In 1986, President Ronald Reagan selected Fletcher to administer NASA for a second time, to help the agency recover from the Space Shuttle "Challenger" accident. Shuttle flights went into a two-year hiatus while Fletcher ensured that NASA reinvested heavily in the program's safety and reliability, made organizational changes to improve efficiency, and restructured its management system. He oversaw a complete reworking of the components of the Shuttle to enhance its safety, including a redesign of the solid rocket boosters, and added an egress method for the astronauts. The Space Shuttle returned to flight on September 29, 1988. Fletcher also approved the Hubble Space Telescope program. He served as Administrator until April 8, 1989, into the term of Reagan's successor, President George H. W. Bush.