Pluto Atmospheric Observations: NH Post-Encounter Phase, 1 Aug 2015- TBD Options

[scalbers]

Most remarkable simulations with the atmospheric scattering and all. Is it that the atmosphere is actually "glowing" right at the location of the Charonshine, or simply bright nearby with concerns about scattering in the camera optics?

Is the bright spot on the dark side signifying anything or some type of ghost image effect?

[Gennady Ionov]

Is it that the atmosphere is actually "glowing" right at the location of the Charonshine, or simply bright nearby with concerns about scattering in the camera optics?

I think that here we have not yet seen the Charonshine - it will be seen well on the next turn virtual NH around Pluto (I try increase gain parameter when NH will be opposite to Sun). Scattering by optics plays an important role, but there all the same basically own atmospheric glow.
At the end animation moment about half of the Pluto disc are illuminated by Sun from right side.
Spot on the top is Nix.

Is the bright spot on the dark side signifying anything or some type of ghost image effect?

This is simulation bug at the southern pole point.
I'm fixed it just now!

[scalbers]

Thanks for the update - I now can see the mini-moon at the very end. With the atmospheric glow on the night side, I wonder if/how multiple scattering is being considered, as that would extend the nighttime area of glow.

[Gennady Ionov]

It's the same bug. At one point, I added a small constant 1e-6 to avoid scratch. But she was not so small, and led to diffuse faint glow of the night-side, thickening to the pole.
Multiple scattering does not considired.
New version:
https://youtu.be/8d9hR22SdZo
Version 2: https://youtu.be/Fs9qq3gnAew
Charonshine:


CharonSet:

[Habukaz]

In case anyone missed it, the 29 June stellar occultation by Pluto yielded an atmospheric pressure of 22 microbars; more than 4 times the 5 microbar pressure found by NH.

This suggests that the atmosphere of Pluto was still growing when NH flew past, although, evidently, some model somewhere is wonky.

“I feel pretty secure that Pluto isn’t starting to freeze out,” says Eliot Young, a planetary scientist at the Southwest Research Institute (SwRI) in Boulder, Colorado.

[...]

“How we link the two, we’re still working on,” says Cathy Olkin, a deputy project scientist for New Horizons at SwRI.

Part of the discrepancy between the spacecraft’s observation and past estimates could be due to the indirect way that astronomers derive the value from Earth-based observations. These studies measure pressure some 50–75 kilo­metres above the dwarf planet’s surface, and researchers use assumptions about the atmosphere’s structure to calculate what that number translates to at the ground.

http://www.nature.com/news/pluto-snow-fore...nundrum-1.18274

[fredk]

The press release caption for PIA19880 says we may be seeing crepuscular rays in the terminator region. I've done a very quick and dirty attempt to enhance that detail. Here's the original frame with gamma tweak:

I created a simple circularly symmetric template to subtract from the image, followed by stretching, to bring out the detail in question:

Some of that detail, eg the brightening at the innermost part of the terminator region, is due to processing - a mismatch between the radial profile of the template and the actual image. I'm sure you could do much better with a better template (in particular one that has an elliptical inner boundary).

But the horizontal streaks should be really on the frame. The question is are they on Pluto or not. If you look closely at the lor jpegs, you can see faint striping more or less parallel to these features, apparently due to CCD noise/dark current. This is a stack of those four frames, and shows those CCD streaks running horizontally across the dark disk:

If you compare this image with the enhanced one, you can see that some of the terminator streaks may be due to these CCD streaks - they line up - but not all. So I suspect we really are seeing crepuscular rays. Another bit of evidence is that the streaking is not visible at the outermost radius of the atmosphere.

It's bad luck that the CCD streaks lined up with the solar direction. Perhaps there will be more frames where that's not the case.

[fred_76]

Hello!

Yesterday night I tried to surimpose a view of the "day" side of Pluto with a composite stacking of the 4 images of atmosphere's view taken the 15th july. Here is the result:


This image is "just for fun" indeed...


