Moon Lander: How We Developed the Apollo Lunar Module (43 page)

During the flight to Grumman’s headquarters and main factory complex in Bethpage, Long land, Wright and I sat behind the pilot in the small, dark cabin of the light plane, lit only by the dim reddish glow of the instruments, looking at the night sky with the moonlit earth below. We talked briefly, trying to reassure each other that the lifeboat mission study we barely remembered had been carefully done and held out the promise that rescue was possible. Then we lapsed into silence, each worrying about whether indeed we could collectively pull it off. In the dark isolation of the cabin, I imagined that I was with my astronaut friends in Aquarius, the mission call-name for Apollo 13’s LM. How would they feel knowing their survival depended upon the ability of the LM to perform an emergency mission for which it had not been designed or tested? What could we all do, on board and on the ground, to improve the odds of this gamble? Doubtless it would be terrifying. But wouldn’t they feel a gradual growth in confidence as the LM continued to supply sustenance minute after minute, hour after hour, with the hiss of the air supply and whir of the fans providing the same reassurance that I derived from the steady baritone drone of the light plane’s engine? And they would know that thousands of engineers and technicians on the Apollo program all over the nation would be exercising their ingenuity to help them meet this challenge. By the time we landed at the brightly lit but deserted Grumman airport I was confident that whatever it took, we would find a way to bring our friends safely home.

We were driven across the runway to Plant 5, where Grumman’s Apollo Mission Support Center was located. As we walked toward the front entrance, I met several of my engineering colleagues who were just arriving. Turning around on the front steps, I saw a flood tide of Grumman engineers heading toward the building, anxiety evident in their tense, lined faces. Although it was three o’clock in the morning, it looked like the normal day shift start time of 8:00
A.M
.; only the bright moonlight jarred that illusion. No one had asked all these people to come into work—they had simply heard about the problem and decided to do whatever they could to help. It was evidence of the dedication of our Grumman team that I will never forget.

Once inside the Mission Support Center, Wright and I met with the shift leader, John Strakosch, who filled us in on the current situation. During the time it took us to fly from Boston the astronauts had succeeded in stabilizing the spacecraft’s attitude, after the oxygen stream had ceased venting from the second, punctured tank. All three crew members were in Aquarius, sustained by the LM’s consumables. They were gradually learning how to maneuver the combined command/service modules and LM using the LM’s reaction control rockets. Because the mass and center of gravity of the combined
modules were so different from that of LM alone, the spacecraft did not respond in anything like the normal manner to which the pilots were accustomed from ground simulations. It gyrated disconcertingly when given straightforward commands to roll, pitch, or yaw.

At NASA’s Mission Control Center in Houston, flight controllers sat at their consoles, intently watching the instrumentation readouts from Apollo 13 as they flickered in greenish symbols on their video screens. In a small back room across the hall from the MCC, the SPAN Room, and at a nearby office building, a support team of about two dozen of Grumman’s top LM engineers was helping NASA find answers to urgent questions such as, What type of Earth return trajectory should be selected? How much time would it take to return? Would the LM’s consumables last that long? What techniques should be used to perform the return maneuvers? Questions requiring research or access to prior test data were forwarded from Houston to Bethpage where more people could be deployed to find the answers.

Our Bethpage Center had four consoles with the same video displays of LM instrument readings beamed from space in real time as did the Mission Control Center. We were able to listen to the flight director, flight controllers, and astronauts on the audio network and talk by telephone with our Grumman people on the scene in Houston. When necessary we could call our subcontractors, suppliers, and consultants from all over the country. This was the first Apollo mission for which I had not been in the SPAN Room in Houston, as close to the center of action as spacecraft contractors were allowed. Despite the greater distance, our access to information and ability to participate in problem solving from Bethpage were excellent.

