NASA is to replace a Space Shuttle main engine on the orbiter Atlantis, being prepared for its STS101 mission to the fledgling International Space Station in mid-April. After finding a defective part inside a metal seal on an engines being prepared for Discovery's mission to the Hubble Space Telescope last year, NASA checked the Atlantis engines and found two potentially damaged seals on one. NASA still hopes to launch the STS101 by 17 April. The mission will conduct maintenance on the Zarya and Unity modules.

Source: Flight International