The correct image is the following one. It is made from the 4 full disk atmo images. The processing is as follows :
- registration on one star
- registration of the whole dwarf planet
- stacking with min/max rejection
- richardson-lucy deconvolution
- log view



The multiple layers structure of the atmosphere is quite intrigating. The dynamic of that structure should be very interesting to understand.

Fred

[scalbers]

That would be interesting to see if a good enough shape model can be developed to simulate these crepuscular rays. It seems that obvious rays would need the mountain height to be somewhat approaching the scale height of the haze, otherwise the contrast would be low.

I have simulated these with my software geared for Earth - I wonder if this could retooled for Pluto...

[Ian R]

My attempt to 'unwrap' the hi-phase angle images, with a hint of color added for artistic purposes:

http://s8.postimg.org/qbg9kqhmb/Pluto_Rays_COLOR.png

[Herobrine]

Looks like ninjas are nearby, but here's an unwrapping of lor_0299236719, lor_0299236749, lor_0299236779, and lor_0299236809. No correction for distortion was performed. A minor level adjustment was performed on some frames to make the brightness curve consistent across all frames. According to the metadata, there was a 0.16% difference in distance-to-target between the first and last frames, amounting to over a pixel of difference in Pluto's diameter, so each image was scaled based on the distance-to-target value in the metadata to correct for this. Alignment was manual, done at 4x scale to allow for some sub-pixel precision. Dimensions scaled-to were 4096, 4098, 4100, and 4103, from nearest to farthest. After alignment, Pluto center was estimated with reasonable confidence that the estimate was within 1 pixel of center at the original scale. The scaled frames were cropped to the region they all shared, yielding a set of 3829x4032 images, which were lightly sharpened with a simple unsharp masking algorithm with radius 6 (1.5 at the original scale) in lieu of deconvolution (because I'm lazy), after which each pixel from each of the four resulting frames (61,754,112 samples in all) was measured for distance from estimated Pluto center and angle from +X relative to Pluto center, and then 2-dimensionally binned in 1 pixel scaled radius x 0.1 degree angle bins (lists of integer sample values, actually, which were later averaged to a floating-point value). The 4000(only 2914 used)x3600 bins were rendered to a 3600x4000 image, which was then cropped to 3600x1748 (to remove incomplete radius space high above the planet), horizontally shifted 25% to place the limb-bound section near the center, gamma-adjusted, and finally scaled to half size (1800x874) to be small enough to upload here.

The horizontal axis spans 360 degrees around the center of the planet, with each horizontal pixel equaling 0.2 degrees. The vertical axis is image-space distance from the center of the planet, with each vertical pixel equaling 0.5 pixels at the scale of lor_0299236719. The bottom of the image is the estimated center of Pluto. Artefacts near the bottom are the result of a shortage of pixels for binning at different angles very near the center. Pluto average radius appears to be about 618 pixels (314 pixels at the scale of lor_0299236719).

Here's a sharpened, level-adjusted, cropped, shifted, and scaled version, including just the limb/terminator and surrounding bright areas.

[HSchirmer]

Quick question- just how intense IS Charonshine? Enough to make a 1 or 2 kelvin difference?

...
In total its make relative temperature difference about 0.00008*2*4=0.00064 ...
In absolute value it is about 0.00064*40K=0.0256 K

Just occurred to me that tiny temperature differences on Pluto that might be enought to drive weather
Those amazing terminator images may have caught "sideways thunderstorms" convecting heat from the days side to the night side.

First bizzare concept - Pluto's N2 ices and N2 atmosphere create a planet-wide equal temperature/pressure bath.
Think of a giant pitcher of ice water, melting or freezing water in a pitcher of ice water does not change the system temperature until all the water is in one phase. N2 ice and N2 atmosphere should be a solid-fluid constant pressure/temperature system.
I've read papers that say Pluto's N2 atmospher and N2 ices should form a contant temperature system, or a constant pressure system , but that idea just sunk in- you literally can not heat up local patches of N2 ice on pluto, it just moves somewhere else, so that all N2 ice on Pluto should be at the same temperature. Instead, you end up heaing up or cooling down ALL surface N2 ice of Pluto. It's sort of a thermodynamic verision of "sea level" on earth.

