It's Sunday, June 1, 1969, and the Apollo 10 astronauts have returned to Houston after a flawless splashdown near American Samoa. Mission control flight director Glynn Lunney called the mission a "110 percent success." The astronauts' return was open to the public, but Apollo 11's won't be – NASA is placing them under a 21-day quarantine to ensure that "moon bugs" do not contaminate the planet.