Ceres is a complex world that shows evidence of cryovolcanism, according to data from NASA’s Dawn mission, which has been orbiting the dwarf planet since March 2015.
Its lone mountain, Ahuna Mons, 2.5 miles (4 km) tall and 10.5 miles wide, has a dome-shaped top that resembles that of volcanic mountains on Earth.
But instead of lava or hot liquid rock, Ahuna Mons spews cold molten ice. Scientists believe the ice it spews is water ice mixed with chlorine salt.
Its young surface indicates the mountain formed within the last 200 million years. Ceres itself, like the solar system, is about 4.56 billion years old.
Unlike the moons of the gas giant planets, Ceres does not experience tidal heating from a larger body, meaning its geology is propelled by an internal heat source.
That source is a combination of heat left over from the dwarf planet’s formation and processes of internal radioactive decay.
Ceres’ surface is spotted with other, lower domed features that could also be produced by cryovolcanism. There are extended linear structures and lobed regions created by flowing material.
A total of six research papers detailing Dawn’s findings at Ceres are published in the September 1 edition of the journal Science.
Among the many findings is the composition of Ceres’ crust, which is a mixture of ice and rock not seen anywhere else in the solar system.
In one of the papers, a research team led by Debra Buczkowski of the Johns Hopkins University Applied Physics Lab in Laurel, Maryland, notes that Ceres’ linear features are caused by subsurface faults.
Dawn’s first target, protoplanet Vesta in the asteroid belt between Mars and Jupiter, long since cooled from its formation and is now “frozen in time,” Dawn principal investigator Chris Russell of UCLA told the website Space.com.
In contrast, “Ceres has been active during its history inside; the interior has been changing, evolving much like the Earth’s interior changes with time,” he said.
While the dwarf planet is known to harbor a significant amount of water, it is unclear whether a subsurface ocean currently exists or once existed and subsequently dried up.
With water and an internal heat source, Ceres could be habitable for microbial life.
“We now know that there is water, and there is enough heat in the interior that that water can be in liquid form,” Russell noted.
“There’s certainly water, or brine, that can flow through the system and reach the surface.”
Ceres also appears to have a thin atmosphere or exosphere, that could be driving the small planet’s interaction with the solar wind.
After orbiting Ceres at a low altitude just 240 miles (385 km) above the surface, Dawn will now spiral to a higher orbit 910 miles (1,460 km) above that surface with the goals of saving fuel and specifically targeting particular regions for further study.
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Laurel Kornfeld
Staff Writer
Laurel Kornfeld is a freelance writer and amateur astronomer from Highland Park, NJ, who enjoys writing about astronomy and planetary science. She studied journalism at Douglass College, Rutgers University, and earned a Graduate Certificate of Science in astronomy from Swinburne University’s Astronomy Online program.
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