A Discussion on Breakthrough Listens Role in the
A Discussion on Breakthrough Listen’s Role in the Quest for Extraterrestrials Ron Maddalena Green Bank Observatory Green Bank, WV © Associated Universities, Inc; May, 2017
4 Extraterrestrial Life Debate – Not New • Philosophy/Cosmology/World-View inspired: ▫ ▫ ▫ Atomist (Epicurus) – 5 th century BC Lucretius – 1 st century AD Giordano Bruno (heretic) – 16 th century Kepler (Moon) – 16 th century Voltaire (Micromegas -- aliens) – 18 th century Thomas Paine • Scientists: ▫ Sir John Herschel (Moon & Sun) – 19 th century ▫ Percival Lowell (Mars) – 1894/95 ▫ Marconi (Detects radio waves from Mars) -- 1920
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6 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
13 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.
14 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 years ? ? ? ? Quoted from: http: //www. seti. org/drakeequation
15 The Drake Equation N = the number of civilizations in our galaxy for which communication might be possible = 28, 000 Mean separation 30 light years (about 10 pc)
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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? )
18 Rare Earth Hypothesis (Pessimistic) N*=Number of stars in the Milky Way: 1011 – 5 x 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 • • •
19 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
20 Likelihood and Unlikelihood of Life • • Astrochemistry Miller-Urey experiment Resiliency, adaptability Evolution • Chemical reaction rates • A single origin • Endosymbiotic ‘event’
"The probability of success is difficult to estimate, but if we never search the chance of success is zero. ” 1959: Guiseppe Cocconi, Philip Morrison
22 What are SETI searches like?
23 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
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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
26 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
28 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
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30 https: //en. wikipedia. org/wiki/KIC_8462852
31 https: //en. wikipedia. org/wiki/KIC_8462852
32 https: //en. wikipedia. org/wiki/KIC_8462852
33 https: //3 c 1703 fe 8 d. site. internapcdn. net/newman/gfx/news/hires/2017/finallyanexp. jpg
34 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
36 Breakthrough Initiatives Breakthrough Listen
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44 And, what would be the consequences if the answer turns out to be: yes? ?
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46 What protocols should scientist follow if a detection is made?
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