Apollo Expeditions to the Moon: Chapter 13

Apollo Expeditions to the Moon

CHAPTER 13.2

ARRANGING FOR SURVIVAL

The knot tightened in my stomach, and all regrets about not landing on the Moon vanished. Now it was strictly a case of survival. The first thing we did, even before we discovered the oxygen leak, was to try to close the hatch between the CM and the LM. We reacted spontaneously, like submarine crews, closing the hatches to limit the amount of flooding. First Jack and then I tried to lock the reluctant hatch, but the stubborn lid wouldn't stay shut! Exasperated, and realizing that we didn't have a cabin leak, we strapped the hatch to the CM couch. In retrospect, it was a good thing that we kept the tunnel open, because Fred and I would soon have to make a quick trip to the LM in our fight for survival. It is interesting to note that days later, just before we jettisoned the LM, when the hatch had to be closed and locked, Jack did it - easy as pie. That's the kind of flight it was.

"There's one whole side of that spacecraft missing," said Lovell in astonishment. About five hours before splashdown the service module was jettisoned in a manner that would permit the astronauts to assess its condition. Until then, nobody realized the extent of the damage.

Vital stores of oxygen, water, propellant, and power were lost when the side of the service module blew off. The astronauts quickly moved into the lunar module which had been provided with independent supplies of these space necessities for the landing on the Moon. Years before, Apollo engineers had talked of using the lunar module as a lifeboat.

The pressure in the No. 1 oxygen tank continued to drift downward; passing 300 psi, now heading toward 200 psi. Months later, after the accident investigation was complete, it was determined that, when No. 2 tank blew up, it either ruptured a line on the No. 1 tank, or caused one of the valves to leak. When the pressure reached 200 psi, it was obvious that we were going to lose all oxygen, which meant that the last fuel cell would also die. At 1 hour and 29 seconds after the bang, Jack Lousma, then CapCom, said after instructions from Flight Director Glynn Lunney: "It is slowly going to zero, and we are starting to think about the LM lifeboat." Swigert replied, "That's what we have been thinking about too."

Oxygen tank No. 2 overheated and blew up because its heater switches welded shut during excessive prelaunch electric currents. Interior diagram (above) of three-foot-tall oxygen tank No. 2 - whose placement in bay 4 of SM is indicated below - shows vertical heater tube and quantity measurement tube. Heater tube contains two 1800-rpm motors to stir tank's 320 pounds of liquid oxygen. Note thermostat at top. Two switches were supposed to open heater circuit when temperature reached 80° F, but spacecraft power supply had been changed from 28 to 65 Vdc - while contractors and NASA test teams nodded - so switches welded shut and heater tube temperature probably reached 1000° F.

A lot has been written about using the LM as a lifeboat after the CM has become disabled. There are documents to prove that the lifeboat theory was discussed just before the Lunar Orbit Rendezvous mode was chosen in 1962. Other references go back to 1963, but by 1964 a study at the Manned Spacecraft Center concluded: "The LM [as lifeboat] . . . was finally dropped, because no single reasonable CSM failure could be identified that would prohibit use of the SPS." Naturally, I'm glad that view didn't prevail, and I'm thankful that by the time of Apollo 10, the first lunar mission carrying the LM, the LM as a lifeboat was again being discussed. Fred Haise, fortunately, held the reputation as the top astronaut expert on the LM- after spending fourteen months at the Grumman plant on Long Island, where the LM was built. Fred says: "I never heard of the LM being used in the sense that we used it. We had procedures, and we had trained to use it as a backup propulsion device, the rationale being that the thing we were really covering was the failure of the command module's main engine, the SPS engine. In that case, we would have used combinations of the LM descent engine, and in some cases, for some lunar aborts, the ascent engine as well. But we never really thought and planned, and obviously, we didn't have the procedures to cover a case where the command module would end up fully powered down."

Top of Apollo 13's fuel tank No. 2 (bottom part is below shelf), photographed before it left North American Rockwell plant. Tank was originally installed in Apollo 10's SM, but was removed for modification and in process was dropped two inches (skin of tank is only 0.02 inch thick). Then it was installed on Apollo 13 and certified, despite test anomalies. In raging heat, it burst and the explosion was ruinous to the SM.

Nestled amid crinkled metal foil used for thermal insulation, oxygen tank No. 2 was mounted above and close to a pair of hydrogen tanks in spacecraft bay.

To get Apollo 13 home would require a lot of innovation. Most of the material written about our mission describes the ground-based activities, and I certainly agree that without the splendid people in Mission Control, and their backups, we'd still be up there.

They faced a formidable task. Completely new procedures had to be written and tested in the simulator before being passed up to us. The navigation problem was also theirs; essentially how, when, and in what attitude to burn the LM descent engine to provide a quick return home. They were always aware of our safety, as exemplified by the jury-rig fix of our environmental system to reduce the carbon dioxide level.

However, I would be remiss not to state that it really was the teamwork between the ground and flight crew that resulted in a successful return. I was blessed with two shipmates who were very knowledgeable about their spacecraft systems. and the disabled service module forced me to relearn quickly how to control spacecraft attitude from the LM, a task that became more difficult when we turned off the attitude indicator.