Feb. 2 (UPI) -- Today, there is only one cryovolcano -- a mountain of icy rock -- on Ceres. But new research suggests the dwarf planet may have once hosted several ice volcanoes.
"We think we have a very good case that there have been lots of cryovolcanoes on Ceres but they have deformed," Michael Sori, a researcher at the Lunar and Planetary Laboratory at the University of Arizona, said in a news release.
Since the discovery of Ahuna Mons, scientists have been befuddled by the mountain's isolation. At nearly half the height of the Mount Everest and with steep, sharp sides, the cryovolcano boasts the features of a relatively young geologic phenomenon. And yet, it appears to be without peers.
"Imagine if there was just one volcano on all of Earth," Sori said. "That would be puzzling."
In a new paper on the subject -- published in the journal Geophysical Research Letters -- Sori and colleagues argue Ceres has hosted additional volcanoes in the past. Over time, these mountains of ice have deformed, disappearing into Ceres' surface.
The deformation process is what's known as viscous relaxation -- the flattening of liquid or semi-liquid objects over time. On Earth, viscous relaxation explains the movement of glaciers.
To see how viscous relaxation might explain the solitary nature of Ahuna Mons, researchers built a model. To be affected by viscous relaxation, Ahuna Mons would have to be composed of at least 40 percent water.
The model found a Ceres cryovolcano composed of 40 percent water would flatten at a rate of 30 to 160 feet every million years. At that rate, a cryovolcano could blend into the ground over the course of several hundred million years.
"Ahuna Mons is at most 200 million years old. It just hasn't had time to deform," Sori said.
As of now, scientists possess only a working theory of Ceres' geologic past. There's no direct evidence of ancient, deformed cryovolcanoes.
"It would be fun to check some of the other features that are potentially older domes on Ceres to see if they fit in with the theory of how the shapes should viscously evolve over time," added Kelsi Singer, a postdoctoral researcher at the Southwest Research Institute in Boulder, Colo. "Because all of the putative cryovolcanic features on other worlds are different, I think this helps to expand our inventory of what is possible."