11

Robert McCann, Ph.D.NASA Ames Research Center

Special Acknowledgments:Dr. Natalie BatalhaDr. Bill Borucki

Kepler’s Exoplanet Discoveries: Implications for the Prevalence of

Extra-Terrestrial Intelligence

Milky Way Galaxy

• Large Barred Spiral• 90K LY in Diameter• ~200B stars• ~20B FGK’s

• <1995 CE:• 1 Planetary System• 1 Intelligent life form capable of putting together a ppt presentation

• Kepler Mission• Primary Goal: Detect Earth-sized planets in HZ of their star• Quantify how plentiful they are

• Giant (95 MP) photometer in space • Launched March 2009• First Light: May 2009

• 167K sun-like stars in FOV• 156K selected for monitoring

Implications for ETI Drake Equation

1961: • Frank Drake develops Drake Equation

• Equation to calculate the number of civilizations in our galaxy that we could potentially receive a signal from.

N = R* x fPlanet x ne x fLife x fIntelligence x fCivilizations x L

N = the number of transmitting/communicating civilizationsR* = galactic birthrate of G/K/M type stars suitable for hosting life (~10/year)fPlanet = the fraction of such stars having planetsne = the number of those planets that are habitablefLife = fraction of those planets on which life originated/evolvedfIntelligence = the fraction of inhabited worlds that developed intelligent lifefCivilizations = the fraction of inhabited worlds that developed civilizations

capable of interstellar communicationL = lifetime of those communicating civilizations

•Kepler: Fraction of sun-like (FGK) stars with a habitable planet• Consolidation of terms fPlanet and ne

55

Kepler-8

KOI-428

(2) Kepler-10

(6)Kepler-11

(3)Kepler-9

Kepler-14

Kepler-7

Kepler-6

Kepler-12

Kepler-4

Kepler-16

TrES-2

HAT-p-7

Kepler-19 (2)

Kepler-13

Kepler-15

KOI-423

Kepler-5

HAT-p-11

Kepler-17

(3)Kepler-18Kepler-21

Kepler-22

Lissauer et al. 2011, Nature, 470, 53

• Proportion of planets in line-of-sight: Rs/Rorbit

• For Earth-sized planets in Earth-sized orbits: • .005 (1/200)• If all 156K stars in Kepler FOV contain an

earth-analog: • Kepler would detect 780 of them

Kepler Modus Operandi: Transit Method

6

Kepler-8

KOI-428

(2)Kepler-10

(6)Kepler-11

(3)Kepler-9

Kepler-14

Kepler-7

Kepler-6

Kepler-12

Kepler-4

Kepler-16

TrES-2

HAT-p-7

Kepler-19 (2)

Kepler-13

Kepler-15

KOI-423

Kepler-5

HAT-p-11

Kepler-17

(3)Kepler-18Kepler-21

Kepler-22

77

Candidates as of June 2010Q0-Q1: May-June 2009

Orbital Period in days

Siz

e R

elat

ive

to E

arth

Jun 2010 (No Earth-Sized Planets)

8

Candidates as of Feb 2011Q0-Q5: May 2009 - Jun 2010

Orbital Period in days

Siz

e R

elat

ive

to E

arth

Jun 2010 Feb 2011

9

Improved Vetting Statistics

0.2 arcsec source offset

9.1 arcsec source offset

10Orbital Period in days

Siz

e R

elat

ive

to E

arth

Candidates as of Dec 2011Q0-Q6: May 2009 - Sep 2010

Feb 2011 Dec 2011 25 Earth-Sized7 Earth-Sized

11

Kepler-8

KOI-428

(2) Kepler-10

(6)Kepler-11

(3)Kepler-9

Kepler-14

Kepler-7

Kepler-6

Kepler-12

Kepler-4

Kepler-16

TrES-2

HAT-p-7

Kepler-19 (2)

Kepler-13

Kepler-15

KOI-423

Kepler-5

HAT-p-11

Kepler-17

(3)Kepler-18Kepler-21

Kepler-22

12Equilibrium Temperature [K]

Siz

e R

elat

ive

to E

arth

Jun 2010 Feb 2011 Dec 2011

HZ Candidates48 with Teq between 185 and 303 K (Earth = 255 K)

13Equilibrium Temperature [K]

Siz

e R

elat

ive

to E

arth

Jun 2010 Feb 2011 Dec 2011

HZ CandidatesTen with Rp < 2 Re (185 K < Teq < 303 K)

14

Only a matter of time before discovery of “ηEarths”• 0 .95 AU < a < 1.37 AU (Kasting et al.,

1993)• 0.8REarth < r < 2REarth

• Q0-Q6: May 2009 - Sep 2010• As of May 2012: Will Double

observation time from 18 to 36 months

• 3 transits of ηEarth’s obtained

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When will we know?

