Astronomers Will Be In a position to Use the World’s Largest Radio Telescope to Seek for Indicators from Extraterrestrial Civilizations

Image of the FAST telescope in China

Back in April, we reported on how a collaboration between the Chinese Academy of Sciences, the Breakthrough Listen Initiative, and the SETI Institute planned to use the new Five Hundred Meter Aperture Radio Telescope (FAST) to search for signs of extraterrestrial life. We have now met with another project scientist to elaborate on some details of their observation plans and the observations they would like to make in the future.

FAST went on its first light in 2016 and was fully operational in January 2020. However, the project has so far only been used by local Chinese scientists. This will change in the coming year, and many groups, including those interested in SETI, stand ready to come up with proposed observation plans that would take advantage of the extraordinarily high sensitivity of FAST, which is 2.5 times greater than the next best available Radio telescope.

The observational plans proposed by the authors of the paper published in Research in Astronomy and Astrophysics have three cornerstones. First they will look at the Andromeda Galaxy, then stars that TESS shows have planets in their potentially habitable zone, and finally, modulated signals that were undetectable by SETI efforts until recently.

Representation of the observatories used by the Breakthrough Lists Initiative
Credit: Breakthrough Hear

The first of these targets, the Andromeda Galaxy, seems like an odd choice for a SETI surveillance mission. Dr. However, Vishal Gajjar, scientist with the Breakthrough Listen Initiative and author of the paper, points out that astronomers have so far completely ignored any potential signals from the galaxy.

This could be because many signals are considered too weak to be recognized by modern instruments. However, with the increased sensitivity of FAST, astronomers could pick up signals at 1019 watts. That seems like a lot of force – it's more than the entire earth's annual consumption. For great civilizations like those that could be considered Kardashev Type II, however, this would hardly be a drop in the ocean. So there is a good chance that we can receive a signal from such a civilization even as far as Andromeda.

Image showing the collapse of the Andromeda Galaxy and how the 19 rays of the FAST telescope work together to depict the whole.The picture shows how the Andromeda galaxy can be broken up into honeycombs, which can then be at the center of FAST's 19 image rays.
Photo credit: D Li. At all

Our nearest neighboring galaxy itself consists of 1 trillion stars that would require a lot to search. Fortunately, FAST has a unique feature that makes it well suited for observing such a densely packed area. It has 19 individual rays that can be aimed at different points in the sky. The team plans to examine the more than 1 trillion stars in the Andromeda Galaxy with 21 hexagonal images. Each of the 4 beams requires 19 different beams that make up the FAST data acquisition system. Each point would take 10 minutes, so the entire survey of the Andromeda Galaxy would only take about 14 hours of observation time.

This would leave plenty of extra time for another of the surveys the team had hoped for – a survey of planets in their star's habitable zone found by the Transiting Exoplanet Survey Satellite (TESS). While Kepler, another planet-hunting telescope, actually found more exoplanets than TESS, most of them are much further away and therefore would have much weaker signals. The average distance to a planet that TESS has studied is between 100 and 200 light years – much closer than what Kepler found. Even if a civilization there didn't intentionally send a signal directly to Earth, we might get glimpses of messages they would send to one another, e.g. B. the control of robotic rovers on another planet or the broadcasting of radio frequency television channels.

Artist illustration of TESS and its 4 telescopes. Photo credit: NASA / MITArtist concept of the Transiting Exoplanet Survey Satellite and its 4 telescopes.
Photo credit: NASA / MIT

Rather than using the Fast L-Band Array (FLAN), which contains the 19 beams that would be so useful for studying Andromeda, the team plans to use a number of single-beam receivers to investigate the TESS candidate planets. These single beam receivers have a much wider bandwidth than the 1050-1450 band available on FLAN. They range from A1 (70-140 MHz) to A1 (2000-3000 MHz). The spectral width of these receivers enables astronomers to view signals that would not be accessible with other telescopes. Aliens could potentially use unconventional signal bandwidths. The greater the frequency a telescope can capture, the more valuable it is to SETI astronomers.

It's not just repetitive signals on a single bandwidth that these astronomers are interested in. Modulated signals, like those that carry data, would be a holy grail of SETI research. With a combination of the sensitivity of FAST and some new AI-powered machine learning algorithms, researchers can finally identify a modulated signal of unknown origin.

Description of FAST and its functions.
Photo credit: UT Youtube Channel.

The Breakthrough Listen team participated in the U.S. Army Artificial Intelligence Signal Classification Challenge. As part of this challenge, they developed an algorithm known as a machine learning classifier that could identify novel modulated signals with 95% accuracy. When applied to SETI, this would help the team identify any type of novel modulated pattern. As with signal bandwidths, aliens may use a completely unknown modulation technique. However, the Breakthrough Listen team's algorithm should be able to detect at least one signal. Translating what it means is left to science fiction books like Contact for now.

Examples of an unmodulated waveform, a waveform using amplitude modulation, and a waveform using frequency modulation.Examples of different types of modulation – frequency modulation (FM) and amplitude modulation (AM). Both are commonly used in consumer stereos
Photo credit: NASA / JPL

Such a translation program may be possible in the future – after all, scientists are smart. Such an effort would require an enormous amount of data to be collected. Currently, FAST is still the best data source for such SETI searches. The Breakthrough List team hopes to receive funding for the search programs described in their article over the next several years. You are already working with a FAST project scientist from Beijing Normal University on some small observation tasks. Recently, this team was given permission to use the FAST telescopes for 14 hours on a SETI project. The largest observations like Andromeda and the TESS planets are still about a year away.

Youtube video announcing the collaboration between Breakthrough Listen and MeerKAT
Photo credit: BerekeleySETI Youtube Channel

Dr. Expressing the team's enthusiasm for working with FAST, Gajjar said they look forward to "conducting some of the deepest radio studies ever conducted". And they can look forward to even more. The Breakthrough Listen team is already busy with MeerKAT, a telescope in South Africa that recently received an updated computer cluster that allows the team to do some advanced frequency calculations that have never been possible before. And the entire MeerKAT system is a forerunner to the square kilometer array that promises to have an impact on the entire field of radio astronomy when it comes online by 2027. Until then, FAST will be an invaluable tool that enables SETI and all other kinds of functions to allow radio astronomy researchers to collect more data and draw better conclusions.

Learn more:
Research in Astronomy and Astrophysics – Ways to Search for Alien Intelligence with the FAST
UT – Breakthrough Lists and NASA team are looking for signs of extraterrestrial intelligence!
UT – How the world's largest radio telescope could be used to search for aliens

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