Thanks to Dawn, NASA now has access to the interiors of Ceres!

Image courtesy: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

New Delhi: The Dawn spacecraft was launched into space by NASA with the mission to conduct a probe into two of the three known protoplanets of the asteroid belt, Vesta and Ceres.

Currently in its second phase, Dawn is presently circling dwarf planet Ceres and has frequently beamed back intriguing images of its exterior.

This time, however, Dawn has helped scientists in measuring variations in Ceres’ gravity by tracking subtle changes in the motion of the spacecraft.

Since Dawn's orbit around Ceres is dominated by gravity, scientists have mapped the variations for the first time in a new study in the journal Nature, which provides clues to the dwarf planet's internal structure, with the help of data collected by Dawn.

"The new data suggest that Ceres has a weak interior, and that water and other light materials partially separated from rock during a heating phase early in its history," said Ryan Park, the study’s lead author and the supervisor of the solar system dynamics group at NASA’s Jet Propulsion Laboratory, Pasadena, California, NASA reported.

As per NASA, Ceres has a special property called "hydrostatic equilibrium," which was confirmed in this study. This means that Ceres' interior is weak enough that its shape is governed by how it rotates. Scientists reached this conclusion by comparing Ceres' gravity field to its shape. Ceres' hydrostatic equilibrium is one reason why astronomers classified the body as a dwarf planet in 2006.

The data indicate that Ceres is “differentiated,” which means that it has compositionally distinct layers at different depths, with the densest layer at the core. Scientists also have found that, as they suspected, Ceres is much less dense than Earth, the moon, giant asteroid Vesta (Dawn’s previous target) and other rocky bodies in our solar system. Additionally, Ceres has long been suspected to contain low-density materials such as water ice, which the study shows separated from the rocky material and rose to the outer layer along with other light materials.

"We have found that the divisions between different layers are less pronounced inside Ceres than the moon and other planets in our solar system," Park said. “Earth, with its metallic core, semi-fluid mantle and outer crust, has a more clearly defined structure than Ceres," Park said.