How Apollo 13 Avoided Disaster

Facing an emergency more dangerous than any simulation could predict, the crew of Apollo 13 had to make their own luck to save their lives.

Are you superstitious? Would you fly on ship number 13? Jim Lovell, Fred Haise, and Ken Mattingly didn't think the number 13 would be unlucky for them. They had trained for many months to fly the third lunar landing mission, Apollo 13. Lovell and Haise planned to spend 33 hours exploring the surface of the Moon, while Mattingly circled above them in the command module Odyssey. The story of what happened instead is a tribute to the bravery, ingenuity, and teamwork not only of the astronauts themselves, but also of the hundreds of controllers, technicians, and scientists who brought three men safely home from outer space. You can decide whether or not the number 13 was unlucky for them at the end of the story.

Thursday, April 9, 1970

Two days before launch: NASA officials decided that Ken Mattingly, 13's command module pilot, must be grounded, as he had been exposed to the measles by another astronaut's son. Ken didn't have the measles, but the doctors feared he might become ill in the middle of the mission. NASA decided to substitute him with the back­up pilot, Jack Swigert.

Saturday, April 11

Launch: At 13:13 Mission Control time, the mighty, 363 foot Saturn V rocket thundered its way aloft, like a skyscraper burning its way into the sky. The crew on top of the giant rocket knew the week ahead of them would be like none other in their lives. Little did they know the same would be true for those they had left back on Earth.

Monday, April 13

9:07 PM (205,000 miles from Earth): The astronauts were now 55 hours into their mission, heading towards the Moon at over 2,000 mph. They would be entering lunar orbit in about 20 hours, and Lovell and Haise would land on the Moon the day after that.

At 8:00 PM, the crew had begun a television transmission, introducing themselves and giving a guided tour through their ships, the command module (CM) Odyssey and the lunar module (LM) Aquarius. At 9:00 PM, the show had concluded, and the crew returned to the more serious business of flying a spacecraft. Ground control wanted Swigert to check on one slight problem: They had been having trouble getting an accurate pressure reading from one of the CM's helium tanks. One way to remedy this was to have Swigert turn on small mixing motors within the tanks, to even out the levels.

9:08 PM: When Mission Control asked Jack to activate the stirring fans, they had no idea, until much later, that this simple action would change the course of manned spaceflight. Painstaking detective work in the weeks that followed eventually revealed the cause of the accident. Months earlier, the Service Module's (SM) oxygen tank #2 had been subjected to more electricity than it was designed for, so when the fans were turned on, a spark must have flown within the tank, instantly igniting the 300 pounds of sub zero gas. The blast tore the SM's side panel off, and ruptured the entire fuel line of the CM. But at this point, the astronauts were unaware of what had happened.

9:09 PM: About 90 seconds after turning on the fans, the crew heard a sudden loud BANG! and felt their ship tremble. Swigert saw a master warning light go on, and uttered those famous words, "OK, Houston, we've had a problem here." Lovell reported that main bus B, half the CM's electrical system, had lost power. Haise had a sinking feeling in his stomach, since he knew the whole system had to be working to continue with the Moon landing.

9:14 PM: Lovell now reported that main bus B was dead and that main bus A, the other half of the system, was losing power. Swiger switched the power input of main bus A over to the re­entry batteries, intended to power the CM during the last minutes of their flight. They couldn't afford to use too much of this power ahead of time, but the ship's guidance system had to remain on or they would be literally lost in space.

9:17 PM: Lovell took manual control of the ship, which had begun twisting and turning uncontrollably. The escaping oxygen was acting just like another engine, pushing them away from their carefully computed trajectory. Since main bus B powered half of the 16 small reaction control system (RCS) thrusters, eight of them were now useless, which made Lovell's job of steadying the craft extremely difficult.

9:22 PM: After Lovell had the ship somewhat under control, the ground asked him to read back the pressures of all the oxygen and hydrogen tanks which fed the CM's fuel cells (the instruments which supplied the CM with power and water). He stunned them all into silence when he reported oxygen tank #2 was at zero. Lovell got up and looked out the window, where he could not view the damaged SM directly, but could see the cloud of escaping gas. He told the ground, "We are venting something into space." Ground control knew they had to save the little power left to keep the guidance system alive, so the crew was told to begin turning off everything but the most essential equipment.

