Ceres' Lone Ice Volcano May Have Had Older Silbings That Vanished Over Millions of Years

A new study revealed that the lone ice volcano in the dwarf planet Ceres might actually have neighbors that progressively disappeared over millions of years.

The study, published in the journal Geophysical Research Letters, showed that it is possible for the mountains of icy rock, called cryovolcanoes, to vanish through the process called "viscous relaxation."

"We think we have a very good case that there have been lots of cryovolcanoes on Ceres but they have deformed," said Michael Sori of the Lunar and Planetary Laboratory at the University of Arizona in Tucson and lead author of the study, in a press release.

Discovered in 2015 by NASA's Dawn spacecraft, Ceres' single cryovolcano Ahuna Mons, stands 2.5 miles tall. Scientists have been long baffled by the existence of the single icy volcano on the dwarf planet. Sori noted that if there was just one volcano on Earth, it would be really puzzling.

Dwarf planet Ceres' lonely mountain Ahuna Mons is seen in this view from @NASA_Dawn: https://t.co/0r2TLg4ji7 pic.twitter.com/BW5eLtTcXU

— NASA (@NASA) September 1, 2016

Aside from being the only icy volcano on Ceres, Ahuna Mons also features steep sides that usually indicate geological youth. Sori noted that the well-defined feature of the icy volcano suggests two possibilities. First, the Ahuna Mons is just as it appears, a solitary icy volcano that was formed recently on an otherwise inactive world. The second possibility suggests that the Ahuna Mons has older companions that were flattened out by viscous relaxation.

Viscous relaxation is the process where solids flow if given enough time. It is the same process responsible for making glaciers flow on Earth. Unlike the rocky volcanoes on Earth, Ahuna Mons contains ice. Due to this, it is possible for any cryovolcanoes in the dwarf planet to be flattened out by viscous relaxation.

To test out their theory, the researchers developed a model using the actual dimensions of Ahuna Mons to predict how fast the mountain might be flowing. The researchers ran the model assuming different water contents of the material that makes up the mountain. The water content ranges from 100 percent to 40 percent. Sori noted that the volcano must have at least 40 percent water ice to be affected by viscous relaxation.

The researchers found that Ahuna Mons should be flattening out at a rate 30 to 160 feet per million years if its water content is more than 40 percent. At that rate, the researchers believe that it is possible for older cryovolcanoes in the dwarf planet to vanish in over hundreds, millions and billions of years.