1. 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

2. 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)

4. 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:
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?

5. 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 ????
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 ???? N = 7·1·0.2·.1·1·0.2·L = ·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.

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. 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 ????
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 ????
L = The length of time such civilizations release detectable signals into space. 1,000,000,000 years ???????????????
Quoted from:

7. 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.

9. 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?)

10. 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

11. 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.

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

13. 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

14. What are SETI searches like?

15. 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

17. Green Bank Telescope Efforts
Kepler Object Follow-up
Kepler Syzygy Observations
SERENDIP VI - Commensal, Data available via
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
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

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

19. Green Bank Telescope Efforts
Kepler Object Follow-up
Kepler Syzygy Observations
SERENDIP VI - Commensal, Data available via
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
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

20. 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

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

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

24. 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

25. https://3c1703fe8d. site. internapcdn

26. http://www. myapplespace

27. 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

28. Breakthrough Initiatives
Breakthrough Listen

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

36. What protocols should scientist follow if a detection is made?