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djellison
QUOTE (lunaitesrock @ Aug 6 2014, 06:31 PM) *
The 3D image is absolutely incredible! I hope that models are eventually made for educational purposes.


Once shape-file data is out there, I'll certainly make a 3D printable STL file that people can get printed at Shapeways or other 3D printing sites.

I've already done Eros, Itokawa and Vesta ( and others )

http://nasa3d.arc.nasa.gov/search/ellison/model
Phil Stooke
"On the other hand, 103P/Hartley and 19/P Borrelly, both of which had a bowling pin shape had jets emanating primarily from the lobes. "

Not Borrelly. Its main jets were from the central smooth area.

http://nmp.jpl.nasa.gov/ds1/img/borrelly_3.jpg

Phil

bobik
QUOTE (Explorer1 @ Aug 6 2014, 06:30 PM) *
Some are pointed at the ground, but others are horizontal, Huygens style.
See https://www.youtube.com/watch?v=k1IFU6kxcD8

ÇIVA-P cameras are inclined downward. You could see the local horizon, but if they "land in one of those green spots closer to the neck of the comet" you would not be able to see "the other half of the comet looming overhead".
MichaelJWP
QUOTE (djellison @ Aug 7 2014, 06:09 AM) *
Once shape-file data is out there, I'll certainly make a 3D printable STL file that people can get printed at Shapeways or other 3D printing sites.

I've already done Eros, Itokawa and Vesta ( and others )

http://nasa3d.arc.nasa.gov/search/ellison/model


They look good, Doug. Do you provide textures and are the models u-v'd or are they just for printing?

I should say I don't often have the time to post here, mostly lurking, but this mission is amazing, living up to all the promise and more. I remember sticking it in the calendar back at the launch date telling myself not to get hopes up too high as there were so many risks to overcome, but kudos to everyone involved in this one.

- Michael
Explorer1
QUOTE (bobik @ Aug 6 2014, 09:58 PM) *
ÇIVA-P cameras are inclined downward.


Yes, that's true. At best, it would just be a big cliff extending up beyond the edge of the frame.
But there will be that descent imaging, and I'm getting Huygens flashbacks...
machi
Descent imaging by ROLIS is limited by onboard memory. So plan is that ROLIS will take few pictures after release from the orbiter, those will be immediately transfered to the orbiter and
then erased. FOV size is easy to find, because if you know distance, you now FOV size on comet. From distance 1000 meters FOV diameter is 1000 meters and resolution is ~1 meter.
Before touchdown ROLIS will take up to 8 images from maximum distance 25-50 meters (FOV 25-50 meters). Only few last images will be better in terms of resolution than
best possible images from OSIRIS camera.
CIVA has 60° FOV. Its cameras has FOV tilted down by 15° (25° for stereo camera) from the Philae's baseplate ("horizontal" plane). So it can see ~270 meters high peaks in distance 1000 meters (this of course depends on actual tilt of the lander).
Source: Space Science Reviews 128.
jgoldader
QUOTE (djellison @ Aug 7 2014, 12:09 AM) *
Once shape-file data is out there, I'll certainly make a 3D printable STL file that people can get printed at Shapeways or other 3D printing sites.

I've already done Eros, Itokawa and Vesta ( and others )

http://nasa3d.arc.nasa.gov/search/ellison/model


Any chance of Gaspra? I did some work on that back before the Galileo flyby; it would be great to print it out.

Thanks!
Jeff
lunaitesrock
New images are up:
http://blogs.esa.int/rosetta/2014/08/07/co...tch-5-6-august/
TheAnt
The closeup is what got my attention.
mmatessa
QUOTE (mcgyver @ Aug 6 2014, 05:03 AM) *
How to figure out scale in these wonderful images?


ESA has the following graphic for the size of the whole comet:


But it would be nice to see reference stadiums, buildings, or cars for the closer images.
machi
BBC released very interesting footage from (evidently) OSIRIS camera. Images are from 3. August 2014.
Now it's possible to derive stereo images directly from the published images.
This is comparison with my "synthetic" stereo image of 67P (it's the lower pair).
You can see that top left image is exactly the same image as lower right image.

