A European spacecraft named Rosetta, after making a roundabout ten-year journey of over four billion miles through space, has finally arrived within a mere 62 miles of Comet 67P/Churyumov-Gerasimenko, which is hurtling through space at a speed of 35,000 miles per hour, as reported by the New York Times.
The 1.3 billion euro spacecraft is named after the Rosetta Stone, the ancient tablet that was the key to deciphering Egyptian hieroglyphics, and scientists hope that this Rosetta’s observations will offer important clues to how the solar system came together.
“After ten years, five months and four days traveling towards our destination, looping around the Sun five times and clocking up 6.4 billion kilometres, we are delighted to announce finally ‘we are here’,” said Jean-Jacques Dordain, the director general of the European Space Agency, as reported in The Telegraph. “Europe’s Rosetta is now the first spacecraft in history to rendezvous with a comet, a major highlight in exploring our origins. The discoveries can begin.”
The comet, a giant object almost the size of Japan’s Mount Fuji, and nicknamed C-G for obvious reasons, is composed of ice, dust and rock. It is a frozen leftover from the formation of the solar system 4.5 billion years ago. In July, Rosetta measured C-G’s surface temperature as minus 94 degrees Fahrenheit.
Rosetta, a boxy structure roughly nine by seven feet, powered by two 47-foot-long solar panels, was launched in 2004, from Kourou, French Guiana. Because the comet is moving far faster than speeds which could ever be achieved by a spacecraft leaving Earth, Rosetta traveled a circuitous route in order to use the gravitational pull of the Earth and Mars to act like a sling shot that propelled the spacecraft into the perfect spot for a rendezvous where it arrived in July 2011–more than two years early–and had to be put into deep space hibernation to await the comet’s next pass. In January, Rosetta was awakened from its slumber and has spent the last seven months catching up with the speedy C-G.
After a frantic chase, Rosetta is now slowing down to the pace of a person walking, about two miles per hour relative to the speed of the comet, in order to observe it more closely.
As Rosetta neared its target, early photographs revealed an unexpectedly irregular shape for the 2.5-mile-wide comet, that seemed to resemble a giant rubber duck. More recent photographs have revealed cliffs, deep shadows and also flat areas with boulders sitting on the surface.
For now, Rosetta and C-G are dancing together through space at a distance of 330 million miles away from the sun, more than three times further from the sun than the Earth.
But it’s a tricky duet because Rosetta must avoid being captured by C-G’s gravity. Therefore, Rosetta is flying in a triangular path in front of C-G in order to map its surface. Eventually, Rosetta will move to within 6.2 miles of the surface and enter into an orbit around the comet.
Come November, after searching for a soft spot to aim for, Rosetta will fire a 62-pound lander named Philae (after the island in the Nile where the Rosetta Stone was found) which will be pulled down by the comet’s gravity and will drop to the surface at a couple of miles per hour. Then Philae will attach itself to C-G with harpoons and hold on for what promises to be a marvelous deep space version of a Nantucket sleighride.
If Philae is successful, it will be the first time that a spacecraft has set down safely on a comet. There have been previous attempts: NASA’s Deep Impact slammed into a comet in 2005, and another mission, Stardust, collected particles of comet dust that contained glycine, an amino acid that is a basic part of life.
Designed to operate through 2015, Rosetta and Philae will make observations as the comet makes its nearest approach to the sun a little more than a year from now, at 115 million miles, still outside the Earth’s orbit. The comet will remain too dim to be seen by the naked eye.
Laurence O’Rourke, of The European Space Agency’s science team, told the New York Times: “This mission isn’t just about arriving at a comet. It’s about studying the comet. It’s about placing a lander on a comet, but again the mission does not end there. The science continues. We’re trying to follow this comet all around its orbit.”
