The bubble-like 'cells' in north Sputnik:



remind me of pillow lava that has been sheared off:



(Image from: https://notnecessarilygeology.wordpress.com...alt-bencorragh/ )

However, the vastly greater scale implies some other process altogether. Perhaps there is some intrusive process involved?....

As for the dark patches/streaks, I think they could be lag left behind after sublimation.

It's common for glaciers to have some sort of patterning around their edges - for example:



The pattern isn't exactly the same, but neither are the materials, gravity, scale, ambient pressure... etc.

Crater ray systems can last for eons, and we don't know that this isn't similar to that, but produced by an internal explosion rather than an impact, which a much higher volume of ejecta.

The absence of smaller impacts on Sputnik means that it is certainly very new, no matter what the origin of it was – at least in terms of whatever the cratering rate is at Pluto. That means that whatever happened, it is either a one-time event that happened recently in those terms or a cyclically-repeating event.

But neither of those inform the details of how fine the substrate is that causes the differences in the "down-wind" direction of obstacles. It could be like powder, or it could be like boulders. Our resolution is far too poor to know yet.

In none of these cases do we have to suppose that wind at any time besides the last, potentially violent, emplacement of material was the agent making the streaks.

Basically, the streaks could be:
something dark on top of white N2 ice,
something dark under clear N2 ice.
different grain sizes of N2 ice,
different forms of N2 ice crystals (hexagon or square),
locations with a mix of the hex and square crystals
locations where latent heat in solid ice is causing patterns
locations where sunlight is causing scalloped ice or suncups

Another case where it's so unfortunate that NH wasn't radar equipped like Cassini.

Not that there was any way that was ever going to happen, but still... If you want to know about fine surface texture, you either land or you use radar.

But, at least we've got better spectral data coming

Agreed, can't discount texture.
And sublimating ice (at least h2o ice) under a constant source of illumination does some amazing things

Next image from NH might arrive Saturday next week (5 September) :-0



https://twitter.com/StephenClark1/status/636229769168711680

Note that the radar signal strength is inversely proportional to the fourth power of the distance. Cassini generally uses radar when flying below 1000 km. NH closest approach was over 12,000 km, resulting in ~20000 times weaker signal (assuming the same transmitter). This is just before getting into the problems with the high relative speed of the flyby.

New Horizons doesn't carry radar, but could it detect a radio signal from earth that bounced off Pluto/Charon.
Does Arecibo transmit any frequencies that New Horizons receives?

Could it detect "Tufnel scattering"
Turn Arecibo volume up to 11,
Point at Pluto/Charon
Play a signal as loud as you can.
Hope NH can hear the radar echo.

So, variables are
Arecibo signal strength, beam width in radians, time to aim dish.
Pluto/Charon visibility based on alt/azimuth at 24hour day.
Pluto Charon surface changes at 6 day/144 hour rotation period.

So, blast a radio signal at Pluto at the same time every day, New Horizons hears it about 4 hours later.
Do this for 6 days, you get rough data on 60' slices of Pluto/Charon

Even before the appearance of detailed pictures, in early July, I advanced the hypothesis that the Charon's genesis more likely not in direct collision of a body with Pluto, while close flyby and dividing the body by tidal forces into at least three parts. One part flew away from Pluto carrying away the excess angular momentum. The second part is Charon.
The third part (I called it Acheron - about 400 km in diameter) was closer to Pluto than Charon, therefore, strongly decelerate due to higher tide on Pluto and warmed his equatorial region.
Soon it became a circular orbit and approached to the surface of Pluto.
Speed relative to the surface in view of the accelerated rotation of Pluto is about 700 m/s.
Touching the surface of Pluto Acheron jumped a few times and then buried in the mantle of Pluto. The upper part of it smashed on the equator of Pluto.
Location of Acheron stopping should be mascon, should therefore be on the line passing through the centers of Pluto and Charon.
This is my crazy idea...
When there were photos with high resolution, confidence in such a scenario has increased. If you look along the equator from zero longitude, there are traces of bounces, and then - the equatorial deceleration trench (Cthulhu) and then stopping place (what was my astonishment when it was called Sputnik - i.e. satellite), then smeared the substance flows.
The main question in this scenario - flowing of Acheron's water ice mantle under the increasing influence of tidal forces. I am currently working on this model.

Your theory involves a 400km diameter object bouncing? Collisions don't behave like that on those kinds of scales...

Also, a theory involving Pluto ripping a large object with tidal forces sounds suspect. Rubble piles don't exist on the scale of your original second body, and Pluto isn't exactly setting any records for tidal forces.

Anyone know what order the images will be arriving? In the order they were taken, or will they be selecting high priority images for early download?

The official Twitter account talks about "Selected High Priority" datasets arriving in September, which could suggest that images will arrive in an order sorted by priority.

Given their size and shapes the polygons of Sputnik Planum are very likely the tops of convection cells. The convecting ice (nitrogen+methane+carbon monoxide) would be shallowest near to the shore so it seems likely that the rising ice within the cells scoured some dark material from the surface the crust underlying the ice before carrying it up onto the surface of Sputnik Planum. The closer to the edge of Sputnik Planum the more dark material is dredged up. This is particularly true in the north of Sputnik Planum where the ice appears to be flowing northwards across a wide front and onto Pluto's ancient crust.

I thought about that, but I think Tombaugh is enriched in CO because of pressure and temperature effects.
What if Tombaugh has an ice cap and a CO ice concentration because Pluto experiences "tidal atmospheric refrigeration" in that area?

Moons cause tides on their planets. On Earth, seas have tides every 12 hours. There are also tides in the ground, and tides in the air.
Estimates of the atmospheric tides suggest they increase normative air pressure by 1%.

On Pluto, the tidal effects are greater, closer distance, and the bodies are closer in size-
so, Pluto's tides should create more than 1% differnece in air pressure- (any atmospheric gurus have a guess on tidal pressure for Pluto?)

Argument- Tombaugh ice cap is a result of atmospheric tides on Pluto which create a static high pressure system at Tombaugh.
A static high pressure system creates volume and temperature effects which create a natural refrigerator effect.
You all remember PV=nRT. Ideal gas equation. The reason refrigerators work.
1) Compress a gas.
2) Wait. Let the gas interact with the surrounding system over time. {e.g. non-adiabatic}
3) Compressed gas leaves the high pressure area, (e.g. expands) it cools. Cooling drives phase changes (snow).

So, the atmosphere in Tombaugh is slightly compressed. Something in the range of 1% or more.
Compression heats air up by a small percentage. Heat flows into the ice cap or is radiated away into the moonless night.
That super-cooled air drifts away from Tombaugh, it expands, it cools, and under the right conditions, it causes CO snow.