EDIT: This version was deleted and was replaced by this one.
atomoid
heres a <sloppy> crosseye of the topography inside that shadowed 'hole' area inside the pole of the smaller clump at right in machi's stereo, this based on the sequence Emily posted earlier
Click to view attachment
algorithm
What is the estimated mass of this object?
What is the mass of the lander?
Depending on the above, the gravitational pull on the lander may be negligable, so it could be.. pick a spot-any spot.
Phil Stooke
It's more about local geology and safety. How smooth is the area? Is it coarse-grained or fine-grained, or maybe quite solid? (from thermal inertia). Is there any evidence of volatiles, or is it depleted, baked dry? Is the area active during the run-up to landing, or is it inert?

Phil

centsworth_II
My estimate of how football stadiums at two locations would look.
Click to view attachment
fredk
QUOTE (machi @ Aug 7 2014, 08:15 PM) *
BBC released very interesting footage from (evidently) OSIRIS camera.

You should find slightly better image quality from the original BBC story here:
http://www.bbc.co.uk/news/science-environment-28659783
machi
Yes, I should.
I saw that article but I have disabled automatic playback for flash so I overlooked this video and Google found the other one.
BTW, here is animated GIF.
anticitizen2
I had to grab larger frames from the video and slow it down

http://i.imgur.com/T8oZl7a.gif

Two days of utter amazement so far

Edit: album of the screen captures: http://imgur.com/a/0Lo1E#0
djellison
QUOTE (MichaelJWP @ Aug 6 2014, 10:42 PM) *
They look good, Doug. Do you provide textures and are the models u-v'd or are they just for printing?


Nope - just un-textured STL's for printing.

QUOTE (jgoldader @ Aug 7 2014, 05:24 AM) *
Any chance of Gaspra?


I'll look into it - but it would be pretty low res so might not be worth the effort.
Dyche Mullins
A few more useful size comparisons.

Click to view attachment
machi
QUOTE (anticitizen2 @ Aug 8 2014, 02:02 AM) *
I had to grab larger frames from the video and slow it down

http://i.imgur.com/T8oZl7a.gif
...


Thanks! It's impossible with my Internet connection to grab this video at full resolution.
Here is very interesting view on the head of the comet 67P from two grabbed images.
Credit for original images: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.
machi
And here is comparison between stereo images with both real images (lower one) and with one synthetic image (top) in the pair.
Thanks to anticitizen2 both pairs have now same resolution but the lower pair is still somewhat blurred.
I deleted the older version.
anticitizen2
And thank you for the 3D images! Those have truly brought me there next to the comet.

I feel like I owe you a dozen gasps of amazement from the people around me as I showed them your image of the comet in 3D
lunaitesrock
The processed photos released to date all have good contrast and likely have been brightened and stretched to some extent. Have any been processed to show the comet's actual appearance?

I haven't seen much discussion on albedo except mention that 67P/C-G is very dark, as would be expected if much of the nonvolatile remnants on the surface are similar in composition to carbonaceous chondrite meteorites.

Karl
nprev
INCREDIBLE, Daniel--thank you!!!!

In my opinion this is by far the most classically 'alien'-looking little world examined by spacecraft to date--straight out of a 1950s B-movie. Amazing to think of how different the processes by which all these odd, jagged landforms arose must be from those we've observed elsewhere. With any luck, though, we'll be able to see those processes in action a bit.
tolis
The smaller lobe (the one with the ``hole'') reminds me of the front part
of a Klingon Bird of Prey.
MichaelJWP
QUOTE (Dyche Mullins @ Aug 8 2014, 01:41 AM) *
A few more useful size comparisons.


Thanks, C-G nowhere near as big as the Death Star then:)
lunaitesrock
QUOTE (nprev @ Aug 8 2014, 12:39 AM) *
In my opinion this is by far the most classically 'alien'-looking little world examined by spacecraft to date--straight out of a 1950s B-movie. Amazing to think of how different the processes by which all these odd, jagged landforms arose must be from those we've observed elsewhere. With any luck, though, we'll be able to see those processes in action a bit.

