”The snow brought us a little bit back to Earth,” says Kathryn Bywaters. A biochemistry student, Bywaters was a member of Mars Desert Research Station crew 42, a team of five men and one woman who spent two weeks last January as if on a mission to Mars. In reality they were in a desert in Utah, ­living in one of two Red Planet simulations operated by the Mars Society. Crew members have actual missions: this crew tested a robotic rover built by the University of Pecs, Hungary. And Bywaters, who is not in this photo, conducted a survey of the desert’s salt-tolerant bacteria. The station is meant to ­simulate as closely as possible what living and working on Mars would be like. But sometimes the illusion is ­broken. Snow doesn’t fall on Mars, but nearby Hanksville, Utah, ­averages 15 centimeters per year.