Ron Maddalena Green Bank Observatory Green Bank, WV A Discussion on Breakthrough Listen’s Role in the Quest for Extraterrestrials How certain are you that other solar systems are common? How certain are you that other Earth-like planets are common? How certain are you that extraterrestrial life is common? How certain are you that extraterrestrial intelligent life is common? How certain are you that it is common for intelligent life to try to communicate its existence to other worlds? How certain are you that intelligent life would colonize? Is it science research? Is it not worthwhile science research? Is it worthwhile? Is it an imperative area of research? Cost and risk versus possible payoff Ron Maddalena Green Bank Observatory Green Bank, WV © Associated Universities, Inc; May, 2017

Extraterrestrial Life Debate – Not New Philosophy/Cosmology/World-View inspired: Atomist (Epicurus) – 5th century BC Lucretius – 1st century AD Giordano Bruno (heretic) – 16th century Kepler (Moon) – 16th century Voltaire (Micromegas -- aliens) – 18th century Thomas Paine Scientists: Sir John Herschel (Moon & Sun) – 19th century Percival Lowell (Mars) – 1894/95 Marconi (Detects radio waves from Mars) -- 1920

The Drake Equation N = the number of civilizations in our galaxy for which communication might be possible R* = The rate of formation of stars suitable for the development of intelligent life. fp = The fraction of those stars with planetary systems ne = The number of planets, per planetary system, with an environment suitable for life. fl = The fraction of suitable planets on which life actually appears. fi = The fraction of life-bearing planets on which intelligent life emerges. fc = The fraction of civilizations that develop a technology that releases into space detectable signs of their existence L = The length of time such civilizations release detectable signals into space. Quoted from: http://www.seti.org/drakeequation Searching for Extraterrestrial Signals is a Lot Like Searching for Unicorns If one can estimate there’s a high likelihood there’s one Unicorn per square mile, then the search would have low costs If one can estimate Unicorns are extremely rare, no more than one per 10,000 square miles, what must one do to definitively determine that not even one Unicorns exists?

The Drake Equation N = the number of civilizations in our galaxy for which communication might be possible R* = The rate of formation of stars suitable for the development of intelligent life. About 7 / year fp = The fraction of those stars with planetary systems. About 1 ne = The number of planets, per planetary system, with an environment suitable for life. About 0.2 fl = The fraction of suitable planets on which life actually appears. 0.1 ???? fi = The fraction of life-bearing planets on which intelligent life emerges. 1 ???? fc = The fraction of civilizations that develop a technology that releases into space detectable signs of their existence. 0.2 ???? N = 7·1·0.2·.1·1·0.2·L = 0.028·L L = The length of time such civilizations release detectable signals into space. An extremely large L is the only way in which N will be anything but trivial.

The Drake Equation N = the number of civilizations in our galaxy for which communication might be possible R* = The rate of formation of stars suitable for the development of intelligent life. About 7 / year fp = The fraction of those stars with planetary systems. About 1 ne = The number of planets, per planetary system, with an environment suitable for life. About 0.2 fl = The fraction of suitable planets on which life actually appears. 0.1 ???? fi = The fraction of life-bearing planets on which intelligent life emerges. 1 ???? fc = The fraction of civilizations that develop a technology that releases into space detectable signs of their existence. 0.2 ???? L = The length of time such civilizations release detectable signals into space. 1,000,000,000 years ??????????????? Quoted from: http://www.seti.org/drakeequation

The Drake Equation N = the number of civilizations in our galaxy for which communication might be possible = 28,000,000 Mean separation 30 light years (about 10 pc) 30 lyrs is about how far we would be able to see an ET using an Arecibo-like radar with our Arecibo telescope. Implies L needs to be something like 1 billion years for a reasonable chance of detection.

We have two actual, singular amazing observations, critical pieces of scientific data. There has never been a detection of an ET signal We have never encountered ET. Fermi Paradox If intelligent life developed elsewhere at some point in the past, then they would have colonized the galaxy by now. Some term in the Drake Equation may be a barrier to the formation of intelligent life L may be relatively short (~100 instead of 109 years?)

Rare Earth Hypothesis (Pessimistic) N*=Number of stars in the Milky Way: 1011 – 5x 1011 ne=Number of planets in the habitable zone fg = fraction of stars in the galactic habitable zone fp = fraction of stars with planets fpm = fraction of planets that are rocky fi = fraction of planets that can develop microbial life fc = fraction of planets that develop complex life fl = fraction of a planet’s lifetime that can support life fm = fraction of planets with a large moon fp = fraction of planetary systems with a outer Jovian planet for ‘protecting’ the inner planets fme = fraction of planets with a low number of extinction events If n_e=1, and all the f’s are 0.1 (which might be too optimistic for a few terms, pessimistic for others), there’s no more than 100 civilizations in our galaxy. Average separation: 8000 lyrs

Rare Earth Hypothesis Other considerations Right kind of galaxy Right kind of star Stable orbit Something must stop the typical planetary migrations that would destroy rocky planets in the habitable zone Fast rotating planet – requires a collision with another planet-sized object Magnetic field Low but not zero intrinsic nuclear radiation Plate tectonics and a tilted axis to promote evolution How did life get started? Complex life? Intelligent life? Chemist/Biologist have some ideas on how to get the chemistry of life started Known chemistry reaction rates cannot produce the complexity of life in less then 10 billion years Panspermia Comets, etc. seeded the Earth with the complex molecules known to form and exist in interstellar space which jump started the chemistry. And then there’s Mars. Chemist/Biologist also have some ideas on why it is inevitable that eventually complex life forms would develop.

