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It’s one of those moments in space exploration when the true immensity of the universe sharpens into clarity. More than 10 years ago, on March 2, 2004, the European Space Agency launched the Rosetta spacecraft. More than 10 years of hurtling through 4 billion miles of black, 10 years of monitoring its progress, 10 years of anticipation. For this moment: The rendezvous with a comet that’s two miles long and 2.5 miles wide.
On Wednesday morning, the European Space Agency (ESA) announced the Rosetta spacecraft opened “a new chapter in solar system exploration,” as it rendezvoused with the comet after firing its thrusters for nearly seven minutes to catch up with it.
“After 10 years, five months and four days traveling towards our destination, looping around the sun five times and clocking up 6.4 billion kilometers, we are delighted to announce finally, ‘We are here,'” proclaimed Jean-Jacques Dordain, ESA’s director general. “Europe’s Rosetta is now the first spacecraft in history to rendezvous with a comet, a major highlight in exploring our origins. Discoveries can start.”
“Here” means in orbit, not actually on the comet. That comes later.
Right now, Rosetta is in a holding pattern about 60 miles (100 kilometers) from the comet, but over the next couple of months that orbit is expected to close in on an altitude of 12 to 20 miles (20 to 30 kilometers). In November, Rosetta is scheduled to send out a piggyback probe, named Philae, to descend to the comet’s surface. Based on temperature readings made by Rosetta’s instruments, scientists have already surmised that the comet has a porous, dusty crust with ice beneath. The surface is strewn with boulders the size of houses, and Churyumenko-Gerasimov’s icy cliffs rise as high as 500 feet (150 meters).
Comets are considered both enigmatic and pivotal to an understanding of the solar system. Since May, the Rosetta has performed 10 maneuvers to catch up to and eventually meet the comet. “If any of those maneuvers had failed,” the organization said, “the mission would have been lost, and the spacecraft would simply have flown by the comet.”
“Arriving at the comet is really only just the beginning of an even bigger adventure, with greater challenges still to come as we learn how to operate in this uncharted environment, start to orbit and, eventually, land,” trumpeted Sylvain Lodiot, ESA’s Rosetta spacecraft operations manager.
Other space missions to comets have been different. Some have made the equivalent of a drive-by. NASA’s Deep Impact collided with its target in 2005.
Scientists are hoping for a smoother landing this time. “Over the next few months, in addition to characterizing the comet nucleus and setting the bar for the rest of the mission, we will begin final preparations for another space history first: landing on a comet,” Rosetta project scientist Matt Taylor said.