LAUREL (United States) • An unmanned Nasa spacecraft whizzed by Pluto yesterday, making its closest approach in the climax of a decade-long journey to explore the dwarf planet for the first time, the United States space agency said.
"The New Horizons spacecraft passes its closest approach mark at Pluto after a three billion mile
(4.8 billion km) journey," a Nasa commentator said as spectators waved flags in a room at the Johns Hopkins Applied Physics Centre outside Washington.
The encounter happened at 7.49am (7.49pm Singapore time), with the spacecraft running on auto-pilot. It was to pass by Pluto at a distance of 12,500km.
"It is a moment of celebration because we have done the anchor leg," said New Horizons principal investigator Alan Stern.
"We have completed the initial reconnaissance of the solar system, an endeavour started under President (John F.) Kennedy more than 50 years ago, continuing today under President (Barack) Obama."
Nasa was expected to receive a signal from the spacecraft later yesterday to find out whether or not it survived the encounter. Experts said there was a one-in-10,000 chance that the craft, the size of a baby grand piano, could collide with debris in the region beyond Neptune, known as the Kuiper Belt.
Nasa was expected to announce whether the spacecraft survived the high-speed fly-by about 13 hours later.
Never before has a spacecraft ventured into the Kuiper Belt, and New Horizons has been on its way there for more than nine years.
The New Horizons mission was launched in 2006, the same year that Pluto was downgraded to "dwarf planet" status due to the celestial body's small size.
New Horizons is the first spacecraft to fly past Pluto, and its seven scientific instruments aim to reveal details of the surface, geology and atmosphere of the planet and its five moons.
Images it collects will be beamed back to Earth if it survives.
What is now known about Pluto could probably fit on a few index cards, according to Mr Stern.
However, with data collected from the New Horizons' mission, what is gathered will enable entire textbooks to be written about the mysterious celestial body.
Already, scientists have learnt from New Horizons that Pluto is 20km-30km larger than previously thought, with a radius of 1,185km.
Scientists have also confirmed the existence of a polar ice cap on Pluto, and found nitrogen escaping from its atmosphere. "This is truly a hallmark in human history," said Nasa's head of the science mission directorate, Mr John Grunsfeld.