Maybe ... we are looking on the wrong planet ?
According to my research :
... O2 n=1.000449 according to this page, but the page explicitly says the numbers are a guideline only and as far as I can tell there are no references. Since I am assuming this n value is at 1atm, you will have to convert the value to reflect the difference pressure at Mars' surface. I am not sure what forumula will help you do this, I am curious about this too, so if you find the formula post it for me. ...
Mars is 95.32 % Carbon Dioxide ... what would our values be if we use the red spectrum at about 700nm on the surface ... OF MARS ?
Using 1.000 449 I get 1.300055 ... closer but I don't believe the builders would be out this much. It gets us to within 99.63 % ... Hmmm maybe I am getting a bit too picky. But I like the fact that it might be on Mars ... makes sense since minus 40 degrees would almost be a normal temperature on Mars ... and Mars is certainly RED thus tying in why the red spectrum. !