QUOTE (climber @ Nov 14 2006, 10:50 AM)
Just curious to know why Beacon is so bright. Any thought before we know?
I've always made the simplest assumption, Climb, that the Beacon rock was the same as all the other pale evaporite we've been driving over since Eagle Crater. (I'm a long-time follower of William of Ockam; i.e. don't postulate diamonds or polished marble, if good-old garden-variety sulfate sandstone will reflect enough light.)
The vertical edge of an evaporite slab facing northward will reflect plenty of light from the northerly-positioned winter sun back towards the north, from where we were looking, back in May and June. All other surfaces in the Victoria region were hidden or roughly horizontal so they would reflect back minimal light even if they were mirrors. Thus, that roughly 1.0 x 0.2 meter evaporite edge was by far the brightest thing we could see in the south - a true beacon.
The same sort of basic optical principles explain why El Dorado always looked black from orbit or from the top of Husband Hill, but has always looked rather light from Low Ridge. The difference is only that the well-sorted basalt sand of ElDorado reflects back little light, while the iron sulfates reflect back plenty.