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takyon [soylentnews.org] writes:

The Dawn spacecraft has entered its lowest-ever orbit around Ceres [skyandtelescope.com]:

Dawn entered orbit around 1 Ceres [wikipedia.org] on March 6, 2015. Up until this year, Dawn's orbits brought it no closer than 483 kilometers (300 miles) from the rock's surface. The complicated process of entering the new 27-hour, 13-minute orbit around the asteroid began on April 16th, when NASA engineers instructed Dawn to fire its ion engines. The new orbit has a periapsis of less than 48 km above the pockmarked surface of Ceres and an apoapsis of 4,000 km.

[...] Attaining a low orbit around Ceres object is no mean feat, as the asteroid's gravitational field [nasa.gov] is lumpy due to the asteroid's uneven composition. NASA engineers looked at over 45,000 possible trajectories before settling on the solution. A lower orbit will allow researchers to map Ceres's gravitational field and hence its internal mass distribution. Surprises may be in store, though: Dawn's reaction wheels failed [nasa.gov] earlier this year, so it now uses its hydrazine-fueled thrusters to control its orientation in space.

[...] We can enjoy the final closeups of Ceres before Dawn falls silent later this year. Then, the excitement in asteroid exploration will shift towards the arrival of the Japanese Aerospace Exploration Agency's Hayabusa-2 at 162173 Ryugu this July, as well as Osiris-REX's arrival at 101955 Bennu this August.

Check out Landslides Along Occator Crater's Rim [nasa.gov] and other recent images [nasa.gov].

162173 Ryugu [wikipedia.org] and 101955 Bennu [wikipedia.org].

Previously: Dawn Mission Extended at Ceres [soylentnews.org]
Dawn's Orbit Around Ceres: A New Low [soylentnews.org]

Related: Ceres May Have Had a Global Surface Ocean in the Past [soylentnews.org]
Evidence of a Seasonal Water Cycle and Surface Changes Found on Ceres [soylentnews.org]

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