APOD: Welcome to a Comet (2014 Nov 14)

[APOD Robot]

Welcome to a Comet

Explanation: The Rosetta Mission lander is safely on a comet. One of Philae's feet appears at the bottom left of this spectacular image of the surface of C67/P Churyumov-Gerasimenko. Still a happy lander, Philae bounced twice before settling and returning images from the surface, traveling a kilometer or so after initially touching at the targeted site Agilkia. A surface panorama suggests that the lander has come to rest tilted and near a shadowing wall, with its solar panels getting less illumination that hoped. Philae's science instruments are working as planned and data is being relayed during communications windows, when the Rosetta spacecraft is above the lander's new horizon.

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[Seriousnow]

OK, so what does this do the the Big Ice snowball theory of comets? Looks like just another rock in space. No info at all so far on whether the comet trail is H2O or not?

[alter-ego]

Boy, between the cracked crumbly ground, the ice-like substance seemingly seeping from cracks in the ground on the right side, and the Philae's foot apparently overhanging an uncertain void, Philae looks to be in a pretty unstable environment. I'd guess Philae is dang lucky to be upright let alone functioning. I can hardly wait for pictures from Rosetta's OSIRIS telephoto camera showing where Philae is.

[Douglas]

Philae's final spot should change dramatically when closer to the Sun.

[geckzilla]

OK, so what does this do the the Big Ice snowball theory of comets? Looks like just another rock in space. No info at all so far on whether the comet trail is H2O or not?

Fear not. That the photo is indistinguishable from any other rock to you does not upset the science behind comets. They're still mostly composed of dirt and ice.

[Douglas]

Moving at 1 m/s .. and trampolining at 1 gram of weight ..

"Bibring said many scientists expected the comet’s surface to be powdery, allowing the lander to settle instead of rebounding back into space.

“It’s not a powder, it’s a rock, so it’s like a trampoline,” Bibring said. “You go there and it ejects you immediately afterwards.”

They'll know soon but the cold of space may claim the lander. Try firing the harpoons repeatedly: at 1 gram of weight it could probably handle tumbling, even. Recoil it off the rock.

http://spaceflightnow.com/2014/11/13/re ... om-philae/

[geckzilla]

That kind of unpredictable maneuver would have to be a last resort. Apparently MUPUS has penetrated the rock. Seems magical to me. I await an explanation for how it happened but you can see updates here:
https://twitter.com/Philae2014

[Czerno o]

ESA have announced they are going to attempt drilling
for comet "soil" samples, as battery power is soon running out.

As a side effect - Newton's re/action principle into play - the operation
might reset Philae's attitude for better (or worse).

Exciting ain't it ?

[RedFishBlueFish]

Astounding image, even if does not fit my imagined view of what a "dirty snowball" should look like, and given that there are not aliens milling about wondering what caused that bump.

So much better seeing one's taxes being spent for exploration rather than destruction.

The landing certainly could have gone worse. At least some data will be collected.

The near disaster of the landing also brings to recollection the, to my untutored thought, absurd and needless complexity of the apparently ego-driven, exhibitionist, dick-swinging landing sequence devised for Mars Curiosity - the success of which gives credence to the arguments of Teilhard de Chardin.

KISS: Keep It Simple, Smarty.

[Joules]

Just look at how fractured that rock is! I wouldn't want to try climbing it at anything close to 1 gravity. Wonder if pressure of melting volatiles is what caused the cracking, or just collision/thermal expansion.
Given what looks to be regular rock surface here, the smooth regions elsewhere have got to be extremely low density to get overall density down to 0.4 g/cm^3.
Likely 50 meter deep pools of fluffy snow or its like. Good thing Philae didn't bounce to one of those or we'd have no signal at all.

[Chris Peterson]

OK, so what does this do the the Big Ice snowball theory of comets? Looks like just another rock in space. No info at all so far on whether the comet trail is H2O or not?

In a white light image, how would you distinguish between rock and various ices? (And the dirty snowball theory has long since lost favor to the icy dirtball theory.)

[Chris Peterson]

The near disaster of the landing also brings to recollection the, to my untutored thought, absurd and needless complexity of the apparently ego-driven, exhibitionist, dick-swinging landing sequence devised for Mars Curiosity - the success of which gives credence to the arguments of Teilhard de Chardin.

KISS: Keep It Simple, Smarty.

What is simple on a comet or asteroid is very different from what is simple on Mars. Mars is possibly the most difficult body in the Solar System to land on- an engineering challenge of huge proportions.

[Guest]

It would be interesting to see the image(s) with the grey scale expanded/enhanced to see additional details that are currently hidden from view. Did they think to put a flash on the camera?

