There are a couple of "New Scientist" articles about caves in space. <http://www.newscientist.com/article/dn9644> is about possibly using lava tubes on the moon as bases for astronauts. <http://www.newscientist.com/article/dn9588> is about caves on Saturn's moon Titan. Linda Starr brought these up at a recent Sandia Grotto meeting. Thanks, Linda! Mark Minton