HiRISE images of Phobos!, "images available NOW". Options

[Stu]

Can't wait to see these...!

MRO images Phobos

[edstrick]

"No, that is Phobos. "
<grins at tedstryk> I have a smurdgy xerox of the article in <i think> Icarus, identifying it in that pic and presenting the little matrix of pixels.

The new pic: "Gosh! Wow!! Boy-Oh-Boh!!!"

I remember watching evening news, probably CBS with Uncle Walter Crankcase <grins> in my college dorm when the first blurry small Mariner 9 press-release pic of Phobos showed up on screen and I ***KNEW*** what it ***HAD TO BE*** before the announcer got the words out. later Mariner 9 pics were considerably better and one or two pretty detailed. But the first one was able to clearly show cratering of different sizes, and I thought "Diseased potato".

My impression is that space-weathering is NOT reddening the materials in the scene, almost entirely darkening them without changing color much. In the color coordinates of the image, bright material on crater rims, knobs, and rounded upper "edges" of things (convex-up surfaces) that can be expected to shed loose debris preferentially down-slope are bright, but typically the same color as surrounding material.

In the extra-enhanced Planetary Soc Blog copy of the image, re-oriented with Stickney and the far limb beyond the crater at left, the blue-white and blue-gray area on the near rim of Stickney has cinnamon reddish patches seemingly embedded in it, one exposed by the crater on the outer slope of the Stickney rim, with red streaks trailing down-slope from topographic high of the rim.

A quite small sharp crater on the rim of Stickney toward the limb at 9:00 clock angle <in this orientation> has a mix of both red and gray-white in clearly defined radial crater rays extending out about 1 small crater diameter. Clearly both materials present where the crater struck.

A smallish crater, rater eroded, on the rim of Stickey at 12:00 clock angle is surrounded by an area of very uniform purplish gray color, medium and dark, NO REALLY BRIGHT PATCHES AT ALL. Some of the purple gray extends out of Stickney. but it also extends into the crater, partway down the crater slope.

Medium reddish brown material seems to form a discrete band at the topographic break between the slope and floor of Stickney. Darker material above it is brown and in one area quite dark magenta-brown, not obviously related to the purple gray crater on the rim of Stickney, but possible related to a very dark band of material extending down the crater wall from an unusual dark spot on the rim at about 11:30 clock angle.

Much of the floor of Stickney is dark, lighter in and around small craters and on knobs. Colors of knobs generally, but NOT always, relate to colors of surrounding material, which varies across the floor of Stickney in no well defined pattern, though the largest patch of gray and blue-gray is connected to the blue-gray on the near rim of Stickney. Smaller, lower contrast color patterns are rather jumbled.

The impression is of an "assembled" body, or one which might once have had well defined structure but was broken and re-assembled. It looks somewhat like a rubble pile, but is heterogeneous on very large scales, with smaller blocks of different material now within large areas of a different material.

Wow.

Clearly, Phobos sampling will get a variety of materials, probably more than one unweathered component, once knobs and boulders are targeted. Clearly, samples from different areas will be needed to understand Phobos's variety.

On to Deimos! <even at lower resolution, the shear colorimetric discrimination shown here will almost have to show something interesting.>