The estimates of time required for Apollo to return varied between two and a half to four days, depending upon the type of trajectory. The flight director announced over the net that a modified “free return” trajectory had been selected, using the Moon’s gravity to whip Apollo around the Moon and send it falling toward the much greater gravitational pull of Earth. Once headed toward Earth, an additional rocket firing would speed up the spacecraft, reducing the return trip to about three and a half days. Two types of information were urgently required: procedures and exact data on timing, pointing, and other parameters for performing the trajectory maneuvers and accurate data of the rates at which each of the life-sustaining consumables was being depleted, together with recommendations on how to conserve them to last until splashdown. It was a good thing that all those Grummanites showed up for work in the middle of the night. Organized according to their technical specialties, the two hundred or more engineers in Bethpage were busy digging out data, conferring with experts by phone, running analyses and calculations, and studying the in-flight and prior ground-test performance of dozens of LM systems and components. We found that the LM batteries were being depleted at an alarming rate, and that immediate, drastic action to
“power down” the LM must be taken to survive until reentry. The required power down was far more severe than any of us wanted. It forced shutdown of the inertial guidance system and the resultant loss of on-board data on Apollo’s position and velocity, leaving the crew freezing in the dark with only the weakest communication link to Earth still active. After double checking our numbers and scouring the possibilities for less drastic measures, we conferred with our Grumman colleagues in Houston and determined we were in agreement. Bolstered with our independent calculations and concurring opinions, they went forth to convince the NASA flight controllers that less-severe remedies would not suffice.

While debates about how soon and how drastically to power down the LM raged on the floor and in the back rooms of the Mission Control Center, the remaining LM power continued to steadily seep away. A hastily prepared simulation in Houston, using the LM mission simulator, convinced NASA of the need for a sweeping LM power down and was used to develop the switch-by-switch procedures to be read up to the crew. With this argument settled, attention turned to the other less immediately critical consumables (water and oxygen), and to the vexing question of how to perform further return trajectory maneuvers without an aligned inertial platform on the spacecraft, if ground radar tracking data showed error buildups that required adjustment.

Within a few hours, activity in the Bethpage Mission Support Center settled into a deceptively comfortable routine. One by one plans were developed to assure that each of the consumables would not be depleted prematurely. We provided a number of alignment and maneuver procedure recommendations for NASA to consider. From an initial feeling of impending doom, the atmosphere in the room had shifted to one of hope and optimism. By midafternoon I found myself drowsing at the console, and I slipped out to get a little sleep on one of the cots in the nurses’ office.

I had not dozed very long before I was aroused by someone calling my name softly and shaking my shoulder. It was Don Schlegel, the shift leader, telling of a new problem: the carbon dioxide (CO
₂
) level was rising at rate that would exhaust the LM’s lithium hydroxide canisters in less than a day. We needed to find a way to use the command module’s canisters, but they did not fit into the LM’s system.

The problem was that with three instead of two astronauts breathing LM’s oxygen, CO
₂
was building up 50 percent faster than the LM system design allowed. We would run out of lithium hydroxide, the chemical used to absorb CO
₂
to keep it from accumulating to toxic levels. Both the CM and the LM carried the lithium hydroxide in replaceable canisters about the size of a large juice can that were normally replaced every twelve hours. But this was one case we designers had not foreseen. The CM and LM canisters were not interchangeable—theirs was square in cross-section, ours was circular. We literally faced the problem of how to fit a square canister into a round receptacle.

In the Mission Support Center we met with our environmental control system and crew systems engineers, including the resident Bethpage representative of Hamilton Standard, supplier of both the CM and LM’s ECS and the spacesuits. Discussions with Grumman and NASA in Houston and with Hamilton Standard at their plant in Windsor Locks, Connecticut, concluded that the best place to devise a solution was at Houston, where accurate mock-ups and some operating equipment of both spacecraft’s systems and the spacesuits were available, and astronauts and the most experienced engineers from NASA and the contractors were on-site. Under the leadership of NASA Crew Systems manager Ed Smylie, a NASA-contractor team in Houston was already at work, with the ground rule that any “fix” had to be something the crew aboard Aquarius could replicate with the materials they had at hand.

