Search for Extraterrestrial Intelligence (SETI) – Part II

Life in the Universe -

Dr. R. L. Hudson (Spring, 2018)

Factors to Consider Need Search Strategies

1. Promising Stars (ca. 1961)

2. Extrasolar Planets N = R* fpl nearth flife fint fciv L 3. Chemistry and Biology (Life)

4. Civilizations Helps to organize our thinking.

Consider Next Problem - Communication

How to Establish ?

Transmit Information

Travel

Long wavelengths “cut” through the dust

1 Nature Provides A Clue How Many Channels?

1638 MHz = 1,638,000,000 Hz

1420 MHz = 1,420,000,000 Hz Noise Atmospheric Galactic H OH Absorption Noise (Synchrotron Radiation) 0.1 Hz / channel

“The Water Hole” (1,638,000,000 – 1,420,000,000 ) / 0.1

Frequency (GHz)  2 billion channels http://www.jb.man.ac.uk/distance/life/sample/seti/Microwave.jpg

And finally, , 1960 National Radio Is it better to give ... Astronomical Observatory

Green Bank, West Virginia

... or receive? Two Stars Observed During One Month

Today Math

National Radio ~ Astronomical 2 billion radio channels Observatory Modern computers measure Green Bank, ~ 250 million channels at once West Virginia

Examine each channel for 1 sec Same Observations … need 8 seconds for total coverage in Under 1 Sec of one star

2 ~ 2 Billion Candidates More Math

~2 billion radio channels in the Cosmic Water Hole Each star needs ~8 seconds for coverage.

For ~2 billion stars will need about 500 years for total coverage!

(by Jon Lomberg)

A Way Forward Scientist A Way Forward Scientist Physical Physical Chemist Chemist

Infrared Infrared Spectroscopist Spectroscopist

Co-founder of Intel Corp. (1968)

Gordon Moore

https://www.flickr.com/photos/intelfreepress/8576174698/in/photostream/lightbox/ https://www.flickr.com/photos/intelfreepress/8576174698/in/photostream/lightbox/

Computing Power Doubles in ~18 Months Radio Wave Receivers Moore’s Law

In ~15 years can study all candidate stars in ~5 years, not 500 years! , Puerto Rico

3 Is it better to give or receive? Signal Sent in 1974 by the

M13

A Globular Cluster

3 minutes

Message Sent to M13 Leaked Signals vs. Directed Signals

Weak Radio Leakage for ~100 years

Weak TV Leakage for ~60 years

Footnotes What Will Be Learned? How about optical SETI? Our Neighbors

Signal Location Signal Strength Signal Wavelength

Need a way to attract Doppler Fluctuation of Signal? attention to our signals

4 What is Expected? Another Approach … Just Go There!

Signal of Abnormal Behavior Space Travel

Codes – Prime Numbers, Patterns

NASA’s Pioneer 10 and 11 Spacecraft, 1972 and 1973 Planets and the

NASA’s Pioneer 10 and 11 Spacecraft, 1972 and 1973 Pioneer Satire

5 Yet More NASA’s Voyager Pioneer Satire I and II Spacecraft, 1977

1977 - Voyager I and II

1973 1979

Io

Ganymede Callisto

Titan Mimas

6 Uranus and Oberon Each Voyager spacecraft carried a Pioneer-like plaque and a record.

Neptune and Triton

The Voyager Record

Languages Sounds Photographs Data

Stars

Speed × Time = Distance

Trillions of miles (and more)

7 Stellar Distances How Much Time?

Trillions of miles (and more) Speed × Time = Distance

Example/ Alpha Centauri star system Speed × Time = 4 × 1013 km

= 4 light years = 4 × 1013 km But what speeds are available?

(Pluto is about 6 × 109 km)

How Much Time?

Speed × Time = Distance To be continued ... Speed × Time = 4 × 1013 km

But what speeds are available?

Technology gives about 12 km / sec

Sources of Material

Most of the images used here are either original, from our class’s textbook, or in the public domain. Material not fitting into these categories has been credited in cases where I knew the sources. I will be glad to add any credits missed.

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