The lunar module atop the Saturn third stage
It’s your turn to be a test pilot, and fly a space mission that is “a test pilot’s dream.” We’re going to fly Apollo 9, launched fifty years ago today, the first flight of a complete moon vehicle, including tucked in a “garage” behind the command ship, the Lunar Module, the “Lem,” the first true spaceship. Which is designed only to fly in space. No streamlining. No heatshield. A spidery creature wholly not of this Earth.
We’re going to fly LM-3, the first lander to incorporate all the changes following the Apollo fire, only the second lander to fly, and the first with astronauts aboard. We’re going to fly LM-3 in an Earth-orbit shakedown run which will range up to a hundred miles from the command ship. Well do that, after a long series of check-out tests, on the fifth day of flight. We’re going to test the trouble-plagued LM-3, its delay the reason Apollo 8, stripped of a lunar module, was targeted for the moon. We hope the problems are behind. A plethora of broken wires in its lightweight wiring. Cracks due to stress corrosion in its tubular skeleton. Finally in January it’d passed its design certification.
This launch marks only the second flight of a Saturn V with a crew aboard, the 364-ft. tall stack which weighs 6.5 million pounds, most of it fuel. As is the LM itself, which is 12 tons of fuel contained in a delicate structure weighing four tons. The count ticks away with the illusion of perfection towards an 11 a.m. liftoff, sunrise long behind, sun lost in the clouds. The last seconds. “Guidance is internal.” Ignition, and the painfully slow liftoff, the five F-1 engines barely able to lift the initial weight. We need ten seconds just to clear the launch tower. “Tower clear.” As the Saturn gulps fuel and its mass is reduced, acceleration increases. We feel it now — but nothing like what comes after the first stage. Separation, and with release, the stack springs forward, and we’re tossed forward hard against our straps. Then a reverse jolt as the second stage ignites. A smooth ride, then our old nemesis, pogo vibrations, longitudinal oscillations created by the harmonics of the center engine, kick the craft as it approaches the end of its six-minute burn. Shutdown and ignition of the third stage for the final two-minute reach for orbit. Much smoother. Shutdown. We’ve achieved orbit, 11 min. 14.66 seconds after launch.
But what could of the violence of those eleven minutes have done to the delicate LM?
Before we can begin to find out, we must master the docking mechanism, the finicky probe that looks as if built out of tinker toys, a device worthy of dirty jokes, although it appears like an innocent stubby tripod, the tip designed to slip into the cone-shaped “drogue” in the LM side, capture it with three latches, the loose “soft dock” Shock absorbers in its mechanism help dampen out vibrations. Then comes retraction, the two vehicles pulled tightly together so that twelve latches around the rim of the tunnel can firmly connect in a “hard dock.” And of course design is made more complex since the probe must be removable to clear the 32-in. diameter tunnel so we can transfer to the LM. It’s never been tested in space and there’s a lot that could go wrong. And if it doesn’t work, we can’t fly the LM.
So after checking out the command ship, we’re ready. A new term enters the lexicon: Transposition and docking. At 2 hrs. 41 min. into the mission, we separate the command ship from the the third stage. As we float out 50 ft. and turn around to face it, four large panels shielding the LM open like the pedals of flowers and are blown free, tumbling away. There is is, our LM-3. We slowly approach and nudge the probe into the drogue. Contact. Soft dock. Retraction. Hard dock. Perfection.
We have a mission.
Four hours into the flight, we push off from the third stage, which goes its own merry way for two test firings of its engine. Six hours into the mission, we fire our main engine, the Service Propulsion System (SPS), in the first test of maneuvering the joined vehicles, a combined length of 57 feet. Just toe-testing the waters, a five second burn.
Day two involves three longer firings of the SPS engine, checking the wiggle-waggle of the combined spacecraft, getting a feel for the stability and maneuverability of the combination. Step by step — all this before even we enter the LM. That will come on day three.