Icy Volcanoes on Ceres
Saline water emanated from the center of the crater Occator on the dwarf planet Ceres until a few million years ago. It is possible that this process is still ongoing today, so that there could be active ice volcanoes. Why is Ceres still active?
The unusual Occator crater is one of the most important keys to understanding the dwarf planet Ceres, which NASA's Dawn spacecraft orbited from March 2015 to October 2018. Dawn had already visited the asteroid Vesta in 2011 and 2012 (see SuW 6/2013, p. 34). From the second station of its discovery tour near Ceres, the probe transmitted tens of thousands of fascinating images and measurement data from other instruments to Earth. The camera system, called Framing Camera (FC), comes from Germany. His recordings offered insights into the shape, formation and development of the largest object in the asteroid belt between the orbits of Mars and Jupiter (see SuW 5/2018, p. 24).
In the final months of the Dawn mission in the summer of 2018, the US space agency NASA changed the orbit of the spacecraft in such a way that the Occator impact crater could be photographed with a particularly high spatial resolution of up to three meters per pixel. Only now was it possible for the scientists involved to fathom the special nature of the crater and its activity.
During the course of the Dawn mission, the roughly 960-kilometre-wide, almost spherical dwarf planet Ceres turned out to be a unique world. Like other atmosphereless objects in the solar system, its surface is covered with impact craters. However, these are often severely eroded, not least because the water ice in the crust practically melts larger craters over many millions of years. In addition, hundreds of mostly small bright regions on a dark background appeared on the surface, some in connection with young impact craters in a slightly bluish tint. …