10/14/03Prof. Lynn Cominsky1 Class web site: lynnc/courses/a305 Office: Darwin 329A and NASA E/PO...

10/14/03 Prof. Lynn Cominsky 1

Class web site: Class web site: http://http://glastglast

.sonoma.edu/~lynnc/courses/a305.sonoma.edu/~lynnc/courses/a305

Office: Darwin 329A and NASA E/POOffice: Darwin 329A and NASA E/PO

(707) 664-2655(707) 664-2655

Best way to reach me: Best way to reach me: [email protected]@charmian.sonoma.edu

Astronomy 305/Frontiers in Astronomy 305/Frontiers in AstronomyAstronomy


Astrobiology Questions (3 Astrobiology Questions (3 weeks)weeks)

Is there life elsewhere in our Solar Is there life elsewhere in our Solar system? system?

Are Earth-like planets common? Are Earth-like planets common? Are we alone?Are we alone?


Group 7Group 7


Are we alone?Are we alone?

Weekly radio show with SETI Institute staff:

http://www.radioamerica.org

7 PM Sunday nights (PST)


Expert OpinionsExpert Opinions From a conference on the subject From a conference on the subject

featuring scientists and theologistsfeaturing scientists and theologists http://www.meta-library.net/http://www.meta-library.net/cqintervcqinterv/alone-frame.html/alone-frame.html

Featuring: Jill Tarter, Alan Guth, Sandra Featuring: Jill Tarter, Alan Guth, Sandra Faber, Seth Shostak, etc.Faber, Seth Shostak, etc.


Searching for signs of Searching for signs of IntelligenceIntelligence

Use form of electromagnetic radiation Use form of electromagnetic radiation that travels throughout the Universethat travels throughout the Universe Visible light – flashesVisible light – flashes Radio waves – continuous signalsRadio waves – continuous signals X-rays or gamma-rays – possible but X-rays or gamma-rays – possible but

unlikelyunlikely Radio waves use least power Radio waves use least power

AM radio – amplitude modulationAM radio – amplitude modulation FM radio – frequency modulationFM radio – frequency modulation


Optical SETIOptical SETI Searches for pulses that arrive within a Searches for pulses that arrive within a

nanosecond in 3 coaligned detectorsnanosecond in 3 coaligned detectors Uses Lick 40 inch telescopeUses Lick 40 inch telescope Aims at known star systems or star clustersAims at known star systems or star clusters


SETI Institute/ Project SETI Institute/ Project

PhoenixPhoenix 1,000 - 3,000 MHz search band – 1 Mhz at a 1,000 - 3,000 MHz search band – 1 Mhz at a

timetime 28 million channel Phoenix receiver can 28 million channel Phoenix receiver can

accumulate radio energy for minutes accumulate radio energy for minutes Sensitive targeted search, aimed at nearby Sensitive targeted search, aimed at nearby

starsstars

Parkes 210 foot telescope in New South Wales Australia

Greenbank 140 foot

telescope in West

Virginia


Allen Telescope ArrayAllen Telescope Array Funded by Microsoft executives Paul Allen Funded by Microsoft executives Paul Allen

and Nathan Myhrvold ($12.5 million so far)and Nathan Myhrvold ($12.5 million so far) Joint effort by SETI Institute and UC BerkeleyJoint effort by SETI Institute and UC Berkeley 350 commercial 6-m satellite dishes 350 commercial 6-m satellite dishes

covering 100 square meterscovering 100 square meters Will cover Will cover frequencies between 1,000 and frequencies between 1,000 and

10,000 MHz10,000 MHz


SETI/SERENDIP IVSETI/SERENDIP IV

Piggyback instrument at Piggyback instrument at the 1000 foot Arecibo the 1000 foot Arecibo radio telescope in radio telescope in Puerto RicoPuerto Rico

40 spectrum analyzer 40 spectrum analyzer boards working in boards working in parallelparallel

Radio wavelengths are Radio wavelengths are best due to low best due to low obscuration over great obscuration over great distancesdistances


SERENDIP/SETI@homeSERENDIP/SETI@home 168 million channels every 1.7 seconds 168 million channels every 1.7 seconds

in a 100 MHz band centered at 1.42 in a 100 MHz band centered at 1.42 GHzGHz

= 35 Gbytes/day!= 35 Gbytes/day! Break it up into small pieces and let Break it up into small pieces and let

othersothers help analyze the datahelp analyze the data Each download sends 107 s of 10 kHzEach download sends 107 s of 10 kHz

data plus some supporting information data plus some supporting information = 0.3 Mbytes= 0.3 Mbytes


Message ConstructionMessage Construction What would a signal look like from What would a signal look like from

an alien being?an alien being? Frank Drake proposed to send a Frank Drake proposed to send a

digital pattern that is given in your digital pattern that is given in your handouthandout

Try to figure out how to rearrange Try to figure out how to rearrange it to make the second image it to make the second image shown in the handoutshown in the handout

What could the areas 1-5 mean?What could the areas 1-5 mean?


