The tenth and final crewed Gemini mission lifted off from Launch Complex 19 with James A. Lovell, Jr. and Edwin E. "Buzz" Aldrin, Jr. aboard. Their task was to prove that the last missing pieces of the lunar puzzle were in hand. After a successful rendezvous and docking with the Agena target vehicle—accomplished despite erratic radar, using Aldrin's manual computations based on his doctoral work in orbital mechanics—Aldrin conducted three extravehicular activities totaling five hours and forty-eight minutes. His success was credited to rigorous neutral-buoyancy training in a swimming pool, a technique still used today. The crew performed a tethered gravity-gradient experiment with the Agena, took ultraviolet photographs of stars, and demonstrated that an astronaut could work productively in the void. On November 15, an automatically guided reentry brought them to splashdown only three miles from the target, within sight of the USS Wasp. The flight lasted 94 hours and 34 minutes. President Lyndon B. Johnson declared that with Gemini's completion, "America is in space to stay." In twenty months, ten crews had flown twelve missions, logged nearly 1,000 hours in orbit, and perfected every technique Apollo would need. The bridge was built. The Moon was next.