10:12 PM: The crew at Mission Control thought that the oxygen leak had been caused by a faulty fuel cell, so they instructed the crew to shut one of them down, hoping that would stop the leak. When this failed, they knew there would be no lunar landing, but there was no time to think about that. Both the crew and the ground controllers knew it was just a matter of time before Odyssey's power ran out completely. Luckily, the astronauts had exactly what they needed just a few feet away; a working spacecraft, their lunar module Aquarius. Ground control said to Swigert, "We are starting to think about the lunar module lifeboat procedures." He replied, "That's what we're thinking about, too." Unfortunately, the LM-­lifeboat idea had only been discussed, and had never been set down in black and white. Although the astronauts were trained to handle many types of emergencies, their current situation was thought so unlikely that Swiger later wrote, "If somebody had thrown that at us in the simulator, we'd have said, 'Come on. you're not being realistic.' "

10:14 PM: Everyone, on the ground and up in the ship, began analyzing Aquarius's provisions. They were now so close to the Moon that a direct turn-around probably wasn't possible, so it appeared they would have to stretch the LM's supplies for almost four days, the time it would take to loop around the Moon and get back. This was cause for some concern, since Aquarius was only built for a two day lifetime, and it now had to support three men instead of two.

10:25 PM: Fred Haise, the lunar module pilot, entered the LM, and with the aid of the ground controllers, quickly improvised a way to activate Aquarius.

10:45 PM: Fred turned on the LM's oxygen; all of the CM's tanks were now empty. Lovell now joined him in the Aquarius and the two of them quickly activated the guidance system, so it could "learn" their position from the CM’s dying computer.

10:55 PM: Haise and Lovell completed the guidance transfer while Swigert finished shutting down Odyssey. A few minutes later, he joined his crew mates in the LM. Odyssey was now dead, but they would need its heat shield a few days from now to survive re­entry, since the LM had no shield.

Alan Bean, Apollo 13...Houston, We Have a Problem, 1995, Acrylic on Aircraft Plywood

Tuesday, April 14

12:00 AM: No one thought about landing on the Moon anymore. The mission now was to return to Earth alive. The first major task was getting back onto a free-return trajectory, a safeguard path that would return them directly to Earth. Apollo 13 had altered its flight path off free-return just 24 hours before the accident, in order to aim for their target area on the Moon, the Fra Mauro highlands. Now, if not corrected, 13 would miss the Earth by thousands of miles, ending up in a weird orbit it could not return from. The astronauts knew they couldn't use the SM's engine, but a short burn of Aquarius's Descent Propulsion System (DPS) engine would put them back on course for Earth. Lovell began requesting the information for the free-return correction, since he realized they were drifting farther and farther off course.

2:43 AM: Commander Lovell pressed a button, and the DPS engine fired for 31 seconds. There was no way to tell from inside the capsule aside from a slight feeling of acceleration, but they were now back on a free return trajectory, a major step in the long trip home.

Now that this was taken care of, the crew calculated how long their provisions would last. It appeared that there would be sufficient oxygen, and probably enough electricity, but water would be a serious problem. Water was needed not just for the men to drink, but more importantly to cool the electronic circuits of the LM. Every piece of equipment turned on used up some of the water, which steamed off into space as the LM's exhaust. The crew tried to salvage every drop they could out of Odyssey with a makeshift hose system, but it was very awkward, and Jack spilled some of the precious liquid on his feet. Because of the power shortage, the temperature had begun to drop, and it took his shoes two days to dry out. Lovell set severe limits on the amount of water they would drink, since every drop would be needed to keep Aquarius's instruments alive. For the next three days, each of them consumed only six ounces a day, one-fifth of normal intake.

4:00 AM: Fred looked at his watch, amazed to see that it had been seven hours since the bang. All of the events since then crowded in his mind in one big blur, as the tension and excitement began to catch up with him. He suddenly felt very very tired, and Lovell told him to go sleep in the now-dark CM, which they renamed "the upstairs bedroom."

10:00 AM: Lovell woke Haise up, and he and Swigert prepared to take their turns sleeping. As Fred took over Aquarius's controls, he told them that he hadn't slept very well. They soon found out why, since the temperature in Odyssey was steadily dropping. The only way to warm up the capsule was to open the window shades and let the Sun shine in, but the intense glare made sleep nearly impossible.

