- #596
Garth
Science Advisor
Gold Member
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That looks like a camera effect of over-exposure to me.
Garth
Garth
Orbit dates altitude(km) pixelsize(m) res/HST period soccerball at
RC3 April 23–May 9 (13,600) (1,300) 24 15 days (3.0 meters)
Survey June 6-30 (4,400) (410) 73 3.1 days (1.0 meters)
HAMO Aug 17–Oct 23 (1,470) (140) 217 19 hours (33 cm)
LAMO Dec 15–end of mission (375) (35) 850 5.5 hours (8.5 cm)
mfb said:No pictures of the bright spots from HAMO orbit so far :(.
marcus said:...
Can you understand their description of pingo formation?
Zeno Ether said:I have compared the previous image with the new and there is something odd. The two bright lights on the right side of the crater are missing. Here is the comparison.View attachment 88495
Are we looking at dynamic changes? Perhaps we are dealing with plumes?mfb said:If the area is really that dynamic, we'll see more changes soon.
I don't know. Would be amazing.Dotini said:Are we looking at dynamic changes?
I don't agree. The two big bright spots on the right have completely vanished in the surrounding terrain, whereas the other dimmer spots are still there in the new processed image. I think maybe NASA has (inadvertently?) erased the spots during post-processing.mfb said:The previous images were overexposed, so many pixels were pure white without contrast. The new ones have a better dynamic range.
Still surprising that the areas are close to the surrounding terrain in the new images. If the area is really that dynamic, we'll see more changes soon.
Zeno Ether said:... 2) the material itself is emitting light.
Let the brightness of the environment be 1, the two "vanishing" spots 2 and the other spots 10, in arbitrary units.Zeno Ether said:I don't agree. The two big bright spots on the right have completely vanished in the surrounding terrain, whereas the other dimmer spots are still there in the new processed image.
The spots are not visible on the night side.Zeno Ether said:I have another question for you. If the light we see were sunlight reflected by the surface of this "material", there should be some direction, where the surface should be visible without receiving the reflected light, according to the laws of optics. So, there should be the possibility for Dawn to capture an image of the spots without the reflection. If this is not possible then maybe 1) the reflection is diffuse (in all directions) or 2) the material itself is emitting light.
OmCheeto said:...
ps. I've sent an email to someone who might have access to the original two images. Crossing my fingers.
2015.09.11 07:15 pm PST
Hi [Om],
I have wondered if you were still following the mission, although I confess to being too busy ever to visit the forum. I'm glad to know your managing to keep busy.
I do have all the Dawn images, but what has been approved for public release is currently available for distribution. Ultimately, of course, all of Dawn's data from all investigations will be released, as it was for Vesta. As we see Occator in each mapping cycle (remember, in this third mapping orbit, we map Ceres six times, or once every 11 days), we will see Occator six times. I imagine that even before the first analysis of the images is complete, our daily release will include some more views which will include raw images. I do recommend some images for the approval process, and based on your message, I will suggest the original images (or something equivalent).
In the meantime, if there's a specific question about the images, let me know.
Thank you for continuing to follow the mission!
Marc
Orbit dates altitude(km) pixelsize(m) res/HST period soccerball at
RC3 April 23–May 9 (13,600) (1,300) 24 15 days (3.0 meters)
Survey June 6-30 (4,400) (410) 73 3.1 days (1.0 meters)
HAMO Aug 17–Oct 23 (1,470) (140) 217 19 hours (33 cm)
LAMO Dec 15–end of mission (375) (35) 850 5.5 hours (8.5 cm)
marcus said:Om, I'm so glad you are keeping in touch with Marc Rayman. If you ever have a good opportunity, would you consider asking him about any IR and visible spectroscopic results about the surface chemistry? We are getting all these pictures, in fine detail and from different angles. So topographical info is obviously building up rapidly.
But he mentions the spectroscopy going on at the same time. Can they tell anything about the chemistry from the wavelengths emitted by the surface?
...
By Marc Rayman
JUNE 29, 2015
...
Several craters here have central peaks. The largest also has a ridge at the center. Note other intriguing geological structures, including the terraced walls of that crater and the contrast between the smooth area in the top half of the picture and the more rugged terrain at the bottom.
...
marcus said:It would be great if Rayman would comment on any of these questions! I share your curiosity about "pingo" mountain-building on Ceres.
I guess the technical term for mountain-building is orogenesis. Oro- a greek root for mountain is not to be confused with "oreo".
I don't completely understand the pingo ice-pimple process. I think it has to do with the the tendency of water to join with other water when it freezes, rather than freezing in a mix with interspersed grains of mineral. Ice likes to bond with other ice, and that can actually create upthrust pressure and a swollen hump.
I would imagine (Rayman may wish to correct this) that the same process that can raise a 70 meter ice-bump on Earth could raise a bump 30 times higher (>2000 meter or 2 km) on Ceres with its 1/30 strength gravity.
marcus said:OK well my pet question is can he tell us anything about the surface composition of Ceres that has been learned from the IR and visible spectra Dawn has taken so far?
And my pingo conjecture which I hope you try out on him is the same processes could be at work, although perhaps more rarely on Ceres, and could create a comparable pressure, so that a Ceres pingo could be on the order of 30 times higher than an Earth pingo.
Apparently yes, and the louche lady of mysteries asked some good questions and received some intriguing answers.OmCheeto said:Did Christopher Russell really do an interview with Linda Moulton Howe?