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Astronomie - New Technologies, Strategies Expanding Search for Extraterrestrial Life

16.02.2020

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Emerging technologies and new strategies are opening a revitalized era in the Search for Extraterrestrial Intelligence (SETI). New discovery capabilities, along with the rapidly-expanding number of known planets orbiting stars other than the Sun, are spurring innovative approaches by both government and private organizations, according to a panel of experts speaking at a meeting of the American Association for the Advancement of Science (AAAS) in Seattle, Washington.

New approaches will not only expand upon but also go beyond the traditional SETI technique of searching for intelligently-generated radio signals, first pioneered by Frank Drake’s Project Ozma in 1960. Scientists now are designing state-of-the-art techniques to detect a variety of signatures that can indicate the possibility of extraterrestrial technologies. Such “technosignatures” can range from the chemical composition of a planet’s atmosphere, to laser emissions, to structures orbiting other stars, among others.

The National Radio Astronomy Observatory (NRAO) and the privately-funded SETI Institute announced an agreement to collaborate on new systems to add SETI capabilities to radio telescopes operated by NRAO. The first project will develop a system to piggyback on the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) that will provide data to a state-of-the-art technosignature search system.

“As the VLA conducts its usual scientific observations, this new system will allow for an additional and important use for the data we’re already collecting,” said NRAO Director Tony Beasley. “Determining whether we are alone in the Universe as technologically capable life is among the most compelling questions in science, and NRAO telescopes can play a major role in answering it,” Beasley continued.

“The SETI Institute will develop and install an interface on the VLA permitting unprecedented access to the rich data stream continuously produced by the telescope as it scans the sky,” said Andrew Siemion, Bernard M. Oliver Chair for SETI at the SETI Institute and Principal Investigator for the Breakthrough Listen Initiative at the University of California, Berkeley. “This interface will allow us to conduct a powerful, wide-area SETI survey that will be vastly more complete than any previous such search,” he added.

Siemion highlighted the singular role the $100-million Breakthrough Listen Initiative has played in reinvigorating the field of SETI in recent years. Siemion also announced the latest scientific results from Listen, a SETI survey in the direction of stars where a distant civilization could observe the Earth’s passage across the sun, and the availability of nearly 2 PetaBytes of data from the Listen Initiative’s international network of observatories.

Other indicators of possible technologies include laser beams, structures built around stars to capture the star’s power output, atmospheric chemicals produced by industries, and rings of satellites similar to the ring of geosynchronous communication satellites orbiting above Earth’s equator.

“Such indicators are becoming detectable as our technology advances, and this has renewed interest in SETI searches at both government agencies and private foundations,” Siemion said.

Life forms, whether intelligent or not, also can produce detectable indicators. These include the presence of large amounts of oxygen, smaller amounts of methane, and a variety of other chemicals. Victoria Meadows, Principal Investigator for NASA’s Virtual Planetary Laboratory at the University of Washington, described how scientists are developing computer models to simulate extraterrestrial environments and to help support future searches for habitable planets and life beyond the Solar System.

“Upcoming telescopes in space and on the ground will have the capability to observe the atmospheres of Earth-sized planets orbiting nearby cool stars, so it’s important to understand how best to recognize signs of habitability and life on these planets,” Meadows said, “These computer models will help us determine whether an observed planet is more or less likely to support life.”

As new programs implement the expanding technical capabilities for detecting extraterrestrial life and intelligence, it’s important to define what constitutes compelling, credible evidence, according to Jill Tarter, of the SETI Institute.

“How strong does the evidence need to be to justify claiming a discovery? Can we expect to find smoking guns? If the evidence requires many caveats, how do we responsibly inform the public,” Tarter asked.

Tarter pointed out that projects such as the University of California at San Diego’s PANOSETI visible-light and infrared search, and the SETI Institute’s Laser SETI search are being built with co-observing sites to reduce false positives. Such measures, she said, will boost confidence in reported detections, but also add to the expense of the project.

The news media also share responsibility for communicating accurately with the public, Tarter emphasized. She cited cases in recent years of “exuberant reporting” of bogus claims of SETI detections. “A real detection of extraterrestrial intelligence would be such an important milestone in our understanding of the Universe that journalists need to avoid uncritical reporting of obviously fake claims,” she said.

“As continuing discoveries show us that planets are very common components of the Universe, and we are able to study the characteristics of those planets, it’s exciting that at the same time, technological advances are giving us the tools to greatly expand our search for signs of life. We look forward to this new realm of discovery,” said Beasley, who organized the AAAS panel.

