American Scientist

The intriguing, snowman-shaped object known as 2014 MU69, nicknamed Ultima Thule, lies one billion miles beyond the orbit of Pluto. Formed around 4.5 billion years ago, it is one of the most ancient objects in the Solar System and the most distant body ever explored by humankind. It resides in the Kuiper Belt, a region of space beyond Neptune filled with frozen remnants from the time of planetary formation. NASA's New Horizons spacecraft reached Pluto in 2015 and continued on to investigate other Kuiper Belt objects. It completed its reconnaissance of Ultima Thule in January 2019.

Ultima Thule

• Ultima and Thule, two planetary building blocks called planetesimals, were separate objects drawn together by gravity, which touched to become what's known as a contact binary.
• Ultima Thule's color was found to be reddish, indicative of organic ices altered by billions of years of irradiation.

Science Objectives

• Map the object's surface composition
• Characterize its geology
• Map its surface temperatures
• Search for surrounding rings or satellites

New Horizons

• Science objectives: map the object's surface composition, characterize its geology, map its surface temperatures, search for surrounding rings or satellites.
• The spacecraft collected 7 gigabytes of data during the Ultima Thule encounter—so much information that it will take two years to download it all.
• For the next 20 months, the probe will relay Kuiper Belt images, spectroscopy data, dust readings, and radiation measurements.
• New Horizons has an anticipated future lifespan of 15 more years. In 2020 scientists will consider whether to attempt the exploration of another Kuiper Belt object.