Highways Into Space: A first-hand account of the beginnings of the human space program (26 page)

For landing, the flight software had been modified so that any down range error detected by the ground tracking during the powered descent could be compensated by a manual crew input to the guidance computer adjusting the landing point, long or short. Apollo XI had guided the LM to a position about three miles long and the Apollo XII landing site was adjusted by four thousand two hundred feet during the powered descent using the Bill Tindall and Emil Schiesser update. When Pete pitched the LM to a more upright attitude as he approached landing, he reported, “There it is, son of a gun, right down the middle of the road.” The actual landing was five hundred thirty-five feet from Surveyor III on November nineteenth, planned for a sufficient distance to preclude kicking up dust all over the Surveyor. Apollo XII featured two moon walks, each about four hours in duration. The crew recovered a camera and other hardware from the Surveyor. And then back into the LM for a rest period before Intrepid lifted off to chase Yankee Clipper in orbit. Dick Gordon had been busy in the CSM with photography assignments, including proposed landing sites for future missions. The docking and return were “nominal” – one of our favorite words. Upon recovery, the crew was rewarded with an R&R stretch in the luxury of the Mobile Quarantine Facility (MQF).

Surveyor with LM in Background

In reaction to the lightning strike after the mission, the mission rules for the launch director decision at the launch site were significantly strengthened. Don Arabian lead the activity to build a Faraday shield around the vehicle on the pad with a very high non-conducting fiber glass pole extending tens of feet above the complex and cables from the top of that tower to conduct any discharges/strikes to the ground and protect the enclosed vehicle and ground equipment. Better field instrumentation was put in place to measure conditions around the Cape that might trigger a discharge. Don lead a major effort to get the rules and the protective cage as good as practical and that effort continues to serve through the Shuttle program. The schedule gave us a welcome relax time for birthdays, Thanksgiving and the month before Christmas. We also began to see a flight schedule, more paced by the study of the science results and the validation of the science plans for the upcoming mission. It was more relaxed than the earlier launch schedule of Gemini and Apollo flights during the 60s. That was more like two to three months between launches. The interval as actually flown became: before Apollo XIII – five months; before XIV – nine months due in part to hardware fixes from the Apollo XIII explosion; leading up to XV – six months; before XVI – nine months; and XVII – eight months. Five months between XII and XIII seemed like a grand luxury compared to five Gemini launches in 1966 and four Apollo launches in 1969.

After the Countdown Demonstration test (CDDT), which started on March 13, 1970, a detanking of the two cryogenic tanks commenced. The first tank dropped normally to fifty percent while the other tank only drained eight percent out – a very small amount. This was attributed to an internal leak path causing refilling of a tank while draining the lox out. There had been an earlier incident in handling the tank, well before installation in the vehicle, and it dropped two inches. This supported the scenario of a mechanically caused misalignment of the concentric tubes in the tank, allowing lox to leak back into the tank and mostly offset the attempt to drain lox out.

So now, for the first time, the heaters in the tank were used to pressurize and expel the lox. Back in 1966, the voltage for the heater was increased from twenty-eight volts to sixty-five volts in order to aid in faster pressurization and lox removal. The sixty-five volts were supplied via a “ground-test-only” harness. However, the sixty-five-volt GSE harness also powered two thermostatic switch circuits, whose function was to protect the tank temperature from exceeding eighty degrees Fahrenheit by opening and unpowering the heater circuit. However, the thermostatic switches were never modified, qualified or acceptance tested at sixty-five volts. It was a serious error in our system of making changes and a reminder of how seemingly minor changes can propagate into something much worse than the situation you think you are improving,

As the tank was drained with the heaters on, the tank warmed and the thermostatic switches tried to open but were welded closed by the sixty-five-volt acing. Therefore, the heaters continued to draw power for hours and the teflon insulation protecting the fan motor wires inside the tank was mostly melted and destroyed.

A partial fill test was conducted on March thirtieth with the same signature of slow drain of the second tank. It was concluded that the leak was internal to the tank –partially refilling instead of draining – and we would not be draining the tank during flight. Therefore, there was not sufficient reason to replace the tank.

And so, the stage was set for the failure to come during Apollo XIII.

It also became more apparent that the media coverage and perhaps the public interest had cooled noticeably from the run up to Apollo XI. The timing was ironic because after some long period of deliberation – maybe years – NASA had agreed to allow two journalists to sit in a small booth within the viewing room, overlooking the floor of MCC. This was never much of an issue for us because the media had full time access to the air/ground loop with astronauts/capcom traffic and the Flight Director loop. So the granting of access added a real visual of the room, available to two journalists and, presumably, more personal than the ever-present TV coverage of the operations floor of MCC.

Certainly, to me, and I would say most others, it simply did not matter. We were familiar with some regular visitor traffic through the viewing room and we all just ignored it. The journalists’ presence made no difference to us. However, it was disappointing to some that the intensity of coverage diminished after Apollo XI. I thought it was a somewhat natural reaction by the media and it did not bother me. The intensity of Apollo XI media coverage could not be maintained indefinitely.