Nature 477, 142-143 (Sept 6, 2011)

?

• Lower S/N ratio than originally designed for

• More transits required

16

20-ppm

30 ppm

1.2-Re, P=365 d 1.0-Re, P=365 d

1.0-Re, P=365 d

1.0-Re, P=225 d

Stellar Noise: simulation vs observation6.5-hr variability is stochastic and will average out over

multiple orbits

Jenkins et al.: Poster 19.14

The goal of true Earth-analogs is

reachable by extending the mission length

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Extrapolation based on Existing Kepler Data

?

Feb 2011

• Catanzarite and Shao (2011): • Defined Earth Analog Planets

(ηEarth):• .95 AU < a < 1.37 AU

(Kasting et al., 1993)• .8REarth < r < 2REarth

• How many should Kepler find?

18

Q0-Q5: May 2009 - Jun 2010

Orbital Period in days

Siz

e R

elat

ive

to E

arth

• Planets cluster between orbital periods of 3 and 40 days• Mathematical extrapolation: Occurrence rate of ηEarth around

sun-like stars is 1.1- 0.3

• If exactly 1.1%, Kepler should detect 9 ηEarths

+0.6%

19

Orbital Period in days

Siz

e R

elat

ive

to E

arth

“The new (2012) Kepler data set shows that the 'completeness' of the February 2011 data set was over-estimated.

For planets over twice the size of Earth with orbital periods shorter than 40 days, detections were expected to be 100% 'complete', so that no more planets remained to be found in the new 2012 data set.”

“The surprise is that a substantial number of planets with sizes and periods in that range were in fact found in the 2012 data release.

At this point we can only say that the revised estimate will likely be higher than the number given in our paper.”

- Joseph Catanzarite, Personal Communication, March 2012

Dec 2011

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Extrapolations

13

• 13*200 = 2604 ηEarths in Kepler’s sample of 153,196 FGK stars

• 20 Billion FGK’s in Milky Way

• ~340 million ηEarths in our Milky Way Alone!

1.1 + 0.6 = 1.7% = ηEarths

The Drake Equation

N = R* x fPlanet x ne x fLife x fIntelligence x fCivilizations x L

If ne = 1.7% (340 million ηEarths)

Implications Fermi Paradox

• Expect to have a large number of civilizations. It is only a matter of time before they develop the ability for intergalactic travel.

If:-you could travel at 10% the speed of light, 0.1 c (3 x 107 m/sec)

And:The average distance between stars is 5 light years (50 years)

And:After 150 years you can spread to the next system, sending newcraft to one or two other systems.

Then:You could colonize the entire galaxy in 10 million years If you travel at 0.01 c, and it takes 5,000 years between hopsit would only take 100 million years to colonize the entire galaxy.

So: Where is Everybody (Fermi Paradox)?

Enrico Fermi

Machine IntelligenceParadox

• In 1981, Frank Tipler used the idea of colonization byself-replicating Von Neumann machines to argue that machineswould spread throughout the galaxy as soon as any civilizationreaches a level to build these machines.

• Because it doesn’t take much more technological capability than what we already have.

• If civilizations are common:

• The universe should be overrun by self-replicating machines.

The Drake Equation

N = R* x fPlanet x ne x fLife x fIntelligence x fCivilizations x L

fLife = fraction of those planets on which life originated/evolvedfIntelligence = the fraction of inhabited worlds that developed intelligent lifefCivilizations = the fraction of inhabited worlds that developed civilizations

capable of interstellar communicationL = lifetime of those communicating civilizations

Answer to Paradox: One or more of these terms must be close to zero

- Microbial life should be widespread in the universe- Complex life such as plants and animal will be extremely rare- Earth is “lucky”- Complex Earth life is the result of an extraordinary set of conditions and random chance events- Microbial life appeared quickly; complex life recently- Earth is also special:

-in the habitable zone-life-friendly atmosphere-Jupiter and the Moon beneficial-placid part of the galaxy

Implications Fermi Paradox

The Drake Equation

Conclusion

We are not alone.But we are very lonely.