SCIENCE FILE / An exploration of issues and trends affecting science, medicine and the environment

Q: Can a human survive in space without a space suit?

A: Yes, if the exposure is for no more than about 15 seconds, according to scientists at San Francisco’s Exploratorium. Because there is no air to conduct heat away from the body, an exposed person would not freeze to death. But after about 15 to 20 seconds, there would not be any oxygen left in the bloodstream to maintain consciousness. Death would come from asphyxiation.

Because of the low pressure, blood and tissues near the surface of the body would begin to boil within two or three seconds, forming pockets of gas under the skin. If the person returned to a pressurized environment in 15 to 20 seconds, however, the gas would be reabsorbed and no permanent damage would probably ensue.