From Bethpage there was not much we could do but kibitz from a distance and offer encouragement. The solution they devised was simple but ingenious: instead of trying to square the circle, they used the hoses and fans that normally attach the backpack to the spacesuit to force oxygen to flow through the lithium hydroxide canister, via a jury-rigged adapter made of stiff paper from the flight manual and duct tape. It worked effectively to remove CO
₂
in laboratory tests both at Houston and Windsor Locks and was approved by the flight director to be transmitted to the flight crew.

We listened as the complex instructions for constructing the fix were relayed to Jack Swigert by CapCom Joe Kerwin. In the darkened cabin the astronauts used their flashlights to see the parts they were building and assembling. After a final cross-check description to Houston of what they had constructed, they switched the oxygen control valve to place the first command module canister on line. About ten minutes later we cheered when we saw on our screens that the CO
₂
level had started to drop. Not a moment too soon, as it had reached thirteen millimeters of mercury, perilously close to the toxic boundary of fifteen millimeters and far above the seven-millimeter level at which the canisters were normally replaced.
²

With that crisis apparently resolved, we reviewed the overall situation with our colleagues in Houston. There remained almost two days until Odyssey, Apollo 13’s command module, would separate from Aquarius and reenter the Earth’s atmosphere. Our projections of consumable usage showed enough water, oxygen, electric power, and lithium hydroxide to last until reentry, with the slimmest margins on power and water. We shared the concern of the flight director and the astronaut office about the crew’s condition. They were very tired and yet seemed unable to sleep, having been in a constant state of tension for more than thirty-six hours. They were cold and shivering in their thin orange flight suits—with the power down the temperature in the LM cabin had dropped to thirty-eight degrees Fahrenheit, and while conserving water they were also dehydrating. We did not know in Bethpage until after
the mission that Fred Haise was also very ill with a kidney infection. He was running a temperature of 104 degrees and at times was very groggy and unresponsive. Such personal details of the astronauts’ health were always discussed by the CapCom using the guarded channel, which was not accessible over the mission-support network.

An additional concern was steadily growing: it appeared that another rocket firing would be required to adjust the flight trajectory for the proper reentry angle. When approaching the upper reaches of the Earth’s atmosphere, the spacecraft must attain a trajectory angle within a very narrow window—5.3 to 7.7 degrees—in order to decelerate properly from its return velocity of twenty-six-thousand miles per hour. Too steep an angle would result in excessive deceleration forces (Gs) that could crush the astronauts’ bodies even as they lay fully supported on their couches and burn away Odyssey’s protective insulation, exposing it to fiery incineration. Too shallow an angle would cause Odyssey to skip off the top of the Earth’s atmosphere like a flat stone skimmed across the water, sending it roaming through the solar system for eternity.

This was the situation we feared most when we recommended the extreme power down of LM to conserve the batteries. With LM’s guidance system shut down, there was no on-board reference of her flight attitude with which to perform the trajectory adjustment rocket burn. Aquarius’ position and velocity along her trajectory could be determined accurately enough from the ground-based radars of the Deep Space Tracking Network, but attitude, the direction in which the LM rocket engine was pointing when fired, could only be established by the crew, using some visible reference they could sight upon. We needed to give the crew some practical suggestions on what to use as an attitude sighting reference.

Ever since the LM’s guidance system had been powered down, Grumman’s guidance, navigation, and control experts had been discussing this problem with their counterparts at NASA and the MIT Instrumentation Laboratory. Whenever someone suggested a technique that appeared to hold promise, it was assigned to an available laboratory to determine whether it could provide the required accuracy. Our Flight Control Laboratory in Bethpage, with its flight attitude table of LM GNC gyros, accelerometers, and other inertial guidance components floating on a frictionless air bearing, was used to check out one such suggestion. From this nationwide fraternal endeavor came a practical solution: the crew should visually align their optical sight with the center of the Earth during the rocket burn, a technique that Jim Lovell had verified sixteen months earlier with an in-flight experiment on Apollo 8. Skillfully keeping the Earth centered in the LM’s window during the fourteen-second descent engine rocket firing, Lovell and Haise executed a perfect trajectory adjustment.
³
A day and a half later a second smaller correction
was performed by burning the LM reaction control jets while using the same sighting technique, to offset a further unexplained flattening of the trajectory reentry angle.