National Geographic : 2001 May
rock where geologist Louise Hose takes a water sample from a spring (left). For her and her colleagues, micro is macro, and the smaller the better. Microbiologist Penny Boston, whose specialty is astrobiology, or extraterres trial life, wonders if the more extreme forms of the Villa Luz microbes "could be an analog to life we might someday find deep beneath the surface of Mars." Watch an interview with pho tographer Stephen Alvarez and find out what life's like on assignment in an acid filled cave at nationalgeo graphic.com/ngm/0105.