- Cognitive function—How will being unconscious for six months affect the human brain, and how long will recovery take? "Is it going to be a couple hours, a couple days?" Bradford says, adding: "We'd like to measure how well you can perform when you get there." A recovery time on the scale of months would obviously be problematic. Bradford says that initial results from case studies showed that some patients who underwent therapeutic hypothermia actually preformed better cognitively after the procedure than before. Then again, before the procedure, those patients were severely injured, so it's hard to say how astronauts would react.
- Muscle atrophy and bone loss—Staying in shape is hard enough for astronauts and cosmonauts who are awake. But add being completely sedentary to a weightless environment and the threats of muscle atrophy and bone loss become much more severe. To counter the physiological effects, Bradford says that astronauts in stasis will be treated with drugs to counter the bone loss, and their muscles will be given an electrical workout, stimulated by small electrical impulses. "We can envision that you're constantly being exercised in this manner," Bradford says.
- Intracranial pressure—One of the more enigmatic challenges faced by long-term spaceflight projects is the effect of intracranial pressure on astronauts. Researchers have noticed that without gravity, fluids in the body tend to move towards the upper body, raising pressure in the skull, and affecting vision. Bradford says that some medical studies have found that induced hypothermia can reduce cranial pressure in situations here on earth, which gives him hope that it could have a beneficial impact on astronauts.
- Radiation—Exposure to radiation is a huge challenge to long distance spaceflight, but Bradford hopes that stasis using hypothermia could reduce the risk. A summary of the proposed method from SpaceWorks says: "Testing in animals has shown that cancerous tumor growth and the effects of radiation are significantly reduced and slowed during the torpor-state (on par with metabolic rate reduction)." In addition, the savings on mass (no living quarters, less food, etc) mean that a transport vessel using stasis could theoretically be heavily armored against radiation in a way that a larger vessel could not.