Latest blog from Dawn is March 31. Things are quiet there so the blogger has had time to make a really long blog – it gets better after the first few pages.
“intensive observations, will recommence on April 24 … Dawn will also conduct measurements when the ground directly beneath it is hidden in the deep darkness of night. These observations were not even envisioned when Dawn’s mission was designed, and it did not perform comparable measurements during its extensive exploration of Vesta … Dawn has lost two of its four reaction wheels, gyroscope-like devices it uses to turn and to stabilize itself”
“Most of the surface reflects nine percent of the sunlight. (For comparison, the moon reflects 12 percent on average, Mars reflects 17 percent, and Vesta reflects 42 percent.) But there are some small areas that are significantly more reflective, including the two most famous bright spots. Each spot occupies only one pixel (2.7 miles, or 4.3 kilometers across) in the best pictures so far. If each bright area on the ground is the size of a pixel, then they reflect around 40 percent of the light, providing the stark contrast with the much darker surroundings. When Dawn’s pictures show more detail, it could be that they will turn out to be even smaller and even more reflective than they have appeared so far. To ensure the best photographic results, controllers are modifying the elaborate instructions for the camera to take pictures of the entire surface with a wider range of exposures than previously planned, providing high confidence that all dark and all bright areas will be revealed clearly.”
“By the time it has transmitted its final RC3 measurements on May 8, the bounty may be more than 2,500 pictures and two million spectra. … Dawn will conduct its studies from four orbital altitudes, called RC3, survey, HAMO, LAMO.”
RC3, April 23 – May 9, 13,500 km altitude
Survey, June 6-30, 2,700 km
HAMO, Aug 4 – Oct 15, 900 km
LAMO, Dec 8 – end of mission, 230 km.
“Ceres is still on the far side of the Sun from the Earth. Earth will get closer and closer until July 22”.