It took 9 1/2-years and 3 billion miles to reach this moment.
Tuesday morning NASA is making a history flyby of the dwarf planet Pluto, which was actually a full-fledged planet when the New Horizons spacecraft blasted off Earth in 2006. The closest the spacecraft will get to the previously unexplored planet is 7,767 miles, and that's expected to happen around 7:49 a.m EDT.
And though scientists do not expect anything to go wrong with the mission, managers said there's only one chance in 10,000 something could go wrong, like a debris strike.
Watch the live flyby right here:
New Horizons has already beamed back information that announced Pluto was larger than previously thought. Measurements by the spacecraft indicate the radius of the dwarf planet spans 736 miles, plus or minus six miles. That's 20 miles to 30 miles bigger than previous estimates. The diameter would be twice that.
Principal scientist Alan Stern said this means Pluto has a lower density than thought, which could mean an icier interior.
"The Pluto system is enchanting in its strangeness, its alien beauty," Stern told reporters Monday.
Watch NASA talk about the mission:
Discovered in 1930, Pluto is the largest object in the so-called Kuiper Belt, considered the third zone of the solar system after the inner rocky planets and outer gaseous ones. This unknown territory is a shooting gallery of comets and other small bodies.
An extension of the $720 million mission, not yet approved, could have New Horizons flying past another much smaller Kuiper Belt object, before departing the solar system.
The Associated Press contributed to this report.
Front page image via NASA/JHUAPL/SWRI.