NASA’s Dawn spacecraft has entered its nearest orbit ever to the dwarf planet Ceres, an icy body in the asteroid belt left over from the formation of the solar system. And Dawn is already turning up stunning results.
The latest images sent back by the spacecraft were captured just 22 miles above a site called Occator Crater. Before June, Dawn was orbiting hundreds of miles over the surface.
This bright region first stood out to astronomers when Dawn arrived at Ceres in 2015. While much of the dwarf planet is dark, the crater’s center has several strange reflective spots that were easily visible from orbit. Scientists suspected that these formed as a mixture of salt and ice erupts onto the world’s surface. Astronomers call this process cryovolcanism.
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These new observations help confirm that those bright spots are the indeed the result of cryovolcanism. The salty material is sodium carbonate, or soda ash. And astronomers say it likely welled up from a reservoir of briny water below the surface of Ceres and spewed onto the surface. Going forward, the new orbit should give Dawn a view of what, if any, geologic activity is happening on Ceres today. The world is about one-fourth the size of Earth’s own moon.