Thursday, September 08, 2016

Comets have air?


Some readers may remember the space probe Philae, which was sent to land on Comet 67P. It malfunctioned and lost contact for a while, then re-established contact before finally shutting down for good. Thanks to photos by Europe's Rosetta spacecraft (of which Philae is the lander), we can now see what happened. According to AFP - in an article titled "Hello Earth! Can you see me? Rosetta spots crashed Philae in comet ditch" (The Japan Times, September 6, 2016) - we are told that upon landing, Philae bounced several times and finally stopped upside down:
The agency released a photo of the washing machine-sized robot lab on the comet's rough surface, one of its three legs thrust dramatically into the air . . . . "Philae is at the foot of a cliff in an extremely rocky zone" of the comet, Rosetta project chief Philippe Gaudon of France's CNES space agency told AFP, after examining the picture. It is now clear that after bouncing, Philae landed the wrong-way up, "with one foot well in the air and its antennas pointing . . . groundwards," he said. That is why communicating with Philae had been so difficult.
Comets have air? Surely not! The article states this twice, but surely doesn't literally mean it. Unless comets have 'atmosphere' - and maybe they do! The photo above reveals that Comet 67P is a helluva rockin place!



At 11:10 AM, Blogger Kevin Kim said...

If I'm not mistaken, comets emit gases as they approach stars—hence the coma.

I wonder why no one thought to build a "this side up" stabilizing and self-righting system into the robot. Also interesting is the idea that the robot stayed in place on the surface of the comet, whose gravitational pull has to be close to nil. If the device bounced while landing, it seems to me that, depending on its angle of approach, it could have bounced right off the comet!

And now I'm also wondering to what extent the robot's bouncy arrival changed the comet's trajectory. Even if the change was only a fraction of a fraction of a degree, that would translate to thousands or even millions of kilometers in the long run.

At 11:45 AM, Blogger Horace Jeffery Hodges said...

I also considered the gases given off by the comet, but didn't expect this to constitute an atmosphere that provided 'air' to stick a leg up into.

Jeffery Hodges

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At 4:02 PM, Blogger Kevin Kim said...

Yes, "into the air" was undoubtedly poor phrasing.

At 10:28 PM, Blogger Horace Jeffery Hodges said...

Yeah, it really stuck out.

Jeffery Hodges

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At 10:35 AM, Blogger Carter Kaplan said...

As I sit here my legs are thrust into the air. But if I go outside and stand under the sky, my legs are thrust into the atmosphere, or maybe downwards into the Earth's gravitational field? Moreover, in any circumstance imaginable one could argue one's legs are sticking into an aperçu, and no one would be the wiser.

At 11:11 AM, Blogger Horace Jeffery Hodges said...

A wise aperçu, Carter.

Jeffery Hodges

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