Rosetta makes it to it's target, now orbiting a comet!

Before reaching the comet, Rosetta flew by Mars in 2007 and took some cool images (with its OSIRIS camera) using various filters, including red/green/blue filters. This means one can create true-colour images from the original images found at psa.esac.esa.int...

Here's a couple I made myself (with a tiny bit of colour and contrast adjustment):

www.pictureshack.us...


www.pictureshack.us...


I'm really wondering why there are not such images of the comet yet. Would be nice to see it in colour.

They've found that the comet is very dark in color, about like coal. Not even any white patches of fresh ice. Color photography is not likely to be of much avail, it seems.
They have seen very faint whitish vapor jetting out of the nucleus. How this is possible, given the absence of exposed ice, is unclear. Outgassing from a comet is supposed to be caused by exposed ice subliming directly to water vapor, under the heat of the Sun.

originally posted by: Ross 54
They've found that the comet is very dark in color, about like coal. Not even any white patches of fresh ice. Color photography is not likely to be of much avail, it seems.
They have seen very faint whitish vapor jetting out of the nucleus. How this is possible, given the absence of exposed ice, is unclear. Outgassing from a comet is supposed to be caused by exposed ice subliming directly to water vapor, under the heat of the Sun.

They didn't say that there are no patches of surface ice at all, only that there are no large patches of ice visible.

Even a dark coal-like surface can have colour, and it is guessed that this comet's surface is reddish or orange-ish in colour, due to hydrocarbons.

Cometary jets can originate from ices below the surface, if the surface is pitted / porous.

a reply to: wildespace

Cometary jets can originate from ices below the surface, if the surface is pitted / porous.

And,
those ices need not be water ices. There are more volatile volatiles than water.

originally posted by: wildespace

originally posted by: Ross 54
They've found that the comet is very dark in color, about like coal. Not even any white patches of fresh ice. Color photography is not likely to be of much avail, it seems.
They have seen very faint whitish vapor jetting out of the nucleus. How this is possible, given the absence of exposed ice, is unclear. Outgassing from a comet is supposed to be caused by exposed ice subliming directly to water vapor, under the heat of the Sun.

They didn't say that there are no patches of surface ice at all, only that there are no large patches of ice visible.

Even a dark coal-like surface can have colour, and it is guessed that this comet's surface is reddish or orange-ish in colour, due to hydrocarbons.

Cometary jets can originate from ices below the surface, if the surface is pitted / porous.

Yes, that's quite true. I stand corrected. It was only large patches of exposed ices that could have been detected, but weren't. Small ice patches, or subsurface ices could be responsible for the vapor plumes.
67P C G is still at a considerable distance from the Sun, though. Volatilization of ices is presumably progressing at a slow rate. I'm hesitant to ascribe substantial vapor plumes to small or subsurface ice deposits.
It seems that we'll have to wait a bit to learn if the comet has a reddish or, orangey cast to it's very dark surface. Very few of even monochrome images are being released. This even applies to the NavCam pictures, which are taken daily. I seem to recall, too, that release of the better, Osiris camera images, were set to be released twice weekly, on Mondays and Thursdays. Very few of those have been presented on the ESA/Rosetta website.

Here's another colour image from Rosetta, before it reached the comet. This time, it's the asteroid 2867 Šteins, imaged by the OSIRIS camera on 5 September 2008:


RGB composite (hopefully in true colours) created by me from raw images

ESA blog about the asteroid: blogs.esa.int...

This is one of the more interesting space missions of late, I just hope the orbiter and lander have zero biological contamination on board!

Getting back to the comet... WOW, this is the closest image yet, at about 1.1 meters/pixel; www.esa.int...

The most "torturous" surface I've ever seen!

originally posted by: wildespace
Getting back to the comet... WOW, this is the closest image yet, at about 1.1 meters/pixel; www.esa.int...

The most "torturous" surface I've ever seen!