Message ConstructionMessage Construction This is the only signal we This is the only signal we

have deliberately sent at have deliberately sent at high power (using Arecibo high power (using Arecibo radio telescope)radio telescope)

1679 bits = 73 lines x 23 1679 bits = 73 lines x 23 bits per linebits per line

Transmission took 3 Transmission took 3 minutesminutes

It was aimed at M31, a It was aimed at M31, a globular cluster near the globular cluster near the edge of our galaxyedge of our galaxy


Drake equationDrake equation

N = RN = R** × f × fpp × n × nee × f × fll × f × fii × f × fcc × L × L wherewhere

N: N: number of communicative civilizations in galaxynumber of communicative civilizations in galaxy

RR**: : rate of formation of suitable stars in galaxyrate of formation of suitable stars in galaxy

ffpp: : fraction of stars with planetary systemsfraction of stars with planetary systems

nnee: : number of planets per system suitable for lifenumber of planets per system suitable for life

ffll: : fraction of planets which actually have lifefraction of planets which actually have life

ffii: : fraction of those planets with intelligent lifefraction of those planets with intelligent life

ffcc: : fraction of those which can communicatefraction of those which can communicate

LL: : lifetime of civilizationlifetime of civilization


Drake Equation ActivityDrake Equation Activity

Take the worksheet and use it to Take the worksheet and use it to make your own estimate of the make your own estimate of the number of civilizations in our number of civilizations in our GalaxyGalaxy


Drake equationDrake equation Rough answer:Rough answer: there are as many there are as many

communicative civilizations per galaxy as their communicative civilizations per galaxy as their lifetimes in years – estimated at about lifetimes in years – estimated at about 10,000 10,000

civilizations per galaxycivilizations per galaxy BUT: in BUT: in RARE EARTH RARE EARTH by Ward and Brownlee by Ward and Brownlee

Jupiter protects us from incoming comets and Jupiter protects us from incoming comets and asteroids which could cause major extinctionsasteroids which could cause major extinctions

Solar systems can’t be too close to galaxy centerSolar systems can’t be too close to galaxy center Solar systems can’t be too far away eitherSolar systems can’t be too far away either Planets cannot have elliptical orbitsPlanets cannot have elliptical orbits Only life forms (besides Earth) will be single-Only life forms (besides Earth) will be single-

celled organisms like bacteriacelled organisms like bacteria


Do you think life exists on other Do you think life exists on other planets?planets?

If so, where? And why? And what type?If so, where? And why? And what type?

A) In our solar system?A) In our solar system?

B) In our galaxy?B) In our galaxy?

C) In the Universe?C) In the Universe?

Question to ponder:Question to ponder:

Explain your reasoning on your worksheet


Alien BandstandAlien Bandstand

A recording executive looking for his next A recording executive looking for his next big hit has turned to the heavens. He has big hit has turned to the heavens. He has found a peculiar signal in some radio found a peculiar signal in some radio telescope data and he is convinced that telescope data and he is convinced that it is music from an alien civilization. He is it is music from an alien civilization. He is offering it for sale.offering it for sale.

Your mission: Determine if this signal Your mission: Determine if this signal really is an alien tune!really is an alien tune!


Wave ReviewWave Review

Wavelength – distance between two Wavelength – distance between two crests or troughs in a wave in spacecrests or troughs in a wave in space

Period – time it takes for 1 wave to pass Period – time it takes for 1 wave to pass byby

Period is also thePeriod is also thedistance between two crests or troughs in time


Let’s play the game!Let’s play the game!

You will meet some interesting charactersYou will meet some interesting characters You will meet some real scientistsYou will meet some real scientists You will have three tools to use to take the You will have three tools to use to take the

data needed to solve the mysterydata needed to solve the mystery There will be a notebook to write down your There will be a notebook to write down your

findings so you can remember thingsfindings so you can remember things There will be a quiz at the endThere will be a quiz at the end


Web ResourcesWeb Resources

SERENDIPSERENDIP

http://seti.ssl.berkeley.edu/serendip/serendip.hthttp://seti.ssl.berkeley.edu/serendip/serendip.htmlml

SETI@homeSETI@home http://setiathome.ssl.berkeley.edu/http://setiathome.ssl.berkeley.edu/ SETI InstituteSETI Institute http://www.seti-inst.edu/http://www.seti-inst.edu/ Rare Earth Debates:Rare Earth Debates:

http://www.space.com/scienceastronomy/rare_ehttp://www.space.com/scienceastronomy/rare_earth_1_020715.htmlarth_1_020715.html

Space Mysteries:Space Mysteries: http://mystery.sonoma.edu http://mystery.sonoma.edu

10/14/03Prof. Lynn Cominsky1 Class web site: lynnc/courses/a305 Office: Darwin 329A and NASA E/PO...

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