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Stuart Atkinson

A Tour of 67P...

Posted By Stuart Atkinson

23-09-2014 17:58 CDT

Topics: Rosetta and Philae, pretty pictures, comets, amateur image processing, comet Churyumov-Gerasimenko, global views

This article originally appeared on Stuart Atkinson's blog and is reposted here with permission.

Another day and another stunning NAVCAM image (or, more accurately, a mosaic of 4 NAVCAM images) released by ESA...

Rosetta view of Comet 67P/Churyumov-Gerasimenko on September 14, 2014

ESA / Rosetta / NavCam

Rosetta view of Comet 67P/Churyumov-Gerasimenko on September 14, 2014
Four-image NAVCAM mosaic of Comet 67P/Churyumov-Gerasimenko, using images taken on September 14, 2014 when Rosetta was 30 km from the comet.

Oh, that’s a beauty isn’t it? With a bit of sharpening up etc, it looks like this...

Comet 67P, sharpened

ESA / Rosetta / NavCam / Stuart Atkinson

Comet 67P, sharpened
Mosaic of 4 Rosetta NAVCAM images, processed and sharpened by Stuart Atkinson.

Oooh, much more menacing!

But look closely and that image gives us a great new view of some of the comet’s most interesting features – its cliffs, craters and peaks...

Context for close-up images

ESA / Rosetta / NavCam / Stuart Atkinson

Context for close-up images

No doubt these have all been imaged in jaw-dropping detail by the OSIRIS cameras, but as the OSIRIS team clearly have no intention of showing the rest of the world those images, I thought I’d get stuck into today’s image release, isolate those features and show them a bit more clearly, hopefully bringing the landscapes of 67P to life a little bit more in the process. Anyway, click on the following images to enlarge them and see what you think.

Love this first one, looks like a fortress on the top of a mountain...VERY Middle Earth...

Rosetta NavCam 67P Sep 14, 2014 detail #1

More intriguing spires...

Rosetta NavCam 67P Sep 14, 2014 detail #2

Incredibly varied landscape, with a huge crater and strange, sculpted peaks and spires nearby...

Rosetta NavCam 67P Sep 14, 2014 detail #3

My eyes keep being drawn to these incredible cliffs which fall away from a broad, boulder-strewn plateau...Remember, this was Landing Site Candidate A...

Rosetta NavCam 67P Sep 14, 2014 detail #4

Just look at that great gaping crater...would anyone really be surprised if a Star Wars space worm leapt out of that, snapping at ROSETTA..?

Rosetta NavCam 67P Sep 14, 2014 detail #5

What intrigued me about this area was that it looked pretty flat and dusty on the original image, but when enhanced and sharpened up a LOT of detail jumps out at you...

Rosetta NavCam 67P Sep 14, 2014 detail #6

These are the mighty cliffs which surround the largest crater seen on 67P, which is close to the area selected to be Philae’s landing site in November. But panic not, they are on the opposite side of the crater to Site J, so as scary looking as they are they shouldn’t really pose much of a threat to little Philae.

Rosetta NavCam 67P Sep 14, 2014 detail #7

...and finally, just look at this boulder.. it has other chunks of rock embedded in it...! :-)

Rosetta NavCam 67P Sep 14, 2014 detail #8

I hope you enjoyed the tour! I know those portraits of some of the surface highlights of 67P are not perfect, but they’ll have to do until we get to see those OSIRIS images... :-)

See other posts from September 2014


Read more blog entries about: Rosetta and Philae, pretty pictures, comets, amateur image processing, comet Churyumov-Gerasimenko, global views


ethanol: 09/23/2014 07:31 CDT

Can't wait for the release of those OSIRIS pictures, though something about the lower resolution makes these look even more like the set of an unexpectedly high-budget 50's sci-fi. I can't say I envy the lander team right now though...

TimR: 09/24/2014 05:01 CDT

PS comments are leaning towards the P67 craters not being from impacts. I do not heard/read what Rosetta investigators are thinking(anyone know?). But I agree. They are like sinkholes. The gravity on P67 and Van der Waal forces must be comparable. Geysers on the Earth expel their super-heated water vertically due to gravity's effect on the creation and erosion of fissures. On P67, the Sun uniformly heats a surface area to a certain depth. The pressures that build from sublimation follow paths of least resistance and are mostly a chaotic set of passages to the surface. This is more like pores on skin. The comet sweats rather than jets. The craters are like patterned ground or gilgai (new term for me, not a geologist). There is a cycle like freeze-thaw => sublimate-freeze. The leftover material from sublimation builds up and becomes a blanket. Philae's MUPUS instrument will determine thermal diffusivity of surface material which should be non-volatile. Researchers should be able to determine a maximum depth at which temperatures are reached to sublimate various volatiles for a given solar radiation level. The depth of these craters might be proportional to this thermal diffusivity (blanketing effect) and to the ratio of volatile to nonvolatile material. Once the blanket of non-volatiles reaches a certain depth, insufficient heat reaches volatiles and the crater reaches a maximum depth. This could explain why most of the craters are about the same depth. Lastly, the expulsion of gases is due to sub-surface pressure over a broad area of sublimation but may also be due to electrostatic charges around the comet from solar UV or Hall Effect- accelerating charged plumes and particulates. A Langmuir probe would have been nice. Anyways, Rosetta researchers are likely well along with hypotheses but must be reserved. The SC were superbly equipped to answer these questions. The researchers are going to blow us away with the mechanics & dynamics of P67.

SherbertDibDab: 09/24/2014 07:58 CDT

Having come across Stuarts amazing images on his blog earlier, it surprised me he didn't show landing site J which is clearly visible in this Navcam photo. I thought I would have a play with my meagre resources (iPhoto) and came up with this. The scale is pretty approximate so please don't take it as fact. I thought it might help people get a handle on the scale and the nightmare job the landing team have given themselves of landing little Philae safely. Given the great things the Rosetta team have already done I for one am not betting against them. After zooming in really close on these images I agree with TimR many of the shadows that appeared to be cast by boulders are actually pits that look like golf bunkers with some evidence of ejecta material of different shades around them. A couple more OSIRIS images from the 30Km orbit would be nice. The last one, possibly the most amazing space probe photo I've ever seen, was on Sep 5th from 67Km, the weekly release schedule seems to have slipped somewhat.

japeth: 09/25/2014 12:27 CDT

it would be fascinating to see a map of local surface gravity vectors on the surface. I can imagine that a spot on the surface near the neck might have substantially lower gravity.

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