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Philae landing on the nucleus of Comet 67P C-G
kenny
post Nov 17 2014, 03:20 PM
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QUOTE (jmknapp @ Nov 17 2014, 02:36 PM) *
So is Philae at rest at 15:43 in the latest image, or still going? Here's the 15:43 location in wider context (red dot):

[attachment=34318:philbounce.png]


In that last cut-out image of Philae over the shadowed area (at 15:43), it still has a long way to go. It will travel for a further 1 hour and 49 mins before reaching its
final resting place at 17:32.
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MahFL
post Nov 17 2014, 03:45 PM
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QUOTE (jmknapp @ Nov 17 2014, 03:36 PM) *
So is Philae at rest at 15:43 in the latest image, or still going? Here's the 15:43 location in wider context (red dot):


No, it's still flying.
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MahFL
post Nov 17 2014, 03:48 PM
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QUOTE (lunaitesrock @ Nov 17 2014, 04:19 PM) *
I don't know what the ground clearance is, but it doesn't look like much.


The gear is designed to flex, remember the impact would have been really gentle, so even if the body made impact no damage would be likely.
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djellison
post Nov 17 2014, 03:53 PM
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There are various papers that explicitly states the gear is designed to take the landing loads, but could well bury itself (the landing gear) in the process.
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anticitizen2
post Nov 17 2014, 04:01 PM
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New version with a very un-scientific cutout of Philae from the 15:23 frame 11 minutes before touchdown.

Didn't resize Philae even though it would be about half a kilometer farther away

If Philae came in from the left, it looks like it dragged its two left feet. There may something similar in the right foot, but it is less apparent.
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kenny
post Nov 17 2014, 04:09 PM
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I think the bigger central depression is actually the main Philae body rather than a leg.
The fourth smaller trailing mark, which is either a double or triple cluster of little depressions, is the last leg to hit with less force, after the other two and
the body took the brunt of the (gentle) impact.
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chemman
post Nov 17 2014, 04:12 PM
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Based on the new OSIRIS images, it appears Philae is heading in a different direction then proposed by the initial CONCERT prediction (i.e. the blue diamond).


--------------------
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-Ned
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kenny
post Nov 17 2014, 04:17 PM
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No, I think we are seeing Philae on a curved track passing through different altitudes, viewed obliquely. So we cannot infer the ground track from that.
Hence a straight line drawn from the initial touchdown point to the 15:43 position does not give us the direction of travel.
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chemman
post Nov 17 2014, 05:00 PM
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ADMIN EDIT: Unnecessary quoting removed. Please be mindful of rule 3.5

Yes, Philae could definitely be on a curved track. However, as far as the obliqueness of the view goes, the view is from above looking down to the north (relative to the image). So in the image at 15:43 the lander is actually more south relative to the the ground then appears in the image. Of course I could have the geometry all wrong, but that's how I see it wink.gif


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fredk
post Nov 17 2014, 05:10 PM
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I've approximately registered the two first bounce site navcam frames and the post-bounce OSIRIS frame - here's the resulting animation:
Attached Image

There are a couple of things of note. First, comparing the navcam "dustcloud" frame with the OSIRIS frame, you can see that the dark splotch extends towards the bottom of the frame from the actual touchdown triple mark. This is consistent with the splotch being the shadow of dust kicked up by the bounce, given that the sun is shining from roughly the top of the frame.

The other thing is that there's no hint of the triple bounce mark in the other navcam frame, although if you look around the frames other features of similar size and contrast are (barely) visible in that navcam frame. Of course it might just be a coincidence of pixel noise cancelling out the triple mark in the navcam frame. But I still wonder if the PS in the caption of this post, which says the other navcam frame was actually taken an hour after the bounce, is incorrect. Notice that the other text on that page and on this image page posted after the blog post still state that the other navcam frame was taken before landing. Also, I can't see any change in shadows between the two navcam frames, whereas if they were taken an hour apart there should be a large change - that's one twelfth of a C_G day.
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climber
post Nov 17 2014, 05:13 PM
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More picts of Philae before and after landing: http://blogs.esa.int/rosetta/2014/11/17/os...ross-the-comet/

Attached Image


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kenny
post Nov 17 2014, 05:25 PM
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QUOTE (chemman @ Nov 17 2014, 05:00 PM) *
Yes, Philae could definitely be on a curved track. However, as far as the obliqueness of the view goes, the view is from above looking down to the north (relative to the image). So in the image at 15:43 the lander is actually more south relative to the the ground then appears in the image. Of course I could have the geometry all wrong, but that's how I see it wink.gif


I thought the same at first, but I think the orbiter is roughly following Philae's ground track because the 3 prior photos are lined up with each other and the landing site.
Rosetta's camera is therefore looking more or less straight down.
After the first touchdown this all changes, and Rosetta continues upwards towards the top of the picture, and is therefore looking somewhat back (down towards the bottom of the picture) at an increasing angle post-landing. Of course Philae could also have bounced off in a somewhat different direction from its line of approach.
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Jam Butty
post Nov 17 2014, 05:41 PM
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WOW... incredible images, incredible mission.

Anyway my take on the initial landing site, overlay of ROLLIS and OSIRIS images showing a before and after. Looks to me like the lander might have caught a strut on that meter sized rock in the landing footprint.

Attached Image

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djellison
post Nov 17 2014, 05:45 PM
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Nice GIF, Jam Butty

One could almost speculate that the slab like 'rock' on the SW corner of the touchdown point has been kicked up significantly by bounce 1 - perhaps it kicked the lander to a harder 'slap down' with the other two legs which triggered the bounce.
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elakdawalla
post Nov 17 2014, 05:53 PM
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I wonder if Philae's shadow is visible in any of the OSIRIS images. It wouldn't be in the tight frames they cropped, but it's worth looking for.

Given that we have SPICE information, I'm wondering if someone could produce a table giving altitude and sub-spacecraft lat and lon for both Philae and Rosetta in 5-minute time steps for the landing phase?


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