WASHINGTON, Aug. 25 (Xinhua) -- NASA is targeting space shuttle Discovery for a launch attempt at 0:22 EDT (0422 GMT) on August 28,NASA's mission management team Chairman Mike Moses said on Tuesday evening.

According to Moses, engineers will evaluate a liquid hydrogen valve that developed problems during tanking operations Tuesday evening. Detailed test data about the valve will be examined before Discovery's fuel tank is loaded with propellant ahead of Friday morning's launch attempt.

NASA on Tuesday delayed a Wednesday morning launch of space shuttle Discovery because of a valve problem detected in the spacecraft's fuel tank.

The valve is inside Discovery's aft compartment. It is used for the flow of liquid hydrogen from the external fuel tank to the main engines.

This has been the second consecutive launch postponement. A previous launch attempt scheduled for Tuesday was called off because of thunderstorms.

Discovery's flight will deliver supplies and equipment to the International Space Station. Inside the shuttle's cargo bay is the Leonardo Multi-Purpose Logistics Module (MPLM), a pressurized "moving van" that will be temporarily installed to the station. The module will deliver science and storage racks, a freezer to store research samples, a new sleeping compartment and the COLBERT treadmill.

Discovery's 13-day mission will also include three spacewalks.