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Astronomers Have Formula for Finding Subsurface Oceans in Exomoons

May 4, 2020
ExoNews Editor

Article by Erik Arends April 23, 2020 (phys.org)

• In the search for extraterrestrial life, we have typically looked at Earth-like planets at a distance from their parent star where the temperature is between the freezing and boiling point of water. But as in our own solar system, most of the liquid water seems to be outside of this ‘habitable zone’ on moons where interior water is heated beyond the melting point by tidal forces.

• In our solar system only Mars and Earth have ‘habitable’ surfaces. But moons within our solar system, such as Enceladus, Europa and six other moons of Jupiter, Saturn, Uranus and Neptune, are examples of celestial bodies that are freezing cold on the surface but may harbor habitable subsurface oceans.

• Researchers from SRON Netherlands Institute for Space Research and the University of Groningen (RUG) have derived a formula that indicates whether a subsurface ocean is present on an ‘exomoon’ and how deep it is. Adding moons to the equation, exoplanet hunters have a much larger field of potentially habitable places to search for extraterrestrial life. In fact, “there could be four times as many habitable exomoons as exoplanets,” says lead author Jesper Tjoa.

• The formula analyzes factors including the diameter of the moon, the distance to its planet, the thickness of the gravel layer on the surface, and the thermal conductivity of the ice or soil layer below the surface to provide a lower limit for the ocean depth.

• Just as “astronomers study starlight shining through the atmospheres of exoplanets” to identify oxygen, for example, says Tjoa, future telescopes “may see geysers like on Enceladus, stemming from a subsurface ocean”, as an indication of life there.

So far, the search for extraterrestrial life has focused on planets at a distance from their star where liquid water is possible on the surface. But within

our Solar System, most of the liquid water seems to be outside this zone. Moons around cold gas giants are heated beyond the melting point by tidal forces. The search area in other planetary systems therefore increases if we also consider moons. Researchers from SRON and RUG have now found a formula to calculate the presence and depth of subsurface oceans in these ‘exomoons.”

In the search for extraterrestrial life, we have so far mainly looked at Earth-like planets at a distance from their parent star where the temperature is between the freezing and boiling point of water. But if we use our own Solar System as an example, moons look more promising than planets. Enceladus, Europa and about six other moons of Jupiter, Saturn, Uranus and Neptune may harbor a subsurface ocean. They all reside far outside the traditional habitable zone—it is literally freezing cold on the surface—but tidal interaction with their host planet heats up their interior.

With moons entering the equation, exoplanet hunters such as the future PLATO telescope—which SRON is also working on—gain hunting ground regarding the search for life. When astronomers find a so-called exomoon, the main question is whether liquid water is possible. Researchers from SRON Netherlands Institute for Space Research and the University of Groningen (RUG) have now derived a formula telling us whether there is a subsurface ocean present and how deep it is.

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Scientists Narrow Search After Shocking Find About Extraterrestrials

June 24, 2019
ExoNews Editor

by Sean Martin June 11, 2019 (express.co.uk)

• Scientists searching for habitable alien worlds usually focus on the ‘habitable zone’, where the region of space is neither too cold nor too warm for life to exist. Star gazers at the University of California Riverside believe that scientists have failed to take into account a build-up of toxic gasses within a planet’s atmosphere which would not allow complex life to evolve.

• For example, any planet on the coldest outer edge of the habitable zone with liquid on the surface would require carbon dioxide at levels thousands of times that of Earth’s to maintain liquid and not have it freeze, according to Edward Schwieterman, lead author of a study published in The Astrophysical Journal. “That’s far beyond the levels known to be toxic to human and animal life on Earth,” said Schwieterman.

• Another inhospitable example is intense ultraviolet radiation as from the Earth’s two closest alien stars – Proxima Centauri and TRAPPIST-1, which would batter any planets within their habitable zones, leading to a build up of poisonous carbon monoxide.

• “This is the first time the physiological limits of life on Earth have been considered to predict the distribution of complex life elsewhere in the universe,” says Timothy Lyons, one of the study’s co-authors and a professor of biogeochemistry in UCR’s Department of Earth and Planetary Sciences, and director of the Alternative Earths Astrobiology Center.

• “As far as we know, Earth is the only planet in the universe that can sustain human life,” concludes Schwieterman.

• [Editor’s Note] I’m sure that there are alien civilizations out there who consider this planet to be blanketed in a “poisonous” gas – oxygen. How can educated ‘experts’ make such ludicrous statements as “Earth is the only planet in the universe that can sustain human life”? Human-type beings exist throughout not only the universe, but throughout the galaxy and our own star system of 52 stars. This is just more disinformation calculated to make the public falsely believe that there is no alien presence on our world, or even close by. Lately, in the press there seems to be a concerted effort to push this Deep State agenda of ‘keep moving, there’s nothing to see here’.

Scientists’ search for aliens has become more focused on a smaller number of planets after making a discovery about the composition of most planets’ atmospheres. Typically, alien hunting experts have been analysing planets which are in the habitable zone of their host star – an region in space where it is neither too cold nor too warm for life to exist.

However, experts from the University of California Riverside (UCR) believe other scientists have failed to take into account a build up of toxic gasses within a planet’s atmosphere which would not allow complex life to evolve.
For example, by using computer models the researchers found that any planet on the outer edge of the habitable zone with liquid on the surface would require carbon dioxide – a greenhouse gas – levels thousands of times that of Earth’s to maintain liquid and not have it freeze.

Edward Schwieterman, lead author of the study published in The Astrophysical Journal, and a NASA Postdoctoral Program, said: “To sustain liquid water at the outer edge of the conventional habitable zone, a planet would need tens of thousands of times more carbon dioxide than Earth has today.

“That’s far beyond the levels known to be toxic to human and animal life on Earth.”

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