Many people consider Apollo 15 to be the crowning glory of the Apollo programme in terms of science. It's therefore quite fitting that the crew managed to find time to pay homage to one of the most famous scientists of all time.
Astronauts being 'allergic' to Moon dust wasn't something NASA had really planned for. A member of its first group of astronauts had nearly been disqualified from the selection process for his hayfever, but was allowed to continue when he (rightly) pointed out there wasn't exactly any pollen in space. That was that, NASA thought. Or, at least, that was that until 1972, when Jack Schmitt landed on the Moon.
During the earliest days of crewed spaceflight, many doctors harboured concerns about what effects zero-gravity would have on the human body. While many of these concerns did not and have not come to fruition, one particular problem continues to linger: 'Space Adaptation Syndrome'.
Although Apollo 9 did not travel to the Moon, it still had a very important role to play in the lead up to the first lunar landing. Here are 10 reasons why it deserves more recognition.
Alan Shepard's road to the Moon was not a straightforward one, so you can't blame him for wanting to have a little fun on the lunar surface. He joked in later life that he was probably better known as 'the astronaut who played golf on the Moon' than he was as the first American in space.