Many are familiar with images of Neil Armstrong and Buzz Aldrin standing beside the Lunar Module (LM) Eagle during the historic Apollo 11 Moon landing. The story of how the LM was developed and tested is a little less familiar.

Four people who know the topic intimately, Bob Craddock, a geologist in the Museum's Center for Earth and Planetary Studies and author of Apollo 11: Artifacts from the First Lunar Landing; Paul Fjeld, who lead the restoration of the Museum’s own Lunar Module (LM-2); Marv Rosenberg, the engineer who oversaw the drop tests of the LM-2; and Rusty Schweickart, the Lunar Module pilot for the Apollo 9 mission, were all on hand at a recent Ask an Expert talk to discuss the work that went into perfecting the Lunar Module (LM-5) for the Apollo 11 mission.

Here are six highlights from that discussion.

1. The first and second Lunar Modules (LM-1, LM-2) were intended to test the ascent and descent stages in space. LM-1 was tested during the Apollo 5 mission and proved the ascent stage, the top portion of the LM that lifted astronauts off the Moon and carried them back to the Command Module, worked properly. Due to the success of this mission, the LM-2 was no longer needed for tests in space—Schweikart noted that LM-2 was “destined to be a hangar queen.”
2. However, LM-2 was still instrumental in the development of future lunar modules. Tests conducted with LM-2 taught the team valuable lessons in testing procedures. Most important, the team recognized that it was more effective for the testing team to be separate from the design team, Schweikart said. Since the testing team was not responsible for the original design of the LM, they were more likely to be impartial when considering alternations to improve performance.
3. The next Lunar Module, LM-3, was the first spacecraft since Gemini 3 that the astronauts were permitted to name. The Apollo 9 team chose the name Spider because of the craft’s spindly legs. Astronauts naming spacecraft had stopped after Gemini 3 pilot Gus Grissom named his craft “The Molly Brown” in reference to a woman who had survived the Titanic, earning herself the nickname “The Unsinkable Molly Brown.” The name alluded to Grissom’s previous flight, Mercury-Redstone 4, during which his spacecraft sank into the Atlantic Ocean upon landing. NASA didn’t appreciate Grissom’s jest.
4. The Apollo 9 mission tested the LM-3’s rendezvous and docking capabilities. It was the first mission where the astronauts left the Command Module and entered the Lunar Module. To get home, the astronauts had to complete a successful rendezvous between the LM and Command Module. “Luckily nobody told us about that until after the mission,” Schweickart said. The Lunar Module was never designed to renter Earth’s atmosphere.
5. Many visitors look at the LM-2 and think it looks fragile, as if it were made of only a thin sheet of foil. But this lightweight design is what made the LM as effective as it was—a heavier LM would require more fuel to return to orbit. Schweickart said the LM-3 was a, “gawky looking bird, but a wonderful flying machine.”
6. LM “drop rig” engineer Marv Rosenberg was responsible for the team that tested the LM by picking it up and dropping it. This convinced NASA that the LM would still function even after dropping two meters (six feet) on the Moon. Rosenberg saved a number of photos of the LM during its testing phases including one of LM technicians, astronaut Michael Collins, and himself sitting on the LM porch and ladder. Collins and fellow Apollo 11 astronaut Buzz Aldrin both signed the photo, and Apollo 13 astronaut Jim Lovell wrote a note saying, “Thank goodness for the Lunar Module,” on the photo. Without the expert design of the LM, the Apollo 13 mission could have been fatal.