The oxygen vent hood called the beanie cap is positioned above the external tank of space shuttle Atlantis.

On Launch Pad 39A at NASA's Kennedy Space Center in Florida, the oxygen vent hood, called the "beanie cap," is positioned above the external tank of space shuttle Atlantis following the rollback of the rotating service structure, or RSS. The RSS is retracted in preparation for Atlantis’ liftoff on the STS-125 mission to service NASA's Hubble Space Telescope. The rotating structure provides protected access to the shuttle for changeout and servicing of payloads at the pad. After the RSS is rolled back, the orbiter is ready for fuel cell activation and external tank cryogenic propellant loading operations. Atlantis' crew will service NASA's Hubble Space Telescope for the fifth and final time. The flight will include five spacewalks during which astronauts will refurbish and upgrade the telescope with state-of-the-art science instruments. As a result, Hubble's capabilities will be expanded and its operational lifespan extended through at least 2014. Launch is scheduled for 2:01 p.m. EDT on May 11. Photo credit: NASA/Dimitri Gerondidakis