New Horizons at Ultima Thule

Image of Ultima Thule taken by the LORRI onboard the New Horizons spacecraft in the Kuiper Belt
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

6.5 billion kilometers (4 billion miles) away from where some Earthlings are celebrating New Year’s Eve, NASA’s New Horizons spacecraft is beginning its close flyby of a tiny world in the Kuiper Belt known as Ultima Thule (2014 MU69.)

Ultima Thule (pronounced “TOO-lee”) resides in the Kuiper Belt, a diffuse band of detritus left over from the formation of our solar system. Ultima Thule was discovered in 2014 by astronomers using the Hubble Space Telescope to look for a conveniently-located new world for New Horizons to aim toward after its successful 2015 encounter with Pluto. From evidence obtained during the object’s occultations of stars, Ultima Thule was determined to be approximately 30 kilometers in diameter and elongated in shape. According to mission scientists, that means it could be one long body, two smooshed together bodies, or two very closely orbiting bodies. The most recent image of Ultima Thule taken by the Long Range Reconnaissance Imager (LORRI) onboard the spacecraft was revealed in a press briefing on NASA TV today, and with only a few pixels the image confirms the object’s elongated shape. The raw image is on the left, sharpened on the right to reveal the shape.

Resolution will increase rapidly during this historic encounter in the Kuiper Belt, but it will take some time for these images to reach Earth. New Horizons radiates these data back to Earth where they are downlinked by the Deep Space Network of radio telescopes, but data rates are minimal at this incredible distance, and there are other spacecraft throughout the solar system regularly downlinking their data to the network. It will take twenty months for all these Ultima Thule encounter data to be completely downlinked. In the meantime, the New Horizons team has prioritized the return of a few first-look images from tonight’s encounter for release to the science community and public over the next few days.