Apollo 9 was the first mission to fly full and complete: Saturn V booster, CSM, LM, and lunar rated spacesuits. They weren’t going to the moon, but they were checking out all the equipment that would take astronauts there.

Jim McDivitt was Commander, David Scott was the Command Module Pilot, and Rusty Schweickart was Lunar Module Pilot. Those designations are a bit misleading. Flying any part of a mission frequently took all hands. It took two people to land on the moon and the Commander was the lead pilot with the Lunar Module Pilot in something like a co-pilot’s role.

This was to be the first flight by a full fledged LM. (By this time NASA had dropped the acronym LEM because the word excursion seemed frivolous, but civilians and the media still called it the LEM.) A LEM mockup had flown unmanned, but the LM that flew on Apollo 9 had been much updated since then.

Apollo 9 lifted off on March 3, 1969 into low earth orbit. The Saturn third stage and attached CSM and LM were then moved into a slightly higher orbit, where the CSM separated, reversed and performed its first docking. The multipart cone which covered the LM was jettisoned at this time. (See 569, and animation in the film Apollo 13). The Saturn V third stage separated at this time and the combined CSM and LM moved away.

The Saturn V third stage had it’s own work to do. It’s engines were fired again to change the orbit’s apogee (high point). Once apogee was reached, the engines fired again to achieve a solar orbit. This firing did not achieve its proper objective, so a third firing took place later. Practically speaking, this merely got the third stage out of the way, but it also gave NASA a chance to once again check the flight characteristics of the Saturn stage which would, on subsequent missions, place the Apollo mission on orbit to the moon.

Aside: if you plan to read more on these subjects you will run into the terms S-IVB, which is the designation for a Saturn V third stage, and SPS, which is the designation for the rocket engine in the Service Module.

Now the CSM was flying backward in orbit attached to the LM, and the LM had opened its struts to a landing stance. The CSM fired it’s rocket for the first time (docking had been done on maneuvering thrusters), raising the orbit and providing the first test for the main engine.

Aside again: this mission should have happened before sending a crew around the moon. Although most of the events of Apollo 9 were firsts, a few things like firing the CSM’s main rocket had already been done on Apollo 8. However, the ability of the linked-up CSM and LM to fly under power had not been tested before.

The next day, the CSM/LM made three more burns, changing orbits and testing the integrity of the CSM/LM connection.

On the third flight day, McDivitt and Schweickart (with backpacks) transferred from the CM to the LM by way of the tunnel between hatches. The day was spent testing out the LM, including a six minute burn of the descent stage engine. McDivitt controlled the last minute manually, throttling up and down and shutting off the engine, just as astronauts would do on a actual moon landing. All this was performed while CSM and LM remained linked-up.

The fourth day of the flight, McDivitt and Schweickart returned to the LM. Schweickart spent thirty-eight minutes testing his spacesuit outside the vehicle. He had also been scheduled to crawl over to the CM to demonstrate how astronauts could be rescued after returning from a moon landing, should the two craft be able to rendezvous, but not dock. Space sickness made this maneuver impossible, but everything in the hardware itself checked out.

On the fifth day of the flight, McDivitt and Schweickart entered the LM for the third and last time, and separated from the CSM.

That is fifty years to the minute before this was supposed to be posted, assuming that my math and data from several different sources were all correct. Great plan, but my internet went down for three days. If fact, this post is coming out about three hours late, but at least I made it before Friday slipped away.

The major test of the LM descent stage engine had already taken place on day three. Now, it fired twice, first to raise the LM’s orbit and then to make it more circular. This was done to separate adequately from the CSM.

The descent stage of the LM was now jettisoned and the ascent stage engine was fired for the first time. This burn moved the LM ascent stage to 75 miles behind and 10 miles below the CSM. Over the next six hours, the LM ascent stage achieved rendezvous and docking. The astronauts moved back into the CSM, and the ascent stage was released. By remote control, it was ordered to fire its engines one last time and burned up in the atmosphere. The descent stage remained in orbit until 1981.

The remainder of the flight was uneventful. The CM splashed down north of Puerto Rico. The SM burned up on reentry, as would all subsequent SMs.

Almost no one remembers Apollo 9. It wasn’t the first Apollo into Earth orbit and it never went near the moon. It was a working astronaut’s flight, one more incremental testing of equipment. But when it was over, everything was ready for the moon landing.

Well, almost everything. There was still the matter of maneuvering the LM downward into a gravity well and out again, and the matter of getting good enough close-up views of the moon’s surface to be sure a landing could be done. Those would be the task of Apollo 10, in May.

One last aside: The April issue of the magazine Astronomy has interviews by the astronauts of Apollo 9. It just came out and I didn’t have time to read it before posting this.