Scientists considered Pluto to be a planet when it was discovered, but then became the first dwarf planet. However, it is not the closest thing to Earth. Ceres is a dwarf planet and the largest object in the Asteroid Belt, and it has a new difference today: the oceanic world. The latest data from NASA’s Dawn mission have proven the planet has a giant reservoir of saltwater hidden under its surface. That makes it one Feasibility home for life in the solar system.
NASA’s mechanical-powered Ionic Dawn spacecraft visited Ceres in 2018, getting as close as 22 miles (35 km) from the surface. Images from Dawn’s approach draw interest as they show some bright spots in Occator Crater 57 miles (92 km) long. The entire planet is only 590 miles (950 km) in diameter, so this crater is quite prominent.
Researchers working on the Dawn mission used geomorphological and topographic data to trace the source of the points once and for all. We now know that the bright spots are the result of salt crystallization on the surface, and these sediments are young – within the past few million years. Salt water with a high salt content will evaporate in a few hundred years, but the crater itself is about 22 million years old. Scientists know that salt mines are getting younger and younger because Ceres is frequently hit by smaller asteroids that darken reflective surfaces over time.
The research team has identified two salt sources deposited on Ceres. The first is a thick puddle of salt water just below the surface. Ceres does not have any internal geological heating, but the Occator crater liquefies the water. That puddle cools after a few million years, but the impact also creates cracks that extend deep down to the surface. The fractures intersect with a larger brine tank that lasts longer on the bottom. Over time, that allows more salt water to seep to the surface where it evaporates and leaves more salt behind.
So Ceres is an oceanic world, at least to some extent. All we can say right now is that its saltwater reservoir is regional, but it is more expandable. This raises the question of whether life can exist on Ceres or not. The high salt content may be uncomfortable for most organisms, but there are enthusiastic microorganisms on Earth that do not mind extremely high salt environments. Perhaps there was something like that living in the ocean of Ceres as well.
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