'Standing' in the neck area one would see the landscape curve to nearly vertical on both sides while rapidly dropping off on the other 2 sides. In some areas adjacent to the neck the landscape would curve to be nearly overhead (like in a rotating donut-shaped space habitat). What a strange place!
bobik
QUOTE (Dyche Mullins @ Aug 8 2014, 01:41 AM) *
A few more useful size comparisons.

new image release biggrin.gif
centsworth_II
QUOTE (lunaitesrock @ Aug 7 2014, 10:16 PM) *
The processed photos released to date all have good contrast and likely have been brightened and stretched to some extent. Have any been processed to show the comet's actual appearance?
The scientist hosting the press briefing refered to the joke about a blank sheet of paper being presented as a drawing of a white cow in a snow storm in saying that he could just about present a totaly black screen as a 'true image' of the comet.
0101Morpheus
It's for the best, I tend to think that our minds don't know how to handle objects with very high albedos. The moon looks bright enough to us but its albedo is only 12%!

Plus the camera would get saturated.
Nebulium
Hello smile.gif

First, think to Adelson's chessboard :

http://web.mit.edu/persci/people/adelson/c...w_illusion.html

As an example of "true" Moon rendition, using a small compact camera I shot a piece of wood charcoal (its albedo is similar to the Moon one) under Sun light in automatic mode :
Light measurement was "spot" on background, on left and center, the background is a 18% grey chart, on right, it is current black paper.

Click to view attachment

- Center is the standard result automatically optimized by the camera : the dark subject was slightly enlighted
- Left was shot with asked 1IL underexposure, in order to obtain the official value of 128 for the background.
- Right is the standard result automatically optimized by the camera : the dark subject was more enlighted, as well as the background.
For me, the most realistic rendition is on left. But on right it shows more shades and details...

PS : Note that the light rendition curve of the compact camera is far from linear and probably histogram adaptative, while scientific cameras are nativly linear...
Gerald
QUOTE (djellison @ Aug 9 2014, 12:17 AM) *
Rotation rate is 12.7 hours. The circumference drawn by the 4km length of the comet ( a 2km radius ) is 12.6 km

So very roughly - it's doing 1km/hr or 0.28m/sec. V^2/r is thus 0.000039 m/sec^2

Surface gravity is approximated as 10^-3 m/sec^2 3 orders of magnitude higher than the centripetal acceleration due to rotation.

Hmm, according to the Wikipedia version, the escape velocity is estimated to 0.46 m/s, corresponding to about 0.33 m/s for a circular orbit.
So I'd say within the current uncertainty, respecting the rotation, the resulting surface gravity at the parts most distant to the center of mass is about zero.
A significantly more compact body with the same angular momentum would be torn apart.

This opens a scenario almost opposing the contact binary approach, meaning head and body could have been broken apart already by centrifugal pseudo-force, and kept together by the stretched "neck", which would give the "rubber" duck metaphor more sense than originally anticipated.
This way the inner of the comet would be exposed at the neck.
Additional momentum could have been provided by impacts or by YORP.
lunaitesrock
This photo from the end of the large lobe is particularly interesting to me especially when viewed under magnification...
http://blogs.esa.int/rosetta/files/2014/08...ull_image_2.png

At 6 o'clock there seems to be layering where bright (icy?) layers show through the mantle of darker material... I count about 6 'steps' climbing to the tall white cliff to the lower left.

At 9 o'clock just to left of center there are boulders which are covered in a mantle of the darker material.

Also at 9 o'clock to the left of those boulders the mantle of darker material seems to have flowed? over rougher surface features, draping the underlying terrain.

At 10 o'clock in the basin there are striations which look to me like some sort of lobate flow/collapse features... perhaps gravel fluidized by sublimation of icy materials underneath. They lead away from the bright cliffs on the left.

At about 12 o'clock immediately to the lower left of the large bright boulder there is a small area of evenly spaced striations which may have flowed from a collapse to the upper right.

The large smooth area in the center with the small linear features (ice layer?) I suspect is not a dust layer but a layer of gravel as was seen on Itokawa in the Muses Sea. I think most of the fine dust would escape with the outgassing of the comet.

