1. Anant Konanahalli Kristine Werling John Toman Ellie Bensinger
Listening For Signals
Anant Konanahalli
Kristine Werling
John Toman
Ellie Bensinger

2. Mission Def-D-6
“Define Drake’s 6th Variable”
Fc = fraction of civilizations that develop a technology that releases detectable signs of their existence into space.

3. Why listen for signals?
The ability of an extraterrestrial civilization to send a signal would indicate their presence and intelligence.
Def-D-6

4. What are we looking for?
“Radio signals coming from outer space that have no causal factors” –SETI
“Narrow-bandwidth radio signals: --SETI
Not known to occur naturally
Indicate artificial source = Extraterrestrial Life
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5. Focus Projects 1) Allen Array Telescope 2) Big Ear 3) SETI@home
Def-D-6 Plan Proposal
Focus Projects 1) Allen Array Telescope 2) Big Ear 3)
Projects to Cut
CETI
Def-D-6

6. Allen Telescope Array: What is it?
‘One Hectare Telescope’
2007 at Hat Creek Observatory, Cascade Mountains
SETI Institute + Radio Astronomy Laboratory
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7. Allen Telescope Array: What does it do?
Purpose Two-Fold
Conventional radio astronomy projects
SETI
SETI Focus
1) Sky sweep survey
2) Targeted Searches
Data collected
4.5 octaves of frequency
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8. Def-D-6

9. Allen Telescope Array: How does it do it?
LNSD array = Large Number of Small Dishes
42 dishes
Pseudo-random arrangement
1 km circle
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10. Allen Telescope Array: How does it do it?
Basic Signal Collection
Radio waves collected at antenna
Radio waves focused
Converted to electrical signals
Amplified
Processed
Beam Width Limitation:
Sinθ= 1.22λ/D
Def-D-6

11. Allen Telescope Array: How does it do it?
Array Advantage
Combined to form equivalent of single large dish
Beam Width Limitation:
Sinθ= 1.22λ/D
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12. Allen Telescope Array: How does it do it?
Adjustments to ‘listen’ in different directions
Alter cable lengths and electronic delays
Bring waves from different direction in-phase
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13. Allen Telescope Array: How does it do it?
Offset Optic or Gregarian Antenna System
“Because sometimes, as in football, going to the side can reduce interference”
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14. Allen Telescope Array: Why Invest?
Array vs Single Large Disk
Lower cost
Easier adjustments/repairs
Easy to add on/improve
Multipurposed
Radio astronomy
SETI
Speed up SETI searches
24hr data collection
Simultaneity
Larger sky area
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15. Allen Telescope Array: Modifications
Expand to the “Square Kilometer Array”
Expand to 350 dishes
Angular resolution of 700 meter diameter dish
Comparable to Robert C. Byrd Telescope and Very Large Array
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16. Ohio State University Radio Observatory (Big Ear)
John D. Kraus, built/design
Small Ear Prototype
NSF grant to start Big Ear
Considerably less than req’d
Had to scale down
2000 ft.360 ft. in length
Main Components
Flat Reflector
Paraboloidal Reflector
Feed Horns
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17. Big Ear: Flat Reflector
340 ft. x 100 ft.
Wire Mesh
Ability to tilt
Unfocused waves
Ground Plane
Wire Mesh was used so that radio waves would reflect, but light waves would pass right through
The flat screen was tilted every 3 or 4 days
The waves only bounce off the flat reflector, but need to be focused
The point of the ground plane was to insulate the telescope so that radio waves could not get in or out (except from the reflected mesh)
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18. Big Ear: Paraboloidal Reflector
360 ft. x 170 ft.
Focused the sent waves
Wavelengths
~21.1 cm (8.3 inches)
MHz
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19. Big Ear: Feed Horns Two Horns Funneled waves Signal Switch (79x)
Why Switch?
See the same area twice in minutes
Removed variation due to drift and sky variation
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20. Big Ear: Recap

