Are we alone? How prevalent is intelligent life in the Universe? How are the recent exoplanet discoveries by NASA's Kepler mission bearing on this question?

1. Kepler’s Exoplanet Discoveries:
Implications for the Prevalence of
Extra-Terrestrial Intelligence
Robert McCann, Ph.D.
NASA Ames Research Center
Special Acknowledgments:
Dr. Natalie Batalha 1
Dr. Bill Borucki

2. 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

3. • Kepler Mission
• Primary Goal: Detect Earth-sized planets in HZ of their star
• Quantify how plentiful they are
• Giant (95 MP) photometer in space • 167K sun-like stars in FOV
• Launched March 2009 • 156K selected for monitoring
• First Light: May 2009

4. 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 civilizations
R* = galactic birthrate of G/K/M type stars suitable for hosting life (~10/year)
fPlanet = the fraction of such stars having planets
ne = the number of those planets that are habitable
fLife = fraction of those planets on which life originated/evolved
fIntelligence = the fraction of inhabited worlds that developed intelligent life
fCivilizations = the fraction of inhabited worlds that developed civilizations
capable of interstellar communication
L = lifetime of those communicating civilizations
•Kepler: Fraction of sun-like (FGK) stars with a habitable planet
• Consolidation of terms fPlanet and ne

5. Kepler Modus Operandi: Transit Method
Kepler-16 (2)
Kepler-10
Kepler-15 Kepler-4
HAT-p-11 Kepler-6 Kepler-22 TrES-2
Kepler-14
Kepler-17 KOI-428HAT-p-7
Kepler-13
KOI-423
Kepler-8
Kepler-5
Kepler-12
Kepler-7
Kepler-11 line-of-sight: Rs/Rorbit
• Proportion of planets in(6)
Kepler-21 Kepler-18 (3)
• For Earth-sized planets in Earth-sized orbits:
Kepler-19 Kepler-9 (3)
• .005 (1/200) (2)
• If all 156K stars in Kepler FOV contain an Lissauer et al. 2011, Nature, 470, 53
earth-analog:
• Kepler would detect 780 of them 5

6. Kepler-16 (2)
Kepler-10
Kepler-15 Kepler-4
HAT-p-11 Kepler-6 Kepler-22 TrES-2
Kepler-14
Kepler-17 KOI-428HAT-p-7
Kepler-13
KOI-423
Kepler-8
Kepler-5
Kepler-12
Kepler-11(6) Kepler-7
Kepler-21 Kepler-18 (3)
Kepler-19 (2) Kepler-9 (3)
6

7. Candidates as of June 2010
Q0-Q1: May-June 2009
Jun 2010 (No Earth-Sized Planets)
Size Relative to Earth
7
Orbital Period in days

8. Candidates as of Feb 2011
Q0-Q5: May 2009 - Jun 2010
Jun 2010 Feb 2011
Size Relative to Earth
8
Orbital Period in days

9. Improved Vetting Statistics
9.1 arcsec source offset
9
0.2 arcsec source offset

10. Candidates as of Dec 2011
Q0-Q6: May 2009 - Sep 2010
Feb 2011 7 Earth-Sized Dec 2011 25 Earth-Sized
Size Relative to Earth
10
Orbital Period in days

11. Kepler-16 (2)
Kepler-10
Kepler-15 Kepler-4
Kepler-22
HAT-p-11 Kepler-6
TrES-2
Kepler-14
Kepler-17 KOI-428HAT-p-7
Kepler-13
KOI-423
Kepler-8
Kepler-5
Kepler-12
Kepler-11(6) Kepler-7
Kepler-21 Kepler-18 (3)
Kepler-19 (2) Kepler-9 (3)
11

12. HZ Candidates
48 with Teq between 185 and 303 K (Earth = 255 K)
Jun 2010 Feb 2011 Dec 2011
Size Relative to Earth
Equilibrium Temperature [K] 12

13. HZ Candidates
Ten with Rp < 2 Re (185 K < Teq < 303 K)
Jun 2010 Feb 2011 Dec 2011
Size Relative to Earth
Equilibrium Temperature [K] 13

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
14

15. When will we know?
?
• Lower S/N ratio than
originally designed for
• More transits required
15
Nature 477, 142-143 (Sept 6, 2011)

16. Stellar Noise: simulation vs observation
6.5-hr variability is stochastic and will average out over
multiple orbits
The goal of true
Earth-analogs is
1.2-Re, P=365 d 1.0-Re, P=365 d reachable by
extending the
mission length
Jenkins et al.: Poster 19.14
1.0-Re, P=225 d
30 ppm
20-ppm
1.0-Re, P=365 d
16

17. 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?
?
17

18. Q0-Q5: May 2009 - Jun 2010
Size Relative to Earth
Orbital Period in days 18
• 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 %
+0.6
• If exactly 1.1%, Kepler should detect 9 ηEarths

19. Dec 2011
“The new (2012) Kepler
data set shows that the
'completeness' of the
February 2011 data set was
over-estimated.
Size Relative to Earth
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.”
Orbital Period in days
“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.
19
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

20. Extrapolations
1.1 + 0.6 = 1.7% = 13 ηEarths
• 13*200 = 2604 ηEarths in Kepler’s sample of 153,196 FGK stars
• 20 Billion FGK’s in Milky Way
• ~340 million η Earths in our Milky Way Alone!
20

21. Implications
The Drake Equation
Fermi ParadoxL
N = R* x fPlanet x ne x fLife x f x f
Intelligence x Civilizations
If ne = 1.7% (340 million ηEarths)
• 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)
Enrico Fermi
And:
The average distance between stars is 5 light years (50 years)
And:
After 150 years you can spread to the next system, sending new
craft 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 hops
it would only take 100 million years to colonize the entire galaxy.
So: Where is Everybody (Fermi Paradox)?

22. Machine IntelligenceParadox
• In 1981, Frank Tipler used the idea of colonization by
self-replicating Von Neumann machines to argue that machines
would spread throughout the galaxy as soon as any civilization
reaches 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.

23. Implications
The Drake Equation
Fermi Paradox
N = R* x fPlanet x ne x fLife x fIntelligence x fCivilizations x L
fLife = fraction of those planets on which life originated/evolved
fIntelligence = the fraction of inhabited worlds that developed intelligent life
fCivilizations = the fraction of inhabited worlds that developed civilizations
capable of interstellar communication
L = 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

24. The Drake Equation
Conclusion
We are not alone.
But we are very lonely.