Posted by: Paul A. Forsyth | August 6, 2014

Rosetta Rendezvous with Comet

Earlier today, the European Space Agency announced that their probe Rosetta arrived at its target, the comet 67P/Churyumov–Gerasimenko, after a flight time of 10 years. (The easiest nickname that I’ve heard for the comet is “ChuGer.” In this comic, Mr. Munroe uses the stand-in “Kevin.”)

From Jim Timmer at Ars:

Earlier this year, Rosetta successfully woke from hibernation, and it’s been imaging the comet during its approach. Early images indicated that 67P/Churyumov-Gerasimenko has a two-lobed structure that some have compared to a rubber duck, albeit one with an unusually large head. The second lobe, corresponding to the duck’s body, is broader and more oblong.

Since the initial approach, Rosetta has eased to within 100km of the comet’s surface and captured detailed images of a very foreign world, one by turns smooth and pockmarked. The comet has been seen spraying a tiny bit of water into space (estimates are 300ml a second, based on Rosetta images), but the complex surface of 67P/Churyumov-Gerasimenko suggests a correspondingly complex history of activity. The comet is currently heading closer to the Sun, which may increase this venting over time.

The plan for the coming weeks is to have the orbiter approach to a distance of 50km before entering a circular orbit at a distance of 30km. Over the coming month, it will search for potential landing spots for Philae, a package of instruments that will tether itself to the comet’s surface. The lander is expected to reach the surface of 67P/Churyumov–Gerasimenko in early November.

ChuGer is in a highly elliptical orbit and takes 6.45 years to orbit the Sun. In the current orbital cycle, the comet is a little over one year from its closest approach to the Sun.

More info on the Rosetta mission from this ESA blog, and also here and here.

So, this is what a comet looks like up close.

Image Credits: (1) xkcd “What If?”; used under a CC BY-NC 2.5 license. (2) Photo by ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA, used for educational and/or informational purposes per ESA’s terms and conditions.

Update (August 6, 2014, 6:15 PM): to clarify, although Rosetta was launched March 2004 (hence the “flight time of 10 years” above), Rosetta has not “just” been flying toward ChuGer for 10 years; the spacecraft made a flyby of Mars in 2007, visited the asteroid 2867 Šteins in 2008, and visited the asteroid 21 Lutetia in 2010.


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