The Search for Life in the The Search for Life in the UniverseUniverseDr. Dan Caton

Professor and Observatory Director

November 9, 2011

What we will look at…What we will look at…

Overview of the search for extraterrestrial Overview of the search for extraterrestrial lifelife

Brief review of exploration in our solar Brief review of exploration in our solar systemsystem

The chances for life elsewhere in our GalaxyThe chances for life elsewhere in our Galaxy The problem of SETI—the search for The problem of SETI—the search for

extraterrestrial extraterrestrial intelligenceintelligence Historical, current and planned searchesHistorical, current and planned searches Efforts to transmitEfforts to transmit Why have we not found ET?Why have we not found ET?

The search for respectabilityThe search for respectability

International Astronomical Union created a Commission on ETL in 1982

Long of InterestLong of Interest

Poster from 1800-01

Intelligent Life Here?Intelligent Life Here?

Started by panspermia?Started by panspermia?

Venus too Venus too hot?hot?

Our MoonOur Moon

Life from Earth, in subsurface ice?

Mars—we looked at this already…Mars—we looked at this already…

Jupiter or Jupiter or Saturn?Saturn?

Maybe on one of the moons?Maybe on one of the moons?

Beneath the ice on Europa?Beneath the ice on Europa?

Or…

Saturn’s Titan: Cassini / Huygens MissionSaturn’s Titan: Cassini / Huygens Mission

Cassini still orbiting Cassini still orbiting Saturn, Saturn, HuygensHuygens probe landed on its probe landed on its moon, moon, TitanTitan a few a few years ago.years ago.

Beyond our Solar System: we turn to Beyond our Solar System: we turn to the stars…the stars…

SETI: Turn SETI: Turn outward for the outward for the

Search for Search for Extraterrestrial Extraterrestrial

Intelligence: Intelligence: Searches and Searches and TransmissionsTransmissions

Will confine Will confine ourselves to Milky ourselves to Milky

Way GalaxyWay Galaxy

Questions to investigateQuestions to investigate

What are the chances that intelligent What are the chances that intelligent life exists?life exists?

What evidence is there for life-What evidence is there for life-supporting extrasolar planets?supporting extrasolar planets?

How does life form and evolve?How does life form and evolve? How do we communicate?How do we communicate?

Can they Can they exist?exist?

Frank Drake

Frank Drake first calculated the chances of there being civilizations in our Galaxy with whom we could communicate.

He developed his equation, which became known as the Drake Equation…

The Drake The Drake EquationEquation

R = Average rate of star formation R = Average rate of star formation (stars/year)(stars/year)

fS = fraction of stars that are “good” Suns = fraction of stars that are “good” Suns fP = Fraction of good stars with planets = Fraction of good stars with planets nnee = number of planets per star in ecoshell = number of planets per star in ecoshell ffll = fraction of planets on which life develops = fraction of planets on which life develops ffii = fraction that develop intelligence = fraction that develop intelligence ffcc = fraction that reach electromagnetic = fraction that reach electromagnetic

communicative phasecommunicative phase L = Lifetime in communicative phase (years)L = Lifetime in communicative phase (years)

N = R fS fP ne fl fi fc L

R = rate of star fromationR = rate of star fromation

R ~ 4 R ~ 4 stars/year in stars/year in our Galaxyour Galaxy

This This probably the probably the best known best known variable in variable in the Drake the Drake EquationEquation

FFSS = fraction of stars that are = fraction of stars that are “good” Suns“good” Suns

O, B stars too O, B stars too short-livedshort-lived

K, M stars – K, M stars – flares flares dangerous?dangerous?

A –F stars just A –F stars just right?right?

FFpp = Fraction of good stars = Fraction of good stars with planetswith planets

Several hundred Several hundred exoplanets now exoplanets now known (+ Kepler)known (+ Kepler)

Something on the Something on the order of 0.1 or order of 0.1 or 10% of stars have 10% of stars have planets? Or, planets? Or, mostmost??

