Answers Your Questions
| From: Richard Salzer, of Maineville,
To: Wayne Hale, flight director
Question: What is composition of the breathing atmosphere provided in the ISS? Is it the same on the shuttle or other flights? Also, what pressure is maintained?
Answer: Breathing air on both the shuttle and ISS is very much like normal sea level air; about three-quarters nitrogen and one-quarter oxygen. Pressure is maintained at around sea level except when a spacewalk is planned. The shuttle gets its air from nitrogen and oxygen tanks in the payload bay with the appropriate pressure regulators. The ISS has tanks as well but normally uses electrolyzed water to provide the oxygen.