NASA’s Dawn spacecraft is now closer to Ceres than ever before. Ceres is the largest known asteroid and the only dwarf planet in the inner solar system. After Dawn entered orbit around Ceres in March 2015, it came no closer than 240 miles (385 km) from its surface. But beginning in April this year, mission control began firing Dawn’s engines to bring it down for a front row view. After a series of complicated maneuvers, the spacecraft now approaches to within 22 miles (35 km) above the surface at closest. Dawn sees Ceres’ heavily cratered dwarf planet from about 127,000 feet up or less than 3½ times the altitude of a jet you’d take to visit Grandma at Christmas.
The spacecraft’s low orbit has already meant some incredibly detailed new views of Ceres’ surface, but it also promises a closer look at how material distributed inside the dwarf planet. Asteroids, moons and planets are lumpy inside with areas of greater and lesser density depending on how they formed and how their interiors evolved over time. Getting “low” allows Dawn to map Ceres’ interior by measuring subtle changes in its gravitational field.
Dawn has already returned several intriguing views of the walls of Occator Crater. Like you, I’m waiting to see new closeups of the briny white spots inside the crater. I’ll post them here as soon as they’re available. Besides photos and gravity measurements, the spacecraft will also explore the minerals that makes up Ceres’ surface in greater detail.
The Dawn mission is expected to end when the spacecraft runs out of fuel, which is expected in a matter of a few months. For updates, click here.