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Drake's equation



Astrobiology Roadmap

Finalized in 2002, NASA's Astrobiology Roadmap outlines multiple approaches to astrobiology research and exploration and suggests ways to prioritize and coordinate them. The document includes guiding principles, goals, and plans for future endeavors. It represents the efforts of over two hundred scientists and technologists—some NASA-related and some not—from a variety of disciplines.

Are We All Alone in the Universe?

This module, from the Japan Science and Technology Corporation, provides excellent background to the search for life in the universe. There is information about all the planets in the solar system and possibilities for life beyond, as well as descriptions of spacecraft and signals that originate from Earth (requires Flash plug-in):

Drake's equationDrake Equation

N = R*• fp • ne • fl • fi • fc • L

Devised in 1961 by astronomer Frank Drake, this equation can be used to estimate the number of civilizations in the universe that have the capacity for technological communication. Although our current knowledge affords us only "best guesses," the equation is useful in outlining which factors to focus research on in the hunt for extraterrestrial life.

Description of the equation on the SETI Institute's site:

Extensive discussion of the equation by astrobiology author David Darling:

Fermi Paradox

"If we're not alone, then where is everybody?" This was the paradox physicist Enrico Fermi expressed while talking with colleagues in 1950 about life "out there." Is the lack of contact from or signs of extraterrestrials proof enough that we're alone in the universe? Maybe, or maybe not.

The SETI Institute ponders the paradox:

Debate about the paradox with Frank Drake, Chris McKay, and others:

Voyager's Greetings to the Universe

When the Voyager 1 and 2 spacecraft were launched in 1977, they each included a gold-plated phonograph record (a "golden record") of natural sounds, greetings in human voices, and a variety of music. The record cover has symbolic instructions that show how to use and understand the record, though scientists still debate whether other civilizations will be able to decipher them.

Golden record on Voyager:

Explanation of the record cover diagram:

A few greetings, sounds, and pictures included on the record:

What Happens if We Do Find Extraterrestrial Life?

The SETI Institute scientists and others are thinking about how to handle the implications of detecting another civilization, from ways to handle information flow to the potential disruptions to our own societies.

"Social Implications a SETI Success":

Anybody Out There?

A lively essay by neurologist and author Oliver Sacks in Astrobiology Magazine:






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