We now know a lot more about that cosmic body, and it looks like a snowman.
Ultima Thule, as the small, icy object has been dubbed, was found to consist of two fused-together spheres, one of them three times bigger than the other, extending about 32 km across. The remaining two lobes formed Ultima Thule, and with its material we have a window into the early solar system.
Signals confirming the probe is healthy and had filled its digital recorders with science data on Ultima Thule reached the mission operations center at 10:29 a.m. EST (3:29 p.m. GMT).
It was the first exploration of such a primitive - and distant - planetary object in human history.
"Reaching Ultima Thule from 4 billion miles away is an incredible achievement".
Its remarkable appearance, unlike anything we've seen before, illuminates the processes that built the planets four and a half billion years ago.More news: Kante strike earns Chelsea slim win at Crystal Palace
Ultima Thule is one of few building blocks left from that process that humans have explored - and the only pristine example from that time.
"This flyby is a historic achievement", said New Horizons principal investigator Alan Stern of the Southwest Research Institute in Boulder, Colorado. "The data we have look fantastic and we're already learning about Ultima from up close".
"This mission has always been about delayed gratification", Stern said on Tuesday.
"And I would say that just because some bad guys once liked that term, we're not going to let them hijack it", he said, prompting a round of applause from team members and guests in the APL auditorium. As a whole, the little world measures 19 miles (30.5 km) long. Stern said the New Horizons team would start writing scientific papers next week, based on the data already in hand, and nearly certainly propose another mission extension to NASA by 2020. The new images and data confirmed the icy space rock's classification as a contact binary. They named the larger region Ultima and the smaller one Thule.
Scientists have ascertained that the object takes about 15 hours to make a full rotation.
So gentle was the initial contact between the two lobes of MU69 that Mr. Moore related it to getting into a fender bender auto accident that produces no damage; you wouldn't bother filling out the insurance claim. "This really puts the nail in the coffin now", Stern said. That means its two lobes are separate objects that have joined together. "This is exactly what we need to move the modeling work on planetary formation forward".
While much higher-resolution images will provide a better sense of the topography and geography of 2014 MU69, what is now known is that the bottom, larger lobe ("Ultima") contains changes in elevation greater than one kilometer and that the upper, smaller lobe ("Thule") may contain a plateau feature. This is how Ultima Thule is now showing itself to NASA and the rest of the planet from 17,000 miles out: The bowling pin of two days ago has now morphed into a snowman - or BB-8, as the Twitterverse is saying.