Don’t really know Don’t really know since just since just starting to find starting to find small planets.small planets.

nnee = number of planets per star in = number of planets per star in ecoshell (the habitable zone)ecoshell (the habitable zone)

nnee ~ 1 - 2 ~ 1 - 2

ffll = fraction of planets on which = fraction of planets on which life developslife develops

ffll = fraction of planets on which = fraction of planets on which life developslife develops

How does life begin? The Miller-Urey How does life begin? The Miller-Urey ExperimentExperiment

1952, University of Chicago. Produced amino acids.

Recent analysis (published 4/2011)Recent analysis (published 4/2011) After Miller’s death in 2007 the vials were re-After Miller’s death in 2007 the vials were re-

examined, including some from unpublished examined, including some from unpublished experiments.experiments.

Vials associated with the original, published Vials associated with the original, published experiment contained far more organic molecules experiment contained far more organic molecules than Stanley Miller realized — 14 amino acids than Stanley Miller realized — 14 amino acids and five amines.and five amines.

The 11 vials scientists recovered from the The 11 vials scientists recovered from the unpublished aspirator experiment, however, unpublished aspirator experiment, however, produced 22 amino acids and the same five produced 22 amino acids and the same five amines at yields comparable to the amines at yields comparable to the original experiment. original experiment.

Newest idea: life formed in ocean Newest idea: life formed in ocean bottombottom

Timeline of Life on EarthTimeline of Life on Earth

Our Ancestors began several Our Ancestors began several million years agomillion years ago

PrimatesPrimates Extinction Extinction

of dinosaurs of dinosaurs allowed allowed mammals mammals (and us) to (and us) to developdevelop

65 My ago65 My ago

Are we the Are we the pinnacle?pinnacle?

Is intelligence inevitable?Is intelligence inevitable?

ffii = fraction = fraction that develop that develop intelligenceintelligence

Evolution and Evolution and natural selectionnatural selection not pointed to not pointed to intelligenceintelligence

Dominant life Dominant life form?form?

If replayed the tape If replayed the tape (Stephen J. Gould)(Stephen J. Gould)

ffii = 1? = 1?

00

ffcc = fraction that reach = fraction that reach electromagnetic electromagnetic

communicative phasecommunicative phase Fraction that Fraction that

invent radioinvent radio Same Same

physics physics everywhere everywhere in Universein Universe

L = Lifetime in communicative L = Lifetime in communicative phase (years)phase (years)

So far, ~ 100 So far, ~ 100 yearsyears

Lots of ways Lots of ways to end … bad to end … bad ones here end ones here end lifelife

Or, we end the Or, we end the “communicati“communicative” part…ve” part…

… … by having signals disappear!by having signals disappear!

Optical fiberOptical fiber Satellite Satellite

TV/RadioTV/Radio Low power Low power

Wi-FiWi-Fi Small cell Small cell

phone phone transmitterstransmitters

Internet TVInternet TV Cell radioCell radio L is L is

important important because…because…

… “… “f’s” multiply out to ~ 1, so N ~ f’s” multiply out to ~ 1, so N ~ 11

So may be 100 So may be 100 ++ 10x or so 10x or so civilizations in the MWG to findcivilizations in the MWG to find

Let’s go look!Let’s go look!

N = R fS fP ne fl fi fc L

We will look in the radio—why?We will look in the radio—why?

Where in radio? Meet ET at the Where in radio? Meet ET at the “Water Hole”“Water Hole”

TV

First search was at Greenbank, WV First search was at Greenbank, WV ……

… … Project Project OzmaOzma

• 1960

• 200 hours observing two nearby solar stars in 21-cm

• nothing found but a secret satellite

85-ft Harvard Dish has 85-ft Harvard Dish has been usedbeen used

Paul Horowitz

NASA thinks big: CyclopsNASA thinks big: Cyclops

Details…

A thousand 100-meter dishesA thousand 100-meter dishes

• Could detect ET’s broadcast, if within 100 ly (>6,000 stars)

• ~5 billion $ (half what we spend in US every day, or <0.5% of US wars cost since 2001)

NASA’s NASA’s nemesisnemesis

William Proxmire, the late Senator from Wisconsin

Golden Fleece Awards

Called off by Carl Sagan

NASA’s initial hardwareNASA’s initial hardware

Software: see a pattern?Software: see a pattern?

