Twenty years ago last Friday, about 200,000 miles above the Earth, the first and only major accident ever to occur in space snapped the entire world abruptly to attention. A little after 9 p.m. Central time, on April 13, 1970, an explosion rocked the Apollo 13 spacecraft, forcing NASA to abort its planned landing on the moon.
The Apollo 13 story parallels a more notorious accident that also occurred in April: the sinking of the Titanic. The analogy between the two may have begun when NASA first used the term ”lifeboat” in referring to Apollo 13`s lunar module after the accident. Indeed the module did serve as a lifeboat, as the explosion forced the astronauts to abandon their lifeless command module.
There were other similarities. In both instances, highly improbable events led to a situation that the designers of neither craft had anticipated. On the Titanic, it was the simultaneous flooding of three compartments in the hull of the ship. On the Apollo 13, it was the loss of all three of its fuel cells, an event considered to be so unlikely that it wasn`t even included in the emergency procedures.
Arthur C. Clarke wrote in an early novel that ”the story of the Titanic`s first and last voyage is one that has to be told anew in every generation, lest men forget the workings of fate and chance.” The flight of Apollo 13 also is such a story.
The commander of Apollo 13 was Navy Capt. James A. Lovell, 42, a veteran astronaut who had served on three previous space flights. Assigned to the lunar module was a civilian test pilot, Fred W. Haise, 36, who had been a research pilot at the NASA Lewis Research Center. The third crew member was command module pilot John L. Swigert, 38, an Air Force veteran of combat missions in the Koran War. Swigert was a last-minute replacement for astronaut Ken Mattingly, who was scrubbed from the flight after he was exposed to German measles.
The first two days of Apollo 13`s journey passed quietly. One minor problem arose when Swigert suddenly realized he hadn`t filed his federal income tax return. Because he had been so busy preparing for the flight, he simply forgot. Later, Swigert was assured that he could apply for a 60-day extension because he was ”out of the country.”
A little after 8 p.m. on the fateful Monday, the astronauts began a live TV broadcast, which was not carried by any of the major networks. So, while most of America watched a Bob Hope special and ”The Carol Burnett Show,” the prelude to one of the most dramatic events to take place in space went unnoticed.
The 50-minute broadcast centered on the lunar module and the equipment it carried. Lovell operated the camera while Haise demonstrated some of the experiments the mission hoped to complete while on the moon. At one point, Lovell pulled out a tape recorder and played the theme music to ”2001: A Space Odyssey.” ”Odyssey” was the astronauts nickname for the command module. Lovell also played a tape of the song ”Aquarius,” from which the lunar module had been given its nickname.
Something goes awry
Shortly after the show ended, a flight controller, who had been watching from behind his console in the mission control room in Houston, noticed on a monitor that something had gone awry in the service module, the third module of the spacecraft, which contained life-support systems and the main propulsion engine. The pressure gauge for one of the oxygen tanks was reading off the scale, on the high side.
To get an accurate reading from the tank, the controller asked that the astronauts do a cryogenic stir, a method of stirring up the gases with fans inside the tank.
Swigert turned on the fans for the stir, including the fan inside tank No. 2. The fan`s motor, it was later discovered, had had the insulation from at least two wires burned off during a preflight test. The combination of a highly volatile gas and an arc of electricity was all that was needed to create an explosion.
The blast rocked the fuselage and set off alarms indicating loss of power in one of two main electrical sources. Swigert, alone in the command module, radioed Houston, ”Hey, we`ve got a problem here.”
Houston`s capsule communicator at the time was astronaut Jack Lousma. He asked Swigert to repeat the transmission. Swigert radioed Houston that the pressure in oxygen tank No. 2 was at zero, pressure in oxygen tank No. 1 was dropping rapidly, and both electrical sources were indicating loss of power. The command module was gasping for its last breath.
In Houston, the mission control team was now a flurry of activity. Through a communications linkup called the loop, flight director Eugene Kranz began to sort through the deluge of information he was receiving. One of his first decisions was to order the astronauts to begin powering up the lunar module so its life support systems could be used.
But the astronauts had already started up the power. Haise and Lovell worked on transferring the navigation system from the command module to the lunar module, while Swigert started emergency procedures for shutting down the command module. The lunar module would now serve as the astronauts` lifeboat. It had been designed to support two men on the moon for 49.5 hours; now was needed to support three men for more than 80 hours.
No turning back
The astronauts had passed the point of no return. By turning back, firing rockets to do so, they would run out fuel. Instead, the spacecraft would have to swing around the moon, using the momentum to slingshot it back to Earth.
