First Time In More Than Two Years

Discovery passed another critical milestone Thursday, as the space shuttle's external fuel tank was filled to launch levels in preparation for its return to flight. The test began at 0814 EDT on Launch Pad 39B at Kennedy Space Center, FL.

During the test, the tank was filled with ultra-cold hydrogen and oxygen propellants, known as "cryogenics." The test is designed to evaluate how the tank, orbiter, Solid Rocket Boosters and ground systems are performing under full "cryo-load."

Throughout testing, engineers observed the effectiveness of key safety modifications made to the External Tank. NASA has replaced the tank's original foam bipod ramp with a new heater system to keep the fitting clear of ice. Experts also paid attention to the newly designed "drip lip," which reduces ice accumulation on the liquid oxygen feedline bellows.

During cryo-loading, NASA's ice/debris team inspected the tank, evaluating ice and frost build-up. While ice formation is normal during cryo-loading, the team compared its development to safety testing completed at various research facilities around the country.

The test concluded at 4 p.m. and was followed by approximately two hours of propellant off-loading. The Rotating Service Structure (RSS) will be rolled back into place by 7 p.m. Friday evening.

Hatch closure of Raffaello, the Italian-built Multi-Purpose Logistics Module, also occurred at 9:18 a.m. in preparation for launch aboard Discovery. The closure signifies yet another significant milestone in NASA's steady progression toward Return to Flight. Inside the 15-by-21 foot Raffaello are 12 "racks," which hold parts, clothing, food and experiments bound for the International Space Station. After the module's contents are delivered, it will be filled with the Station's used supplies and concluded experiments for transportation back to Earth.

FMI: www.nasa.gov