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Ocean worlds beyond Earth: NASA's hunt for life through water
Water, the cradle of life as we understand it, is no longer unique to Earth. From subsurface oceans on frozen moons to water vapor in extraterrestrial atmospheres, NASA's findings are redefining what we know about the universe.
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With its Ocean Worlds initiative, NASA is spearheading a high-stakes search for liquid water, thought to be the most critical factor for the presence of extraterrestrial life. (source:
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Water in the universe
With the ease of imagining Earth as the single "blue planet," it's simple to forget that water is much more prevalent than previously thought. NASA says the Orion Nebula, which is a star-forming region 1,300 light-years from Earth, churns out 60 Earth oceans' worth of water daily.
That is not a romanticism but an estimate grounded in observation of water vapor clouds churning through interstellar space. These immense clouds of water are the material out of which stars, planets, and even life itself arise.
The ocean world of the solar system
Just a little closer to home, our solar system features a remarkable number of "ocean worlds", bodies that have liquid water present today or that have evidence of having had such in the past. Earth is only. But the others?
Europa, one of Jupiter's moons, has a hidden ocean beneath its icy crust that is potentially two times the size of all Earth's oceans combined.
This saltwater ocean is maintained in a liquid state due to the internal heat of the moon and potentially has the proper chemical conditions for life.
Enceladus, one of Saturn's moons, is smaller than the state of Arizona and harbors a global subsurface ocean. In 2005, NASA's Cassini spacecraft picked up gigantic plumes of water vapor rising from its south pole. The plumes reported at hundreds of kilometers high carry organic compounds, hydrogen, and salt, suggesting hydrothermal activity deep within.
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Then there's Ganymede (another Jupiter moon), Callisto, Titan, and even dwarf planet Ceres, all thought to have or at least to have had liquid reservoirs. Altogether, NASA now recognizes over a dozen ocean worlds in our solar system alone.
Mars: The desert planet with a mysterious past
Mars, the Red Planet, is now a dry and dusty world, but it wasn't always. Ancient lakebeds and riverbeds, as well as polar ice caps, indicate a watery past. A 2018 radar survey indicated that liquid water could still be present beneath the ice cap at the South Pole, buried beneath ice and rock.
While only about 0.03% of all Earth's water is still visible on Mars today, the hunt goes on for underground aquifers with possibly still-existent microbial life.
Did you know there is water outside the solar system?
NASA's space telescopes have ventured well outside our solar neighborhood in the search for water. By analyzing spectra, scientists have identified water vapor in the atmospheres of over 10 exoplanets. Some are in the "Goldilocks Zone," where conditions may be suitable for water to exist in a liquid state on the surface, opening up the intriguing possibility of habitable alien planets.
The James Webb Space Telescope will exponentially increase our capability to research such worlds, enabling scientists to scan atmospheric composition and even discern signs of biological processes if they're present.
Water is not merely a molecule; it's the universal solvent that can accommodate advanced chemistry and harbor life. NASA's plan is basic but profound: "Follow the water." Wherever liquid water exists, whether under a shell of ice, in a crater, or churning in extraterrestrial clouds, it becomes the top priority in the quest for life.
Missions such as Europa Clipper, which will launch in 2024, and Dragonfly, bound for Titan during the 2030s, are intended to explore these ocean worlds like never before. Equipment will take magnetometer readings, scan surface chemistry, and even try to fly through water plumes to sample them.
In all, NASA has recognized at least 15 bodies in our solar system with evidence of water in some way. The number will likely increase as exploration continues.
The universe, once conceived as arid and unfriendly, now seems full of the building blocks of life.
The existence of water in the solar system and elsewhere is no longer speculation; it's a scientific fact. From the ancient Martian lakes to icy moons filled with vapor, water defines planetary geography and the course of space exploration. As NASA's Ocean Worlds program demonstrates, the quest for water is a quest for ourselves, for life in the universe, and for a deeper understanding of our place in it.
Disclaimer: This article is drafted on the basis of information sourced from NASA's official website
