“We’ve never, in the history of spaceflight, gone to an object we’ve known less about,” Stern said. “We know its orbit, we know its color, we know a little bit about its shape, and its reflectivity. We can’t even get the rotational period. I thought we’d have that 10 weeks ago.”

Ultima Thule wasn’t even discovered at the time of New Horizons’ launch in 2006. The mission, originally billed as an exploration of the then-planet Pluto, was extended after Ultima Thule, a teeny, wonky-shaped object estimated at less than 20 miles long, was first identified with the Hubble Telescope in the summer of 2014. And it has remained stalwartly enigmatic ever since.

But this oblong orb probably has a lot to say. Researchers believe that objects like Ultima Thule are the Solar System’s version of primordial soup: A time capsule from the pre-planet era that’s been orbiting the Sun undisturbed for the past 4.6 billion years. Which means getting up close and personal with Ultima could yield some critical insights into what the building blocks of our solar system looked like at their inception.

In the days leading up to the flyby, the Applied Physics Laboratory was abuzz with the fervor of sleep-deprived scientists, engineers, and staffers eager for their long-awaited moment of truth. On Sunday, Project Scientist Hal Weaver cheerily predicted that most of his team would be running on pure adrenaline for the entirety of New Year’s week.

Last minute meetings turned into all-nighters; scientists signed up to work in shifts. Some personnel even began toting sleeping bags, pillows, and air mattresses onto the premises. But it was probably Mark Holdridge, New Horizons’ Encounter Mission Manager, who took the cake—by pitching a full tent in his office.

Mark Holdridge, New Horizons’ encounter mission manager, pitched a tent in his office in the days leading up to the flyby in preparation for the long nights at the Applied Physics Laboratory. Image Credit: Hong Kang, Johns Hopkins University Applied Physics Laboratory

“We’re here for the exploration,” Alice Bowman, Mission Operations Manager, or MOM, of New Horizons’ Mission Operations Center, said at Sunday’s press briefing. “We’re happy to spend the night if that’s what it takes.”

On New Year’s Eve, scores of scientists, reporters, and space enthusiasts from around the country congregated at the Applied Physics Laboratory’s Kossiakoff Center. In the moments before midnight, a sea of scientists sipped champagne from plastic cups; wide-eyed children in space-themed t-shirts flitted in and out of the room waving American flags. As the first minutes of 2019 ticked onto the clock, rock and roll legend Brian May took the stage, debuting an anthem celebrating New Horizons’ historic journey. But for once, the lead guitarist of Queen was only the opening act.

Thirty-three minutes after the crowd rang in the new year, the New Horizons spacecraft came within 2,200 miles of Ultima Thule’s surface, capturing humankind’s first bits of data on the most primitive and most distant object ever explored.

But the true moment of elation—and relief—came several hours later, around 10:30 a.m., after a message heralding the spacecraft’s safety had digitally traversed the six-hour trip between New Horizons and Earth. Each signal beamed down confirmed that each of the probe’s subsystems remained on track to bring humanity news of an unexplored world.

“We have a healthy spacecraft,” Bowman proclaimed from the Mission Operations Center, before wrapping members of her team in a series of exuberant embraces.

As of yet, there still isn’t a great photo of Ultima Thule; most have shown it as a pinprick of light amidst a starry backdrop. Even at closest approach, New Horizons was about 2,200 miles from the object’s surface—a distance that’s over a hundred times longer than Ultima Thule’s predicted width.

An image of Ultima Thule, taken before the flyby and unveiled on New Year's Day. Ultima Thule may be a single, peanut-shaped object, or two objects stuck together; it's also still possible that there are two closely associated objects orbiting each other. New Horizons is thought to be approaching it from the side, as if descending down onto the top of a rotating propeller. Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

On New Year’s Day, the New Horizons team unveiled a new image taken just prior to closest approach that strongly hints at the rocky relic’s true physique. In the picture, Ultima looks to be a peanut-shaped smear, measuring about 22 miles long and around 9 miles across at its widest. More high-resolution images that will clarify Ultima’s shape, color, and surface topography should be in the team’s hands over the next couple days. “The team is raring to go,” Stern announced moments after the 12:33 a.m. countdown.

And more data will trickle in through the summer of 2020. The entire spacecraft operates on less power than a pair of 100-watt light bulbs, and from four billion miles away, its signal is weak. But information is still streaming back to Earth at about 1,000 bits per second. The answers will come—slowly, but surely.

In a way, this makes the path forward even more exciting. For Olkin, the days have blurred in the best way possible. “We’re just so excited to see everything,” she says. “New Year’s Eve, January 1… Every day’s a celebration. It’s work, but we all do it because we love it.”

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