That is superb. Humans can be pretty damn clever sometimes (and pretty damn stupid most of the time).

Yes, a fantastic landscape, like one from a wild imagination, yet it's real!
The very white patches at upper left could be small patches of snow, which have otherwise eluded detection.
The ragged promontory at the upper middle of the images has more of the fine parallel linear features, and those that cross them at right angles. Some of the vertical ones are more obvious, as shadows help define them.
These exist on the lower down rough area, as well as at the very top edge of the nucleus, where they appear on a spur or small ridge. Notable, too, is the tall, sharp spire, in this same area.

originally posted by: Rob48

originally posted by: wildespace
Getting back to the comet... WOW, this is the closest image yet, at about 1.1 meters/pixel; www.esa.int...

The most "torturous" surface I've ever seen!

That is superb. Humans can be pretty damn clever sometimes (and pretty damn stupid most of the time).

Actually we are very much both, most of the time.

It's just that the stupidity gets reported on a daily basis while the clever quietly go about their work to make missions like this eventually happen.

originally posted by: JadeStar

originally posted by: Rob48

originally posted by: wildespace
Getting back to the comet... WOW, this is the closest image yet, at about 1.1 meters/pixel; www.esa.int...

The most "torturous" surface I've ever seen!

That is superb. Humans can be pretty damn clever sometimes (and pretty damn stupid most of the time).

Actually we are very much both, most of the time.

It's just that the stupidity gets reported on a daily basis while the clever quietly go about their work to make missions like this eventually happen.

Thanks for restoring my faith in humanity a tiny bit

originally posted by: Ross 54
The very white patches at upper left could be small patches of snow, which have otherwise eluded detection.

I think these are just smooth dusty surfaces reflecting more sunlight than the craggy surfaces. The comet is very dark overall, so any patches of ice would appear very, very bright.

The ragged promontory at the upper middle of the images has more of the fine parallel linear features, and those that cross them at right angles.

It's been proposed (at the UMSF forum, I think) that this is the comet's internal structure, exposed through erosion or outgassing. We might be looking at the comet's porous structure, seen here filled with dust and rocks.

The small bright patches I noticed were even brighter than the surrounding bright areas, which suggested the higher albedo of snow. I've read that they had expected to find at least some exposed ice on the surface of the comet.

I haven't read the remarks about the surface texture of the comet at the Unmanned Spaceflight forum yet, but will look for them there. That site has been quite good on other aspects of 67P C G.
I'm given to wonder why random porosity would give the impression of consistently straight, parallel lines, over fairly wide areas, and even appearing at right angles to each other, in some cases.

Reviewed the Rosetta threads at the Planetary Society's Unmanned Space Flight forum, as discussed above. Didn't find anything specifically about the connection of the comet's supposed porosity to its surface texture.
Portions of the surface have been likened to fabric, with its consistent warp and woof of fibers at right angles to each other. Another geological explanation may account for this texture, but what it would be is unclear. It would have to be workable under highly unusual conditions.
There is presumably a shallow crust of carbonaceous materials which is subject to disruption by volatilization of the underlying ice. This would occur in the absence of any real atmosphere, and with only very weak gravity.
So far as I am aware, the multitude of straight and parallel lines seen on the surface of 67P C G have not been discerned on other comets which have been closely examined.

A primary and secondary landing site have been selected for the Philae lander, it was announced this morning. The prime site, designated 'J', but soon now to have a proper name, is in a relatively flat area, near the edge of the large crater-like feature on the 'head' lobe of the comet's nucleus. It is also near two small pits, believed to be sites of venting of gases, sublimed directly from volatile ices. The article, linked below, has further details, together with photographs of the primary landing site.
www.skyandtelescope.com...

a reply to: GaryN

Oh I have not heard of the EU theory care to explain?.

a reply to: boymonkey74

Oh and I wanna lick that old thing to see what it tastes like.
Cool mission and photos I can't wait to see more.