NASA's New Horizons probe has achieved another milestone on its already historic mission to our solar system's erstwhile ninth planet: it is now officially the closest any human-made spacecraft has ever come to Pluto! And it will be only getting closer each day (by about a million kilometers!) until it finally makes its closest pass by the dwarf planet and its family of frozen moons on July 14, 2015.
The previous distance record was held by the Voyager 1 spacecraft, which came within 983 million miles (1.58 billion km) of Pluto on Jan. 29, 1986. New Horizons surpassed that distance on Friday, Dec. 2., after 2,143 days of cruising interplanetary space.
(In the meantime Voyager 1 is 11 billion miles out, far past the orbit of Pluto and making the transition into interstellar space. It is still faithfully reporting back to Earth although at that distance it takes about 14 hours for the signal to get here!)
New Horizons is one of the fastest machines ever created. It speeds through space at nearly 35,000 mph (55,500 km/hr)... almost 20 times faster than a bullet. And even at that speed it will take over 9.5 years to arrive at Pluto, but the halfway mark has already been reached and the countdown has begun to New Horizons' long-awaited arrival at the mysterious distant world.
"We've come a long way across the solar system," said Glen Fountain, New Horizons project manager at the Johns Hopkins University Applied Physics Laboratory. "When we launched it seemed like our 10-year journey would take forever, but those years have been passing us quickly. We're almost six years in flight, and it's just about three years until our encounter begins."
New Horizons will not orbit or land on Pluto but will pass by closely enough to allow its high-definition camera (LORRI) to image the dwarf planet's surface in unprecedented detail, resolving features as small as 200 feet across.
After the close encounter New Horizons will venture out into the Kuiper Belt, a distant region of icy bodies and other Pluto-like worlds. Plans to visit another Kuiper Belt Object (KBO) are still being developed. But first things first: Pluto awaits!
"What a cool milestone!" said New Horizons Principal Investigator Alan Stern of the Southwest Research Institute. "Although we're still a long way - 1.5 billion kilometers from Pluto - we're now in new territory as the closest any spacecraft has ever gotten to Pluto, and getting closer every day by over a million kilometers."
Read more on the New Horizons mission page.
Image: New Horizons sails ever onwards and outwards. Credit: Southwest Research Institute (Dan Durda)/Johns Hopkins University Applied Physics Laboratory (Ken Moscati)