Tuesday Afternoon: Mission Control had decided on the best course back to Earth. The crew spent the rest of the day preparing for a major burn after passing the Moon (known as the PC+2 burn), which would get them back at about noon Friday. The most important task before then was verifying the LM's guidance coordinates. Without an exact position, they might not fire the engine properly, missing Earth entirely. Normally, a position check was easy; They merely had to sight a bright star through a small scope built into Odyssey and compare its position to where the computer said it should be. On Apollo 13, however, nothing was easy. They could not use Odyssey's sighting scope, and the one in Aquarius was not meant for deep space use. It was only intended to be used during final lunar descent, so it was mounted into the LM facing in one direction, and could not be moved. 

The crew would have to maneuver the whole ship to find their guide star. When they attempted to do the check, they found they couldn't see a thing, since the ship was surrounded by a halo of ice crystals, the frozen remains of the oxygen they had lost. From inside the capsule, it was impossible to tell these tiny particles from the true stars, as they glittered brilliantly with reflected sunlight. This proved to be one of the tensest moments of the journey, for they all knew that without accurate coordinates, there was no way to carry out the PC+2 burn correctly. RETRO (the man in charge of re-entry) suddenly came up with an idea. He thought of one star that could never be mistaken for a piece of ice: the Sun. An alignment with the Sun, they knew, wouldn't be 100 percent accurate, but it would be close enough to complete the PC+2 burn. Lovell didn't feel entirely confident with this method, but it was the only choice they had. After he had entered the Sun's position into the computer, everyone breathed a little easier when they found it matched up, meaning they were right on course.

6:30 PM: Apollo 13 passed its former destination, coming no closer than 158 miles to the lunar surface. All communications would be blocked by the Moon's body for the next half-hour. While the ground crews were patiently waiting to regain the radio signal, Commander Lovell was busy preparing for the important PC+2 burn. When he looked up, he saw his crew mates, both on their first spaceflight, glued to the windows, talking and taking pictures like a couple of tourists.

"Would you look at that!" "This is great!" Lovell reminded them of the importance of the upcoming burn: "Look, you guys, if you don't get back to work, you're not going to get those pictures developed!"

8:41 PM: The time for the ultra-crucial PC+2 burn had arrived. Lovell took the DPS engine throttle in hand, and for five minutes gently built up to the precise speed the ground controllers had determined for them. Fred felt himself pressed back with the acceleration, and he peered out the window. It seemed to him as if they were rising straight up from the Moon's surface, as if perhaps they had just been ejected from one of the jagged craters below.

Wednesday, April 15

12:00 AM: While the astronauts got some needed rest, NASA pulled the White team, one of four work-shifts of flight controllers, off duty. The other three teams could handle the routine workload, because White team had to write a new re-entry program, taking into account the special problems of Apollo 13. Usually, it took three months to create a re-entry checklist, which would often be as large as a telephone book. White team had 2 days to complete the task.

3:00 AM: Lovell was awake again, and reported that the temperature in Odyssey was in the forties. Mission Control suggested putting on their spacesuits for warmth, but Lovell thought that they would be too clumsy. There were blankets aboard, packed in with an emergency-splashdown survival kit, but they chose not to take them out. They could not afford to clutter up the capsule with the other items, like canned food and a rubber raft.

7:00 AM: Lovell and Swigert were working on a project that Haise had begun before going "upstairs." The ground had told them this would be "like making a model airplane, but when you're done, it'll look more like an RFD mailbox." The device they were casually joking about would be responsible for their lives in a few hours. They needed a way to install the CM's air filters into the LM's air system, or they would suffocate on the carbon dioxide they were exhaling. They solved this problem by taping hoses from a moon-suit to a plastic bag around the air filter, making sure the connections were air-tight.

10:30 AM: When a warning light flashed on, indicating a dangerous level of carbon dioxide, Lovell turned on their makeshift air-scrubber, and a few minutes later, the air levels were back to normal. Once again, certain death had been avoided by quick-thinking ground controllers.

1:00 PM: White team got down to the serious business of outlining the last six hours of 13's journey, with the help of every available expert on the spacecraft's systems. The 40 men present began breaking into smaller groups to hammer out the details of the re-entry. The major problem was finding a way to have Aquarius do most of the work, including reactivation of Odyssey. The only power left in Odyssey was in the 2 percent remaining splashdown batteries (since Jack had used one of them during the accident to keep the guidance alive), which could only power the ship for the final two hours of the flight.