”My concern was increasing all the time,” Lovell said later. ”It went from, `I wonder what this is going to do for the landing` to, `I wonder if we can get back home again.”`
As the astronauts neared the moon early Tuesday morning, a new team of flight controllers, headed by flight director Glynn Lunney, began checking various timeframes for recovery. Of the four primary recovery locations-the mid-Pacific, the west Pacific, the Atlantic and the Indian Ocean-only the mid- Pacific had a recovery ship in position.
Lovell said later that his main concern was to get back into the Earth`s atmosphere where ”it would be better to burn up like a meteor than to not come back at all.” He also said that if the three men had become marooned in space, they would have continued until the spacecraft`s ”consumables”-air, water and power-ran out. The only other option would have been to depressurize the cabin, bringing the catastrophe to an immediate end.
One important step in getting back to Earth required that the astronauts use the descent engine of the lunar module to place the spacecraft on a free return trajectory-one that would take the astronauts around the moon and back toward Earth-without exhausting their fuel supply.
The quiet that surrounded the spacecraft as it traveled through the vacuum of space was in sharp contrast to the vociferous debating now going on back at Houston. The controllers were doing all they could to stay ahead of the problems they were encountering. The efforts of many people were needed in a rescue effort that attracted worldwide concern. Twelve nations, including the Soviet Union, volunteered ships to aid in the spacecraft`s recovery.
The first of two course-correcting rocket firings, or burns, went off without a hutch and, at 6:21 p.m. Tuesday, the astronauts disappeared behind the moon, losing radio contact with Houston. Swigert and Haise, who were seeing the moon up close for the first time, spent most of the 28 minutes of radio silence snapping pictures and absorbing a view of the moon from a perspective that only a few people had ever experienced.
To Lovell, the moon was old hat. He had circled it 10 times during the Apollo 8 mission. Lovell had accumulated more time in space than any other person.
The world watches
The second burn also went off without a hitch, putting Apollo 13 right on track and headed for the mid-Pacific. That accomplished, attention Wednesday quickly shifted to conserving the consumables by shutting off as many systems as possible. But with most systems shut down, the temperature in the lunar module began to drop, making it difficult for the astronauts, who were tired and thirsty, to sleep.
While the world followed every development of the rescue effort, mission control began making the final preparations for the re-entry. There were still many problems to be worked out and many unanswered questions: What effect did the long exposure to cold have on the command module`s three batteries, which were needed to power the spacecraft through re-entry and later to power the radio beacon used in locating the spacecraft during recovery? Would Swigert have any control of the command module during re-entry, or would its mechanisms be frozen? The questions kept NASA`s computers and simulators running around the clock.
By Thursday evening, with re-entry less than 15 hours away, most of the astronauts` time was spent going over the checklists that Houston had radioed up earlier. The emergencies on Apollo 13 were so vast that no checklist on board the spacecraft could be used without being altered or completely rewritten.
At 1 a.m. Friday the exhausted astronauts began final preparations for re-entry. Their first order of business was to power up the lunar module; it was needed to supply power and perform maneuvers right up to the moment it was jettisoned, less than two hours before re-entry. At that time the command module would be powered only by its own three re-entry batteries.
As Haise and Lovell began switching on various systems in the lunar module and aligning the guidance mechanisms, Swigert, alone in the command module, commented that the ”Earth is whistling in like a high-speed freight train.”
After a final course correction at 6:53 a.m., the astronauts prepared to jettison the service module. Swigert fired the pyros-explosive devices used to separate connected modules-and Haise and Lovell used the lunar module`s control thrusters to pull away from the dead service module.
The procedure worked well, and the astronauts got their first glimpse of the damaged service module. An entire panel, 5 1/2 by 12 feet, was missing. Cameras in hand, the astronauts scurried about the spacecraft snapping pictures as the service module tumbled into view. The pictures would be used to aid the investigation into the accident.
Shortly after, the lunar module Aquarius was set free. As the module departed on its separate course, later to burn up in the atmosphere over the coast of New Zealand, the capsule communicator, Joseph Kerwin, made this transmission: ”Farewell, Aquarius, and we thank you.”
The final hour of Apollo 13`s flight was followed by more people than perhaps any other single event in history. One-third of the world`s population listened over radio stations and watched on TV as the crew members of Apollo 13 faced the last challenge of their perilous journey.
A little before noon, Apollo 13 re-entered the atmosphere, about 400,000 feet above the Earth`s surface. For three long minutes, all communications with the astronauts were blacked out as the air molecules surrounding the spacecraft became ionized, blocking radio signals.
At 12:08 p.m., the charred command module splashed down in the Pacific just 5 miles from the recovery ship Iwo Jima, making it one of the most accurate splashdowns on record. When the three astronauts arrived on board 45 minutes later, the band played ”Aquarius.”
The odyssey of Apollo 13 finally had ended.
