On January 1st, 2019, at 12:33 a.m. EST (5:33 a.m. GMT), NASA’s New Horizons spacecraft will fly past a Kuiper Belt object known as 2014 MU69 (nicknamed Ultima Thule).
A schedule of New Horizons Ultima Thule flyby events. Image credit: NASA.
Ultima Thule is orbiting in the heart of Kuiper Belt, a debris field of icy bodies — ranging in size from dwarf planets like Pluto to smaller planetesimals and comets — left over from the Solar System’s formation 4.6 billion years ago.
The nearly circular orbit of Ultima Thule indicates it originated at its current distance from the Sun.
Planetary researchers find its birthplace important for two reasons: (i) because that means this Kuiper belt object is an ancient sample of this distant portion of the Solar System, and (ii) because temperatures this far from the Sun are barely above absolute zero.
Southwest Research Institute scientist Dr. Marc Buie and members of the New Horizons science team discovered Ultima Thule using the NASA/ESA Hubble Space Telescope on June 26, 2014.
In 2016, a research team led by Southwest Research Institute’s Dr. Simon Porter determined it had a red color.
In 2017, a NASA campaign traced out its size — just about 20 miles (30 km) across — and irregular shape when it passed in front of a star, an event called a ‘stellar occultation.’
From its brightness and size, New Horizons team members calculated its reflectivity, which is only about 10%, or about as dark as garden dirt.
Beyond that, nothing else is known about it — basic facts like its rotational period and whether or not it has moons are unknown.
Artist’s impression of New Horizons encountering a Pluto-like object in the distant Kuiper Belt. Image credit: NASA / JHUAPL / SwRI / Alex Parker.
“From Ultima Thule’s orbit, we know that it is the most primordial object ever explored,” said Dr. Cathy Olkin, New Horizons deputy project scientist at Southwest Research Institute.
“I’m excited to see the surface features of this small world, particularly the craters on the surface.”
“Young craters could provide a window to see the composition of the subsurface of Ultima Thule. Also by counting the number and impactors that have hit Ultima Thule, we can learn about the number of small objects in the outer Solar System.”
“New Horizons will map Ultima Thule, map its surface composition, determine how many moons it has and find out if it has rings or even an atmosphere,” said New Horizons principal investigator Dr. Alan Stern, also of Southwest Research Institute.
“It will make other studies, too, such as measuring Ultima Thule’s temperature and perhaps even its mass. In the space of one 72-hour period, Ultima Thule will be transformed from a pinpoint of light — a dot in the distance — to a fully explored world. It should be breathtaking!”
“New Horizons is performing observations at the frontier of planetary science, and the entire team looks forward to unveiling the most distant and pristine object ever explored during a spacecraft flyby,” said New Horizons project scientist Dr. Hal Weaver, of the Johns Hopkins University Applied Physics Laboratory.
“From mission design to navigation to operations, our team worked very hard to get the spacecraft where it needs to be for this historic exploration in the Kuiper Belt,” said New Horizons mission operations manager Dr. Alice Bowman, also from the Johns Hopkins University Applied Physics Laboratory.
“After guiding New Horizons for 13 years and more than 4 billion miles (6.4 billion km), we are poised to conduct the farthest flyby in history and reveal a new world.”
