Moon Lander: How We Developed the Apollo Lunar Module (39 page)

The fifth day in orbit was the crucial part of the mission for the LM—the demonstration of LM’s flight maneuverability, and its ability to rendezvous in orbit from a far distance. My colleagues and I scrutinized the instrumentation readouts on our consoles carefully as the crew reactivated Spider’s systems. Hundreds of pressure, temperature, voltage, current and other measurements located in all the systems were sampled several times a second, giving us detailed real-time information on the LM’s health and performance. Any measurement that strayed out of preset normal limits triggered caution and warning alarms in the cockpit and on the ground consoles. With all systems activated, Spider looked good to the crew, to the flight controllers, and to me. Over the net came Flight Director Gene Kranz’s crisp voice: “Apollo 9, you’re ‘go’ for LM sep” (lunar module separation).

No longer joined at the head to Gumdrop, Spider cavorted briefly, testing her reaction control system, and then pirouetted slowly before Gumdrop’s windows, preening for Dave Scott’s inspection. He pronounced her beautiful. After forty-five minutes of maneuvering within 3 miles of Gumdrop, McDivitt fired the descent engine, putting more distance between the two spacecraft. He encountered “chugging” of the descent engine between 10 and 20 percent thrust, which smoothed out completely above 40 percent. Subsequent firings increased the separation distance to over 110 miles, where the pilots could no longer see each other’s spacecraft. Spider’s crew then separated the ascent from the descent stage while igniting the ascent engine in an orbital simulation of lunar liftoff, and successfully completed orbital rendezvous with Gumdrop, which could be seen from over 45 miles away. Everything worked perfectly except Spider’s tracking light, which failed at stage separation. McDivitt and Schweickart spent more than six hours in Spider apart from Gumdrop, exercising all the systems. They proved in flight that the LM could leave the CSM, find its way back to it, and dock safely.
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Spider performed so consistently well that I never felt any apprehension as I watched each critical event of the mission click off like clockwork. I could hardly believe that this agile machine, dancing so gracefully through space, was the same crotchety beast with the broken wires and structural cracks that had given us fits for over two years of ground testing. Was our LM design and construction really good after all, or were we just lucky? I was not sure, but
thought it was some of both. I was glad we had practiced all those mission simulations. Although the anomalies during the real mission were benign compared with the deviltry concocted by NASA’s simulation director, we handled them effectively, and we had an excellent follow-up system in place to assure that the entire list was closed out before the next mission, which would be even more demanding.

After they returned to Gumdrop, the crew closed Spider’s docking hatch for the last time and set her free. Ground control radioed a firing signal to Spider’s ascent engine to park her in a highly elliptical orbit, and the crew watched her depart until no longer visible. As in the coming lunar missions, Grumman’s job was done, even though the mission was still in progress and the crew in space. I joined the rest of my colleagues at the airport and flew back to New York, where four days later I watched Gumdrop’s triumphant splashdown in the Atlantic near Puerto Rico. An hour later the crew was safely aboard the USS
Guadalcanal
, grinning broadly and obviously glad to be home safely. At a jubilant ceremony in Washington, Vice President Spiro Agnew awarded NASA Service Medals to Gen. Rip Bolender and Lew Evans to acknowledge the lunar module’s successful initiation as a manned space flying machine. The way was now clear for the final rehearsal, a mission that would take the complete Apollo spacecraft around the Moon.
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The best accolades to my ears came at the crew’s postmission debriefing in Houston. McDivitt and Schweickart were enthusiastic about the LM’s performance: “That LM is a great flying machine. And when it’s just the ascent stage alone, it’s very quick. It snaps to the controls like a fighter plane, or a sports car. It was super to fly!”

LM Brushes the Moon: Apollo 10

“Son of a bitch!”

Apollo 10 lunar module pilot Gene Cernan’s startled exclamation over the network snapped me out of the lethargy in which I had been dreamily scanning the LM’s readouts on the console monitor. Suddenly there were wild excursions in pitch and yaw, and much reaction control system thruster firing. Snoopy seemed to be throwing a fit, thrashing about in space. Howard Wright was already on the phone with Jack Russell, Grumman’s stabilization and control subsystem engineer in nearby Building 45.

