College College Space and Planetary Sciences

Ultima Thule: The Ultimate New Horizons Mission

The famous New Horizons mission is heading to Ultima Thule, an interesting Kuiper Belt Object. It will be the furthest object in the solar system that gets a flyby and a thorough analysis.

The New Horizons mission famously captured the first up-close photos of Pluto and its system of moons. As the New Horizons probe continued onwards into the depths of space, a new target for the mission was located in 2015. Now, New Horizons is getting ever closer to this new target, which was formerly called 2014 MU69. Recently, the New Horizons team chose the name “Ultima Thule” to refer to this Kuiper Belt Object (KBO), while the International Astronomical Union decides on an official name.

The name “Ultima Thule” came from a poll that was held late last year where people could post their own name ideas for 2014 MU69. Some of the names that were also considered were: “Abeona, Pharos, Pangu, Rubicon, Olympus, Pinnacle, and Tiramisu.” Yes, I am not making that up, NASA almost named a KBO after a dessert. Personally, I was hoping for Rubicon, but the chosen name has an interesting meaning. Ultima Thule literally means “beyond the borders of the known world,” which is certainly accurate, since this KBO will be the furthest object we ever encountered up close. The Voyager spacecraft are much farther than New Horizons, but the farthest object they have analyzed up close is Neptune. (1)

Animation from NASA, ESA, SwRI, JHU/APL, and the New Horizons KBO Search Team

This KBO was discovered in 2014, hence the original name 2014 MU69, and scientist collected valuable data about it using the Hubble Space Telescope. The original measurements of Ultima Thule were around 30 to 45 kilometers wide. The orbit is quite large, as Ultima Thule orbits the Sun once about every 295 years, which also puts it at around 44 AU (2) from the Sun. The KBO also has a low eccentricity and inclination. The eccentricity of an orbit determines how skewed it is on a plane, while the inclination is the angle of the orbit compared to the typical place of reference in our solar system. The low values in both the inclination and eccentricity is highly unusual for a KBO, since most have eccentric and heavily inclined orbits. Even Pluto has a significant inclination compared to our solar reference plane. This might mean that Ultima Thule is one of the original objects within the Kuiper Belt, as it has not been influenced by Neptune or any other significant bodies in the outer solar system. (3)

Recent discoveries made by the New Horizons probe make Ultima Thule an even more exciting place than before. The KBO was tracked by New Horizons as it occluded a star, which gave even more accurate measurements about the object, orbit, and shape. Evidence points at Ultima Thule being a binary system like Pluto and Charon but on a much smaller scale. This puts Ultima Thule at a smaller 20 kilometers across with the possibility of a small moon. Scientists also determined that Ultima Thule is red or has a red tint to it, and this will be interesting to see verified once New Horizons reaches this KBO. This historic flyby will occur on New Year’s Day in 2019, so be sure to mark your calendars to not miss the exciting data and pictures that will come from this mission. (4)

A sketch of the occultation event that revealed the shape of KBO and its moon.
Image from NASA, ESA, SwRI, JHU/APL

References and Footnotes:

(1) https://www.nasa.gov/feature/new-horizons-chooses-nickname-for-ultimate-flyby-target

(2) 44 AU is equal to about 6.6 billion kilometers

(3) https://www.hou.usra.edu/meetings/lpsc2015/pdf/1301.pdf

(4) https://www.nasa.gov/feature/does-new-horizons-next-target-have-a-moon

1 comment on “Ultima Thule: The Ultimate New Horizons Mission

  1. Pingback: The Eccentric and Tilted Orbits of the Kuiper Belt – The Student Scientist

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