I can't wait for higher resolution photos to come down. The geology of this object is so varied. I would bet that the processes which formed all features of the comet and the comet itself will be unraveled over the next few years.
MarsInMyLifetime
QUOTE (lunaitesrock @ Aug 8 2014, 10:25 PM) *
This photo from the end of the large lobe is particularly interesting to me especially when viewed under magnification...
http://blogs.esa.int/rosetta/files/2014/08...ull_image_2.png


I wonder whether these "boulders" may be ice features not unlike fumarole "smokers" in Earth's deep underwaters, or snow chimneys. Near the middle top of that image you linked, one object appears to have a hook-shaped shadow, and in the bottom right quarter is what appears to be a cylindrical tower that casts a notably long shadow, almost like the overhead images of Mars dust devils. Comet Hartley 2 (EPOXI mission) seemed to have these as well. Yes, more closer!

[Edit: not Borrelly but Hartley. Thanks, Phil!]



TheAnt
QUOTE (Phil Stooke @ Aug 8 2014, 10:04 PM) *
Not a pain, it just means the cartographers have long-term employment!

Phil


I would rather compare it to the work of the meteorologists, with a situation changing by the day or week. =)

@MarsInMyLifetime: I think you're on the spot there! =)
machi
I found multiple articles where authors use known cometary rotation periods for determination of limits for shapes and density.
Very interesting is fig.15. in Photometry of cometary nuclei: Rotation rates, coloursand a comparison with Kuiper Belt Objects by C. Snodgrass, S. C. Lowry and A. Fitzsimmons.

QUOTE (nprev @ Aug 8 2014, 07:39 AM) *
INCREDIBLE, Daniel--thank you!!!!

In my opinion this is by far the most classically 'alien'-looking little world examined by spacecraft to date--straight out of a 1950s B-movie. Amazing to think of how different the processes by which all these odd, jagged landforms arose must be from those we've observed elsewhere. With any luck, though, we'll be able to see those processes in action a bit.


Yes, this is beautiful crazy comet. From all comets observed from spacecrafts I think that this one is the best for detailed investigations.
I hoped that 67P will be similar to the Wild 2 and it's actually even more crazy than "too wild Wild 2"! smile.gif
mcgyver
QUOTE (machi @ Aug 6 2014, 05:08 PM) *
And here is cross-eye version of the same stereo image:

Parallel-eyes images can be directly seen in 3d-enabled TV sets just at a click of a button on the remote control.
mcgyver
QUOTE (machi @ Aug 8 2014, 02:13 AM) *
And here is comparison between stereo images with both real images (lower one) and with one synthetic image (top) in the pair.

In which way "syntethic"?!?
machi
It's image which is combination of two images. It can be obtained by warping to another image or reprojection to another image.
I haven't automatic software for this so I did this manually in Sqirlz Morph.
I gave example of this here.
This process is time consuming and its quality is dependent on the author (as it's not automatic) but it's usable when other methods are unreachable.
scalbers
QUOTE (MarsInMyLifetime @ Aug 9 2014, 04:42 AM) *
I wonder whether these "boulders" may be ice features not unlike fumarole "smokers" in Earth's deep underwaters, or snow chimneys. Near the middle top of that image you linked, one object appears to have a hook-shaped shadow, and in the bottom right quarter is what appears to be a cylindrical tower that casts a notably long shadow, almost like the overhead images of Mars dust devils. Comet Borrelly seemed to have these as well. Yes, more closer!

Yes the pointed shadows and hook shape are pretty fanciful. Sounds like a nice candidate landing site, except the green dots on their landing site map aren't that close by. Maybe there are other "chimneys" that coincide with the green landing dot candidates. These would be ones in the yellow region of the map with alternating light/dark periods of sunlight.

Any chimneys that would also be in view of the active neck area would be an added bonus.

On the other hand, a landing site might have to be smooth enough to be safe, depending on their navigation accuracy.
Phil Stooke
Those pics were of Hartley, not Borrelly.

