From Discover: “Everything Worth Knowing About … Alien Contact” Almost

DiscoverMag

Discover Magazine

June 12, 2017 [Up in social media today 9.3.17]
Sarah Scoles

NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

The search for extraterrestrial intelligence (SETI) has been going for more than 50 years, with ever more sophisticated detection systems and creative ideas about how E.T. might come calling. Astronomers haven’t heard anything yet, but perhaps it’s only a matter of time. Check out what they’ve been looking for, how they would know if they found it and what the aftermath might be.

How to Listen

The universe emits many signals of its own. Black holes send out bursts of radio waves, X-rays and gamma rays. The dusty disks of forming planetary systems shine in infrared waves. Scientists must separate those so-called dumb signals from the smart signals that might come from extraterrestrials. Because of that necessary sifting, they assume that aliens would try to make their messages look different from the natural pings of the universe. In general, astronomers look for two hallmarks of technology.

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Jay Smith

Frequency compression: Narrowband signals come in on a small range of frequencies, like an individual radio station. Broadband signals spread across a wider range, like a broadcast that contains the whole FM band at once. Natural objects can only make signals so skinny, so if scientists see one that covers a tiny range of frequencies — like a laser or a satellite ping — they know it had to come from technology.

Time compression: Scientists look for signals that last only for a flash and repeat, perhaps in a pattern that looks purposeful.

BONUS! Almost-but-not-quite-natural-looking: Astronomers also keep their telescopes’ eyes out for anything that looks nearly natural. When researchers discovered fast radio bursts — superquick bursts that release at least as much energy in milliseconds as the sun does in a month — they threw around “aliens” as a (dim) possible explanation. And when astronomers discovered a star in 2015 whose light seems to occasionally get blocked by something big, one researcher proposed it was an alien megastructure. We still aren’t sure what causes either phenomenon, but scientists are studying them as natural emissions from the universe.

Are We There Yet?

You wouldn’t dip a glass in the ocean, come up with no fish inside and conclude, “No fish exist.” Astronomer Jill Tarter often says that’s where humans are with SETI.

SETI’s Jill Tarter

To fill enough glasses to get a good sense, researchers want to look at 1 million stars within 1,000 light-years of Earth and scan all the frequencies between 1 and 10 gigahertz. When they’ve done that, maybe they’ll have caught a fish or two — or will at least be able to say more about how many swim in the cosmic sea. Here’s how close they’ve gotten, proportionally, to that goal.

99.959% How much searching astronomers still have to do to “cover” 1 million stars.

0.041% How much of that search they have completed, for all radio SETI projects.

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Jay Smith

Cinematic SETI

Sometimes, fictional film people meet extraterrestrial beings. When the encounters are good, they are very, very good. But when they are bad, they are horrid — and leave humans destabilized or dead. Here, we’ve ranked some of the most famous first-contact movies according to how naughty or nice the aliens are, as well as how realistic they, their technology and Earth’s response are.

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Our Best Bets

Just as you wouldn’t bird-watch in interior Antarctica, you wouldn’t search for aliens in inhospitable environments. Astronomers have discovered thousands of planets, but only a few so far meet our basic requirements for possibly hosting life: being rocky and in the habitable zones around their stars (where water can stay liquid). Here are a few potentially life-friendly star systems where astronomers will aim their alien-seeking telescopes.

Proxima Centauri

Centauris Alpha Beta Proxima 27, February 2012. Skatebiker

The star system closest to our sun has a planet — Proxima b — similar to Earth’s mass. No one knows if it has any water, but it’s just 4 light-years away, so maybe we could find out in person someday.

Wolf 1061

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Wolf 1061. http://www.drewexmachina.com/2015/12/19/habitable-planet-reality-check-wolf-1061/

The second planet in this star’s solar system is the next-closest Earth-ish-sized planet in a habitable zone, after Proxima b. It’s just 14 light-years from where you’re sitting right now.

GJ 667

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http://www.learnabouttravelmaps.info/pics/g/gliese-667-cb.html

A mere 22 light-years away, this solar system has three super-Earth planets — between Earth’s and Uranus’ mass — in the habitable zone. And in the hunt for extraterrestrial life, every possibility counts.

TRAPPIST-1

Some 39 light-years away, this sun has three potentially rocky planets in its habitable zone and — bonus — four additional rocky planets. That’s seven Earth-ish-sized planets in one spot!

A size comparison of the planets of the TRAPPIST-1 system, lined up in order of increasing distance from their host star. The planetary surfaces are portrayed with an artist’s impression of their potential surface features, including water, ice, and atmospheres. NASA

Kepler 186

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NASA

About 561 light-years away, the fifth planet discovered in this dwarf-star system circles its star’s habitable zone. The planet was the first astronomers found with a size similar to Earth’s.
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Searches Past and Present

1960 Astronomer Frank Drake performs the first modern SETI experiment, called Project Ozma (after a Wizard of Oz character). With an 85-foot radio telescope in Green Bank, W.Va., he looks at two sunlike stars for signs of alien technology.