Apollo 13 was still drifting slightly off course, and the FIDO (trajectory officer) on duty was planning the next course correction for later that night. If not corrected, 13 would come in too shallow, and skip off the Earth's atmosphere like a rock across water.

Wednesday Evening: With less than 48 hours to re-entry, White team was working desperately on outlining 13's re-entry program. The chief EECOM (electrical and environmental controller) had constructed a rough timetable or the others to work from, making sure that each step would take place in the proper sequence, and no power was being wasted.

The other members of the team were busy finding solutions to problems that no one ever imagined possible. In addition to everything else, there appeared to be a good chance tropical storm Helen would be in the splashdown area on Friday. The meteorologists wanted to shift the landing site, but RETRO stubbornly refused.

10:00 PM: Ground control told the crew to begin preparing for the course correction. As with the previous corrections, their position had to be verified before they would know exactly how to do the burn. The guidance system had been shut down following the PC+2 burn, since it used up too much power, but they had an emergency alternate method that had been developed for Apollo 8, the first flight out of Earth orbit. Lovell, who flew on Apollo 8, remembered the plan; It involved aligning the ship with Earth's night-side shadow, since this had to be a straight line with the Sun.

10:31 PM: While Lovell took the throttle in hand once again and fired the DPS engine, Haise was busy keeping the scope centered on Earth's shadow, manually adjusting their heading with the lunar module's small RCS thrusters. Swigert watched the clock, calling off the seconds until Lovell completed the burn.

Thursday, April 16

3:00 AM: Fred and Jack were sleeping in the cramped quarters of Aquarius, since the CM was now too cold for comfort. The crew no longer referred to Odyssey as "the bedroom"; it was now called "the refrigerator" since the temperature was down to 38 degrees. The doctors on the ground were becoming very concerned about the astronaut's health. Even the cold and lack of sleep were minor problems compared to the danger of dehydration. Without water, the human body's delicate balance of chemicals is upset, and the brain cannot function properly. The men on the ground were afraid that this could affect the crew's performance during re-entry.

4:30 AM: Ground control was instructing Swigert on how to transfer some of Aquarius's power into Odyssey, a process that would take at least 15 hours. Lovell was a little worried about this, since the power usually flowed from the CM to the LM, not the other way around. He hoped that they wouldn't short out both ship's electrical systems.

12:00 PM: White team's re-entry checklist was almost complete. The last procedure was to run it through a computer called the CM/LM Integrator, which would make sure there were no conflicts in the sequence of events or problems with the shared power usage. As soon as his was done, Ken Mattingly (who hadn't caught the measles after all) would run through the procedures in a spacecraft simulator.

Thursday Afternoon: The crew kept themselves busy while waiting for the checklist by preparing for their move back into Odyssey. All of the unneeded equipment and the garbage they had accumulated in the CM had to be transferred into Aquarius. RETRO informed them they had to pack Odyssey with a few hundred pounds of dead weight from the LM to take the place of the Moon rocks they didn't have. The capsule's weight on re-entry had been calculated precisely long before the launch, and no one wanted to take any chances. The astronauts were glad to have the work; It took their minds of the cold. Cabin temperature in the CM was now 35 degrees, and just 10 degrees warmer in Aquarius.

7:00 PM: Lovell was getting impatient for the checklist, as his home planet was looming larger and larger out the window. Although they were still 100,000 miles away, the Earth's gravity had increased their speed to 4,000 mph, and it would continue increasing until re-entry. He finally interrupted the CAPCOM (capsule communicator), who was filling the time with some routine questions, by saying, "We can't just wait around here to read the procedures all the time up to the burn! We've got to get them up here, look at them, and then we've got to get to sleep!" A few minutes later, Ken Mattingly arrived with the checklist he had just finished rehearsing. He proceeded directly to the so microphone and began reading to Swigert, "OK, let me take it from the top..."

10:00 PM: After two hours of tedious repetition and double checking, Mattingly and Swigert completed the read-up. The main concern was for Jack to get it 100 percent accurate, since everyone could sense how close to exhaustion he was. As soon as Swigert was done copying down all the information, Mattingly began reading up the LM checklist to Fred.

