Artist’s conception of the Dawn spacecraft approaching the dwarf planet Ceres. Credit: NASA/JPL-Caltech
And today (Dec. 1) comes a special day for Dawn — when it turns its cameras to Ceres to capture the world, which will appear about nine pixels across. The reason? Besides scientific curiosity, it turns out to be a perfect calibration target, according to NASA.
“One final calibration of the science camera is needed before arrival at Ceres,” wrote Marc Rayman, the mission director at the Jet Propulsion Laboratory, in a recent blog post.
“To accomplish it, the camera needs to take pictures of a target that appears just a few pixels across. The endless sky that surrounds our interplanetary traveler is full of stars, but those beautiful pinpoints of light, while easily detectable, are too small for this specialized measurement. But there is an object that just happens to be the right size. On Dec. 1, Ceres will be about nine pixels in diameter, nearly perfect for this calibration.”
The Dawn spacecraft’s first image of Ceres, taken July 20, 2010. Credit: NASA/JPL-Caltech/MPS/DLR/IDA
In October, the Dawn blog said that more pictures of Ceres are planned on Jan. 13, when Ceres will appear 25 pixels across. This won’t be quite the best view ever — that was taken by the Hubble Space Telescope, which you can see below, — but just wait a couple of weeks. The mission planners say that by Jan. 26, the images will be slightly better. On Feb. 4, they will be twice as good and by Feb. 20, seven times as good.
As with the calibration photo taken today, these photos in 2015 will have a double purpose: optical navigation. It’s to help the spacecraft figure out where to go, because our pictures of Ceres are so fuzzy that mission planners will need more exact information as the mission proceeds.
You can read more information about the picture-taking, and Dawn’s planned approach to Ceres, in the Nov. 28 entry of the Dawn blog.
Pictures of the asteroid Ceres taken by the Hubble Space Telescope and released in 2005. It shows the asteroid rotating over two hours and 20 minutes, which is about a quarter of a day on Ceres (nine hours). At the time, scientists said the bright spot is a mystery. Credit: NASA, ESA, J. Parker (Southwest Research Institute), P. Thomas (Cornell University), and L. McFadden (University of Maryland, College Park)
About Elizabeth Howell
Elizabeth Howell is the senior writer at Universe Today. She also works for Space.com, Space Exploration Network, the NASA Lunar Science Institute, NASA Astrobiology Magazine and LiveScience, among others. Career highlights include watching three shuttle launches, and going on a two-week simulated Mars expedition in rural Utah. You can follow her on Twitter @howellspace or contact her at her website.- FASHION WEEK - USA Fashion and Music News
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