Nasa's New Horizons spacecraft has made contact with Earth, confirming its successful flypast of Pluto, after a journey to the far reaches of the solar system that has taken nine-and-a-half years and 3 billion miles (4.88bn km). At precisely 8.52.37pm Eastern US time, the probe "phoned home" to mission control in Maryland, 13 hours after it flew within 7,750 miles (12,472km) of Pluto. Scientists greeted the news of its safe passage with cheers and tears, calling it a historic day for space exploration. The successful mission means humans – specifically, the US – have now reached all nine planets of our solar system. Although Pluto was reclassified as a dwarf planet in 2006 – just months after New Horizons set off on its mission – Charles Bolden, Nasa's chief administrator, said he hoped that decision would be reconsidered. The New Horizons spacecraft had passed by Pluto and its five moons at 7.49am EDT (12.49 BST/9.49pm AEST) on Tuesday. It spent the following eight hours continuing to collect data and images from the last major unexplored body in our solar system, before sending out its signal home. The contact with flight controllers at the Johns Hopkins University applied physics lab in Maryland, some four-and-a-half hours later, sparked a wave of shouts and applause from the crowd gathered to watch the historic moment unfold. Pluto flyby Alice Bowman, the mission operations manager, said no errors or problems with the probe had been recorded: "We have a healthy spacecraft. We've recorded data of Pluto's system and we're outbound from Pluto ... Just like we practised, just like we planned it. We did it." Managers had estimated there was a one in 10,000 chance a debris strike could destroy the probe as it soared just 7,750 miles (12,472km) – about the distance from New York to Mumbai – from Pluto. With 99% of the data gathered during the encounter still on the spaceship, New Horizons' survival was critical to the mission. Bowman said she had had concerns before the signal was received. "You have a lot of faith in your children, but sometimes they don't do exactly what you want them to do ... so you worry. But our spacecraft did exactly what it was supposed to do and the signal was there." "This is truly a hallmark in human history," said John Grunsfeld, Nasa's associate administrator for science. US president Barack Obama tweeted in praise of the mission, calling it "a great day for discovery and American leadership". Since contact was re-established, so far only engineering data has been downloaded. But from early Wednesday morning US time (5.50am ET/10.50am BST/7.50pm AEST), scientific data will begin to be transferred to mission control. This will bring fresh images of Pluto – at 10 times the resolution of even the best pictures so far seen – as well as a wealth of information on the planet, as well as the moon Charon and its other satellites. These will be unveiled at a press conference later on Wednesday. Already, the images and measurements relayed from New Horizons has changed scientists' understanding of Pluto, which is smaller than Earth's moon. Once considered an icy, dead world, the planetoid has yielded signs of geological activity, with evidence of past and possibly present-day tectonics, or movements of its crust. "This is clearly a world where both geology and atmosphere climatology play a role," said Alan Stern, New Horizons' lead scientist, with the Southwest Research Institute in Boulder, Colorado. 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. "We explore because we are human and we want to know. I hope that Pluto will help us on that journey," Hawking said. 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. Source: The Guardian and Reuters
