Twenty-four hours before closest approach, Ultima Thule still takes up only two pixels in images taken by New Horizons' camera screen.
Its New Horizons spacecraft has survived the most distant exploration of another world - a tiny, icy object almost six and a half billion kilometers away from Earth.
At 10:28 am EST today, New Horizons made its pre-programed "phone home", letting the mission team back on Earth know that the craft completed the flyby unharmed.
NASA TV will provide live coverage of the New Horizons signal-acquisition, confirming the probe's status and flyby success.
Stern said the goal is to take images of Ultima that are three times the resolution the team had for Pluto.
As the clock strikes midnight on the east coast of the United States, you can tune in to NASA TV to join the space agency at mission control in the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, as the world celebrates the arrival of New Horizons at Ultima Thule.
"Reaching Ultima Thule from 4 billion miles away is an incredible achievement".
The crowd ushered in 2019 at midnight, then cheered, blew party horns and jubilantly waved small USA flags again 33 minutes later, the appointed time for New Horizons' closest approach to Ultima Thule. Measurements taken Saturday showed that the spacecraft was within 20 miles of its intended flyby distance from Ultima Thule, and that the timing of the encounter will be within 2 seconds of what was expected.
A few black-and-white pictures of Ultima Thule might be available following Tuesday's official confirmation, but the highly anticipated close-ups won't be ready until Wednesday or Thursday, in color, it is hoped.
The observations should help scientists ascertain how deep-freeze objects like Ultima Thule formed, along with the rest of the solar system, 4.5 billion years ago. "We're very confident in the spacecraft and very confident in the plan that we have for the exploration of Ultima", said Alan Stern, principal investigator for New Horizons, at a December 31 press conference. "We've just accomplished the most distant flyby", she said. If a solo act, it's likely 32 kilometres long at most.
Scientists made a decision to study it with New Horizons after the spaceship, which launched in 2006, completed its main mission of flying by Pluto in 2015, returning the most detailed images ever taken of the dwarf planet.
That better data won't take long to start turning up. "Kudos to the science team and mission partners for starting the textbooks on Pluto and the Kuiper Belt".
Ultima Thule was named for a mythical, far-northern island in medieval literature and cartography, according to Nasa.
"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. "What we'll very soon learn about this primordial building block of our solar system will exponentially expand our knowledge of this relatively unknown third region of space".