NASA’s Dawn spacecraft has captured another series of photos in its fifth orbit of the dwarf planet Ceres.
This image of the limb of Ceres shows a section of the northern hemisphere. Prominently featured is Occator Crater. Dawn took this image on Oct. 17, 2016, at a distance of about 920 miles above the surface. Image credit: NASA / JPL-Caltech / UCLA / MPS / DLR / IDA.
Dawn has gathered thousands of images and other information from Ceres since arriving in orbit on March 6, 2015.
After spending more than eight months studying the dwarf planet at an altitude of about 240 miles (385 km), the probe headed for a higher vantage point in August, 2016.
In October, while Dawn was at its 920-mile (1,480 km) altitude, it returned new images and other valuable insights about Ceres.
On Nov. 4, the spacecraft began making its way to a sixth science orbit, which will be over 4,500 miles (7,200 km) from the dwarf planet.
While Dawn needed to make several changes in its direction while spiraling between most previous orbits at Ceres, engineers have figured out a way for the spacecraft to arrive at this next orbit while the ion engine thrusts in the same direction that Dawn is already going.
This uses less hydrazine and xenon fuel than Dawn’s normal spiral maneuvers. The probe should reach this next orbit in early December.
One goal of Dawn’s sixth science orbit is to refine previously collected measurements.
The spacecraft’s gamma ray and neutron spectrometer, which has been investigating the composition of Ceres’ surface, will characterize the radiation from cosmic rays unrelated to Ceres.
This will allow scientists to subtract ‘noise’ from measurements of the dwarf planet, making the information more precise.
This image shows Occator Crater, with its signature bright areas. Dawn scientists have found that the central bright spot, which harbors the brightest material on Ceres, contains a variety of salts. The brightest parts of these features are overexposed in this image, which had an exposure time intended to capture details in the surrounding terrain. Dawn took this image on Oct. 18, 2016, at a distance of about 920 miles above the surface. Image credit: NASA / JPL-Caltech / UCLA / MPS / DLR / IDA.
The latest images, taken from Dawn’s fifth science orbit (920 miles above the surface of Ceres), show Occator crater with its mysteriously bright spots.
Measuring 57 miles (92 km) across and 2.5 miles (4 km) deep, the crater displays evidence of recent geologic activity.
A recent study suggests that the bright material in Occator is comprised of salts left behind after a briny liquid emerged from below, froze and then sublimated, meaning it turned from ice into vapor.
The impact that formed the crater millions of years ago unearthed material that blanketed the area outside the crater, and may have triggered the upwelling of salty liquid.
