Hello readers! Today we are travelling to Ceres, a dwarf planet in the asteroid belt located between Mars and Jupiter. Ceres is not very large–about the size of Texas, at 476 kilometers (276 miles) across. It was first discovered in 1801 and in 2015, was visited by the spacecraft Dawn.
Today’s featured article, however, was written before Dawn arrived at Ceres. “Ceres: Predictions for near-surface water ice stability and implications for plume generating processes“, written by Timothy Titus and published in the first few months of 2015 in the American Geophysical Union’s journal Geophysical Research Letters. While more recent articles concerning Ceres and the information from Dawn exist, I have not found any that can be accessed without payment; as I want my readers to also have easy access to the articles, I avoid these. I may someday do an update to this post when such material becomes more open.
Today’s article uses pre-Dawn knowledge to investigate the possibility of cryovolcanoes on Ceres. Cryovolcanoes are cold versions of volcanoes, sometimes called ice volcanoes; they work similarly to volcanism on Earth, but instead of molten rock, their ‘lava’ is ice-based. Some observations of Ceres showed plumes of water vapor from the mid-latitudes, and others did not. Two possibilities were presented; cryovolcanism, or sublimation, such as is seen on comets (sublimation is when a solid turns immediately to a gas without becoming a liquid in between; think of dry ice).
The author ran a model (adapted from one that others have used for Mars) to see if water ice would be stable (i.e. it would remain as-is) at, near, or somewhat below the surface of Ceres. Whether sublimation or cryovolcanism, the water vapor had to come from somewhere. The result was that ice would be stable in some regions, not in others. It was not likely to be stable in the mid-latitudes, which suggests the water vapor was from cryovolcanism, as there would not have been sufficient ice at the proper depth to allow sublimation.
What the findings suggested was that cryovolcanism of some form was the more likely culprit. The mantle would likely be warm enough for liquid water, and cryomagmatism would allow for the movement of the icy ‘magma’ to replenish an area’s supply of near-surface ice. Of course, the author had several uncertainties due to the lack of data, and looked to the arrival of Dawn at Ceres.
Well, Dawn has been at Ceres for a couple of years now. It has imaged Ahuna Mons, which appears to be a geologically recent, salty and muddy cryovolcano. It has been suggested that there were once others, which are no longer visible. Ceres also has a thin atmosphere–sometimes, depending on the sun’s activity.
Science never stops; there’s always something new to learn.
In fact, Dawn is still in operation, on an extended mission.
American Geophysical Union. New Research Shows Ceres May Have Vanishing Ice Volcanoes. AGU, 2 Feb 2017. Web.
A news article discussing research, wherein former cryovolcanoes are hypothesized.
Dunford, Bill. Ceres: In Depth. National Aeronautics and Space Administration, n.d. Web.
NASA page with a lot of info on Ceres.
National Aeronautics and Space Administration. Dawn’s Blue Glow (Artist’s Concept). NASA/JPL/CalTech. 2 March 2015. Web.
An artist’s concept image of Dawn approaching Ceres, used in the post.
Perez, Martin, ed. Ceres’ Temporary Atmosphere Linked to Solar Activity. National Aeronautics and Space Administration, 6 April 2017. Web.
NASA article about research into Ceres’ atmosphere.
Rayman, Marc. Dawn Mission Status Updates. Jet Propulsion Labratory/ California Institute of Technology/ National Aeronautics and Space Administration, 5 May 2017. Web.
Updates into the current state of the Dawn mission.
Steigerwald, Bill. NASA Discovers “Lonely Mountain” on Ceres Likely a Salty-Mud Cryovolcano. National Aeronatics and Space Administration, 1 Sept 2016. Web.
An article on Ahuna Mons and how it is suspected to be a cryovolcano. Also where I got the second image in this post.
Titus, T. N. (2015), Ceres: Predictions for near-surface water ice stability and implications for plume generating processes, Geophys. Res. Lett., 42, 2130–2136, doi:10.1002/2015GL063240
Today’s main article.