Get live updates on New Horizons flyby of a distant Kuiper Belt object

Editors note: This story will be updated December 31January 1 with dispatches from astronomy writer Lisa Grossman, who will be at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., with the New Horizons team. You can also see her updates on Twitter (@astrolisa) and on Science News Instagram feed (@sciencenewsmagazine).

Updated 10:40 a.m., December 31

New Horizons is speeding toward Ultima Thule at a whopping 14 kilometers per second. On December 30, the New Horizons team made a two-second adjustment to the timing of imaging and data gathering the spacecraft will do during the flyby. And the first of two “fail-safe” downloads of data from New Horizons completed successfully, ensuring that some information is in hand even if something goes catastrophically wrong during the the flyby.

This was New Horizons view of Ultima Thule on December 24:

The image is a combination of three 0.5-second-exposure images taken using the highest resolution of LORRI, or the Long Range Reconnaissance Imager, on board the spacecraft.

The last images that New Horizons sends home before the flyby will show the space rock as just five to seven pixels across — but that may be enough to answer some questions about Ultima Thule. For example, its about 30 kilometers wide, as far as we can tell — but we dont yet know if its a single object or two objects orbiting close to each other. And it doesnt seem to have rings, but its not crazy to think it might, even though its tiny. Asteroids Chariklo and Chiron, and dwarf planet Haumea all have rings despite their diminutive sizes.

Original post, 6:00 a.m., December 30:

After a journey of almost 13 years and more than 6.5 billion kilometers, New Horizons is about to meet a tiny, mysterious space rock called 2014 MU69.

The spacecraft will zip past MU69, also called Ultima Thule, at 12:33 a.m. Eastern Standard Time on January 1, at a speed of 14 kilometers per second. (See our preview story for more on the mission.) The New Years Eve party at the Johns Hopkins University Applied Physics Laboratory will be broadcast on APL's YouTube channel and on the APL Facebook page. (The flyby activities are also scheduled to be broadcast on NASA TV, despite the federal government shutdown.)

The broadcast will begin with a news briefing at 2 p.m. on December 31, and will pick up again with scientific lectures at 8 p.m. The countdown to the flyby starts just into the new year at 12:15 a.m. on January 1.

While there will certainly be celebration at the time of the flyby, NASA wont get confirmation from New Horizons that all went well right away. Just as when it flew past Pluto in 2015, New Horizons will focus all its energy on collecting data as it passes by MU69, rather than transmitting anything to Earth. MU69 is so far away that it will take six hours for a signal to go from the spacecraft to Earth. And the data downlink is so slow at that great distance that it will take until about September 2020 for all the science data to return to Earth.

But hopefully, when we wake up in 2019, well know that New Horizons is safe and has lots to tell us about MU69. Stay tuned.

Editor's note: The first update was updated to correct the speed of New Horizons. It's 14 kilometers per second, not 14,000 kilometers per second.