Comet 67P’s course takes it through summertime sun
It’s summer on comet 67P, and things seem to be heating up a bit. The comet just passed through its perihelion, the point in its orbit closest to the sun. From this point onward the comet will begin moving away from the sun again, looping back out into deep space to continue its six-and-a-half year orbit. That doesn’t mean the summertime is over though, as temperatures are rising, as is the activity levels of the comet itself.
Bursting with activity
As the comet has approached the sun, our intrepid reporter, the Rosetta spacecraft, has been capturing activity along the way. Dust, gas and even boulders of yet-to-be-determined size have been breaking off from the comet’s peanut-shaped core. In one dramatic instance, a jet of ice and gas was caught on camera, spraying out of the comet like a geyser over the course of 18 minutes. This pattern fits with observations of comets in general, which develop “tails” of gas and dust as they streak by the sun. As frozen materials melt and expand, pieces can break off and drift along side the comet’s core.
While the perihelion put 67P between Earth’s and Mars’ orbits, this doesn’t mean temperatures have peaked at this point. These temperature increases are very gradual and slightly cumulative, so just as the summer solstice on Earth isn’t likely to be the warmest day of the year, 67P’s warmest days are yet to come. We don’t know exactly how that will play out though, as nobody has ever been in a position to measure these thing before.
Moving back the front-row seats
The team behind the Rosetta spacecraft are expecting more debris from the comet, and so they’ve been moving the satellite further and further away to avoid collisions. While it was once in a tight, 18 mile orbit around the comet’s core, Rosetta is now a safer 186 miles out. While all systems are go for this eye in the sky, the same can’t be said of Philae. The deployed lander’s dramatic mission has been quiet lately, as a recent “phone home” has proven to be a one-off event. Hopefully the lander is just distracted with some beach reading before letting us know what the conditions are on the surface of the comet.
Source: Rosetta: Comet 67P makes closest approach to Sun by Jonathan Webb, BBC News