The colorful map above was created from images taken by Dawn during its recent high-altitude mapping orbit. All those colors come from several spectral filters used to snap the images. These include infrared, red and blue. The false-color view hints at what Ceres’ surface is made of.
You see the redder colors? It indicates areas of Ceres’ surface that reflect light strongly in the infrared. Blue colors show enhanced reflectivity at shorter wavelengths. And green shows areas where albedo, that’s the overall brightness, is enhanced.
Scientists use this technique in order to highlight subtle color differences across Ceres, which would appear fairly uniform in natural color. This can provide valuable insights into the mineral composition of the surface, as well as the relative ages of surface features.
You can even make out what appears to be Occator crater (where Ceres’ infamous bright spots are).
NASA also released a pair of topographic images highlighting two of Ceres most prominent features. The first image shows a tall, conical mountain.
Dawn was 915 miles above the surface when it snapped the above image on August 22, 2015. As Dawn gets closer and closer to Ceres’ surface, the resolution in images sees a drastic bump. This image’s resolution is 450 feet per pixel.
Dawn entered the record books when it reached Ceres in March. It’s the only spacecraft to orbit two extraterrestrial destinations, Vesta in 2011 and now Ceres.
It wasn’t all smooth sailing for Dawn, though. In 2010, one of its reaction wheels began to malfunction when it experienced increased friction. But Dawn continued with the other three. A second reaction wheel encountered the same problem in August 2012.
Losing two of four reaction wheels could have been a disaster. Luckily, JPL and Orbital Sciences Corporation were up for the challenge. They began working on a method to operate with just two reaction wheels after the first one malfunctioned. A year before the second reaction wheel malfunctioned, the software needed to operate on two reaction wheels was installed in the Dawn’s main computer.
The new software allows for hybrid control of Dawn by using the last two reaction wheels and the hydrazine-powered jets of the reaction control system. Dawn’s team even have a plan in place in case if the last two reaction wheels fail. The hydrazine thrusters should provide enough control for Dawn to complete its mission in this worst case scenario.
Dawn hasn’t had to use this hybrid control yet, and will only need to during the final phase of its mission. In the next few months, Dawn will enter its final orbital altitude at just 230 miles above Ceres’ surface. Here, it will take various measurements and continuing capturing images. Will we finally have an answer for Ceres’ mysterious bright spots? Scientists hope so.
Next year, Dawn is expected to run out of hydrazine, and its mission will come to an end. Without hydrazine, Dawn can’t point its instruments at Ceres, its antenna at Earth or its solar arrays at the sun.