Featured Research

from universities, journals, and other organizations

First system developed for assessing the odds of life on other worlds

Date:
November 29, 2011
Source:
Washington State University
Summary:
A modeling expert has proposed a new system for classifying exoplanets using two different indices -- an Earth Similarity Index for categorizing a planet's more earth-like features and a Planetary Habitability Index for describing a variety of chemical and physical parameters that are theoretically conducive to life in more extreme, less Earth-like conditions.

Within the next few years, the number of planets discovered in orbits around distant stars will likely reach several thousand or more. But even as our list of these newly discovered "exoplanets" grows ever-longer, the search for life beyond our solar system will likely focus much more narrowly on the relatively few of these new worlds which exhibit the most Earth-like of conditions.

For much of the scientific community, the search for alien life has long been dominated by the notion that our own planet serves as the best model of conditions best suited to the emergence of life on other worlds. And while there's an undeniable logic to seeking life in the same sort of conditions in which you already know it to be successful, there are scientists like Dirk Schulze-Makuch, an astrobiologist with the Washington State University School of Earth and Environmental Sciences and Abel Mendez, a modeling expert from the University of Puerto Rico at Aricebo, who also see such a model as the product of a potentially limiting form of earthling-biased thinking.

To Schulze-Makuch and his nine fellow authors -- an international working group representing, NASA, SETI,the German Aerospace Center, and four universities- the search for life on other worlds is really driven by two questions.

"The first question is whether Earth-like conditions can be found on other worlds, since we know empirically that those conditions could harbor life," Schulze-Makuch said. "The second question is 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 the December issue of the journal Astrobiology, Schulze-Makuch and his co-authors propose a new system for classifying exoplanets using two different indices -- an Earth Similarity Index (ESI) for categorizing a planet's more earth-like features and a Planetary Habitability Index (PHI) for describing a variety of chemical and physical parameters that are theoretically conducive to life in more extreme, less Earth-like conditions.

Similarity indices provide a powerful tool for categorizing and extracting patterns from large and complex data sets. They are relatively quick and easy to calculate and provide a simple quantitative measure of departure from a reference state, usually on a scale from zero to one. They are used in mathematics, computer imaging, chemistry and many other fields.

The two indices proposed by the group mark the first attempt by scientists to categorize the many exoplanets and exomoons that are expected to be discovered in the near future in accordance with their potential to harbor some form of life.

"As a practical matter, interest in exoplanets is going to focus initially on the search for terrestrial, Earth-like planets," said Schulze-Makuch. "With that in mind, we propose an Earth Similarity Index which provides a quick screening tool with which to detect exoplanets most similar to Earth."

But the authors believe that focusing exclusively on earth-based assumptions about habitability may well be too restrictive an approach for capturing the potential variety of life forms that, at least in principle, may also exist on other worlds.

"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."

The paper's authors concede that attempting to rate the probability that life of some unknown form could exist on any given world is an intrinsically more speculative endeavor. But the alternative, they argue, is to risk overlooking potentially habitable worlds by using overly restrictive assumptions.

"Our proposed PHI is informed by chemical and physical parameters that are conducive to life in general," they write. "It relies on factors that, in principle, could be detected at the distance of exoplanets from Earth, given currently planned future (space) instrumentation."

The paper was written by Alfonso Davila, of SETI; Alberto Fairen, of NASA; Abel Mendez of the University of Puerto Rico at Aricebo; Philip von Paris, of the German Aerospace Center; David Catling, of the University of Washington; Louis N. Irwin, of the University of Texas-El Paso, and Marina Resendes de Sousa Antonia, Carol Turse, Grayson Boyer and Dirk Schulze-Makuch, all of Washington State University.


Story Source:

The above story is based on materials provided by Washington State University. The original article was written by Robert Strenge, WSU News. Note: Materials may be edited for content and length.


Journal Reference:

  1. Alfonso Davila et al. A Two-Tiered Approach to Assessing the Habitability of Exoplanets. Astrobiology, 2011

Cite This Page:

Washington State University. "First system developed for assessing the odds of life on other worlds." ScienceDaily. ScienceDaily, 29 November 2011. <www.sciencedaily.com/releases/2011/11/111121104159.htm>.
Washington State University. (2011, November 29). First system developed for assessing the odds of life on other worlds. ScienceDaily. Retrieved September 1, 2014 from www.sciencedaily.com/releases/2011/11/111121104159.htm
Washington State University. "First system developed for assessing the odds of life on other worlds." ScienceDaily. www.sciencedaily.com/releases/2011/11/111121104159.htm (accessed September 1, 2014).

Share This




More Space & Time News

Monday, September 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Space Shuttle Discovery's Legacy, 30 Years Later

Space Shuttle Discovery's Legacy, 30 Years Later

Newsy (Aug. 30, 2014) The space shuttle Discovery launched for the very first time 30 years ago. Here's a look back at its legacy. Video provided by Newsy
Powered by NewsLook.com
Experiment Tests Whether Universe Is Actually A Hologram

Experiment Tests Whether Universe Is Actually A Hologram

Newsy (Aug. 27, 2014) Researchers at Fermilab are using a device called "The Holometer" to test whether our universe is actually a 2-D hologram that just seems 3-D. Video provided by Newsy
Powered by NewsLook.com
SpaceX’s Falcon 9 Rocket Explodes After Liftoff

SpaceX’s Falcon 9 Rocket Explodes After Liftoff

Newsy (Aug. 23, 2014) The private spaceflight company says it is preparing a thorough investigation into Friday's mishap. Video provided by Newsy
Powered by NewsLook.com
Did Russia Really Find Plankton On The ISS? NASA Not So Sure

Did Russia Really Find Plankton On The ISS? NASA Not So Sure

Newsy (Aug. 21, 2014) Russian cosmonauts say they've found evidence of sea plankton on the International Space Station's windows. NASA is a little more skeptical. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins