advanced civilizations. Technosignatures are a subset of the larger and far more mature search for biosignatures — evidence of microbial or other primitive life that might exist on some of the billions of exoplanets we now know exist.

And as a sign of this renewed interest, a technosignatures conference was scheduled by NASA at the request of Congress (and especially retiring Republican Rep. Lamar Smith of Texas.) The conference took place in Houston late last month, and it was most interesting in terms of the new and increasingly sophisticated ideas being explored by scientists involved with broad-based SETI.

“There has been no SETI conference this big and this good in a very long time,” said Jason Wright, an astrophysicist and professor at Pennsylvania State University and chair of the conference’s science organizing committee. “We’re trying to rebuild the larger SETI community, and this was a good start.”… Read more

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