Though it’s still 172 million km from its target, the New Horizons spacecraft has caught a first glimpse of Ultima Thule, a mysterious Kuiper Belt object.
With Pluto now firmly in its rearview mirror, NASA’s New Horizons spacecraft is steadily chugging towards Ultima Thule, a Kuiper Belt object located, on average, about 44 AU from the Sun (one AU is the average distance of the Earth to the Sun). By comparison, Pluto’s orbit is around 33.63 AU.
On August 16, and at a distance of 172 million km from Ultima Thule, New Horizons used its telescopic Long Range Reconnaissance Imager (LORRI) to snap four dozen images. The data was transmitted back to Earth, where NASA scientists, to their delight, managed to create a composite image and discern the dim object from all the background noise produced by stars.
Happily, the location of Ultimate Thule, or (486958) 2014 MU69 as it’s officially known, was exactly where NASA scientists had predicted. That means New Horizons is right on track.
“The image field is extremely rich with background stars, which makes it difficult to detect faint objects,” Hal Weaver, a New Horizons project scientist and LORRI principal investigator, said in a statement.
“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.”
This picture is significant for several reasons.
First and foremost, it’s super cool — it’s an actual photograph of a 30km-wide object located 6.5 billion km from Earth. Secondly, these images are now the most distant ever taken from Earth (New Horizons just broke its own record). And lastly, New Horizons proved that it’s now able to visually detect its target, which means mission planners can adjust the spacecraft’s trajectory if needed.
According to NASA’s itinerary, New Horizons will zoom past Ultima Thule on 1 January 2019 (yep, New Year’s Day) at 2:33PM AEST. (It boggles the mind to think that, after travelling for billions of kilometres, NASA knows its its arrival time down to the minute. I only wish my own navigation skills were that accurate.)
Once the rendezvous happens, it’ll be the most distant object ever visited by a human-built spacecraft.
We don’t know much about Ultima Thule, but steady observations and measurements over the past several years suggests it’s irregularly shaped, not spherical, and possibly not one object but two objects (a binary pair). But with Ultima Thule now within visual distance of New Horizons, we’ll likely know a lot more about it soon.