Phil


lunaitesrock
Closer and closer. 81 km now.

http://blogs.esa.int/rosetta/2014/08/09/cometwatch-8-august/
brellis
Is the lander still asleep? If so, will it be powered up only after touchdown? Searching the web, I've learned there are batteries that can/will be used after touchdown and recharged once the solar panels are unfurled - but I'm curious to know if we are aware of the status of its instruments and batteries at this point. Thanks!
machi
Lander is awake from February or March. All instruments and batteries are fine (you can find articles about it on Rosetta's blog).
It has two different batteries. Non-rechargeable for high priority science after landing and rechargeable for long term operations.
fredk
QUOTE (MarsInMyLifetime @ Aug 9 2014, 05:42 AM) *
one object appears to have a hook-shaped shadow, and in the bottom right quarter is what appears to be a cylindrical tower that casts a notably long shadow

I think the hook is an illusion: I see the lower "hook" part of the shadow as the shadow of a second, smaller boulder immediately below the larger one. And the long shadows towards the bottom of the frame seem to be the result of a very low illumination angle.

That's not to say that this isn't an insanely cool place!
bobik
QUOTE (brellis @ Aug 9 2014, 11:17 PM) *
Is the lander still asleep? ...

Go to the Philae Virtual Control Room - telemetry in (almost) real time. wink.gif
Explorer1
From August to October 2014:
QUOTE
Philae Science Observations during Rosetta Comet approach
.
This might be a sign of images of the solar panels like the 2007 Mars flyby (the cameras have to be tested prior to landing anyway, right?).
climber
From rosetta.jpl.nasa.gov... Couldn't copy paste the link which show a picture of the target by the COSISCOPE camera.

Now that comet 67P/Churyumov-Gerasimernko is within our reach, Rosetta's mass spectrometer COSIMA, managed by the Max Planck Institute for Solar System Research in Germany, is beginning to reach for cometary dust. Literally.
On Sunday 10 August 2014, COSIMA will expose its first of 24 targetholders aiming to collect single dust particles. This might take a while. After all, from dust particle modeling, 67P/C-G's coma is still comparable to a high-quality cleanroom. But, as 67P/C-G travels closer to the Sun along its orbit, the comet's activity will increase and more dust will be within reach. For now, we are planning to keep the target exposed for one month, but checking on a weekly basis if the model predictions are not too low and if we are lucky.

COSIMA's targets were developed and prepared by the Universität der Bundeswehr in Germany. Each of these targets measures one square centimetre. It consists of a gold plate covered by a 30 µm thick layer of "metal black" (gold in this case), which has a very low albedo due to its high porosity.

Tests in the laboratory have shown that this layer should decelerate and capture cometary dust particles impacting with velocities of ~100 m/s. The grazing incidence illumination by LED's combined with the very low albedo of the target will provide high contrast for collected cometary grains, in particular if they stick out of the "gold black" layer.

As a reference, an image of this target has been obtained before cometary dust exposure on 19 July 2014 by the COSISCOPE camera, COSIMA's built-in microscope which was developed by Institut d'Astrophysique Spatiale (CNRS/Université Paris Sud, France).

The image shows…. well, basically nothing. But that's the point. We will identify the dust grains we collect on the target's surface by comparison with this empty target. The COSISCOPE microscope will take new images every week from now onwards.

The grains we identify will then be analysed in mid-September, thus providing the first in-situ analysis of cometary grains with a high mass resolution. COSIMA uses the method of Secondary Ion Mass Spectrometry. This means that the dust particles are in for quite a ride! They will be fired at with a beam of Indium ions. This will spark individual ions (we say secondary ions) from their surfaces, which will then be analysed with COSIMA's mass spectrometer.

All in all, this will help us understand what material cometary dust is made of, and that is the major science goal of COSIMA.
Nebulium
Hello smile.gif

From :

http://rosetta.jpl.nasa.gov/news/cosima-reaches-dust

A picture of the target by the COSISCOPE camera :



Credits: ESA/Rosetta/MPS for COSIMA Team MPS/CSNSM/UNIBW/TUORLA/IWF/IAS/ESA/BUW/MPE/LPC2E/LCM/FMI/UTU/LISA/UOFC/vH&S
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