NASA set Apollo 9 as the mission to do the first full crewed test of the Lunar Module (LM) in Earth orbit. The goal was to prove the LM could separate, maneuver, rendezvous, and dock—steps required before attempting a landing on the Moon.
Apollo 9 launched on a Saturn V from Kennedy Space Center, carrying astronauts James McDivitt, David Scott, and Russell Schweickart. It was the first mission to fly the complete Moon-landing hardware set (Command/Service Module plus Lunar Module) with a crew.
After reaching orbit, the Command/Service Module (CSM) separated from the Saturn V third stage, turned around, and docked with the LM. This “transposition and docking” let the crew pull the LM out of its launch adapter, a key procedure for later lunar flights.
With the spacecraft safely clear, mission controllers restarted the Saturn V third stage (S-IVB) to push it into a much higher orbit. This exercise helped confirm the stage and mission procedures that would be used on missions heading toward the Moon.
The astronauts powered up the LM “Spider” and began systematic checks of its systems while still docked. These tests focused on verifying that the LM could support two crew members and operate as an independent spacecraft.
Russell Schweickart performed a spacewalk to test the Apollo spacesuit’s Portable Life Support System (PLSS), a backpack that provided oxygen, cooling, and communications without an umbilical. David Scott did a “stand-up EVA” from the Command Module hatch to observe and assist.
The crew test-fired the LM’s descent engine while in Earth orbit. Proving this throttleable engine worked in space was crucial because it would later control the powered descent toward the lunar surface.
McDivitt and Schweickart flew the LM away from the CSM, placing it in a nearby orbit and beginning the mission’s most important demonstration. This showed astronauts could safely operate the LM as a separate vehicle and still find their way back to the CSM.
During the separated flight, the crew jettisoned the LM descent stage and fired the ascent engine in space. This was a vital proof that, after a future lunar landing, the ascent stage could lift off from the Moon and return to the orbiting CSM.
After maneuvering in separate orbits, the LM successfully rendezvoused with and docked to the CSM. This demonstrated the navigation, timing, and crew procedures needed for a real lunar mission, where docking would be required to reunite the crew before returning to Earth.
With the core tests complete, the crew separated from the LM and left it in orbit. Ending the LM portion of the mission marked that the primary engineering goal—proving the LM’s crewed operation end-to-end—had been achieved.
Apollo 9 returned to Earth and splashed down in the Atlantic Ocean, where the crew and spacecraft were recovered by the U.S.S. Guadalcanal. The successful return closed the first crewed LM test mission and cleared a major technical hurdle on the path to the first Moon landing.
Apollo 9 (1969): Crewed Lunar Module Testing in Earth Orbit