Scientists Detail the Next Era in the Search for Extraterrestrial Life

A slew of new data releases, search programs and advances in telescope technology are setting the stage for the next era in the search for extraterrestrial life, say researchers who participated in a press briefing at the 2020 AAAS Annual Meeting in Seattle, Washington.

The briefing participants included scientists from the Search for Extraterrestrial Intelligence (SETI) – an astronomical institute that searches for signs of intelligent life in the universe – who announced a new search program, reviewed progress in existing telescope initiatives, and detailed the largest release of telescope data in the history of the institute.

The panel also included a researcher who has modeled how the James Webb Space Telescope – the upcoming successor to the Hubble Space Telescope – might have difficulty with detecting oxygen, a potential chemical signature of life, on planets outside of the solar system.

Humans have long wondered whether other intelligent civilizations may lie in the stars, but until recently the search for any cosmic neighbors was still in its infancy. The 1984 establishment of SETI by prominent scientists Jill Tarter – a participant in the briefing – Thomas Pierson, Carl Sagan and others kicked off the search for intelligence in earnest.

Since then, SETI and other programs have been combing the skies for any light emissions that might give away the existence of advanced civilizations. These include radiation that is inconsistent with natural astrophysical events, as well as anomalies in the brightness and behavior of stars and other objects.

The recent discovery of thousands of exoplanets orbiting nearby stars has also spurred scientists to begin searching for biological signs of life in planetary atmospheres. One of the objectives of the James Webb Space Telescope will be to study the atmospheres of these exoplanets and search for the building blocks of life, such as water and oxygen.

Andrew Siemion, director of the Berkeley SETI Research Center and lead investigator of Breakthrough Listen, spoke about new results and made several program announcements. Siemion has spent years working at SETI and Breakthrough Listen, a collaborative project that searches for signs of extraterrestrial technology with radio telescopes.

Siemion announced for the first time a brand-new collaboration between SETI and the Karl G. Jansky Very Large Array, a network of radio telescopes in New Mexico that is one of the world’s premier astronomical observatories. The observatory has never hosted a search program from SETI before, but Siemion said that recent advances in technology will allow SETI to begin conducting searches there.

The collaboration “will allow a comprehensive search of the northern sky, and will allow for targeted observations of nearby stars,” he said in a previous interview.

Siemion also described new results from a paper examining the Earth Transit Zone – a narrow band in the sky of major interest to astronomers. In the same way that astronomers detect exoplanets by studying how they transit across their stars, the Earth Transit Zone is a region in the sky where civilizations may be able to detect the existence of Earth, according to a 2016 study.

Although the Earth Transit Zone has long piqued the interest of those seeking intelligent life, the new paper is one of the first actual surveys of the zone, according to Siemion. In the new study, graduate student Sofia Sheikh examined 20 stars inside the Earth Transit Zone, which ranged from 23 to 457 light years away from the solar system.

Siemion also detailed the second major release of data from Breakthrough Listen, which represents the largest ever data release in the search for extraterrestrial intelligence. The data include radio and optical telescope measurements of 100 nearby stars as well as 1,500 locations within the galactic plane.

The data release also represents a major accomplishment in collaborative research and open-source science, he said. As with the first major release in 2019, all of the data will be available in an online archive for other researchers to parse through and examine.

Victoria Suzanne Meadows, a professor of astronomy at the University of Washington in Seattle  described her recent work in modeling how the James Webb Space Telescope – slated to launch in March 2021 – may be able to detect chemical signatures associated with life forms on other worlds. Meadows and her team have been using sophisticated climate models to understand how the activities of life forms might affect the atmospheres of exoplanets.

In one recent modeling study, her group simulated the ease of detecting oxygen – a potential sign of water or living organisms – with the James Webb on potentially habitable exoplanets or planets similar to Venus. They predicted that it would be challenging for the telescope to detect water or oxygen being produced by life forms in both Venus-like and habitable atmospheres, but that it may be possible to detect oxygen produced from the loss of oceans in the planet’s past. 

The SETI Institute is also hard at work on other projects to expand their ability to detect possible signals coming from technologically advanced civilizations, according to Jill Tarter, chair emeritus for SETI research at the SETI Institute in Mountain View, CA.

Tarter spoke about LaserSETI and PanoSETI, two upcoming telescope projects that will allow scientists to better detect quick light signals such as laser bursts that only last fractions of a second. Until now, these types of optical signals have been largely undetectable for scientists, Tarter said.  

The aim of these programs – still in the early stages – is to be able to sweep the night sky at all times, which Tarter says is the best way to search for short signals. LaserSETI will install 96 cameras in 12 sites around the world to give full coverage, while PanoSETI will consist of domed observatories that will focus on up to 10,000 square degrees of the sky. Given full funding, the first observatories for PanoSETI could be operational by spring of 2021, according to Tarter.

“Both of these observatories will give us sensitivity to transient signals, with very low false positive rates, and confidence in any direction,” Tarter said in an interview. “Searchers for technosignatures have not yet probed this short time domain.”