Can New Equation Calculate Odds of Alien Life?

Image: Artist's impression of the view from a relatively close planet orbiting a cool dwarf star. Credit: ESO/M.Kornmesser Could a mathematical formula help scientists find ET?

SETI pioneer Frank Drake thought so. Or at least Drake believed that an equation would give seekers of intelligent life beyond Earth a clue about what their odds are.

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The so-called Drake Equation, published in 1961, was the first attempt to quantify the number of advanced civilizations in the Milky Way based on the rate of star formation in the galaxy, the fraction of stars with planets, the number planets suitably located to support life, and other metrics.

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Now, a team of scientist is suggesting an alternative equation based on a planet's chemistry and its "origin of life"-type events.

"It has somewhat of the methodology of the Drake Equation because it's trying to compute some parameter that might help you evaluate the prevalence of life in the cosmos," said astronomer Seth Shostak, with the SETI Institute in Mountain View, Calif., and who was not involved in the study.

SETI is an acronym for The Search for Extraterrestrial Intelligence.

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The new study is based on the idea that life's origin on early Earth, and presumably other planets, was not a one-shot process.

The idea is that there were "lots and lots of experiments going on and it may be that they actually helped one another, though not deliberately ... Some molecule that's made over here by accident and which isn't alive may help that molecule over there, which also is not alive, take another step toward something that is alive," Shostak said.

"They're just trying to put all that into some mathematics so that it gives you some idea of the probability that all that will work. That's my take on it," Shostak said.

Origin of life-type events, "may be the critical difference between cosmic environments where life is potentially more or less abundant but, more importantly, points to constraints on the search," SETI researchers Caleb Scharf, with Columbia University, and Leroy Cronin, with the University of Glasgow, write in the new study.

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Their research also points out that if planets in a star system swap spit, so to speak, with meteorites from one body landing on the other, chances of life arising on either or both of those worlds is higher than for planets in more isolating conditions.

The new equation also could have practical results, especially when combined with the search for potentially habitable exoplanetary systems, Scharf and Cronin said.

The study is published in this week's edition of the Proceedings of the National Academy of Sciences.

We've been conjecturing about life on Mars for centuries. In popular culture, the concept of intelligent life on Mars was championed by astronomer Percival Lowell in the late 1800s and his theories on the Martian canals. Science fiction writers -- always game for some reckless conjecture -- took up the banner from there.

Perhaps the most famous Martians in the history of sci-fi and popular culture, the invaders in H.G. Wells' 1898 novel "War of the Worlds," have since spawned dozens of films, TV shows, comic books and one very famous radio drama.

Telescopic observations of Mars in the late 19th and early 20th centuries appeared to show long surface lines that some believed were man-made (well, Martian-made) irrigation canals. Italian astronomer Giovanni Schiaparelli made this map of Mars from his notes on the telescope images.

Science fiction writers often depicted Martians as an advanced humanoid race intent on conquering Earth. In "Flash Gordon's Trip To Mars" (1938), Azura Queen of Mars subjugates her own Martian people. Ray Bradbury would later conceive of a kinder, gentler race in "The Martian Chronicles."

Space explorer stories were a regular staple in the pulp fiction magazines of the early 1900s, and Edgar Rice Burroughs was another author to speculate at length on Mars' inhabitants. His Martians included the six-limbed, green-skinned Tharks and humanoid Red Martians.

The so-called Grey Alien is a kind of archetype image of an extraterrestrial -- not necessarily from Mars -- that has arisen from fictional depictions, alleged alien abduction stories and conjecture on what an advanced race of beings would look like.

On July 25, 1976, NASA's Viking 1 orbiter captured the above image on the surface of Mars' Cydonia region. The infamous "Face on Mars" prompted decades of speculation, although scientists have long dismissed the image as an example of pareidolia; e.g. seeing shapes in the clouds, or Jesus in your toast.

Legendary Looney Tunes animator Chuck Jones created the character of Marvin the Martian in 1948 as a foil for Bugs Bunny. As devotees of Saturday morning cartoons know, Marvin is forever plotting to destroy the Earth by way of his Illudium Q-36 Explosive Space Modulator. Apparently, we obstruct his view of Venus.

Director Tim Burton played around with B-movie tropes and pop art notions of Martians in his 1996 film "Mars Attacks!" Brian De Palma followed up a few years later with "Mission to Mars," a huge critical and commercial bomb. (Although the French critics liked it -- really.)

As is its eternal wont, pop culture is constantly recycling its own ideas -- Martians included. In 1999, Christopher Lloyd starred as the titular alien in director Donald Petrie's reboot of the 1960s TV show "My Favorite Martian," which was itself inspired by earlier pulp sci-fi stories.

Of course, these are only some of the ways we've envisioned Martians over the years. But how do we look to the Martians? Um, pretty small. This first-ever image of the Earth taken from Mars was snapped by the Mars Exploration Rover Spirit in 2004.