In January 2004 President Bush announced the Vision for Space Exploration, calling for the Space Shuttle fleet to complete the ISS and be retired by 2010, to be replaced by a newly developed Crew Exploration Vehicle for travel to the Moon and Mars. In 2004, NASA Administrator Sean O'Keefe canceled a planned servicing of the Hubble Space Telescope and decided that future missions would all rendezvous with the ISS to ensure the safety of the crew. In 2006, his successor, Michael Griffin, decided to have one more servicing mission to the telescope, STS-125, which flew in May 2009. The retirement of the Space Shuttle was delayed until 2011, after which no further crewed spacecraft were launched from the United States until 2020 when SpaceX's Crew Dragon Demo-2 mission successfully carried NASA astronauts Doug Hurley and Robert Behnken to the ISS.