[Chris Peterson]

Just look at how fractured that rock is! I wouldn't want to try climbing it at anything close to 1 gravity. Wonder if pressure of melting volatiles is what caused the cracking, or just collision/thermal expansion.
Given what looks to be regular rock surface here, the smooth regions elsewhere have got to be extremely low density to get overall density down to 0.4 g/cm^3.

I think one mistake is to assume we're seeing nothing but rock. There could be a lot of frozen volatiles there, mixed with silicate dust, and we'd be hard pressed to tell the difference visually. Consider where comets formed, very far from the Sun where all the volatiles were in gas or solid form and there was never enough heat to melt them. Consider a region where the density was so low that material accreted slowly and through relatively gentle collisions, not the high energy impacts of the inner system. We're probably looking at something that is more of a rubble pile than a solid body. I imagine an interior that is a mix of silicates, ices, and voids, and an exterior where we see mostly silicates simply because the outermost volatiles have sublimated away after dozens of perihelion passages. Perhaps the surface was further scrambled during the loss of volatiles, but this comet may never have gotten all that close to the Sun, and its ejection processes may be fairly calm.

[Chris Peterson]

It would be interesting to see the image(s) with the grey scale expanded/enhanced to see additional details that are currently hidden from view. Did they think to put a flash on the camera?

There's plenty of light. They only need to use a longer exposure to get details in the darker regions. Keep in mind that ESA does not release all their data the way NASA does. We're only seeing a few images; I expect that they are holding onto many more that we may not see for a long time.

[sunlight]

What is that ROD like thing at the 5 o'clock position at the bottom of the image? It even casts a shadow!

[Chris Peterson]

What is that ROD like thing at the 5 o'clock position at the bottom of the image?

I believe that was earlier identified (in another discussion) as part of the CONSERT instrument, a microwave antenna.

[sunlight]

What is that ROD like thing at the 5 o'clock position at the bottom of the image?

I believe that was earlier identified (in another discussion) as part of the CONSERT instrument, a microwave antenna.

Looks embedded in he rock !?

[sunlight]

What is that ROD like thing at the 5 o'clock position at the bottom of the image?

I believe that was earlier identified (in another discussion) as part of the CONSERT instrument, a microwave antenna.

Looks embedded in he rock !? Look at the shadow how it comes out of the tip of it. If you are right, then the antenna is touching the rock.

[Chris Peterson]

I believe that was earlier identified (in another discussion) as part of the CONSERT instrument, a microwave antenna.

Looks embedded in he rock !?

So it does. That's why we have to be very careful in how we interpret images. We are easily fooled. It is wise to maintain a high degree of skepticism about our interpretations of imagery, especially imagery from an unfamiliar environment. It is the nature of our brains to force what we see into narrow patterns of experience, and that simply doesn't work in a case like this. Heck, that might not even be rock that the antenna isn't embedded in!

[MargaritaMc]

http://asterisk.apod.com/viewtopic.php? ... 00#p234900

[Douglas]

Here's one for you: "oscillations in the magnetic field in the comet's environment"

http://www.huffingtonpost.co.uk/2014/11 ... 43956.html

http://www.space.com/27737-comet-song-r ... craft.html

And just for insight, what does that rock next to the lander look like? Too-dry concrete, right?

[geckzilla]

The near disaster of the landing also brings to recollection the, to my untutored thought, absurd and needless complexity of the apparently ego-driven, exhibitionist, dick-swinging landing sequence devised for Mars Curiosity - the success of which gives credence to the arguments of Teilhard de Chardin.

You said it yourself. You are ignorant. I suggest you do some reading.

I believe that was earlier identified (in another discussion) as part of the CONSERT instrument, a microwave antenna.

Looks embedded in he rock !?

So it does. That's why we have to be very careful in how we interpret images. We are easily fooled. It is wise to maintain a high degree of skepticism about our interpretations of imagery, especially imagery from an unfamiliar environment. It is the nature of our brains to force what we see into narrow patterns of experience, and that simply doesn't work in a case like this. Heck, that might not even be rock that the antenna isn't embedded in!

To me it looks more like the CONSERT antenna is serving as a foot in this picture while the foot that was supposed to support Philae is not touching anything the way it should be. The surface is very bumpy and Philae is sideways so the picture is quite disorienting. So, not necessarily embedded, but it definitely looks to be touching. Philae's mass on this comet is light enough that it could rest on one's fingertip.

[ta152h0]

it was noted that Phylae would be taking images as it descends. Is ESA quarantining the images for later release ?

[Ron-Astro Pharmacist]

To me this appears the leg may have disturbed the ridge of material and compacted it . If so, it has the consistency of soft asphalt. It seems very fortunate to have ended upright on all three legs because what we learn from Rosetta will attest or repudiate what role the next generation of comet explorations become.
Could you imagine the excitement of a cup of comet would bring back on Earth? I hope that would feel more like a home run than a run home that ebola fears arose. As it looks - Rosetta has destiny written all over it.