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In 1960, radioastronomer Frank D. Drake, then at the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia, carried out humanity’s first attempt to detect interstellar radio transmissions. Project Ozma was named after the queen of L. Frank Baum’s imaginary land of Oz — a place “very far away, difficult to reach, and populated by strange and exotic beings.” The stars chosen by Drake for the first SETI search were Tau Ceti in the Constellation Cetus (the Whale) and Epsilon Eridani in the Constellation Eridanus (the River), some eleven light years (66 trillion miles) away. Both stars are about the same age as our sun.

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Frank Drake

1961 A small SETI conference takes place in Green Bank, at which Drake presents what’s now called the Drake Equation, which scientists use to estimate how many extraterrestrial civilizations may exist in our galaxy.

Drake Equation, Frank Drake, Seti Institute

1973 Ohio State University undertakes a SETI program with its Big Ear Observatory.

Ohio State Big Ear Radio Telescope

1979 The University of California, Berkeley, begins a long-lived project called SERENDIP — the Search for Extraterrestrial Radio from Nearby Developed Populations — at Hat Creek Observatory in Northern California.

The most recently deployed SERENDIP spectrometer, SERENDIP V.v, was installed at the Arecibo Observatory in June 2009 and is currently operational.

NAIC/Arecibo Observatory, Puerto Rico, USA

The digital back-end instrument is an FPGA-based 128 million-channel digital spectrometer covering 200 MHz of bandwidth. It takes data commensally with the seven-beam Arecibo L-band Feed Array[2] (ALFA).

The next generation of SERENDIP experiments, SERENDIP VI, is in rapid development with a view to deploy it in early 2014 at both Arecibo and the Green Bank Telescope.

GBO radio telescope, Green Bank, West Virginia, USA

SERENDIP VI will also look for fast radio bursts.[3] SERENDIP VI receivers went into service in 2014-2015.

1983 At Harvard University, astronomer Paul Horowitz launches Project Sentinel, using an 84-foot radio telescope.

1988 NASA endorses its SETI studies, and scientists begin building the instruments they need to perform a search.

1992 NASA’s SETI project, now the High Resolution Microwave Survey (HRMS), turns paperwork and plans into a physical project at Goldstone Observatory in California and the Arecibo radio telescope in Puerto Rico.

1993 Just a year after its start, HRMS ends when Congress cancels its funding.

1995 The private SETI Institute raises philanthropic funds and starts Project Phoenix, a reincarnated version of HRMS.

1995 Horowitz continues his SETI work at Harvard with the Billion-Channel Extraterrestrial Assay (BETA).

1999 Berkeley launches the citizen science project SETI@home, which lets your computer, in its downtime, dip into SERENDIP data.

SETI@home, BOINC project at UC Berkeley Space Science Lab

2004 Allen Telescope Array. First conceived by SETI pioneer Frank Drake, the idea has been a dream of the SETI Institute for years. However, it was not until early 2001 that research and development began, after a donation of $11.5 million by the Paul G. Allen Family Foundation. In March 2004, following the successful completion of a three-year research and development phase, the SETI Institute unveiled a three-tier construction plan for the telescope. Construction began immediately, thanks to the pledge of $13.5 million by Paul Allen (co-founder of Microsoft) to support the construction of the first and second phases. The SETI Institute named the telescope in Allen’s honor. 2005 The SETI Institute begins building a telescope dedicated to searches for aliens.Overall, Paul Allen has contributed more than $30 million to the project.

SETI/Allen Telescope Array situated at the Hat Creek Radio Observatory, 290 miles (470 km) northeast of San Francisco, California, USA

2015 METI (Messaging Extraterrestrial Intelligence) International begins an optical SETI program at the Boquete Observatory in Panama.

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Boquete Observatory

2016 The $100 million Breakthrough Listen project, sponsored by Russian magnate Yuri Milner, begins a 10-year search that includes both radio and optical strategies.

Breakthrough Listen Project

Telescopes:

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100 Meter Robert C. Byrd Green Bank Telescope

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64-metre diameter Parkes Telescope

Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA


Automated Planet Finder Telescope at Lick Observatory

SETI Institute

Still To Come:

LASER SETI

July 31, 2017
New Laser SETI project will look for signals that most telescopes cannot see.
Please visit https://www.indiegogo.com/projects/laser-seti-first-ever-all-sky-all-the-time-search-science#/ to learn all about Laser SETI.

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