“We also look forward to the coming decade, when we hope to build a next-generation Very Large Array, which will be able to search a volume of the Universe a thousand times larger than that accessible to current telescopes — making it the most powerful radio technosignature search machine humanity has ever constructed,” Beasley added.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Quelle: NRAO

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BREAKTHROUGH LISTEN’S SEARCH FOR INTELLIGENT LIFE (SETI) RELEASES UNPRECEDENTED DATA SURVEY OF MILKY WAY’S GALACTIC CENTER, EARTH TRANSIT ZONE AND INTERSTELLAR COMET 2I/BORISOV

Data Sharing from $100M SETI Initiative Doubles Publicly Accessible Data for Global Study and Analysis.

SEATTLE – February 14, 2020 – The Breakthrough Listen Initiative today released data from the most comprehensive survey yet of radio emissions from the plane of the Milky Way Galaxy, the region around its central, 4-million-solar-mass black hole, and observations of the interstellar comet 2I/Borisov.

Breakthrough Listen Principal Investigator Andrew Siemion announced the release of the nearly two petabytes of data at the annual meeting of the American Association for the Advancement of Science. It marks the second “data dump” from the four-year-old, $100M search for extraterrestrial intelligence (SETI) initiative. A first download of a petabyte of radio and optical telescope data was released in June 2019, marking the largest release of SETI data in the history of the field.

The raw data – yet to be fully analyzed by astronomers – comes from a survey of the radio spectrum between 1 and 12 gigahertz (GHz). About half was captured via the Parkes Radio Telescope in New South Wales, Australia, which, because of its location in the Southern Hemisphere, is perfectly situated and outfitted to scan the entire galactic disk and galactic center. Parkes is part of the Australia Telescope National Facility, owned and managed by the country’s national science agency, CSIRO.

“The galactic center – the most extraordinarily energetic area of our galaxy, is an integral focus of our data gathering with all of our facilities,” said Siemion. “It is there that an advanced civilization might somehow harness the energy of the supermassive black hole at the center of the Milky Way Galaxy to signal its existence.”

The remainder of the dataset was recorded by the Green Bank Observatory in West Virginia (the world’s largest steerable radio dish), and the Automated Planet Finder (an optical telescope built and operated by UC Berkeley, and located at Lick Observatory outside San Jose, California).

Breakthrough Listen, based at UC Berkeley, is supported by a $100 million, 10-year commitment from the Breakthrough Initiatives, founded in 2015 by Yuri and Julia Milner to explore the universe, seek scientific evidence of life beyond Earth and encourage public debate from a planetary perspective.

“For the whole of human history, we had a limited amount of data to search for life beyond Earth. So all we could do was speculate. Now, as we are getting a lot of data, we can do real science – and, with making this data available to the general public, so can anyone who wants to know the answer to this deep question,” said Yuri Milner, Founder of Breakthrough Initiatives.

“Since the first Breakthrough Listen data release last June, we have doubled the amount of data captured and made publicly available,” said Breakthrough Listen lead system administrator Matt Lebfosky. “We are excited by the many use cases for this information, and it is our hope these data sets will ultimately reveal new insights – be it evidence of other intelligent life in the universe or as-yet-undiscovered natural astronomical phenomena.”

Earth Transit Zone Survey

In releasing the new radio and optical data, Siemion highlighted an initial analysis of a small subset of radio emissions from 20 nearby stars that are aligned with the plane of Earth’s orbit – the Earth Transit Zone. These stars are situated such that an advanced civilization located around them could observe the Earth pass in front of our sun (a “transit” like those identified by NASA’s Kepler and TESS space telescopes).

Conducted by the Green Bank Telescope, the Earth Transit Zone Survey took observations in the radio frequency range between 4 and 8 gigahertz, the so-called C-band. The data were then analyzed by former UC Berkeley undergraduate Sofia Sheikh, now a graduate student at Pennsylvania State University, who looked for bright emissions at a single radio wavelength or a narrow band around a single wavelength. She submitted her analysis of these observations to the Astrophysical Journal.

“This is a unique geometry of the Earth Transit Zone” Sheikh said. “It is the method that we on Earth have used to discover other exoplanets, so we can imagine that this same geometry might be how other intelligent species find planets such as ours, as well.”