“Ask them to be sure the AGS is still in attitude hold,” Russell advised immediately.

Wright and I passed this word on to Scott Simpkinson, NASA’s senior person in the SPAN Room. We could hear the crew’s heavy breathing over their open mike on Snoopy as Comdr. Tom Stafford struggled to regain control. Stafford jettisoned the LM descent stage, the next planned activity before igniting the ascent engine to leave low lunar orbit and rendezvous with John
Young in Charlie Brown. Despite Snoopy’s being over thirty degrees off its proper flight attitude, this critical function was executed flawlessly—explosive bolts and nuts, guillotine cutter, deadface connector fired in unison, and the descent stage fell away stably as Stafford ignited his RCS thrusters. The released ascent stage continued to thrash spasmodically about all three axes. A warning light said they were approaching gimbal lock of the guidance platform. Stafford took over manually and worked the attitude control switches, and Snoopy calmed down.

Playing back the last few minutes’ data, the flight controllers determined that the AGS had been mistakenly switched to automatic mode while the crew was correcting a minor rate gyro disturbance, and Snoopy’s tantrum was the result. Although AGS was normally a backup to the primary navigation and guidance system, to be used only if PNGS failed, for Apollo 10 it was being used to control the ascent into rendezvous orbit to demonstrate its capability in flight. In the automatic mode it searched for and locked onto the command and service modules, producing the unwanted attitude gyrations. Stafford’s switching had already restored it to the correct “attitude hold” setting.

Over the net I heard CapCom Charlie Duke tell the crew they had corrected an improper AGS switch setting that had caused the disturbance, and everything on Snoopy looked good. They were cleared to fire the ascent engine for rendezvous orbit insertion. The whole unsettling episode had taken about three minutes.

The ascent engine ignited smoothly, and Snoopy ascended from skimming the forbidding mountains of the Moon at fifty thousand feet as its orbital velocity increased. Soon we would know if the orbital mechanics, rendezvous procedures and communications that had been demonstrated in countless simulations, and in Earth orbit on Apollo 9, would work as well in close proximity to that enigmatic gray eminence, the Moon. Its uneven mass concentrations (mascons) could perturb the analysts’ orbital calculations; its lack of shielding atmosphere left Apollo’s radios open to solar radiation interference. These concerns, together with the desire for close reconnaissance of the tentatively selected first lunar landing site, were NASA’s basis for performing the Apollo 10 low-altitude lunar-orbit mission, instead of going directly for a landing.

Stafford and Cernan enjoyed their smooth upward ride, and commented that they could see the Moon’s features receding away from them. At the end of the ascent burn, they were in the correct attitude and flight path for rendezvous, 48 miles from Charlie Brown, on whom they had radar lock and visual sighting. Snoopy’s crew had first seen Charlie Brown from 100 miles away, and Young had seen them through his sextant at 155 miles. Steady communications with each other and Houston kept both crews aware of what was happening. Rendezvous closure and docking were routinely successful, as Stafford skillfully positioned the skittish lightened Snoopy close to Charlie Brown, and Young firmly thrust his probe into Snoopy’s drogue and was rewarded
by the reassuring snap of twelve capture latches engaging.
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Lunar-orbit rendezvous, so long debated and studied with apprehension, proved to be a “piece of cake.”

With the crew reunited in Charlie Brown, Snoopy was jettisoned, and its ascent engine was again commanded to fire, placing the LM ascent stage into a long, elliptical orbit around the Sun. Wright and I packed up and left the SPAN Room for the airport, our job completed. Except for those three minutes of excitement, we had little to do in SPAN because Snoopy performed so well. The descent engine showed none of the chugging that alarmed McDivitt on Apollo 9, probably because of some minor modifications we had made to the engine controls. The Saturn boost on Apollo 10 was a hard one, with rough Pogo vibrations on all three stages so strong that the crew worried if the spacecraft had held together, but neither Snoopy nor Charlie Brown showed any ill effects.

