globaljustin writes "Alan Drysdale, a systems analyst in advanced life support and a contractor with NASA concluded, "Small women haven't been demonstrated to be appreciably dumber than big women or big men, so there's no reason to choose larger people for a flight crew when it's brain power you want," says Drysdale. "The logical thing to do is to fly small women." Kate Greene, who wrote the linked article, took part in the first HI-SEAS experiment in Martian-style living, and has some compelling reasons for an all-women crew, energy efficiency chief among them: Week in and week out, the three female crew members expended less than half the calories of the three male crew members. Less than half! We were all exercising roughly the same amount—at least 45 minutes a day for five consecutive days a week—but our metabolic furnaces were calibrated in radically different ways. During one week, the most metabolically active male burned an average of 3,450 calories per day, while the least metabolically active female expended 1,475 calories per day. It was rare for a woman on crew to burn 2,000 calories in a day and common for male crew members to exceed 3,000. ... The calorie requirements of an astronaut matter significantly when planning a mission. The more food a person needs to maintain her weight on a long space journey, the more food should launch with her. The more food launched, the heavier the payload. The heavier the payload, the more fuel required to blast it into orbit and beyond. The more fuel required, the heavier the rocket becomes, which it in turn requires more fuel to launch.