In the ten years since its launch from Cape Canaveral, NASA’s Dawn spacecraft has orbited the two largest worlds in the asteroid belt and overcome defective components that threatened to derail the mission on its 4 billion-mile voyage, discovering unexpectedly rich geologic tapestries suggesting both destinations have a watery past.
NASA’s Dawn spacecraft successfully observed Ceres at opposition on April 29, taking images from a position exactly between the Sun and Ceres’ surface. Mission specialists had carefully maneuvered Dawn into a special orbit so that the spacecraft could view Occator Crater, which contains the brightest area of Ceres, from this new perspective.
Scientists have long thought that Ceres may have a very weak, transient atmosphere, but mysteries lingered about its origin and why it’s not always present. Now, researchers suggest that this temporary atmosphere appears to be related to the behaviour of the Sun, rather than Ceres’ proximity to the Sun.
NASA’s Dawn spacecraft has continued its survey of the dwarf planet Ceres this year, discovering rock-bound ice hidden just beneath the airless world’s rugged surface and a handful of icy outcrops inside craters in the northern hemisphere, raising hopes that Ceres could have once held a buried habitable ocean of liquid water.
The brightest area on Ceres stands out amid shadowy, cratered terrain in a dramatic new view from NASA’s Dawn spacecraft, taken as it looked off to the side of the dwarf planet. Dawn snapped this image from about 920 miles (1,480 kilometres) above Ceres in its fifth science orbit, in which the angle of the Sun was different from that in previous orbits.
By tracking subtle changes in the motion of NASA’s Dawn spacecraft, scientists have mapped the variations in Ceres’ gravity for the first time, providing clues to the dwarf planet’s internal structure. The new data suggest that Ceres has a weak interior, and that water and other light materials partially separated from rock during a heating phase early in its history.
Ceres is covered in countless small, young craters, but none are larger than 175 miles (280 kilometres) in diameter. To scientists, this is a huge mystery, given that the dwarf planet must have been hit by numerous large asteroids during its 4.5 billion-year lifetime. Where did all the large craters go?