Scientists knew back in February 1999 that Hubble was on its way to failing but said there was little that could be done then to launch a rescue mission. Three shuttle missions that got off the ground but were tripped up by glitches. The first was Discovery on STS 96 in May, which had to be held back for repairs after a hailstorm caused damage to its external tank. The second was Columbia's flight in July. Due to bad wiring it could have suffered an early engine shutdown after launch which would have resulted in an emergency landing.
Backup systems keep the engines running.
The last was Discovery, which had its launch delayed nine times over two months. The X 33 program which has been criticized for delays, technical problems and an increase in costs resulting in a negative impact on space shuttle and space station operations. Calls to NASA headquarters on the topic of the upcoming hearing weren t returned.