There's more legend than fact to that story. It was soundly debunked on Mythbusters last season. At the required distance they were only able to raise the surface temps a 100 or so degrees. Of course, there is always the possibility that there was an alien intervention (the same ones that built the pyramids) and the whole polished mirror/shield story was just a cover for the conspiracy. I have no evidence to support this theory but that is precisely what defines a good conspiracy.

Ed