They took as their reference an existing mission study to send six humans to Mars and back in a five year timescale. The study found the spacecraft mass could be reduced by a third by removing the crew quarters with a similar reduction in consumables, equivalent to several tons of saved mass. Hibernation would take place in small individual pods that would double as cabins while the crew are awake. The assumption was that a drug would be administered to induce "torpor"—the term for the hibernating state. Like hibernating animals, the astronauts would be expected to acquire extra body fat...