As an expert in the field of space medicine and human physiology, I can provide you with an informed answer regarding the survivability of a human in space.

Without a spacesuit, a human can only survive for a few seconds to a couple of minutes in the vacuum of space. The lack of oxygen and the extreme cold would be immediately dangerous. However, the body's fluids would not boil immediately due to the low rate of evaporation in the vacuum, contrary to some popular misconceptions. The most immediate threat would be decompression sickness and trauma to the lungs and circulatory system as gases in the body expand rapidly.

With a properly functioning spacesuit, a person could survive for a much longer period. Spacesuits are designed to provide life support, including oxygen, temperature regulation, and protection from radiation. The exact duration would depend on the suit's life support systems, the availability of consumables like oxygen and water, and the individual's physical condition. In general, a well-supplied astronaut could survive for several hours to potentially days, depending on the specific circumstances.

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At most, an astronaut without a suit would last about 15 seconds before losing conciousness from lack of oxygen. (That's how long it would take the body to use up the oxygen left in the blood.) Of course, on Earth, you could hold your breath for several minutes without passing out.read more >>