Upload
buddy-turner
View
219
Download
0
Tags:
Embed Size (px)
Citation preview
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.
Def-D-6
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
Def-D-6
Def-D-6 Plan Proposal
Focus Projects1) Allen Array Telescope2) Big Ear 3) SETI@home
Def-D-6
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
Def-D-6
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
Def-D-6
Allen Telescope Array: How does it do it? LNSD array = Large Number of Small
Dishes 42 dishes Pseudo-random arrangement 1 km circle
Def-D-6
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
Def-D-6
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
Def-D-6
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
Def-D-6
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 Components1. Flat Reflector2. Paraboloidal Reflector3. Feed Horns
Def-D-6
Big Ear: Flat Reflector
340 ft. x 100 ft. Wire Mesh Ability to tilt Unfocused
waves Ground Plane
Def-D-6
Big Ear: Paraboloidal Reflector
360 ft. x 170 ft. Focused the sent waves Wavelengths
~21.1 cm (8.3 inches) 1411-1420 MHz
Def-D-6
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
variation Def-D-6
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
Def-D-6
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.
Def-D-6
• 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
Def-D-6
SETI@home: How it Works
Searches for possible radio transmissions from ETs
Uses observational data from Arecibo
Data digitized and sent to SETI@home Def-D-6
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 interest Def-D-6
SETI@home: Possible Modifications
Alternative to Arecibo telescope Better hardware quality Increased marketing efforts
Def-D-6
CETI
Communication with Extraterrestrial Intelligence
Subset of SETI Researching effective
means of communication
Def-D-6
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)
Def-D-6
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
Def-D-6
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
Def-D-6
First Things First
Fund programs that are looking for incoming data
Most likely way of detecting life Once we find something, then maybe
CETI
Def-D-6
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
Def-D-6