Three days later the Apollo 10 crew was safely aboard the USS
Princeton
in the Pacific, their mission accomplished with finesse. The final hurdle had been cleared, and Apollo was ready to land on the Moon. Looking up at that smiling white orb on a mild late spring night, I felt a profound sense of wonder. It was really going to happen—men would walk on the Moon. Recalling all the years of work, failures, and frustrations, it was hard to believe that our dogged, fumbling efforts were close to achieving their goal. In three spaceflights our LM had performed better than I believed possible—nothing like the problem-ridden ground tests I remembered from S/CAT. Each LM was markedly improved over its predecessor, as the Grumman Engineering, Manufacturing, and Test teams became more skillful at correcting problems and devising better ways to do things. Very soon we would see if LM-5, the next in line, would be up to all the challenges that landing and taking off from the Moon’s unknown surface would entail.

15

One Giant Leap for Mankind

Apollo 11

On 16 July 1969 I settled into my familiar desk in the SPAN Room and watched and listened, on the TV monitors and over the net, the awesome spectacle of the 330-feet-tall, six-million-pound monster called Saturn 5 awakening with a rumbling roar of bright orange flame and black smoke. Shaking the white, crumbling ice sheath off its flanks like a gigantic fire-breathing dragon shedding its skin, and slowly shuddering upward, it gathered speed as its huge bulk cleared the launch tower. The thunderous roar hit the crowds on the beach and in the viewing stands a few seconds later, seeming to come up from the vibrating ground below as well as from the sky above. In a crackling, roaring jumble of sound the giant began to look smaller and more distant as, ever accelerating, it gained the speed that would place it far out of sight and into orbit.

As command was switched from Kennedy Space Center to Houston, a reassuring stream of “Go” and “Looking good” flowed from the booster flight controllers, and the large altitude-velocity plot on the wall in Mission Control showed a steady progression of real data points moving up the predicted line. After two minutes and forty seconds the mighty S-1C stage completed its burn and dropped away, taking its five outsized, 1.5-million-pound-thrust rocket engines with it. We saw the stage separation in the TV image from the range tracking camera. Six and a half minutes later the S-2 stage, which burned hydrogen and oxygen with a brilliant white flame, shut down and was jettisoned, leaving the single rocket engine of the S-4B stage to compete the burn to Earth orbit. When later reignited, the S-4B provided the remainder of the twenty-six-thousand-mile-per-hour velocity required to escape Earth’s gravity and reach the Moon. Verifying the fixes made since Apollo 10, the crew reported almost no Pogo oscillations from the Saturn stages.

The Real Thing

After all the simulations and preparatory missions, it was hard to believe that this was the real thing; they were going to make our LM do everything it had been designed to do this time. I prayed that everything would work right.

Coasting silently in an escape trajectory toward the Moon, Columbia separated from the spacecraft/LM adapter, the hollow truncated cone that housed the LM during liftoff. She turned around and docked with Eagle and jettisoned the SLA. It was Eagle and Columbia, joined head to head and sailing to the Moon. The next two days passed uneventfully, with the spacecraft on target and looking good, the LM still quiescent.

Occasionally I walked down the hall to the VIP viewing area, where I could watch the activities on the main floor of the Mission Operations Control Room. This busy room, packed with flight controllers and their consoles, had become a familiar sight to people the world over, as the TV coverage frequently showed the action and zoomed in on some of the key players, with an all-knowing commentator piously intoning to the world what they were probably talking about, based on the mission problems of the minute. Speakers in the VIP area played the NASA public information channel coverage of the flight, which included all the open channels used by the flight director, CapCom, and the astronauts. The VIP area was usually almost empty during the noncritical mission times when I could drop in, but Joe Gavin and Lew Evans were liable to be there at any hour, so it was a good place to meet informally with them.

Grumman’s president Lew Evans enthusiastically supported the company’s ambition to play a major role in the Apollo program. He took his role as Grumman’s leader very seriously. Alone among the Apollo contractor presidents he made a point of being on public display in the VIP area when LM was active in a mission. He solemnly said he did it so he could be there to take our lumps if anything went wrong with the LM—or to receive congratulations if all went well, as the dour look gave way to his infectious Welsh grin. A nontechnical lawyer and businessman, he had implicit faith that Gavin and I would work our engineering magic to keep Grumman from disgrace.