As NASA’s Dawn spacecraft closes in on Ceres, new images show the dwarf planet at 27 pixels across, about three times better than the calibration images taken in early December. These images were taken with the Framing Camera, and are mostly meant to help the tiny craft stay on course. The best is yet to come, as Dawn will deliver increasingly detailed images of the dwarf planet as it continues its approach. NASA expects that Dawn will achieve orbit around Ceres on March 6, and once there it will stay in orbit for 16 months.

The Dawn spacecraft observed Ceres for an hour on Jan. 13, 2015, from a distance of 238,000 miles (383,000 kilometers). A little more than half of its surface was observed at a resolution of 27 pixels, but even from this distance you can see some of the surface detail, and a bright spot we think is some kind of volcanic activity. This animated GIF shows bright and dark features.
Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

“We know so much about the solar system and yet so little about dwarf planet Ceres. Now, Dawn is ready to change that,” said Marc Rayman, Dawn’s chief engineer and mission director, based at NASA’s Jet Propulsion Laboratory in Pasadena, California.

The best images of Ceres taken so far are still from NASA’s Hubble Space Telescope, taken in 2003 and 2004. The images in the animated GIF above are about 80 percent of Hubble’s resolution, so they’re a bit fuzzier. By the end of January, though, there will be another imaging opportunity, and the pictures Dawn sends back will surpass anything the Hubble could deliver.

The Dawn space probe, with ion drive blazing, approaches the proto-planet Vesta in the asteroid belt. (artist’s conception) Image credit: NASA/JPL

Ceres is the largest body in the main asteroid belt, which lies between Mars and Jupiter. It has an average diameter of 590 miles (950 kilometers), and is thought to contain a large amount of ice. At that diameter, it’s just big enough to have sufficient gravity to pull it into that familiar round planet shape. Ceres is only about a third as dense as Earth, and obviously a lot smaller, so the gravity there is only about 3 percent of  what we experience. That’s low enough that even the most seasoned astronaut would have difficulty walking there. For reference, the Moon has about one sixth of Earth’s gravity, and Mars has about one third.

As for the composition of Ceres, some scientists believe that the surface is covered in frost, under which there should be a thin layer of dust and rubble as a crust. Beneath that is likely to be more ice, but the evidence of volcanic action suggests that Ceres is internally heated somehow, and that makes it possible for there to be an ocean of liquid water in the planet’s core.

“The team is very excited to examine the surface of Ceres in never-before-seen detail,” said Chris Russell, principal investigator for the Dawn mission, based at the University of California, Los Angeles. “We look forward to the surprises this mysterious world may bring.”

The spacecraft was launched in 2007. Vesta is the second largest object in the asteroid belt, with an average diameter of 326 miles (525 kilometers). Dawn arrived there on June 16, 2011. After taking more than 30,000 images of Vesta over a year’s time, Dawn fired up its ion drive, left orbit and started heading for Ceres. It’s taken this long to get within visual range of Ceres. A ship that has nothing but ion drive takes forever to get anywhere, but the fact that Dawn has it allowed it to be the first spacecraft of any kind to be sent on two deep space missions.

JPL manages the Dawn mission for NASA’s Science Mission Directorate in Washington. Dawn is a project of the directorate’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. The University of California at Los Angeles (UCLA) is responsible for overall Dawn mission science.

Orbital Sciences Corp. in Dulles, Virginia, designed and built the spacecraft. The Dawn framing cameras were developed and built under the leadership of the Max Planck Institute for Solar System Research, Gottingen, Germany, with significant contributions by German Aerospace Center (DLR), Institute of Planetary Research, Berlin, and in coordination with the Institute of Computer and Communication Network Engineering, Braunschweig. The Framing Camera project is funded by the Max Planck Society, DLR, and NASA/JPL. The Italian Space Agency and the Italian National Astrophysical Institute are international partners on the mission team.

We’re watching this mission with particular interest, since SCIFI.radio’s new radio serial space adventure Halfway Home is set on both Ceres and Vesta.

As Dawn gets closer, the scientific discoveries and the wealth of images that lead to them should be amazing. Bookmark SCIFI.radio, and be sure not to miss these exciting developments!

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