The Apollo XIII crew was Jim Lovell, Fred Haise and Ken Mattingly through many of our training runs. However, late in the flow, Ken was replaced by the backup Jack Swigert as the CM pilot, because of a medical concern for Ken’s exposure to a child with measles. Jim Lovell was the veteran of two Gemini flights and Apollo VIII. As with all other astronauts, the term “rookie” is really not applicable to the other two crewmen because of their total involvement and training in all the steps leading to this flight and their test flight pilot experience. For example, Fred Haise made it his business to know all about the LM, even to knowing where all the critical wires in the LM were routed behind the close out panels and how to use that knowledge for a hot start if necessary. Jack Swigert was the astronaut office initiator of the malfunction procedure methodology for the CSM. It turned out that Ken never developed measles, but a bias to the cautious side lead to his being bumped from the flight and later assigned to Apollo XVI. Although never done before, the CM pilot was the easiest person to swap out because his critical role at the moon was the solo tending of the CSM while the other two crewman landed. Nevertheless, I am sure it gave Deke and Jim a serious round of discussions.

Milt Windler was the lead Flight Director for XIII and was on duty for the launch phase. The countdown was normal and the Saturn V rumbled off the pad at 2:13 p.m. EST on April 11, 1970. Then, shades of Apollo VI, the second stage center engine shut down more than two minutes early. The Trench was able to verify that the guidance would perform well and the vehicle should burn all the propellant through the other four engines and end up close to a normal orbit, which it did. Then, a “GO for TLI,” the SIVB burned and we had the prospect of a quiet coast out to the moon.

About two-and-one-half days into the flight, I came out to MCC at about 8:30 p.m. CST on the evening of April 13, 1970, expecting a quiet night on the console. Gene’s White team was coming to the end of a long day for the crew, finishing with a narrated TV tour of the LM. They were back in the CSM getting ready for a sleep period. After reading the Flight Director log and catching up with Gene, I went on a walk-around through the back rooms to take the pulse of the team. As a routine procedure at that time, the crew was asked to turn on the fans in the cryo tanks to get a uniform mixture in the tanks for the sleep period. The vehicle was two hundred five thousand miles from earth, eighty percent of the way to the moon and just beginning to fall into the influence of the lunar gravity.

And this was the moment when the bare, and now-powered, fan wires contacted a metal surface in the tank, discharged in the oxygen rich environment of the tank and caused an explosion.

55:55 GET (Ground Elapsed Time since liftoff)

The crew report of, “Houston, we’ve had a problem here” changed the narrative from the start of a crew sleep period to something else – uneasy, but still not clear. Somebody turned to me and said, “Glynn, you may want to get back to the front room –NOW.” I did and plugged in at the Flight Director console to hear a confusing array of multiple indications of problems such as, “Main bus B under volt, fuel cell disconnect, O2 tank low pressure.” At first, it was necessary to be careful and rule out the possibility that some electrical/instrumentation problem was creating the appearance of a bad situation.

56:14 GET (0:19 minutes since problem start)

The fact of a really serious condition began to dawn on the team as the crew reported seeing the spacecraft venting particles out the window. (That’s where the O2 is going and why the O2 tank pressure is so low. And that could be associated with the loud bang initially reported by the crew.) We soon realized that this was not a matter of preserving the landing mission, but this was now about saving the crew. Gene’s team struggled to save what they could of the CSM cryo/fuel cell systems for further use and to reconfigure some of the systems so they would operate properly in the face of the electrical system failures. A CSM power down was started at 56:22 GET and reached a level of forty-one amps.

56:25 GET (0:30 minutes since problem start)

EECOM was concluding that this was not an instrumentation problem and two fuel cells were indeed lost. At about this point, the crew became involved in trying to control some unexpected vehicle rates, which were assumed to be due to the venting.

56:31 GET (0:36 minutes since problem start)

The pressure in the other oxygen tank, O2#1, was reported low and still dropping. More power down was needed. MCC had the crew turn on tank heaters and then the fans to try to arrest the pressure loss – but to no avail. Minutes later, the CM O2 surge tank was isolated to conserve it for entry. We had only one fuel cell and its supply tank of cryogenic oxygen was expected to go to zero in two hours or less. It was near time to start using the LM as a lifeboat. But a few things remained to be done first.

In trying to find a way to assist Gene and his team, I was already engaged with Jerry Bostick who was sorting options with the Trench for how to return home from this point. Jerry guided the Trench team through the options. John Llewellyn was also on scene to ride shotgun with Tom Weichel. John was able to focus on the downstream decisions while Tom was occupied with the immediate aftermath of the problem. It is very easy to understand that there was a very strong sentiment in MCC not to go to the moon, but to turn around, and get on the way home ASAP.

Understandable as that attitude was, it would take about six thousand feet per second to perform the necessarily very large maneuver. The only propulsion system with that much power was the Service Propulsion System (SPS) located in the service module. And we had some real concern that the service module had been damaged in whatever had caused the original loud bang. But more importantly, there was a limited amount of power in the CSM entry batteries that would have to be used for a powered-up SPS propulsion maneuver, about fifty amps. A major burn is normally done with the higher power capability of 1 or more fuel cells, but the last fuel cell was fading fast. The necessary electrical power drain would probably come close to depleting the small entry batteries (the only power available for entry) and we did not yet know if they could be recharged. And as another decisive negative consideration, in order to make the burn achieve six thousand feet per second, it would be necessary to jettison the mass of the LM descent stage, which contained most of the batteries and cooling water needed for the trip home. I summarized this situation for Gene, as described above, with Jerry’s help and the Trench confirming the situation and our assessment of options. This was not even a close call. We had to go around the moon.

56:48 GET (0:53 minutes since problem start)

Gene agreed and announced the go around the moon decision to the team.