Working Life is a monthly column in which Texans talk about their jobs. Alexandra Whitmire, fifty, works at NASA’s Johnson Space Center, where she studies how prolonged isolation and confinement might affect astronauts during spaceflight.Psychology was kind of an accident. I had switched my major four times when I was an undergraduate at the University of Texas at Austin and settled on English. But I still wasn’t sure, so I thought I would double-major instead of changing my major again. I chose psychology and quickly came to love it. It appealed to me to measure complex human behavior using both qualitative and quantitative observations.A mission to Mars presents a bunch of challenges. Your circadian rhythm is thrown off on Mars because the day is approximately 39…