This is a plot of signal (intensity of dots) in frequency vs. time

Here it isHere it is

A test: detection of Pioneer 10A test: detection of Pioneer 10

But—Congress killed NASA’s SETI project…

First Intentional TransmissionFirst Intentional Transmission

The signal: The signal: digitaldigital

Let’s look at why digital …

Digital advantage sketch…Digital advantage sketch…

GraphicalGraphical

The message consists of 1679 bits, arranged into 73 lines of 23 characters per line (these are both prime numbers, and may help the aliens decode the message).

It consists, among other things, of the Arecibo telescope, our solar system, DNA, a stick figure of a human, and some of the biochemicals of earthly life.

For less than 3 minutes it was the brightest source in the MWG at that frequency.

Target: M13 (30,000 ly…)Target: M13 (30,000 ly…)

Our unintentional signalsOur unintentional signals

Radio is line-of-sightRadio is line-of-sight What is not received (most What is not received (most

is not), leaks out into spaceis not), leaks out into space Lets tune into …Lets tune into …

……Channel Channel

EarthEarth

As seen As seen from from BarnardBarnard’s Star’s Star

NA East

Coast sets

NA East

Coast rises

Western Europe rises

Western Europe sets

Aust. Japan rise

Aust. Japan set

Cartoon…Cartoon…

PionePioneer 10 er 10 & 11 & 11 PlaquPlaqu

es es (1972(1972

-3)-3)

Voyager Record: “Best of Earth”Voyager Record: “Best of Earth”

Images and Images and SoundsSounds

• “Best of Earth”

• Narrated by Kurt Waldheim (1918-2007), then U.N. Secretary General and now known (embarrassingly..) to have been a Nazi war criminal. Friend of fellow Austrian Aaaaanold….

SETI@homeSETI@home

Uses data from …

““Parasitic” observations at Arecibo Parasitic” observations at Arecibo TelescopeTelescope

Allen ArrayAllen Array 350 6.1-m dishes350 6.1-m dishes 1 – 10GHz (the 1 – 10GHz (the

“water hole”)“water hole”) Artist conceptArtist concept

Funded by Funded by Microsoft co-Microsoft co-founder Paul Allen founder Paul Allen (and COB, Charter (and COB, Charter Communications)Communications)

Newer, offset Newer, offset Gregorian designGregorian design

SETI Inspired Carl Sagan’s SETI Inspired Carl Sagan’s ContactContact

Ellie Arroway (Jodi Foster) loosely based on (real) Jill Tarter, former head of NASA SETI, now at the SETI Institute

Why no detection? …Why no detection? …

……Enrico Fermi: Enrico Fermi:

“Where is “Where is everybody?”everybody?”

Would not be complete without Would not be complete without mentioningmentioning

Maybe in Historical Times? (Ezekiel Maybe in Historical Times? (Ezekiel 1)1)

4 I looked, and I saw a windstorm coming out of the 4 I looked, and I saw a windstorm coming out of the north—an immense cloud with flashing lightning and north—an immense cloud with flashing lightning and surrounded by brilliant light. The center of the fire surrounded by brilliant light. The center of the fire looked like glowing metal, 5 and in the fire was what looked like glowing metal, 5 and in the fire was what looked like four living creatures. In appearance their looked like four living creatures. In appearance their form was human, 6 but each of them had four faces form was human, 6 but each of them had four faces and four wings. 7 Their legs were straight; their feet and four wings. 7 Their legs were straight; their feet were like those of a calf and gleamed like burnished were like those of a calf and gleamed like burnished bronze. 8 Under their wings on their four sides they bronze. 8 Under their wings on their four sides they had human hands. All four of them had faces and had human hands. All four of them had faces and wings, 9 and the wings of one touched the wings of wings, 9 and the wings of one touched the wings of another. Each one went straight ahead; they did not another. Each one went straight ahead; they did not turn as they moved. ….turn as they moved. ….

Interesting, but which myths do we choose to believe? Interesting, but which myths do we choose to believe? (Brown Mountain Lights and the Cherokee myths…(Brown Mountain Lights and the Cherokee myths…

That’s our SETI discussion .. That’s our SETI discussion .. Questions?Questions?