NASA's Dawn probe is snapping stunning new views of the dwarf planet Ceres as the spacecraft pushes ever higher above the small world.
In one image, Ceres' huge Occator Crater shows its central bright region, the brightest on Ceres. The crater itself is 57 miles wide, and 2.5 miles deep. That makes it 77 times larger than the Barringer Crater in Arizona. Dawn took the picture when it was about 920 miles above the surface, in early October.
According to Fox News, planetary scientists think the bright spots might be from briny material bubbling up during geologic activity; the liquid would sublimate away leaving the salts behind. Another asteroid slamming into Ceres could also cause upwelling, which is what some think happened at Occator Crater.
Astronomy Magazine states that the latest theory to explain the bright white splotches is that despite forming millions of years ago, the crater is geologically active. The impact may have triggered the upwelling of a salt-rich liquid from within Ceres, the brine emerging at the surface and rapidly freezing before ice sublimated into vapor leaving behind fresh salt deposits.
Dawn's new orbit will be 4,500 miles from Ceres. NASA is sending the probe to higher altitudes where it can make additional measurements. For example, the spacecraft will use its gamma ray and neutron spectrometer to look at the cosmic rays that suffuse the space around the asteroid, to compare them with readings closer in. The background "noise" can then be separated from the signal, allowing more scrutiny of Ceres' composition.
Ceres started working its way to the new orbit on Nov. 4. While the primary mission was completed in July, NASA extended the mission as the probe was still functioning.
It will stay in orbit around the only dwarf planet in the inner solar system until it runs out of propellent, at which point it will stay in a permanent orbit around Ceres.