The spacecraft team that brought us close-ups of Pluto will ring in the new year by exploring an even more distant and mysterious world.
The image was taken on Sunday, when the spacecraft was still 1.5 million kilometres from its 12:33 a.m. ET rendezvous on January 1.
New Horizons zoomed past the small celestial object known as Ultima Thule three-and-a-half years after its spectacular brush with Pluto.
EVER, " tweeted the project's lead scientist, Alan Stern of the Southwest Research Institute. The Ultima Thule rendezvous was more complicated, given its 4 billion-mile (6.4 billion-kilometre) distance from Earth, the much closer gap between the spacecraft and its target, and all the unknowns surrounding Ultima Thule.
The rewards will come over the next 20 months as New Horizons slowly transmits the estimated seven gigabytes of data collected during the flyby.
New Horizons acquired gigabytes of photos and other observations during the pass, however, because of the vast distance between the spacecraft and Earth, it will take until September 2020 to retrieve all of the data stored on the probe.
"We have a healthy spacecraft", said mission operations manager Alice Bowman, as cheers erupted in the control rooms at Johns Hopkins Applied Physics Laboratory in Maryland.
Scientists speculate Ultima Thule could be two objects closely orbiting one another.
Real-time video of the actual flyby was impossible, since it takes more than six hours for a signal sent from Earth to reach the spaceship, and another six hours for the response to arrive.
NASA kicked off the new year with a midnight flyby of the most distant Solar System object ever visited by a manmade spacecraft.
New Horizons first launched in 2006 with the goal of doing a flyby study of the Pluto system by 2015.
"It is probably the best time capsule we've ever had for understanding the birth of our solar system and the planets in it, " Stern said.
This artist's impression of Ultima Thule depicts it as a contact binary, two smaller objects that orbit each other and are so close that they touch.
NASA's live stream of the event was very informative, providing details about the mission and animations to show where the spacecraft was in relation to Ultima Thule.
Scientists say Ultima Thule represents a class of objects known as "cold classicals" in the Kuiper Belt, a broad stretch of icy material beyond the orbit of Neptune.
"Ultima Thule is 17,000 times as far away as the "giant leap" of Apollo's lunar missions", Stern noted in an opinion piece in The New York Times.
Ultima Thule was named for a mythical, far-northern island in medieval literature and cartography, according to Nasa.
The encounter with Ultima Thule will be brief and technically demanding, even more so than New Horizons' Pluto flyby.
"This is just a first glimpse of what is rapidly going to get better from here on out, " Spencer said.