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Oh, OSIRIS…

If you’re following the ESA ROSETTA mission to Comet 67P yesterday was a VERY good day for you, because there was a double whammy of ROSETTA goodness. First, 2pm UK time, right on schedule, a new NAVCAM image of the comet was released, showing another side of 67P…

Comet_on_13_August_2014_-_NavCam

…and with a bit of enhancing and processing (come on, you knew it was coming!) that turns into this…

Comet_on_13_August_2014_-_NavCam c

Ooh, that’s pretty isn’t it? Well, pretty in a “God, that’s an ugly, blasted, tortured, gnarly chunk of primitive solar system debris!” kind of way. Look closely on that flat “plain” in the middle there and you’ll just be able to see that strange, meandering fracture, crack… thing… first shown on Arrival Day on one of the first OSIRIS images to be released…

Comet_details_node_full_image_2

I hope OSIRIS will be targetted to take a closer look at that feature because it strikes me as being a promising place to look for changes as the comet nears the Sun. Actually, I’m sure they’ve already targetted it, they just haven’t let us see the pictures yet; they’re encrypted on a hard drive somewhere in Germany, on a computer standing on a plinth, wrapped up in chains and surrounded by a security field of dozens of laser beams, in the centre of a huge vault protected behind a 6ft thick door, but I’m sure we’ll be able to rove our eyes over them at some point… 🙂

I’m joking there, obviously… the door is only 4ft thick… No, seriously, not every OSIRIS image is being kept behind bars, at the moment one is being released every week, and we were given one to drool over and explore yesterday afternoon. And… well… take a look. Click on it to enlarge it – I’ll wait for you to pick your jaws up off the floor and come back, ok?

Comet_on_7_August_a

I know… isn’t that just ridiculously incredible??? Look at the detail!! Look at the structures, the features! That camera is astounding! When that image appeared I Saved it quickly, and then must have spent a good hour just roaming around it, exploring, imagining I was flying over it in an astronaut jet-pack, swooping low over the surface, my feet barely clearing the tops of the ridges and outcrops as I stared down at an alien landscape littered with enormous boulders and carved and sculpted into all kinds of bizarre shapes by millennia of thawing, freezing and thawing again. Just spectacular. Then I saw that actually a PAIR of OSIRIS images had been taken, of this same view but a short time apart, which allowed the team to make a beautiful 3D image, which has to be seen to be believed.

It was wonderful seeing those new images, and all credit to the OSIRIS team for letting us see them. But, yes, I’ll admit it, it will sound ungrateful but it made me very, very impatient to see more OSIRIS images, because I don’t even think that’s one of them most interesting areas of the comet! Over the horizon there are some absolutely crazy things going on! Oh, I know, we’ll see those in time, right now the science team’s priority has to be finding a safe-but-interesting landing site for Philae to set down on later in the year… but still… just imagine what wonders other OSIRIS images are showing…

Anyway, let’s take a closer look at some of the features revealed on the latest image to be released. I think the most eye-catching area is on the neck, where there are a LOT of big boulders and rocks clustered together, casting very cool shadows across the dusty landscape… Again, click on this image (and all those that come after it) to enlarge it and show it properly…

crop1

That’s stunning, isn’t it? I wonder how big those boulders are? And where did they come from? Did they fall from the ridge in the foreground – the one casting the dark shadows on the neck itself, far below – after eroding out of it? Or did they tumble down from the slopes higher up in the image? Hmmm, If they had done you’d expect there to be trails leading across that dusty slope to them… but then again, maybe those trails were covered over afterwards by fresh deposits of material? Fascinating to speculate, isn’t it?

