Recently, NASA laid out its roadmap for the search for extraterrestrial life. As of today there are more than 4,000 possible and 1,810 confirmed exoplanets. Out of these there are 100 possible and 21 confirmed planets in the habitable zone and new planets are being found almost daily.
However, believing that a planet has the potential to sustain life and actually finding a planet with life on it are two different things. All potentially inhabited exoplanets are many light years away. Unless NASA is successful in designing a warp drive, it will take many years and hundreds of millions of dollars to investigate each planet.
It is important that researchers choose good candidate planets and new research published in the journal Astrobiology may help. Researchers at the University of East Anglia (UEA) have shown the importance of oceans to creating a stable, habitable environment.
“We know that many planets are completely uninhabitable because they are either too close or too far from their sun. A planet’s habitable zone is based on its distance from the sun and temperatures at which it is possible for the planet to have liquid water. But until now, most habitability models have neglected the impact of oceans on climate,” said Professor David Stevens from UEA’s school of Maths in a statement.
The research team applied a computer simulation of ocean circulation to a hypothetical ocean covered Earth-like planet. They observed different planetary rotations and their impact on climate on this hypothetical planet and, in turn, what those climate changes meant for the potential for the planet to sustain life.
“Oceans have an immense capacity to control climate. They are beneficial because they cause the surface temperature to respond very slowly to seasonal changes in solar heating. And they help ensure that temperature swings across a planet are kept to tolerable levels. We found that heat transported by oceans would have a major impact on the temperature distribution across a planet, and would potentially allow a greater area of a planet to be habitable,” said Stevens.
While water exists in many places in our solar system, including Mercury, Earth’s moon and even the gas giants and some asteroids, the presence of water is not the same as the presence of oceans. On many planetary or other bodies, the ice is frozen at the poles or beneath the surface. It is believed, however, that Jupiter’s moon Europa and Saturn’s moon Titan may hold oceans beneath the surface.
There is also water on Mars and it appears that the Red Planet once had oceans, rivers and streams which are no longer flowing. If humans are going to live on Mars in any large numbers it will likely be necessary to restore the oceans and get the water flowing again.
“Mars for example is in the sun’s habitable zone, but it has no oceans – causing air temperatures to swing over a range of 100OC. Oceans help to make a planet’s climate more stable so factoring them into climate models is vital for knowing whether the planet could develop and sustain life. This new model will help us to understand what the climates of other planets might be like with more accurate detail than ever before,” said Stevens.
The more we know about exoplanets the better for our search for intelligent extraterrestrial life. Life, similar to our own, would certainly be more likely to exist on a planet with a stable and temperate climate and oceans seem to play a key role in that.