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The Dawn spacecraft has entered its lowest-ever orbit around Ceres:
Dawn entered orbit around 1 Ceres 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 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 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 and other recent images.
162173 Ryugu and 101955 Bennu.
Previously: Dawn Mission Extended at Ceres
Dawn's Orbit Around Ceres: A New Low
Related: Ceres May Have Had a Global Surface Ocean in the Past
Evidence of a Seasonal Water Cycle and Surface Changes Found on Ceres
(Score: 3, Interesting) by requerdanos on Thursday June 14 2018, @09:39PM (1 child)
I don't think Ceres has very much gravity to use as a force to base an orbit on, either. Impressive.
I wonder about the sequence of looking at the 45,000 trajectories, what the process was that the NASA engineers followed in looking at each one, how long it took, to what extent "looking" consisted of careful slide rule calculation vs Kerbal Space Program saying "That one doesn't work either, how bout this instead".
The TFA pictures of Ceres are beautiful and affect me in a way that I didn't expect (after all, it's just a big rock).
(Score: 3, Interesting) by takyon on Thursday June 14 2018, @10:51PM
Ceres [wikipedia.org] is unlike other asteroid targets in that it likely has a subsurface ocean and could possibly have life in that ocean.
It has very low surface gravity, but is still likely to be one of the top 10 colonization targets for mankind.
At any rate, it is a big ball of real estate and materials, and is relatively close and can support solar power better than Jupiter's moons. 10/10 dwarf planet.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: -1, Offtopic) by Anonymous Coward on Friday June 15 2018, @12:57AM
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