At Space Center Houston, the official visitor center of the NASA Johnson Space Center, visitors learn about space science—from its dramatic history and exciting present to its compelling future. Space Center Houston offers unparalleled exhibitions, attractions, special presentations, and hands-on activities, telling the story of NASA’s manned space flight program. Space Center Houston has the world’s largest collection of moon rocks and lunar samples for public view. Featured the exhibitions are Gemini and Apollo space capsules on loan from the Smithsonian National Air and Space Museum. The Saturn V rocket, essential to the success of the Apollo missions, also on loan from the Smithsonian, is one of only three left in existence.