In Sheikh’s research, she pointed the Green Bank Telescope at each star for five minutes, pointed away for another five minutes, and repeated that process twice more. She then eliminated any signal that didn’t disappear when the telescope was pointed away from the star. Using this method she sorted through an initial million radio spikes – eliminating those caused by Earth-based signal interference. Ultimately, the last four unexplained signals turned out to be from passing satellites.

While Sheikh and her team found no technosignatures of civilizations, their analysis and other detailed studies conducted by the Breakthrough Listen group are gradually narrowing potential locations and capabilities of advanced civilizations that could exist in our galaxy.

“Because I purposely looked at nearby targets, my search was sensitive enough to locate a transmitter on par with the strongest transmitters on Earth,” Sheikh said. “We can infer that there is nothing as strong as our Arecibo telescope beaming a signal toward us. Even though this is a very small project, we are starting to get at new frequencies and new areas of the sky.”

Sheikh noted that her mentor, Jason Wright at Penn State, estimated that if the world’s oceans represented every place and wavelength we could search for intelligent signals, we have, to date, explored only a hot tub’s worth of it.

“We didn't find aliens, but we are setting very rigorous limits on the presence of a technologically capable species, by screening for the first time for data between 4 and 8 gigahertz on the radio spectrum,” Siemion said. “These results notch another rung on the ladder for the next team who comes along and wants to improve on our experiment.”

Visit from an interstellar comet, 2I/Borisov

Breakthrough Listen also released observations of the interstellar comet 2I/Borisov, which had a close encounter with our sun in December 2019, and is now on its way out of the solar system. The group had earlier scanned the interstellar rock, ’Oumuamua, which passed through the center of our solar system in 2017. Neither exhibited technosignatures.

“If interstellar travel is possible and if other civilizations are out there (all of which we don't know), and if they are motivated to build an interstellar probe, then some fraction greater than zero of the objects that are out there are artificial interstellar devices,” said Steve Croft, a research astronomer with the Berkeley SETI Research Center and Breakthrough Listen. “Just as we do with our measurements of transmitters on extra-solar planets, we want to put a limit on what that number is.”

According to Siemion, Breakthrough Listen looks for electromagnetic radiation that is consistent with a signal that we know is produced by technology and is inconsistent with the background noise from natural astrophysical events. This also requires eliminating signals from cellphones, satellites, GPS, internet, WiFi, and myriad other human sources.

Siemion emphasizes that the Breakthrough Listen team intends to analyze all data released to date, systematically and iteratively. Only 20 percent of the captured data have been analyzed thus far.

NRAO Partners with SETI Institute

Marking a milestone in the growth of the SETI community internationally, the National Radio Astronomy Observatory (NRAO) and the privately-funded SETI Institute also announced an agreement to add SETI capabilities to radio telescopes operated by NRAO. The first project will develop a system to piggyback on the National Science Foundation's Karl G. Jansky Very Large Array (VLA) and provide data to state-of-the-art digital back-end SETI Institute equipment.

“This important collaboration is a wonderful leap forward for the global SETI effort – bringing together teams of dedicated researchers and additional telescopes, and boosting the capacity and rigor with which we scan the skies,” said Siemion, who in addition to his position at the University of California, Berkeley is the Bernard M. Oliver Chair for SETI at the SETI Institute. “This interface with the VLA will allow us to conduct a powerful, wide-area SETI survey that will be vastly more complete than any previous such search.”

“As the VLA conducts its usual scientific observations, this new system will allow for an additional and important use for the data we're already collecting,” said NRAO Director Tony Beasley. “Determining whether we are alone in the universe as technologically capable life is among the most compelling questions in science, and NRAO telescopes can play a major role in answering it.”

Quelle: BREAKTHROUGH

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Breakthrough Listen scans Milky Way Galaxy for beacons of civilization

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Artist’s concept of a nearby civilization signaling Earth after observing our planet crossing in front of the sun. Astronomers have now scanned 20 nearby stars in the Earth transit zone in search of such signals. (UC Berkeley image courtesy of Breakthrough Listen)

The Breakthrough Listen Initiative today (Friday, Feb. 14) released data from the most comprehensive survey yet of radio emissions from the plane of the Milky Way Galaxy and the region around its central black hole, and it is inviting the public to search the data for signals from intelligent civilizations.

