A small, ice-cold world 1.6 billion kilometers outside Pluto gets visitors to New Year's Day.
NASA's New Horizons spacecraft will fly through a mysterious object nicknamed Ultima Thule.
This will be the most distant world humanity has ever explored.
The fly took place three and a half years after New Horizons swung past Pluto and produced the first close-up photo of the dwarf planet.
This time, the drama will open 6.4 billion kilometers from Earth, so far it will be 10 hours before flight controllers in Laurel, Maryland, know whether the spacecraft survived close encounters.
Leading scientist Alan Stern said the team had worked for years now and now, "that happened !!"
Originally published as Spacecraft to the world past Pluto