July 24, 2019
Paul Scott Anderson
For the last few decades, the search for extraterrestrial intelligence has focused on detecting radio signals. But a new collaboration between Breakthrough Listen and VERITAS will focus on looking for laser-like flashes of light.
VERITAS will be used to help search for laser-like optical light pulses that could be beacons from an advanced alien civilization. Image via MIT/New Atlas.
The Search for Extraterrestrial Intelligence (SETIInstitute) has traditionally looked for radio signals of artificial origin, i.e. coming from an alien civilization at least as advanced as our own.
We humans have been broadcasting radio waves into space for about 100 years now, since Marconi pioneered long-distance radio transmission. The reasoning has been that other civilizations might use radio, too. While that approach continues to be highly debated, there is another kind of search that is starting to be considered more seriously now as well: looking for optical signals – brief flashes of light like pulsing lasers – that could be used as beacons to communicate over interstellar distances.
On July 17, 2019, Breakthrough Initiatives – founded in 2015 by entrepreneur Yuri Milner – announced a new partnership with the VERITAS Collaboration to focus on this strategy. VERITAS (the Very Energetic Radiation Imaging Telescope Array System) will search for such pulsed optical beacons, as well as radio signals, with its array of four 12-meter telescopes at the Whipple Observatory in Amado, Arizona.
Breakthrough Listen, part of Breakthrough Initiatives, has already been conducting searches using its still-ongoing radio frequency survey and spectroscopic optical laser survey. But VERITAS can take the search to a new level. It was built to detect cosmic gamma rays and is the most powerful telescope array in the world for studying high energy astrophysics. As it turns out, it can also be used to look for “pulsed optical beacons” – laser-like pulses of light – that are very short in duration, only a few nanoseconds (one nanosecond is a billionth of a second).
Closer view of one of the 4 telescopes in the VERITAS array. Image via CfA/SciTechDaily.
An advantage of this method is that any artificial pulses could outshine stars that happen to lie in the same direction. The use of all four telescopes would also help to eliminate false positives from any detections made. VERITAS will provide a unique way of expanding the search for alien intelligence beyond previous methods, as noted by Yuri Milner:
“When it comes to intelligent life beyond Earth, we don’t know where it exists or how it communicates. So our philosophy is to look in as many places, and in as many ways, as we can. VERITAS expands our range of observation even further.”
Andrew Siemion at the Berkeley SETI Research Center added:
“Breakthrough Listen is already the most powerful, comprehensive, and intensive search yet undertaken for signs of intelligent life beyond Earth. Now, with the addition of VERITAS, we’re sensitive to an important new class of signals: fast optical pulses. Optical communication has already been used by NASA to transmit high definition images to Earth from the moon, so there’s reason to believe that an advanced civilization might use a scaled-up version of this technology for interstellar communication.”
VERITAS will be able to detect very faint light signals, if any exist, according to Jamie Holder at the University of Delaware:
Just how sensitive is VERITAS? The most powerful lasers on Earth can transmit a pulse of 500 terawatts lasting only a few nanoseconds. If one were placed at the distance of Tabby’s Star – that weird dimming star about 1,470 light-years away – then VERITAS could detect it. However, most of the stars that VERITAS will observe are 10-100 times closer than that, so feasibly a pulse of light 100-10,000 times fainter than that earthly laser could be found.
VERITAS being able to search for alien light signals is a great bonus, since that is not what it was designed for. As David Williams at the University of California, Santa Cruz said:
“It is impressive how well-suited the VERITAS telescopes are for this project, since they were built only with the purpose of studying very-high-energy gamma rays in mind.”
In California, the SETI Institute is also using Lick Observatory‘s 40-inch Nickel Telescope on Mount Hamilton with a new pulse-detection system, to look for similar laser beacons from civilizations many light-years distant. Optical SETI has its advantages over radio SETI, such as no radio signal interference, according to Frank Drake, director of the Carl Sagan Center for Research:
One great advantage of optical SETI is that there’s no terrestrial interference. It’s an exciting new field.
This Lick experiment is unique as it uses three light detectors (photomultipliers) to search for bright pulses that arrive in a short period of time (less than a billionth of a second). Light from the star itself can also trigger the detectors as well, but seldom will all three photomultipliers be hit by photons within a billionth of a second time frame. This means few false alarms are expected, only about one per year.
New and novel ways of looking for evidence of extraterrestrial intelligence are welcome, since the previous, traditional SETI method of just searching for radio signals is considered by many to be antiquated. Would a civilization thousands or millions of years more advanced then us still be using radio waves to communicate? SETI and other searches should be as broad as possible, and consider alternate possibilities for the best chance of success. With billions of stars in our galaxy alone, the hunt for such signals is like looking for a needle in a haystack. VERITAS is just one such alternate method, but it is a good start.
