The Lunar Lander originally had two docking hatches, one at the top center of the cabin and another in the forward position, or nose, of the vehicle, with a tunnel in each location to permit astronauts to crawl from one pressurized vehicle to the other…
Since the lunar module would fly only in space (earth orbit and lunar vicinity), the designers could ignore the aerodynamic streamlining demanded by earth’s atmosphere and build the first true manned spacecraft, designed solely for operating in the spatial vacuum.
Max Faget’s position was that considering the difficulty of the job, if each mission was successful half the time, it would be well worth the effort. But Gilruth thought that was too low. He want a 90% mission success ratio and a 99% ratio for Astronaut safety. Walt Williams who was currently running the Mercury program believed that astronaut safety needed to be limited to only 1 failure in a million which was 99.9999%.
…From the information they gathered on the existing technical problems, Disher and Tischler concluded that prospects were only one in ten that Apollo would land on the moon before the end of the decade….