Apollo 8 was planned as a test of the lunar module in Earth orbit. But the lunar module would not be ready before early 1969. On Friday, August 9, 1968, the NASA manager George Low proposed sending Apollo 8 to the Moon instead. That same afternoon, he and three colleagues flew to Huntsville to discuss it.
NASA then had only four months to prepare. The flight in December 1968 became the first human voyage to another celestial body.