Likelihood and Unlikelihood of Life Astrochemistry Miller-Urey experiment Resiliency, adaptability Evolution Chemical reaction rates A single origin Endosymbiotic ‘event’

1959:Guiseppe Cocconi, Philip Morrison "The probability of success is difficult to estimate, but if we never search the chance of success is zero.” 1959:Guiseppe Cocconi, Philip Morrison

What are SETI searches like?

What are SETI searches like? Optical – encoded messages on collimated light beams Infrared – the signature of Dyson spheres (Soviet Union/Russians) Radio (US) 1-5 GHz High time resolution High frequency resolution Pointed observations toward particular stars Commensal/Piggy-back experiments

Green Bank Telescope Efforts Kepler Object Follow-up Kepler Syzygy Observations SERENDIP VI - Commensal, Data available via SETI@Home Breakthrough Listen - 20% of GBT’s observing time dedicated to search, Data available publicly Tabby Star – Directed observations BTL with the GBT 2 million stars in 10 years, all stars within 30 light years Every day 4 terra bytes of data are taken & processed. Takes 3x as much time to process as it takes to take Reduced data will be available to anyone for further processing SETI@Home 20% of the GBT’s observing time will be dedicated to observing BTL targets Other science projects can be going on simultaneously Commensal SETI with the GBT via SERENDIP VI Piggy-backs on the data taken by most project toward the objects of interest for other types of science Probably uses 80% of the GBT observing time Data already available via SETI@Home

Kepler Syzygy Observations Earth STAR Planet 1 Planet 2 Significantly not to scale!!

Green Bank Telescope Efforts Kepler Object Follow-up Kepler Syzygy Observations SERENDIP VI - Commensal, Data available via SETI@Home Tabby Star – Directed observations Breakthrough Listen - 20% of GBT’s observing time dedicated to search, Data available publicly BTL with the GBT 2 million stars in 10 years, all stars within 30 light years Every day 4 terra bytes of data are taken & processed. Takes 3x as much time to process as it takes to take Reduced data will be available to anyone for further processing SETI@Home 20% of the GBT’s observing time will be dedicated to observing BTL targets Other science projects can be going on simultaneously Commensal SETI with the GBT via SERENDIP VI Piggy-backs on the data taken by most project toward the objects of interest for other types of science Probably uses 80% of the GBT observing time Data already available via SETI@Home

Tabby’s Star KIC 8462852 (Tabitha Boyajian's Star) "WTF Star“ (Where's The Flux?) Planet Hunters Project Large fluctuations in optical light Lack of Infrared flux Planet Hunters - amateurs & professional collaboration – Kepler observations Small, frequent light dips (day long) with occasional large dips of up to 22% (Jupiter 1%) Fluctuations not known to come from a main sequence F star material blocking the star’s light Not planets – wrong light curves No IR, which would be expected from debris around a star Gradually fading since 1890 (some dispute) of ~20% in 100 years. Kepler measures 0.3% / yr Young: with coalescing material – negative observations in the IR Planetary collision – should produce warm dust, low likelihood of a collision. Again no IR Star consumed a planet – increased the brightness of the star, which is currently recovering from (i.e., dimming back to normal), surrounded by planetary debris

https://en.wikipedia.org/wiki/KIC_8462852

https://en.wikipedia.org/wiki/KIC_8462852

https://en.wikipedia.org/wiki/KIC_8462852 “A swarm of large comets in a highly eccentric orbit with lots of smaller bodies and gas and dust in between them. “ Comets in the star’s Kuiper belt perturbed into the inner stellar system by the passing of a nearby star Could comets in such a large number exist? Observations don’t show the existence of a cold dust in a Kuiper-like belt around the star https://en.wikipedia.org/wiki/KIC_8462852

https://3c1703fe8d. site. internapcdn https://3c1703fe8d.site.internapcdn.net/newman/gfx/news/hires/2017/finallyanexp.jpg

http://www. myapplespace http://www.myapplespace.com/photos/image/12954/halo-artificial-ring-world

Breakthrough Listen with the Green Bank Telescope World’s Deepest SETI survey All stars within 15 light years One Thousand stars within 150 light years One million nearby stars 100 Galaxies 1 day of Breakthrough = 1 year of any previous survey Breakthrough Listen Yuri Milner, Steven Hawkings, Facebook, Google World’s Deepest SETI survey with the Green Bank Telescope All stars within 15 light years One Thousand stars within 150 light years One million nearby stars 100 Galaxies

Breakthrough Initiatives Breakthrough Listen

And, what would be the consequences if the answer turns out to be: yes??

What protocols should scientist follow if a detection is made?