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Update on Dawn spacecraft at Ceres

When will we see new images of the mysterious bright spots on Ceres’ surface?

This artist’s concept shows Dawn thrusting with its center ion engine high above the night side of Ceres, which displays only a narrow crescent below the spacecraft. The gentle but efficient thrust allows Dawn to change the shape of its orbit. It will complete this first phase of orbital maneuvering on April 23.. Image via NASA/JPL

This artist’s concept shows Dawn thrusting with its center ion engine high above the night side of Ceres, which displays only a narrow crescent below the spacecraft. The gentle but efficient thrust allows Dawn to change the shape of its orbit. It will complete this first phase of orbital maneuvering on April 23. Image via NASA/JPL.

NASA said yesterday (April 6, 2015) that the Dawn spacecraft has performed flawlessly, continuing to thrust with its ion engine as planned, since its capture by the gravity of dwarf planet Ceres on March 6. The thrust, combined with Ceres’ gravity, is gradually guiding the spacecraft into a circular orbit around the dwarf planet. All of the spacecraft’s systems and instruments are in excellent health, NASA said.

NASA had told us a month ago that new images would be coming in early April, and we are continuing to receive questions about the bright area on Ceres, shown in the Dawn photo below, which was taken on February 19.

No new images of this area yet, but if you want to follow the news about the spots, look to Marc Rayman – who is the Dawn spacecraft’s chief engineer and mission director at NASA’s Jet Propulsion Laboratory – and who is doing a fantastic job blogging Dawn updates at dawnblog.jpl.nasa.gov.

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This image was taken by NASA's Dawn spacecraft of dwarf planet Ceres on Feb. 19 from a distance of nearly 29,000 miles (46,000 kilometers). It shows that the brightest spot on Ceres has a dimmer companion, which apparently lies in the same basin. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

This image was taken by NASA’s Dawn spacecraft of dwarf planet Ceres on February 19 from a distance of nearly 29,000 miles (46,000 kilometers). It shows two mysterious bright spots on Ceres, apparently lying in the same basin. Image via NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

In Rayman’s most recent blog post (March 31, 2015), he writes that:

Even after it entered orbit, Dawn’s momentum carried it to a higher altitude, from which it is now descending. From March 2 to April 9, so much of the ground beneath it is cloaked in darkness that the spacecraft is not even peering at it. Instead, it is steadfastly looking ahead to the rewards of the view it will have when its long, leisurely, elliptical orbit loops far enough around to glimpse the sunlit surface again.

When will that be? In the first of the planned images, on April 10, the dwarf planet will appear as a thin crescent. The next images will come on April 14 and are expected to reveal a slightly larger crescent in even greater detail. Rayman writes:

… on April 14 (and extending into April 15), Dawn will obtain its last navigational fix before it finishes maneuvering. Should we look forward to catching sight of the bright spots then?

In truth, we do not yet know. The spots surely will be there, but the uncertainty is exactly where ‘there’ is.

We still have much to learn about a dwarf planet that, until recently, was little more than a fuzzy patch of light among the glowing jewels of the night sky.

Learn a lot more from Rayman about Dawn’s orbit around Ceres, and what scientists expect to find, at his blog.

In the meantime, know that – over the past month – Dawn has been following its planned trajectory on the dark side of Ceres, the side facing away from the sun. After orbital insertion, as Dawn’s momentum carried it to a higher altitude above the dwarf planet, it reached a maximum of 46,800 miles (75,400 kilometers) in altitude on March 18.

Yesterday, NASA said, Dawn was about 26,000 miles (42,000 kilometers) above Ceres, descending toward the first planned science orbit – labeled RC3 in the second diagram below – which will be 8,400 miles (13,500 kilometers) above Ceres’ surface.

Stay tuned.

Image via NASA/JPL

Dawn’s capture into orbit around Ceres on March 6, 2015. The sun is off the figure far to the left, and Ceres’ north pole points up. The farther Dawn is to the right side of Ceres here, the smaller a crescent it sees, because the illumination is from the left. The white circles are at one-day intervals. The trajectory is solid where Dawn is thrusting with its ion engine, which is most of the time. The labels show four optical navigation sessions, where it pauses to turn, point at Ceres, conduct the indicated observation, turn to point its main antenna to Earth, transmit its findings, turn back to the orientation needed for thrusting, and then restart the ion engine. Image via dawnblog.jpl.nasa.gov

Dawn's four mapping orbits.  It'll enter the first orbit, RC3, in April 2015.  Image via dawnblog.jpl.nasa.gov

Dawn’s four mapping orbits. It’ll enter the first orbit, RC3, in April 2015. Image via dawnblog.jpl.nasa.gov

The bright spots aren't the only Ceres mystery of interest to scientists.  Dawn had this view of Ceres on Feb. 19 at a distance of 28,000 miles (46,000 kilometers). Among the puzzling features is the large structure below and to the right of center. Pictures in RC3 will be more than three times sharper. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

The bright spots aren’t the only Ceres mystery of interest to scientists. Among the puzzling features is the large structure below and to the right of center in this image acquired by Dawn on February 19. Pictures in the RC3 orbit (see above) will be more than three times sharper. Image via NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Bottom line: People are asking when we will see closer images of those two bright spots on the dwarf planet Ceres. Dawn has been orbiting above Ceres’ night side, but will get its next images of the dayside – and maybe the bright spots – around mid-April. Scientists aren’t sure because the surface of Ceres has never been explored in detail. Dawn, which began orbiting Ceres on March 6, 2015, will provide the first-ever images!

Deborah Byrd

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