Preliminary Results Published From New Horizons Flyby of MU69 'Ultima Thule'

RockDoctor writes: The NASA/SWRI/Lowell Observatory (and at least 3 universities) team managing the download of data from New Horizons has released a first look at the results downloaded so far. At the time of writing, about 4 days of about 600 days of downloading had been completed. The next milestone hinted at is for March 2019 when the LPSC (Lunar & Planetary Science Conference) will get another batch of data as the various science teams get more data out of the pipeline.
Results: Firstly the overall shape -- as hinted by the occultation results from nearly a year ago -- is a contact binary. There is a lot of work going on from that, about how it could have formed, its accretion history and thermal history. The rotation period is better known (and this will improve as more data is downloaded) at 15=/-1 hours. The mass remains unknown. The mass ratio of the two components (nicknamed 'Ultima' and 'Thule') is suspected to be the same as their volume ratio -- 2.6:1; to get an accurate mass, observation of a satellite is needed, but the trajectory change for the spacecraft is unlikely to be large enough to estimate the mass well. Very little data has come down yet about the mineralogy, but the color suggests there is less water ice on MU69 than on Nix, the satellite of Pluto similar in size to MU69. The reason for a bright region to mark the junction between the two lobes is not known. That'll be the sum of the data for the next 10 weeks until the 50th LPSC on March 18th.

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