At a media briefing today in Seattle as part of the annual meeting of the American Association for the Advancement of Science (AAAS), Breakthrough Listen principal investigator Andrew Siemion of the University of California, Berkeley, announced the release of nearly 2 petabytes of data, the second data dump from the four-year old search for extraterrestrial intelligence (SETI). A petabyte of radio and optical telescope data was released last June, the largest release of SETI data in the history of the field.

The data, most of it fresh from the telescope prior to detailed study from astronomers, comes from a survey of the radio spectrum between 1 and 12 gigahertz (GHz). About half of the data comes via the Parkes radio telescope in New South Wales, Australia, which, because of its location in the Southern Hemisphere, is perfectly situated and instrumented to scan the entire galactic disk and galactic center. The telescope is part of the Australia Telescope National Facility, owned and managed by the country’s national science agency, CSIRO.

The remainder of the data was recorded by the Green Bank Observatory in West Virginia, the world’s largest steerable radio dish, and an optical telescope called the Automated Planet Finder, built and operated by UC Berkeley and located at Lick Observatory outside San Jose, California.

“Since Breakthrough Listen’s initial data release last year, we have doubled what is available to the public,” said Breakthrough Listen’s lead system administrator, Matt Lebofsky. “It is our hope that these data sets will reveal something new and interesting, be it other intelligent life in the universe or an as-yet-undiscovered natural astronomical phenomenon.”

“For the whole of human history, we had a limited amount of data to search for life beyond Earth. So, all we could do was speculate. Now, as we are getting a lot of data, we can do real science and, with making this data available to general public, so can anyone who wants to know the answer to this deep question,” said Yuri Milner, the founder of Breakthrough Listen.

Moonset photo of Very Large Array

Moonset, around 2:30 a.m., at the Very Large Array on the Plains of San Agustin, about 50 miles west of Socorro, New Mexico. The VLA is teaming up with the SETI Institute to capture data that can be searched for intelligent signals.

The National Radio Astronomy Observatory (NRAO) and the privately-funded SETI Institute in Mountain View, California, also announced today an agreement to collaborate on new systems to add SETI capabilities to radio telescopes operated by NRAO. The first project will develop a system to piggyback on the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) in New Mexico and provide data to state-of-the-art digital backend equipment built by the SETI Institute.

“The SETI Institute will develop and install an interface on the VLA, permitting unprecedented access to the rich data stream continuously produced by the telescope as it scans the sky,“ said Siemion, who, in addition to his UC Berkeley position, is the Bernard M. Oliver Chair for SETI at the SETI Institute. “This interface will allow us to conduct a powerful, wide-area SETI survey that will be vastly more complete than any previous such search.”

“As the VLA conducts its usual scientific observations, this new system will allow for an additional and important use for the data we’re already collecting,” said NRAO Director Tony Beasley. “Determining whether we are alone in the universe as technologically capable life is among the most compelling questions in science, and NRAO telescopes can play a major role in answering it.”

Earth transit zone survey

In releasing the new radio and optical data, Siemion highlighted a new analysis of a small subset of the data: radio emissions from 20 nearby stars that are aligned with the plane of Earth’s orbit such that an advanced civilization around those stars could see Earth pass in front of the sun (a “transit” like those focused on by NASA’s Kepler space telescope). Conducted by the Green Bank Telescope, the Earth transit zone survey observed in the radio frequency range between 4 and 8 gigahertz, the so-called C-band. The data were then analyzed by former UC Berkeley undergraduate Sofia Sheikh, now a graduate student at Pennsylvania State University, who looked for bright emissions at a single radio wavelength or a narrow band around a single wavelength. She has submitted the paper to the Astrophysical Journal.

Parkes radio telescope in Australia

Australia’s Parkes radio telescope, 210 feet in diameter, conducted the most comprehensive survey yet of radio emissions from the Milky Way galaxy in search of technosignatures from advanced civilizations around other stars. (Photo courtesy of CSIRO)

“This is a unique geometry,” Sheikh said. “It is how we discovered other exoplanets, so it kind of makes sense to extrapolate and say that that might be how other intelligent species find planets, as well. This region has been talked about before, but there has never been a targeted search of that region of the sky.”

While Sheikh and her team found no technosignatures of civilization, the analysis and other detailed studies the Breakthrough Listen group has conducted are gradually putting limits on the location and capabilities of advanced civilizations that may exist in our galaxy.

“We didn’t find any aliens, but we are setting very rigorous limits on the presence of a technologically capable species, with data for the first time in the part of the radio spectrum between 4 and 8 gigahertz,” Siemion said. “These results put another rung on the ladder for the next person who comes along and wants to improve on the experiment.”

