Gas Tanks

A total of four gas tanks will be delivered during this mission, two pressurized oxygen tanks and two pressurized nitrogen tanks. These tanks will provide a replenishable source of gas and will also be used to pressurize and depressurize the new Airlock. Canadarm2 will be operated by Susan Helms on flight day seven and nine as she grapples one-by-one each tank from a pallet in Atlantis' cargo bay and brings them close to the Airlock. Canadarm2 will hand off each tank to spacewalkers who will latch them in place and connect cables and hoses. This manoeuvre is performed manually for safety reasons. (Credit: NASA)