Expedition 49 crew member and NASA astronaut Kate Rubins works with a Nitrogen Oxygen Recharge System tank aboard the International Space Station.

Expedition 49 crew member and NASA astronaut Kate Rubins works with a Nitrogen/Oxygen Recharge System (NORS) tank aboard the International Space Station. The tanks are designed to be plugged into the station's existing air supply network to refill the crew’s breathable air supply. Each tank is pressurized up to 10,000 pounds per square inch to giving the station an atmosphere of nitrogen and oxygen like that of Earth, the system provides the pure oxygen astronauts breathe before beginning a spacewalk. The gases also are used in the station's ammonia-based cooling system and for other secondary uses.