One of NASA’s most recent discoveries could alter the criteria for what other planetary objects will be considered potentially habitable. Scientists have discovered that Saturn’s small, frozen Death Star moon Mimas could be an “stealth ocean world”.
Researchers explained their findings about Mimas in a study published in the journal Icarus this month. The study stems from information collected during the last days of NASA’s 20-year Cassini mission, which ended in September 2017. NASA reports that the Cassini spacecraft plunged into Saturn’s atmosphere and was “crushed by its planet’s forces before being vaporized “.
Southwest Research Institute geophysics specialist Alyssa Rhoden, who is co-leader of NASA’s Ocean World’s Research Coordination Network, had been trying to prove that Mimas was a frozen inert satellite when she found evidence of an existing ocean.
Mimas, the smallest and innermost of Saturn’s 82 moons, is nearly nine times smaller than Earth’s moon. The crater-covered moon is not quite round in shape, NASA scientists have found, and is easily distinguished by a giant 80-mile impact crater that stretches a third of the way across its face and has outer walls 3 miles high. NASA claims the moon’s indent looks like “Star Wars’ Death Star”.
“Because the surface of Mimas is heavily cratered, we thought it was just a frozen block of ice,” she said in a statement. “[Interior water ocean worlds],, such as Enceladus or Europa, are fractured and may show signs of geological activity. “
Interior Water Ocean Worlds (also known as IWOWs) are planetary objects with oceans that lie beneath rock or ice. According to the Southwest Research Institute, they can also be found at a large distance, which increases the potential number of worlds in the galaxy.
NASA has called Europa, Jupiter’s smallest moon, “the most promising place in our solar system to find present-day environments suitable for some form of life beyond Earth.”
Scientists believe that Mimas is different from other moons with oceans, such as Europa. The study states that if its ocean is found, this could have important implications for ocean world identification and prevalence.
“It turns out that Mimas’ surface was misleading us,” Rhoden stated. “Our new understanding has greatly increased the definition of a potential habitable planet in our solar system.” If Mimas is able to have an ocean, this represents a new category of small, stealth ocean worlds that don’t betray its existence. To have both an ocean flowing and a crust that is not frozen through, Mimas needs to be equipped with tidal heat processes. These are derived from orbital and rotational energies.
Scientists created tidal heating models based on readings captured from the Cassini spacecraft before its grand finale into oblivion in 2017, and found that the moon’s ocean has been covered by an “ice shell” between 14 to 20 miles thick. Rhoden stated in a statement that most of these models are fine-tuned to achieve the results they show. The evidence of an internal ocean was just discovered by Rhoden, who used the best iceshell stability scenarios to observe librations.
This discovery is a step in the right direction.
“Evaluating Mimas’ status as an ocean moon would benchmark models of its formation and evolution,” Rhoden said. This would allow us to better understand Saturn’s rings, mid-sized moons and the existence of potential habitable oceans moons at Uranus. Mimas are a fascinating target that deserves continued research. “