It’s official: NASA’s New Horizons, which visited Pluto back in 2015, has successfully completed a flyby of 2014 MU69—the most distant object a spacecraft has ever studied up close.
NASA celebrated the event with lots of fanfare just after midnight on New Year’s Day (Eastern Time), which is when the spacecraft actually made its closest approach of the alien rock. But that countdown was really just wishful thinking: New Horizons is more than 4 billion miles away from Earth, so it takes hours to transmit data back home. No one knew whether or not the mission had been successful until just after 10:30 a.m. Tuesday, when New Horizons finally checked in. With a spacecraft moving more than 30,000 miles per hour and targeting an object just 20 miles across, there’s not a lot of wiggle room for mistakes in your trajectory; success was far from guaranteed.
While the mood on Monday night was totally jubilant—there’s no fear of failure when you’re doing a fake countdown—folks in mission control looked nervous waiting for a true indication of the flyby’s success. Most of that tension eased as soon as confirmation of a strong signal came through, but the team still had to wait several minutes for the right data to download. At 10:34, Mission Operations Manager Alice Bowman appeared to murmur “I think we did it,” keeping her voice low and smile small while she awaited true confirmation. It wasn’t until 10:36 that the team received word of good science data from MU69, meaning that New Horizons had successfully used its instruments to pick up information on the object and was sending that precious data home.
“We have a healthy spacecraft, we’ve just accomplished the most distant flyby,” Bowman said. She added that the data they’d download later in the day would “help us understand the origins of our solar system.”
MU69 isn’t a particularly unique object, at least as far as we can tell—it’s probably a pretty typical resident of the Kuiper Belt. But that still sparks plenty of scientific interest. The Kuiper Belt is so cold and far from the sun’s light that objects therein are likely quite unchanged from the way they were when they first wound up there in the earliest days of our solar system. The hope is that studying bodies like MU69 will help us better understand the building blocks that formed our planet and the ones around us, and how (and why) they came together.
During a press conference later on Tuesday, the team released a second image taken before the closest approach (the first, released on Monday, is at the top of this post). Check it out:
While the artist’s impression on the right shows a peanut-shaped little world, scientists aren’t quite ready to confirm that MU69 is a single body; it might actually be two rocks moving in tandem. Even this unprecedented image is far too fuzzy to be sure.
“It’s okay to laugh,”project scientist Hal Weaver said of the blurry shot in a press conference. “But it’s better than what we had yesterday.”
We can expect NASA to release clearer shots—ones taken during the closest approach—on Wednesday, assuming New Horizons actually managed to point its camera at the right patch of space to capture them. The New Horizons team expects to settle MU69’s shape once and for all with those images, though the highest resolution photos won’t actually arrive until February. Because of the long delay when downloading data from a spacecraft as distant as New Horizons, scientists have to carefully prioritize their payloads. It will take 20 months for everything collected during the flyby to arrive on Earth.
Rather delightfully, NASA believes that MU69’s axis of rotation is such that, from our perspective, it’s spinning like a propeller. That’s one mystery already (possibly) solved; scientists had wondered why they didn’t see the object dimming and brightening as it spun, which can be explained by the fact that we’re always seeing its sunlit side.
If past flyby missions are any indication, the New Horizons team will tease out a few potential scientific findings—with plenty of hedging—in the coming days, but most of the stuff we learn about MU69 will come out months and years from now, as scientists on Earth pore over the data and interpret (and debate) its meaning. In other words, the mission is far from over. And as for New Horizons itself, the spacecraft might have enough juice to hit one more target. NASA is working on identifying a potential place to visit even farther out in the Kuiper Belt, which New Horizons could swing by sometime in the next decade.
This post has been updated.