NASA’s New Horizons sailed past the tiny planet Pluto in the distant reaches of the solar system on Tuesday, capping a journey of 3 billion miles (4.88 billion km) that began nine and a half years ago.
The spacecraft passed by the ice-and-rock planetoid and its entourage of five moons at 7:49 am EDT (1149 GMT). The event culminated an initiative to survey the solar system that the space agency embarked upon more than 50 years ago.
“Pluto just had its first visitor,” President Obama tweeted. “Thanks NASA. It’s a great day for discovery and American leadership.”
About 13 hours after its closest approach to Pluto, the last major unexplored body in the solar system, New Horizons phoned home, signalling that it had survived its 31,000 miles per hour (49,000 km per hour) blitz through the Pluto system.
‘A tremendous moment’
Managers had estimated there was a 1-in-10,000 chance a debris strike could destroy New Horizons as it soared just 7,750 miles (12,472 km) – about the distance from New York to Mumbai – from Pluto.
But right on time, New Horizons made radio contact with flight controllers at the Johns Hopkins University Applied Physics Lab outside Baltimore, sparking a wave of shouts and applause from an overflow crowd gathered to watch the drama unfold.
“This is a tremendous moment in human history,” said John Grunsfeld, NASA’s associate administrator for science.
Sending back its first post-flyby signal took another four-and-a-half hours, the time it takes radio signals, travelling at light speed, to travel the 3 billion miles (4.88 billion km) back to Earth.
“This is clearly a world where both geology and atmosphere climatology play a role,” said Alan Stern, New Horizons lead scientist. He noted that it appears that nitrogen and methane snow fall on Pluto.
“Now the solar system will be further opened up to us, revealing the secrets of distant Pluto,” British cosmologist Stephen Hawking said in a message broadcast on NASA TV.
It will take about 16 months for New Horizons to transmit back all the thousands of images and measurements taken during its pass by Pluto. By then, the spacecraft will have travelled even deeper into the Kuiper Belt, heading for a possible follow-on mission to one of Pluto’s cousins.