This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Many of the moons orbiting Saturn, Uranus and Neptune likely conceal oceans of liquid water beneath miles of icy shell. Because life as we know it needs water, these buried oceans rank among the most promising places to search for life beyond Earth.
But the outer solar system is akin to a celestial demolition derby. Scientists suspect some of today's moons are reassembled remnants of earlier generations of moons, shattering and reforming from space debris. One question arises: Do these collisions also destroy a moon's ocean and, with it, any chance for life?
A University of Maryland-led study published in the journal Nature Astronomy offers an answer. After simulating violent collisions on frozen moons, researchers found that even the biggest crashes don't fundamentally change whether these icy worlds can hold an ocean. "The big question we asked was whether these destructions help moons have oceans afterward or whether they delete the ocean and reset the moon into a cold, dead world," explained the study's lead author Marc Neveu, an astronomy associate research scientist at UMD.
"What we found was that those big collisions don't really matter as far as oceans are concerned. If there was an ocean before, there's likely to be an ocean after and vice versa." The finding surprised Neveu and his co-authors at the Southwest Research Institute in Colorado and the Weizmann Institute of Science in Israel. "These simulations were pretty much the biggest collisions we could come up with," Neveu said.
"If those didn't make a difference, it's unlikely smaller ones would either." In the new study, the researchers connected two very different kinds of computer simulations. One type recreated the violent physics of a cosmic crash, tracking how millions of rock and ice fragments shatter, heat up and clump back together. The other approach simulated the slow burn of a moon's interior over billions of years, following how heat builds and escapes from the core and whether ice can melt into an ocean.
Combining these two methods allowed the researchers to follow two sizes of moons, roughly 500 and 1,000 kilometers in radius, as the moons were struck by smaller space rocks, blown apart and reassembled. The team then fast-forwarded through 4.5 billion years of each simulated moon's afterlife and found that moon sizes played a bigger role than expected in determining a collision's aftereffects. "In larger moons, the energy of the crash converts into extra heat that can actually thicken up an existing ocean for a couple of billion years.
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