Europe’s Rosetta, after a Hollywood-style chase that lasted more than 10 years and spanned a distance of 4 billion miles, has become the first ever spacecraft to orbit a comet. The ESA’s Rosetta probe will now orbit the comet — dubbed 67P, or affectionately “the rubber duck” – for a few months, in preparation for an even more exciting event later in the year: In November, Rosetta will deploy Philae, the first ever spacecraft to attempt a landing on a comet. Philae carries a bunch of instruments, including a drill, to find out once and for all what actually goes on on a comet — including, hopefully, whether comets really are the vehicle by which prebiotic molecules or early microorganisms spread throughout the early Solar System. Rosetta project scientist Matt Taylor, speaking about today’s successful orbital insertion, sums it up rather succinctly: “For me this is the sexiest, most fantastic mission there’s ever been.”
The Rosetta spacecraft was launched aboard an Ariane 5 rocket way back in March 2004. To reach comet 67P, which orbits the Sun every 6.45 years, Rosetta has traveled a grand total of 6.4 billion kilometers (3.97 billion miles), using the gravity of both Mars and Earth to gather enough speed to sling-shot into the comet’s path. The comet is traveling through space at around 55,000 kph (34,000 mph), but somehow the boffins at the ESA managed to maneuver Rosetta in such a way that, despite playing interstellar catch-up for 10 years, its relative speed is now just 2.2 mph (1 meter per second) faster than the comet. The close relative speed was required for today’s maneuver, which inserted Rosetta into orbit around the comet.
The photo at the top of the story was taken on August 3, just before orbital insertion. It’s pretty awesome when you bear in mind that the comet is only about 2.5 miles across. Seen from one of Earth’s telescopes, it would be nothing more than a one-pixel blur.
One of the primary reasons that 67P was chosen as a target was due to its orbital period. A comet spends most of its life in the cold expanse of deep space — but every few years, it passes by its parent star and starts to melt, shedding tons of ice and dust into space. This is what causes a comet to “bloom” or become fuzzy — and when Earth passes through this debris, called the comet’s coma, it causes a meteor shower. Comet 67P will hit its perihelion — its closest point to the Sun — in August 2015, and Rosetta will have the best seat in the universe.
If all goes to plan, the European Space Agency will also deploy and land the Philae lander on 67P in November 2014. While Rosetta is armed with lots of imagers and spectrometers, Philae has a bunch of its own instruments — and, perhaps most importantly, a big ol’ drill. Philae will drill into the core of the comet to analyze its composition — and the ESA scientists don’t really know what they’ll find. Philae will attach itself to the comet with two harpoon guns, incidentally.
The ESA director general, Jean-Jacques Dordain, was rather excited about today’s successful orbital insertion. “After ten years, five months and four days travelling 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’.” Matt Taylor, a Rosetta project scientist, spoke a little more frankly. “For me this is the sexiest, most fantastic mission there’s ever been. It’s ticking a number of boxes in terms of fascination, exploration, technology and science – predominantly science.”
As for what scientific data Rosetta and Philae will actually return, we’ll have to wait and see. Considering this is the first time that humanity has orbited or landed on a comet, and the hypothesis that comets may have played an important role in the distribution of life (or at least the building blocks of life) around the Solar System, we could be in for some very interesting findings indeed.
link:extremetech
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