Second bizzare concept- Tiny variations in heating/sublimation might drive amazing storms in Pluto's atmosphere.
On Earth, a 1% difference in atmospheric pressure creates a high or low pressure system. A 5% difference is a hurricane, a 10% difference is a tornado. Estimates for Pluto are a 1K temp increase doubles the N2 vapor pressure. Wow, a 1K temperature increase creates a 100% pressure difference. So, something as tiny as a .025 K increase in temperature due to relflected light from Charon, might create a 2.5% atmospheric pressure difference- that percentage difference on earth is sufficient to drive a tropical storm.

[alan]

Some topography o the limb visible in these

http://pluto.jhuapl.edu/soc/Pluto-Encounte...0x630_sci_3.jpg
http://pluto.jhuapl.edu/soc/Pluto-Encounte...0x630_sci_3.jpg
http://pluto.jhuapl.edu/soc/Pluto-Encounte...0x630_sci_4.jpg
http://pluto.jhuapl.edu/soc/Pluto-Encounte...0x630_sci_3.jpg

[Gennady Ionov]

Just occurred to me that tiny temperature differences on Pluto that might be enought to drive weather
Those amazing terminator images may have caught "sideways thunderstorms" convecting heat from the days side to the night side.

Second bizzare concept- Tiny variations in heating/sublimation might drive amazing storms in Pluto's atmosphere.
On Earth, a 1% difference in atmospheric pressure creates a high or low pressure system. A 5% difference is a hurricane, a 10% difference is a tornado. Estimates for Pluto are a 1K temp increase doubles the N2 vapor pressure. Wow, a 1K temperature increase creates a 100% pressure difference. So, something as tiny as a .025 K increase in temperature due to relflected light from Charon, might create a 2.5% atmospheric pressure difference- that percentage difference on earth is sufficient to drive a tropical storm.

That was my calculation for the case when there is no atmosphere. Pluto atmosphere is the thermostat and it is necessary find a flow of nitrogen which compensate the additional heat from Charon. The heat flux is 5.67e-8 * 0.0256 * 4 * 40 * 40 * 40 = 0.37 mW / m^2. At nitrogen evaporation heat 200 kJ / kg, this gives 1.9e-9 kg / s / m^2. If the heated area have radius of 300 km we get 530 kg / s. At the same time across the cylindrical surface nitrogen flow was 0.3 g / sec / m. At a pressure of 1 Pa it is about 1.7 kg per square meter of nitrogen accounted, so the speed of the wind caused by light of Charon be only about 0.2 mm / s. It is negligible!

[Herobrine]

The weekly SOC release was about 90 minutes ago. 8 LORRI images were released.
Below is the full list of new images. They are all part of "P_MULTI_DEP_LONG_1_L1" and show a backlit Pluto with atmosphere/haze illuminated.
http://pluto.jhuapl.edu/soc/Pluto-Encounte...0x630_sci_3.jpg
http://pluto.jhuapl.edu/soc/Pluto-Encounte...0x630_sci_3.jpg
http://pluto.jhuapl.edu/soc/Pluto-Encounte...0x630_sci_3.jpg
http://pluto.jhuapl.edu/soc/Pluto-Encounte...0x630_sci_3.jpg
http://pluto.jhuapl.edu/soc/Pluto-Encounte...0x630_sci_3.jpg
http://pluto.jhuapl.edu/soc/Pluto-Encounte...0x630_sci_3.jpg
http://pluto.jhuapl.edu/soc/Pluto-Encounte...0x630_sci_4.jpg
http://pluto.jhuapl.edu/soc/Pluto-Encounte...0x630_sci_4.jpg

[Nafnlaus]

Tried stacking them to see if I could bring out any detail that wasn't immediately near the limb. No luck.