The Kuiper Belt Object Formerly Known as Ultima Thule

New Horizons images of the Kuiper Belt Object Arrokoth taken from many angles have been used to determine its 3D shape, providing insight into the KBO’s origins. The flattened shapes of the two lobes and the tight alignment of their poles and equators are evidence an orderly, gentle merger of two objects forming from the same cloud of particles. Arrokoth appears to have come together slowly, growing from “locally-sourced” materials found in a small part of the early solar nebula. Such an object would not have formed in a more chaotic accretion environment.

Video Credit: NASA / JHUAPL / SWRI / James Tuttle Keane

Ultima Thule in Color

This composite image of Kuiper Belt Object 2014 MU69 (aka Ultima Thule) isfeatured on the cover of the May, 2017 issue of the journal Science. It was compiled from data obtained by the New Horizons spacecraft as it flew by Ultima Thule on New Years Day. The image combines color data with detailed high-resolution panchromatic pictures to present the view as the human I would see it.

Image Credits: NASA / JHUAPL ./ SWRI / Roman Tkachenko

The Shape of Ultima Thule

Here’s NASA’s description of this brief video: This animation depicts a shape model of Ultima Thule created by the New Horizons science team based on its analysis of all the pre-flyby images sent to Earth so far. The first half of the movie mimics the view from the New Horizons spacecraft as it approached Ultima Thule and has the “snowman” shape that was so frequently mentioned in the days surrounding the New Year’s 2019 flyby. The movie then rotates to a side-view that illustrates what New Horizons might have seen had its cameras been pointing toward Ultima Thule only a few minutes after closest approach. While that wasn’t the case, mission scientists have been able to piece together a model of this side-view, which has been at least partially confirmed by a set of crescent images of Ultima Thule (link). There is still considerable uncertainty in the sizes of “Ultima” (the larger section, or lobe) and “Thule” (the smaller) in the vertical dimension, but it’s now clear that Ultima looks more like a pancake than a sphere, and that Thule is also very non-spherical. The rotation in this animation is not the object’s actual rotation, but is used purely to illustrate its shape.

Video Credit: NASA / JHU APL / SWRI

Ultima Thule Up Close

The most detailed images to date of Ultima Thule—obtained just minutes before New Horizons’ closest approach on New Year’s Day—have a resolution of about 33 m per pixel. Their combination of higher spatial resolution and a favorable viewing angle offer an excellent opportunity for studying the surface of Ultima Thule. The Kupier Belt Object is probably the most primitive body ever observed by a spacecraft.

This  composite picture was processed from nine images taken about 6-1/2 minutes before the closest approach to Ultima Thule using the spacecraft’s Long Range Reconnaissance Imager with exposure times of 25 ms.

Image Credits: NASA / JHU APL / SWRI / NOAO

Ultima Thule in the Rear View Mirror

This animation was assembled from images taken by the New Horizons Long Range Reconnaissance Imager after the spacecraft flew past Ultima Thule on New Year’s Day. The central frame of the sequence was taken on at 05:42:42 UT when the spacecraft was 8,862 km past the Kuiper Belt Object and 6.6 billion km from Earth. The KBO’s illuminated crescent is blurred in the individual frames because long exposure times were required boost the camera’s signal level. The Sun’s light is roughly 2000X dimmer at Ultima Thule that here on Earth. This is the farthest movie of any object in our Solar System ever made by a spacecraft.

Image Credits: NASA / JHUAPL / SWRI / NOAO