A new analysis shows that there are likely to be more Earth-like exoplanets with liquid water than previously thought, greatly increasing the chance of finding life. The work found that although conditions are not ideal for liquid water to exist on a planet’s surface, many stars have geological conditions suitable for liquid water beneath the planet’s surface.
Presenting the work at the Goldschmidt geochemistry conference in Lyon, lead researcher Dr. Lujendra Ojha (Rutgers University, New Jersey, US) said, “We know that the presence of liquid water is essential for life. Our work shows that this water can be found in places that we did not think much about . This increases the chances of finding environments where life, in theory, could flourish.”
Researchers have found that even if the surface of a planet is frozen, there are two main ways to generate enough heat to allow water to melt underground.
Lujendra Ojha said, “As Earthlings, we are lucky at the moment because we have the right amount of greenhouse gases in our atmosphere to make liquid water stable at the surface. The surface temperature can be approx. which is -18 ° Celsius, and most liquid water on the surface will freeze completely.
“A few billion years ago, this actually happened on our planet and the surface liquid water completely froze. However, this does not mean that the water is completely solid everywhere. For example, the heat from of radioactivity deep in the Earth can be hot enough water to stay Even today, we can see this happening in places like Antarctica and the Canadian Arctic, where despite the cold temperatures, there are large underground pools of liquid that water, sustained by heat generated from radioactivity. It may still be happening today at the south pole of Mars.”
Dr. Ojha continued, “Some of the moons you find in the solar system (for example, Europa or Enceladus) have a lot of water underground, even if their surfaces are completely frozen. This is because their interiors are always which is broken by the gravitational effects of the large planets they orbit, such as Saturn and Jupiter. This is similar to our Moon’s tidal effect, but stronger. This makes the moons of Jupiter and Saturn prime candidates for in the search for life in our Solar System and many future missions are planned to investigate these bodies.”
The analysis looked at planets found around the most common type of stars—suns called M-dwarfs. These are small stars, which are cooler than our sun. About 70% of the stars in our galaxy are M-dwarfs and most of the rocky and Earth-like exoplanets found orbit M-dwarfs.
“We modeled the possibility of creating and sustaining liquid water on exoplanets orbiting M-dwarfs by only considering the heat generated by the planet. We found that if one considers the possibility of liquid water generated by radioactivity, it is likely that a high percentage of these exoplanets may be hot enough to sustain liquid water – much more than we thought.”
“Before we start considering this sub-surface water, it is estimated that around a rocky planet every 100 stars there is liquid water. One hundred times more likely to find liquid water than we think. There are about 100 billion stars in the Milky Way Galaxy. That represents very good chances for the beginning of life elsewhere in the universe.”
The first mission to an “ice world” type moon is NASA’s Europa Clipper which will launch in 2024 and reach Jupiter’s moon Europa in 2030.
Commenting, Prof. Abel Méndez, (Director of the Planetary Habitability Laboratory, University of Puerto Rico in Arecibo) said, “The prospect of oceans hidden under the ice sheets expands the potential of our galaxy for more habitable worlds. The great challenge is to develop ways to find these habitats with future telescopes.” Professor Méndez was not involved in this work.
The work based on the presentation is published in the journal Communication in Nature.
The Goldschmidt Conference: conf.goldschmidt.info/goldschm … /2023/meetingapp.cgi
Presented at the Goldschmidt Conference
Citation: Study increases probability of finding water on other worlds by 100-fold (2023, July 10) retrieved on July 12, 2023 from https://phys.org/news/2023-07-probability-worlds -fold.html
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