Scientists Propose New Search for Extra-terrestrial Life

Posted November 21st, 2011 at 11:30 pm (UTC-4)

Artists' conception of the 6 Earth-mass exoplanet Gliese 667 C (Graphic: NASA/JPL)

Artists' conception of the 6 Earth-mass exoplanet Gliese 667 C (Graphic: NASA/JPL)

An international team of scientists is about to embark on a unique search for life on planets far beyond our solar system.

So far, astronomers have found 702 planets outside of our solar system and that number is expected to reach several thousand or more within the next few years.

As the list of newly discovered exoplanets continues to grow, some scientists worry the search for extra-terrestrial life will narrow, focusing on just a few of these new worlds, especially those with Earth-like conditions.

That’s because the scientific community’s search for alien life is widely based on the idea that Earth serves as the best model when considering which conditions that are best suited to hold life on other planets.

In other words, many scientists tend to look at a planet that either mimics, or merely has some of the important traits of Earth, before considering a search for extra-terrestrial life.

However, other scientists see that approach as a limiting form of earthling-biased thinking.

That’s where the research team,  led by Dirk Schulze-Makuch, an astrobiologist at Washington State University, and Abel Mendez, a modeling expert from the University of Puerto Rico, comes in.

The team is proposing to narrow the search for extra-terrestrial life based on two basic questions:  whether Earth-like conditions can be found on other worlds – since its’ already known that those conditions can harbor life – and  whether conditions exist on exoplanets that suggest the possibility of other forms of life, whether known to us or not.

In a paper to be published in Astrobiology, the team suggests a new system for classifying exoplanets by using two different indices.

One would be an Earth Similarity Index (ESI) for categorizing a planet’s more earth-like features. The second is a Planetary Habitability Index (PHI), which describes a variety of chemical and physical parameters that are theoretically conducive to life in conditions unlike those on Earth.

“Habitability in a wider sense is not necessarily restricted to water as a solvent or to a planet circling a star,” the paper’s authors write. “For example, the hydrocarbon lakes on Titan could host a different form of life. Analog studies in hydrocarbon environments on Earth, in fact, clearly indicate that these environments are habitable in principle. Orphan planets wandering free of any central star could likewise conceivably feature conditions suitable for some form of life.”

Using the proposed system, researchers have already found that two planets in the Gliese 581 systemGJ 581 c and GJ 581d – may have habitats comparable to Mars, Jupiter’s moon Europa and Saturn’s moon Enceladus.

Rick Pantaleo
Rick Pantaleo maintains the Science World blog and writes stories for VOA’s web and radio on a variety of science, technology and health topics. He also occasionally appears on various VOA programs to talk about the latest scientific news. Rick joined VOA in 1992 after a 20 year career in commercial broadcasting.

6 responses to “Scientists Propose New Search for Extra-terrestrial Life”

  1. VEE says:

    I am quite estatic to know, if the new earthlike planet recently discovered, has ife on it. The scientific worlds should be truth about it and not hide any valuable information that can have an impact on our lives.

  2. Franco says:

    Yeah I agree, for some reason i’m interested in how the living creatures look.

  3. David says:

    The mistake is to believe that most aliens are very much like us. Actually, though alien species are similar to human species, many of them are far more evolved than we are, a few are less evolved while even fewer are exactly at the same level as us. If we only look for planets that are suitable for people like us, we are restricting ourselves too much and making the task especially difficult. Those aliens who are more evolved than us can easily survive in environments which are impossible for us to live in. See for more info

    • Franco says:

      Your very right. Some species probably don’t need oxygen and water. But looking at every planet will take forever, in my opinion looking at a planet that’s very much like ours increases the chances and reduces time spend.