At left is an image of a crowded star field captured by the Long Range Reconnaissance Imager aboard NASA’s New Horizons spacecraft that shows the location of Ultima Thule, a Kuiper Belt body the probe will fly past on 1 January. At right is a processed view with stars subtracted, clearly showing the target and confirming New Horizons is on course. Image: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Four months and more than 172 million kilometres (107 million miles) away from a New Year’s Day flyby, NASA’s New Horizons spacecraft finally caught sight of its post-Pluto target, a small Kuiper Belt body left over from the birth of the solar system.
The photo was captured by the spacecraft’s Long Range Reconnaissance Imager, or LORRI, on 16 August, part of a sequence of 48 images taken during the spacecraft’s first attempt to spot 2014 MU69, nicknamed Ultima Thule by the New Horizons team. To the team’s delight, the target was exactly where they expected it to be based on imagery from the Hubble Space Telescope.
“The image field is extremely rich with background stars, which makes it difficult to detect faint objects,” said Hal Weaver, New Horizons project scientist and LORRI principal investigator from the Johns Hopkins Applied Physics Laboratory. “It really is like finding a needle in a haystack.
“In these first images, Ultima appears only as a bump on the side of a background star that’s roughly 17 times brighter, but Ultima will be getting brighter and easier to see as the spacecraft gets closer.”
Launched on 19 January 2006, New Horizons completed its primary mission by flying past Pluto on 14 July 2015 and beaming back a treasure trove of images and data about the famously demoted dwarf planet.
In the wake of the Pluto flyby, mission managers used Hubble to find another target along the spacecraft’s path – Ultima Thule – and adjusted the probe’s flight path to set up a 1 January 2019 flyby. The new target is roughly 1.6 billion kilometres (1 billion miles) beyond Pluto, making it by far the most distant body in the solar system to get a close-range inspection.
Over the next four months, additional images from New Horizons will help flight controllers fine-tune the spacecraft’s trajectory.
“Our team worked hard to determine if Ultima was detected by LORRI at such a great distance, and the result is a clear yes,” said Alan Stern, New Horizons principal investigator at the Southwest Research Institute. “We now have Ultima in our sights from much farther out than once thought possible. We are on Ul