Team #6 Presentation - Department of Earth and Planetary Sciences
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Transcript Team #6 Presentation - Department of Earth and Planetary Sciences
LISTENING FOR SIGNALS
Anant Konanahalli
Kristine Werling
John Toman
Ellie 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 Projects
1) Allen Array Telescope
2) Big Ear
3) SETI@home
Projects to Cut
1) CETI
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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?
• Basic Signal Collection
Radio
waves
collected at
antenna
Radio
waves
focused
Converted
to electrical
signals
Amplified
Processed
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:
D
Sinθ= 1.22λ/
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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”
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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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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.
2.
3.
Flat Reflector
Paraboloidal Reflector
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?
See the same area twice in 2.5-5 minutes
2. Removed variation due to drift and sky variation
1.
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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
Earth-borne signal reflected off space debris
2. One-time burst
1.
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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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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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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)
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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 interest
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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.jpg
http://www.setileague.org/photos/miscpix/drakeqn.jpg
http://www.scienceprog.com/wp-content/uploads/2008i/DSP1/Radar_location_and_DSP.gif
http://voices.yahoo.com/seti-detects-alien-signal-outer-space-we-are-2745373.html
http://setiathome.berkeley.edu/sah_about.php
http://openseti.org/OSSearch.html
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