two 2001 space shuttle missions, one of the three
Main Engines was replaced by a newly enhanced Block
II Main Engine for testing. Once the engineers were
satisfied with the test results, they replaced all
three engines on Space Shuttle Atlantis before STS-110.
The three new engines provided the shuttle with a
flawless launch on April 8, 2002.
enhanced engines incorporate an improved high-pressure
fuel turbopump with a stronger integral shaft/disk
and tougher-than-steel bearings. The new design also
eliminates welds in the turbopump by using a casting
process for the housing. This makes the pump stronger
and should increase the number of flights between
major overhauls. The new turbopump is not much larger
than an automobile engine, yet it generates 360 times