Sheikh noted that her mentor, Jason Wright at Penn State, estimated that if the world’s oceans represented every place and wavelength we could search for intelligent signals, we have, to date, explored only a hot tub’s worth of it.

“My search was sensitive enough to see a transmitter basically the same as the strongest transmitters we have on Earth, because I looked at nearby targets on purpose,” Sheikh said. “So, we know that there isn’t anything as strong as our Arecibo telescope beaming something at us. Even though this is a very small project, we are starting to get at new frequencies and new areas of the sky.”

Beacons in the galactic center?

The so-far unanalyzed observations from the galactic disk and galactic center survey were a priority for Breakthrough Listen because of the higher likelihood of observing an artificial signal from that region of dense stars. If artificial transmitters are not common in the galaxy, then searching for a strong transmitter among the billions of stars in the disk of our galaxy is the best strategy, Simeon said.

Breakthrough Listen graphic of Earth

Breakthrough Listen, based at UC Berkeley, collects petabytes of data from the Green Bank Telescope in West Virginia (right) and the Parkes radio telescope in Australia (left) and makes it available to the science community to analyze in search of signals from intelligent civilizations. (Graphic courtesy of Breakthrough Listen)

On the other hand, putting a powerful, intergalactic transmitter in the core of our galaxy, perhaps powered by the 4 million-solar-mass black hole there, might not be beyond the capabilities of a very advanced civilization. Galactic centers may be so-called Schelling points: likely places for civilizations to meet up or place beacons, given that they cannot communicate among themselves to agree on a location.

“The galactic center is the subject of a very specific and concerted campaign with all of our facilities because we are in unanimous agreement that that region is the most interesting part of the Milky Way galaxy,” Siemion said. “If an advanced civilization anywhere in the Milky Way wanted to put a beacon somewhere, getting back to the Schelling point idea, the galactic center would be a good place to do it. It is extraordinarily energetic, so one could imagine that if an advanced civilization wanted to harness a lot of energy, they might somehow use the supermassive black hole that is at the center of the Milky Way galaxy.”

Visit from an interstellar comet

Breakthrough Listen also released observations of the interstellar comet 2I/Borisov, which had a close encounter with the sun in December and is now on its way out of the solar system. The group had earlier scanned the interstellar rock ‘Oumuamua, which passed through the center of our solar system in 2017. Neither exhibited technosignatures.

Hubble photo of comet 21/Borisov

NASA’s Hubble Space Telescope took this photo of the interstellar comet 2I/Borisov in October 2019, two months before its closest approach to the sun. (Photo courtesy of NASA, ESA and D. Jewitt, UCLA))

“If interstellar travel is possible, which we don’t know, and if other civilizations are out there, which we don’t know, and if they are motivated to build an interstellar probe, then some fraction greater than zero of the objects that are out there are artificial interstellar devices,” said Steve Croft, a research astronomer with the Berkeley SETI Research Center and Breakthrough Listen. “Just as we do with our measurements of transmitters on extrasolar planets, we want to put a limit on what that number is.”

Regardless of the kind of SETI search, Siemion said, Breakthrough Listen looks for electromagnetic radiation that is consistent with a signal that we know technology produces, or some anticipated signal that technology could produce, and inconsistent with the background noise from natural astrophysical events. This also requires eliminating signals from cellphones, satellites, GPS, internet, Wi-fi and myriad other human sources.

In Sheikh’s case, she turned the Green Bank telescope on each star for five minutes, pointed away for another five minutes and repeated that twice more. She then threw out any signal that didn’t disappear when the telescope pointed away from the star. Ultimately, she whittled an initial 1 million radio spikes down to a couple hundred, which she was able to eliminate as Earth-based human interference. The last four unexplained signals turned out to be from passing satellites.

Siemion emphasized that the Breakthrough Listen team intends to analyze all the data released to date and to do it systematically and often.

“Of all the observations we have done, probably 20% or 30% have been included in a data analysis paper,” Siemion said. “Our goal is not just to analyze it 100%, but 1000% or 2000%. We want to analyze it iteratively.”

Breakthrough Listen, based at UC Berkeley, is supported by a $100 million, 10-year commitment from the Breakthrough Initiatives, founded in 2015 by Yuri and Julia Milner to explore the universe, seek scientific evidence of life beyond Earth and encourage public debate from a planetary perspective.

Quelle: UC Berkeley

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