Here’s a cropped view of the same area from the OTHER OSIRIS image released yesterday, which gives a slightly different perspective…

crop6

Oh there’s so much going on there…

And then there’s this

crop2 arrow

That, arrowed, is a crater. I know what you’re thinking – so what! We knew comets have craters on them already, what’s the big deal? Well, look around it… look at the whole image… how many OTHER craters can you see, eh? Ah, maybe now you get it. Aren’t many, are there? And the crater arrowed is a “ghost” crater, semi-covered with material that softens its outline and makes it a bit blurry, not like the craters we see on orbital images of asteroids, the Moon and Mars. That suggests that the crater has been covered by material relatively recently (in astronomical terms, not, like, last week). But what? Dust falling off nearby slopes? Dust falling out if the sky after an active period in the comet’s history? In fact, if you look closely, I think there are hints of other craters nearby…

crop2 ghost craters

…but I might be wrong about those, they might just be knobs and knubs on the landscape that now look like the remains of craters after being covered by dust. Intriguing anyway…

And then there’s this fantastic view…

crop3

Why is it “fantastic”? Because it shows things are happening – or at least have happened – on the nucleus. Look closely and you can see at least two places where big rockfalls have occurred…

crop3 debris fans

Looking at one of those areas more closely…

crop3b

That is an absolute textbook image of a rockfall from a slope, which has sent debris spreading out across the ground below. We see those a lot here on Earth, and have even seen them *happening* on Mars too…

0f1d7452-ced4-4203-b99f-43747e66a9cd

av2c

And if you look a little further over, there’s this… (yellow ring)…

crop3 debris fans slump

…which looks a lot like a classic “slump” feature to me, where a section of a wall just gives way and, well, slumps down… like this one on Mars (this is one of my very favourite martian craters, by the way…)

slump

crop3 slump b

Elsewhere on the main image, we see this…

crop4

What is that? A heavily eroded crater? (cue Spock eyebrow lift) Fascinating

But one particular area which caught my eye was this, a small area of the edge of the closest part of the comet to ROSETTA at the time the image was taken.

Comet_on_7_August_a edge

It seems to me that if we’re looking at that terrain from such a low angle, then we’re almost getting the kind of a view we might have from ground level, or at least if we were flying close to the surface heading towards that area. So, zooming in on it, enhancing it and straightening it up, is THIS what it it would be like to by flying at low altitude over the surface of 67P and seeing the landscape of dust-covered, icy hills and rocky plains opening up ahead of you..?

crop7

Just imagine that…

So, there you are, a quick “tour” of some of the fascinating features seen on the latest OSIRIS image. It will probably be another week until we see the next one, so I hope you enjoy many hours’ wandering over this release yourselves. To finish off this post, here’s my enhanced and sharpened version of one of the images released yesterday…

Comet_on_7_August_a enh

Later today there should be another NAVCAM image released into the wild, and we’ll look at that soon after.

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5 Responses

  1. Hi,

    Thanks for these great images and commentary. I am enjoying showing them to my daughter and inspiring her to be interested in what goes on out there.

    I do have a question on the comet, it seems like it has eroded heavily in the center. Is there an explanation for why this would be and would it be expected that it would eventually separate into two separate pieces at some point?

    • Thanks for your comment, and for reading 🙂 There are two possibilities. Either 67P is a single body, eroded in the middle as you say, or it is tow individual bodies which came together some time in the past and stuck together. This is quite common “out there” – we have seen many double asteroids and comets – and it’s even got a name, a “contact binary”. Some experts say say that if, in the future, the two parts of 67P do split they will drift apart for a while, but then come back together again, reforming a single body. Maybe that’s already happened, maybe even more than once? ROSETTA will hopefully tell us. 🙂

      • Thanks for the reply, I have been appreciating your blog for some time.

        I hadn’t considered the joining of two objects, but that makes a lot of sense. I’m looking forward to seeing what changes we witness as it approaches the sun.

  2. […] with a crazy world: eine Reportage aus Darmstadt. Auch weitere Versuche hier, hier und hier, die Kernstrukturen zu […]

  3. Stu,is that “Mars Rockfall pic upside down?Or has the picture been taken from above?

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