The world's fastest spaceship is being readied for a scheduled Jan. 17 launch, with the craft reaching Pluto by the summer of 2015.
Pluto, nearly 4 billion miles from Earth, is the only planet in the Solar System that has never had a human-engineered visitor.
The piano-sized spacecraft named New Horizons will spend five months in the vicinity of Pluto, taking pictures and gathering other data.
The $700 million mission is the first space expedition aimed specifically at a celestial body beyond Neptune.
NASA hopes to launch New Horizons from Cape Canaveral as early as possible during a 29-day window that opens at 1:24 p.m. on Jan. 17.
The spacecraft will travel at nearly 30,000 mph and it will take nine hours to pass Earth's moon. In contrast, it took the Apollo astronauts three days for that trip.
If launch occurs before Feb. 3 the probe will get a gravity boost as it passes Jupiter, increasing its speed to 47,000 mph, UPI reports.