New Horizons' eagerly awaited "phone home" command, indicating if it survived the close pass - at a distance of just 2,200 miles (3,500 kilometers) - is expected January 1 at 10:29 a.m. (1529 GMT).
"We've been taking images of Ultima Thule ever since August from onboard the spacecraft, but it's just a dot in the distance that grows brighter and brighter and brighter".
The piece of rock measures 30 kilometers (19 miles) in diameter and was chosen as a target after it became the first solar system object to have been discovered after the New Horizons launch in 2006.
The scientists believe that Ultima can provide clues about the formation of dwarf planets like Pluto and also help understand how the solar system was a billion years ago. It was detected by scientists in 2014 using the Hubble Space Telescope.
Already there is reason to believe something odd lies just around the corner. Officially known as 2014 MU69, it got the nickname Ultima Thule in an online vote. And even though there are reasonable explanations for this, having to deal with a mystery so early on does nothing but to entice researchers even further.
As San Antonio rings in the New Year, NASA expects to celebrate a historic first flyby on the edge of our solar system.
Britain makes winning start to Hopman Cup
Bencic beat Katie Boulter 6-2 7-6 in her opening clash of the tournament to help Switzerland clinch victory over Great Britain. With the mixed doubles then a dead rubber, Cornet and Pouille took a consolation win for France 4-3, 4-2.
"Because this is a flyby mission, we only have one chance to get it right", said Alice Bowman, missions operations manager for New Horizons. Those is circular orbits like Ultima Thule have remained there throughout the solar system's 4.5 billion year history in temperatures close to absolute zero.
Scientists say Ultima is like a big frozen mummy born in the distant galaxy and should act like a time capsule because its frozen terroir should preserve its history. In past, New Horizons has already bewildered scientists by the photos of Pluto. It's fitting, considering New Horizons' pioneering journey.
What has made the task even more challenging for the Quebec City native is the fact that it takes six hours for the signal from Earth to reach the spacecraft and another six hours to return.
The distances involved are so huge that transmitted data takes two days to reach to Earth.
New Horizons is scheduled to pass Ultima Thule at its closest point at 11:33 p.m. Monday. Compensating for that somewhat is that the dim sunlight in the Kuiper Belt left it past the "snow line" for a variety of gasses, meaning those gasses froze out to form particles.
"The Voyagers and Pioneers flew through the Kuiper Belt at a time when we didn't know this region existed", Jim Green, director of NASA's Planetary Science Division, said in a statement.
"Across the whole team, people are ready, they're in the game, we can't wait to go exploring", Stern added. "It's been three-and-a-half years (since the Pluto flyby), we've worked so hard, people are ready to see that payoff and see what we can learn about the birth of our solar system". "To me, that is what's most exciting - this is pure exploration and fundamental science!"