NASA's unmanned New Horizons spacecraft is speeding closer to an historic Pluto flyby.
It's expected to sweep past the previously unexplored dwarf planet early tomorrow morning, New Zealand time.
The dwarf planet is bigger than scientists previously thought; it is now believed to have a diameter of more than 2000km.
"This is near the end of the first golden age of space exploration," says space commentator Matthew Pavletich. "Some people are saying you can bookend the first age of space exploration with this mission and it's been underway for 9-and-a-half years and it's travelled far more than 3 billion miles… it has been an epic odyssey," he said on TV3's Paul Henry programme this morning.
Mr Pavletich says the New Horizons project has spanned more than 12 years' work for scientists, with the data gleaned from the flyby coming back to Earth over several months.
"The speed is slower than a dial-up modem, they're sending it back through 5 billion kilometres of space – it's just extraordinary."
As the space craft approaches Pluto, the resolution of images it is taking doubles every few hours, says Mr Pavletich.
"[Pluto] is frozen almost exactly the way it was created so many billions of years ago and this probe is funded more or less from the loose change down the back of Congress' budget – it's the price of a couple of Harry Potter movies, and we get to explore a new world."
Watch the video to see the interview with Mr Pavletich.