21. Big Ear: WOW! Signal Jerry R. Ehman 1977 Coded Intensity
Found at 1420 MHz
Sagittarius
Lasted 72 seconds, not replicated
Even Very Large Array could not detect
Earth-borne signal reflected off space debris
One-time burst
Intensity was scaled using an alphanumeric code, the 6EQUJ5 then shows an increasing intensity up to a peak of about 30 times normal deep space
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22. Big Ear: Justifications for Use
Started from NSF grant of $48,000
$450,000 today with inflation
Need to resolve this signal via further investigation
Physically impossible for WOW! to bounce off of debris, 1420 MHz is restricted, something is up.
Very Large Array ($78.5M) is very similar and has made key observations of black holes and protoplanetary disks.
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23. SETI@home: Overview Released to the public in May of 1999
Over 5 million users worldwide
Has completed 2 million hours of computing time
Primary Goals
1) to do useful scientific work by supporting an observational analysis to detect intelligent life outside Earth
2) to prove the viability and practicality of the 'volunteer computing' concept.
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24. SETI@home: How it Works
Searches for possible radio transmissions from ETs
Uses observational data from Arecibo
Data digitized and sent to
Wire Mesh was used so that radio waves would reflect, but light waves would pass right through
The flat screen was tilted every 3 or 4 days
The waves only bounce off the flat reflector, but need to be focused
The point of the ground plane was to insulate the telescope so that radio waves could not get in or out (except from the reflected mesh)
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25. SETI@home: How it Works
Parses data into millions of very small chunks
Anyone can download software onto their computer
Personal computers use processing power to analyze these chunks (variations)
How it Works
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26. SETI@home: Justifications
doesn’t use government funding
Berkeley has found ways to work with small budgets and donations
Increasing power of home computers/laptops
Other applications of interest
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27. SETI@home: Possible Modifications
Alternative to Arecibo telescope
Better hardware quality
Increased marketing efforts
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28. CETI Communication with Extraterrestrial Intelligence Subset of SETI
Researching effective means of communication
CETI
- Majority of SET involves listening, but there is a part of the SETI movement dedicated to trying to communicate with ET by sending out messages
Communication with Extra-Terrestrial Intelligence
Subsect of SETI in many projects and institutions
researching most effective means of communication
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29. Previous CETI projects
Arecibo Message (1974):
Radio message to starcluster M13
Binary- DNA, Map of Solar System
Cosmic Calls 1 and 2 (1999)
Sent to several stars
Contained text, audio, video, “Rosetta Stone” version of Arecibo
Doritos Commercial
(2008)
Arecidbo: binary message sent via radio waves containing atomic numbers of elements in DNA, graphic of our solar system, etc
Cosmic calls 1,2: - "Rosetta Stone", copy of Arecibo Message, Bilingual Image Glossary, the Braastad message, as well as text, audio, video and other image files submitted for transmission by everyday people around the world. The "Rosetta Stone" was composed by Stephane Dumas and Yvan Dutil and represents a multi-page bitmap that builds a vocabulary of symbols representing numbers and mathematical operations.
Doritos: held a contest, winner’s commercial was broadcast to a solar system 42 ly away
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30. CETI entails… Hiring social scientists: Douglas Vachok
Creating mathematical and scientific languages
Creating pictorial languages
Lincos: Lingua cosmica
Figuring out best representation
Binary, Radio, Pulse
Freudenthal, Hans. - Lincos; Design of a Language for Cosmic Intercourse
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31. Noble but not necessary yet…
Already so much data to decode
“Linear A” problem
Un-decoded early human language
SETI- Interstellar Message Composition
Closest Earth like planet: Gliese 581 system
20 light years away
40 year exchange
Receiving so much data from other projects, put manpower on interpreting this data!
Difficult to decode when you know nothing about the society – fundamental modes of communication
Vachok- director of interstellar communication entire department devoted to CETI, only social scientist employed by SETI
- I think the idea of sending messages to aliens is very romantic its not where we should be focusing our resources. Reallocating these funds to the projects previously discussed could help givethose projects the green light: ie SETI would save $100,000 a year by eliminating this department
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32. First Things First Fund programs that are looking for incoming data
Most likely way of detecting life
Once we find something, then maybe CETI
Suggests that there is the possibility of a dialogue between cultures
We have only been emitting for about 100 years, which is fraction of earths existance
Other society would have to be in this 100 year window of development at exact same time
And who knows how long this phase will last.. Our emissions are dwindling converting to other technologies that don’t leave atmosphere
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33. References
Douglas A. Vakoch. "To the Stars, Silently." Leonardo 37.4 (2004): Project MUSE. Web. 7 May <  
Douglas A. Vakoch. "The Art and Science of Interstellar Message Composition." Leonardo 37.1 (2004): Project MUSE. Web. 7 May <
Freudenthal, Hans. Lincos; Design of a Language for Cosmic Intercourse. Amsterdam: North-Holland Pub., 1960.
"SETI Institute." SETI Institute. N.p., n.d. Web. 07 May 2013.
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