Voyager 1 reaches interstellar space

[john]

After traveling ten years and 4 billion miles the Rosetta spacecraft has caught up with it's target comet. The comet is traveling at 55,000 kilometers per hour (relative to the sun I would guess) which is more than 10X the speed of a bullet shot from a typical rifle. Impressive accomplishment.

...To catch it, the team needed to get Rosetta into the comet’s orbit. As the spacecraft made four orbits around the sun, it flung itself around Earth, then around Mars, and then around Earth twice more, accelerating and adjusting its course along the way. On its route to match the comet’s path, Rosetta also flew by two main belt asteroids, in 2008 and 2010, and field-tested many of its 21 instruments.

In the summer of 2011, Rosetta passed through the main asteroid belt, between the orbits of Mars and Jupiter, and continued out toward Jupiter’s orbit. At that distance from the sun, the spacecraft’s 104-foot-span solar panels were producing less and less energy, so mission controllers put Rosetta into its planned hibernation, shutting down everything but minimal heating for vital components. The spacecraft slept for almost three years. A wake-up alarm went off this past January as Rosetta was inbound on the interception lap, 500 million miles from the sun....

...After about two months, Rosetta will draw to within 19 miles, close enough to be captured by the comet’s gravity (only a tiny fraction of Earth’s). Rosetta will wind its orbit closer, while at mission control, scientists will scour the surface maps for a smooth landing site. Rosetta is carrying a 220-pound lander, Philae, named after the Nile River island where archeologists found an obelisk confirming the Rosetta translation. “We fly within three kilometers [1.9 miles] of the surface and drop the lander,” says Jansen.

...In December, the inbound comet will get within 400 million miles of the sun, about the distance from the sun to the main asteroid belt. Here, the sun’s heat will start to bring it alive. Gas jets will belch from its surface, and a hazy atmosphere called a coma will form from ice and dust, and stretch out to become an incandescent tail. For the next month and perhaps longer, Philae will ride Churyumov-Gerasimenko like a bronco buster, “not bothered too much by all this,” Jansen says, and Rosetta will escort the two, transmitting data from its 11 instruments and the 10 on the lander. The instruments will map the comet’s surface, analyze the composition of the nucleus, coma, and tail, measure the size and momentum of the material emanating from the surface, and image the comet from the ultraviolet to the infrared

...Rosetta will continue to orbit until the disturbance from the comet’s powerful gas jets overcomes the spacecraft’s ability to control its angle. Then it will move out of orbit, but keep up with the comet as closely as possible. The comet will make its closest approach to the sun—112 million miles—on August 13, 2015, then head back to Jupiter’s neighborhood, with Rosetta keeping pace and Philae clinging to its back.

Read more: http://www.airspacemag.com/space/rosetta...z39fdyrXxz