Breakthrough Listen is a comprehensive initiative to search for evidence of intelligent, technological life from nearby stars to the universe at large. The objective is to examine one million nearby stars, all the stars in the galactic plane and 100 nearby galaxies, for both radio and optical signals. Not a small undertaking, but if there is to be any chance of finding an alien light show, then we must look.
This is how far human radio broadcasts have reached into the galaxy – not the black square – but the little blue dot at the center of that zoomed-in square. The ever-expanding bubble announcing humanity’s presence to anyone listening in the Milky Way is now only about 200 light-years wide, in contrast to our 100,000-light-year galaxy. Graphic created by Adam Grossman. Read more from Emily Lakdawalla at the Planetary Society.
Search for extraterrestrial intelligence expands at Lick Observatory
New instrument scans the sky for pulses of infrared light
March 23, 2015
By Hilary Lebow
The NIROSETI instrument saw first light on the Nickel 1-meter Telescope at Lick Observatory on March 15, 2015. (Photo by Laurie Hatch)
Astronomers are expanding the search for extraterrestrial intelligence into a new realm with detectors tuned to infrared light at UC’s Lick Observatory. A new instrument, called NIROSETI, will soon scour the sky for messages from other worlds.
“Infrared light would be an excellent means of interstellar communication,” said Shelley Wright, an assistant professor of physics at UC San Diego who led the development of the new instrument while at the University of Toronto’s Dunlap Institute for Astronomy & Astrophysics.
Wright worked on an earlier SETI project at Lick Observatory as a UC Santa Cruz undergraduate, when she built an optical instrument designed by UC Berkeley researchers. The infrared project takes advantage of new technology not available for that first optical search.
Infrared light would be a good way for extraterrestrials to get our attention here on Earth, since pulses from a powerful infrared laser could outshine a star, if only for a billionth of a second. Interstellar gas and dust is almost transparent to near infrared, so these signals can be seen from great distances. It also takes less energy to send information using infrared signals than with visible light.
UCSC alumna Shelley Wright, now an assistant professor of physics at UC San Diego, discusses the dichroic filter of the NIROSETI instrument. (Photo by Laurie Hatch)
Frank Drake, professor emeritus of astronomy and astrophysics at UC Santa Cruz and director emeritus of the SETI Institute, said there are several additional advantages to a search in the infrared realm.
“The signals are so strong that we only need a small telescope to receive them. Smaller telescopes can offer more observational time, and that is good because we need to search many stars for a chance of success,” said Drake.
The only downside is that extraterrestrials would need to be transmitting their signals in our direction, Drake said, though he sees this as a positive side to that limitation. “If we get a signal from someone who’s aiming for us, it could mean there’s altruism in the universe. I like that idea. If they want to be friendly, that’s who we will find.”
Scientists have searched the skies for radio signals for more than 50 years and expanded their search into the optical realm more than a decade ago. The idea of searching in the infrared is not a new one, but instruments capable of capturing pulses of infrared light only recently became available.
“We had to wait,” Wright said. “I spent eight years waiting and watching as new technology emerged.”
Now that technology has caught up, the search will extend to stars thousands of light years away, rather than just hundreds. NIROSETI, or Near-Infrared Optical Search for Extraterrestrial Intelligence, could also uncover new information about the physical universe.
“This is the first time Earthlings have looked at the universe at infrared wavelengths with nanosecond time scales,” said Dan Werthimer, UC Berkeley SETI Project Director. “The instrument could discover new astrophysical phenomena, or perhaps answer the question of whether we are alone.”
NIROSETI will also gather more information than previous optical detectors by recording levels of light over time so that patterns can be analyzed for potential signs of other civilizations.
“Searching for intelligent life in the universe is both thrilling and somewhat unorthodox,” said Claire Max, director of UC Observatories and professor of astronomy and astrophysics at UC Santa Cruz. “Lick Observatory has already been the site of several previous SETI searches, so this is a very exciting addition to the current research taking place.”
NIROSETI will be fully operational by early summer and will scan the skies several times a week on the Nickel 1-meter telescope at Lick Observatory, located on Mt. Hamilton east of San Jose.
The NIROSETI team also includes Geoffrey Marcy and Andrew Siemion from UC Berkeley; Patrick Dorval, a Dunlap undergraduate, and Elliot Meyer, a Dunlap graduate student; and Richard Treffers of Starman Systems. Funding for the project comes from the generous support of Bill and Susan Bloomfield.
Optical SETI has its advantages over radio SETI, such as no radio signal interference, according to Frank Drake, director of the Carl Sagan Center for Research:
“One great advantage of optical SETI is that there’s no terrestrial interference. It’s an exciting new field.”
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Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.orgin 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.