LISTENING FOR SIGNALS

Anant Konanahalli Kristine Werling

John TomanEllie Bensinger

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.

Why listen for signals?• The ability of an extraterrestrial civilization to

send a signal would indicate their presence and intelligence.

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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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Def-D-6 Plan Proposal

Focus Projects1) Allen Array Telescope2) Big Ear 3) SETI@home

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Projects to Cut 1) CETI

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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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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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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Allen Telescope Array: How does it do it?

Radio waves

collected at

antenna

Radio waves

focused

Converted to

electrical signals

Amplified Processed

• Basic Signal Collection

Beam Width Limitation:

Sinθ= 1.22λ/D

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Allen Telescope Array: How does it do it?• Array Advantage

Combined to form equivalent of single large dish

Beam Width Limitation:

Sinθ= 1.22λ/DDef-D-6

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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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” Def-D-6

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 Def-D-6

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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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

1. Flat Reflector2. Paraboloidal Reflector3. Feed Horns

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Big Ear: Flat Reflector

340 ft. x 100 ft. Wire Mesh Ability to tilt Unfocused

waves Ground Plane

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Big Ear: Paraboloidal Reflector

360 ft. x 170 ft. Focused the sent waves Wavelengths

~21.1 cm (8.3 inches) 1411-1420 MHz

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Big Ear: Feed Horns

Two Horns Funneled waves Signal Switch

(79x)

Why Switch?1. See the same area twice in 2.5-5

minutes2. Removed variation due to drift and sky

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Big Ear: Recap

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

1. Earth-borne signal reflected off space debris2. One-time burst

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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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• Released to the public in May of 1999• Over 5 million users worldwide• Has completed 2 million hours of computing time

Primary Goals1) 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.

SETI@home: Overview

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SETI@home: How it Works Searches for

possible radio transmissions from ETs

Uses observational data from Arecibo

Data digitized and sent to SETI@home

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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) Def-D-6

SETI@home: Justifications

SETI@home 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 interestDef-D-6

SETI@home: Possible Modifications

Alternative to Arecibo telescope Better hardware quality Increased marketing efforts

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CETI

Communication with Extraterrestrial Intelligence

Subset of SETI Researching effective

means of communication

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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)

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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

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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

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First Things First

Fund programs that are looking for incoming data

Most likely way of detecting life Once we find something, then maybe

CETI

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References

Douglas A. Vakoch. "To the Stars, Silently." Leonardo 37.4 (2004): 265-265. Project MUSE. Web. 7 May. 2013. <http://muse.jhu.edu/>.  

Douglas A. Vakoch. "The Art and Science of Interstellar Message Composition." Leonardo 37.1 (2004): 32-34. Project MUSE. Web. 7 May. 2013. <http://muse.jhu.edu/>.

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.http://www.redorbit.com/media/uploads/2004/10/6_3e3fcbe6f4bfa435cdb6eeb6ff721f3c2.jpghttp://www.setileague.org/photos/miscpix/drakeqn.jpghttp://www.scienceprog.com/wp-content/uploads/2008i/DSP1/Radar_location_and_DSP.gifhttp://voices.yahoo.com/seti-detects-alien-signal-outer-space-we-are-2745373.htmlhttp://setiathome.berkeley.edu/sah_about.phphttp://openseti.org/OSSearch.html

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