“Mars, A Traveler’s Guide,” by Ruth Nestvold is pretty dark. Funny, but dark. You realize quickly that you are reading the data feed from an online help system. The unseen human is stranded with no better help than a wiki. It reminds me of the old Bob Newhart routines, where he used to tell stories from one side of a phone conversation. Here, you follow what happens through what queries are being made. Or not made.