The Stain - Page 15

> ...in astronomy NIR is good for detecting dust, is that what they are using it here for?

I don't think so. The reflected near-infrared spectrum can be used in the same way as the visible and UV spectra to help identify minerals. Think of it as an extended visible spectrum. For example, the reflected spectrum from vegetation has characteristic peaks at the green and also near-infrared frequencies.

Ok. I guess we will just have to wait until the wheels break and hope the PCMA doesn't so we can get a full sol or two of observations of the PCCT so we can see what it does throughout a sol.

Stain on Sol 2599.

Changes from sol 2472 to 2594:

sol 2594-2604 ( May 12-22, 2011 ) animation near the calibration target:

This is how a clean area of the deck should behave. Notice that the sundial stain does not behave this way.

Because the cleanest area should best produce a specular reflection? It took me a moment to get this (Duh!). Do we have any shots of the stain where we would especially expect a sun reflection if the deck was clean? I seem to remember an image where the rays from the sun came at a low angle.

Sol 2583 ( May 1, 2011 ) backlit stain ( and deck ):

see Flickr comments.

Does it look like part of the stain (the part around the solar panel) is projecting above the deck? By a greater amount than some of the wires visible in the scene?

The stain seems to be fading, but notice the dark circles now under TWO corners of the sundial platform.

Perhaps frost or ice is occasionally trapped under the sundial platform. Maybe when it finally melts or sublimates, the water vapor is blown out from the corner and hydrates the red dust, making it darker. In this scenario, the stain can fade either by a covering of fresh dust or by dehydration.

sol 2626-2630 3D changes to the sundial stain after a cleaning event:

Good eye Barsoomer!

Note that the old stain has mostly been blown away by the cleaning event - and a new stain is again forming behind the sundial.

This "stain" thingie is amazing.

It seems like a new stain only emerges after the old one fades and/or is covered by fresh reddish dust.

Yeah>>>

Its a real Martian experience, so-called 'stain'!

yt
dx

Cleaning event meaning wind gusts. ‘Stain’ reappears. coincidence or causal?

The image in reply 290 is from Sol2628. A cleaning has occurred, but the new stain is not evident yet.

The previous emergence of the stain, shortly after we left Santa Maria crater, was not associated with a cleaning event.

The stain is like the Phoenix: a new stain arises from the "ashes" of the old.

A little bit more on Sol 2635.

sol 2635 (Jun 23, 2011 ) L267 of the new stain:

The fourth stain continues to grow. Some of the filters seem to show a smudge in the narrow strip beyond the sundial platform where the stain first seemed to manifest:

sol 2646 ( Jul 4, 2011 ) L0R0:

still spreading.

sol 2373 ( Sep 27, 2010 ) annotated orthogonal projection of the sundial stain:

I thought I had posted this before but apparently not.

Notice that the stain does not appear to be coming from behind the sundial - but from under the left back corner chip.

Perhaps there is something "special" about that chip? I don't think I have ever seen an identification of the actual chip minerals and their location on the sundial. A google search for "rover sundial color chip mineral" didn't turn up anything useful.