A Non intrusive pigment analysis?
The DStretch method to analyze pictographs might be able to photographically analyze the pigment and possible even the method to apply the pigment. If the color enhancement is standardized and the photo method (flash, time of day, type of lighting, angle, camera setting) is consistent, then a comparative pigment (source of material) and the binder could even be identified IF it has any distinguishing color additive itself. Some development could be started with the end goal much like a Munsell chart.
Constellations or random placement? 
The Navajo stars has probably been analyzed since the 90's for any constellation identification. I would wonder the ratio of identifiable constellations to the random placement of stars on the ceilings (Coyote did his job well). I would also like to see what might be an acceptable star placement. I have seen the pottery and rugs that do indeed indicate constellations, but I would suggest that constellations came much later in the stories as a result of more education or the Navajo youth and to resolve their questions. The merging of star (pictograph crosses) and dots (round holes) in Navajo story telling into the origin of the stars could be the adaptive nature of the storyteller. The figure on the left is from Wijijii, Chaco, as shown in Living the Sky and shows the constellation Ursa Major. This is a spring constellation and is in reverse of the actual star layout. When asked about star reversal, Black God is used as evidence of the viewpoint of the gods to show the stars. I have difficulty in accepting this premise.
Navajo Star Origin?
If the stars in the ceiling at step house and the one noted in southeast Utah (Von Del Chamberlain, 1989) predate the Navajo time period, then the possibility that the Navajo could have adapted their star ceilings from these or other examples. The later presence of Navajo travelers to these locations would have to be established in two or more situations.
Pre-History Astronomy Origin? 
McKim Malville (in his new revised prehistoric astronomy, 2008 book) presents the ancient pueblo unique astronomy observation of the major lunar standstill. If a basketmaker petroglyph shows equinox and solstice markers and later, the Anasazi added further petroglyph sky observation to the same panel, would not that be very cool? The above cave Quad figure is likely basketmaker or earlier (fully repatenized) and shows a shaft of light that disappears into the legs on Summer Solstice. The lines to the left and to the right are probably Ancient Pueblo (half repatenized) and the lines tie into other sky observations. This site is still being reviewed.