1:00 PM: Mattingly finished with Haise in just 45 minutes, since his part was not quite as complicated as Swigert's. By the time they were finished, there were only 6 hours remaining until the procedures detailed in the checklists would begin. Ground control knew that the crew needed all the rest they could get before then, so they stopped all radio communications for the next two hours.

Alan Bean, Studies of a Crater Triplet, 2005, Acrylic on Plywood

Friday, April 17

2:00 AM: CAPCOM called up to 13 with some changes in the checklist, and Swigert answered sleepily. As soon as he had copied them down, CAPCOM asked Jack if he was going back to sleep. He replied, "It’s almost impossible to sleep. All of us have the same problem. It's just too cold to sleep. we'll try… but it's just awful cold."

2:30 AM: The crew of Apollo 13 was given some good news for a change. TELMU (the person in charge of the LM's systems) told them that they were now close enough to use some of the reserve power to warm up Aquarius. Although the small heaters would take a long time to warm the cabin, the crew felt better already, just knowing they were on. Haise looked out the window at the expanding Earth below and said: "It's going to be an interesting day."

4:00 AM: White team took over the final shift of flight control, as of them hoping they had taken every precaution. FIDO was finishing the calculations for the final course correction, scheduled for a few minutes after 7:00 AM.

5:00 AM: Swigert re-entered the lifeless Odyssey, which was cold and clammy with water droplets everywhere. It was time to try the power transfer from Aquarius. Lovell’s fears about this were understandable, but the ground controllers had found a way to "fool" the circuits. Swigert allowed a tiny bit of the CM's power to flow into the LM, the usual procedure, and then he quickly reversed the polarity, drawing the LM's energy back into Odyssey. The first need for the borrowed power was to thaw out the CM's control thrusters, which would take a few hours. Everyone breathed easier when they saw the transfer was successful; It meant that Odyssey's electrical system had not been totally damaged. Earth was now only 55,000 miles away, and the planet's gravity had increased their speed to 6,000 mph.

7:00 AM: The ground controllers were closely watching their monitors, double-checking Lovell's preparations for the final course correction, just a few minutes away. The strain was beginning to show on Lovell, as he had to be alerted to some incorrect figures he had entered into the computer. Time was running out. Earth was just 41,000 miles away, and 13 was streaking in to meet it at 7,000 mph. Finally, a few minutes after 7:00, the burn was successfully completed, lining up the ship exactly along their re-entry path. RETRO wanted to pinpoint the splashdown site as close as possible, since tropical storm Helen was approaching the projected location.

7:15 AM: Jack was busy in Odyssey, preparing to jettison the damaged SM. He was working slowly and cautiously, since the controls to free the SM were dangerously close to those that would separate Aquarius. He had made himself a large red sign that said "NO!" and had taped it over the button that would release the LM. Fred asked Jack if he was ready to blow the bolts holding the SM, and he replied, "Stand by... and put your fingers in your ears!" Swigert hit the switch to release the wrecked module, and the ships shook with a motion he described as "rippling."

Jim and Fred were busy in the LM, using the RCS thrusters to make sure there was no danger of collision. Jack jumped out of his seat and grabbed his camera, because Mission Control had told him he could expect to see the SM drift by his window, and they wanted photographs of it to examine the damage. He waited and waited, but saw only the blackness of space. Suddenly, a shout came from Aquarius, "There it is!" Jack rushed down to join his comrades at the LM window, and all three began taking pictures, stunned by what they saw. 

It was difficult for the crew to make out many details of the wreckage, since it was already a few hundred feet away, twisting and tumbling as it fell towards Earth along a different re-entry path. Lovell told the ground, "... There's one whole side of that spacecraft missing... the whole panel is blown out... from the base to the engine." Haise added, "It’s really a mess." One of the flight controllers told Lovell, "Well, James, if you can't take any better care of the spacecraft than that, we might not give you another." The astronauts were actually glad they had not seen their sorry-looking craft earlier, for it only gave them something else to worry about. Now that they had seen evidence of how violent the accident had been, there was the frightening possibility that the heat shield had been damaged. They knew there was no chance of survival without an intact shield, but nobody spoke about it.

9:30 AM: The time had finally arrived for Jack to activate the splashdown batteries fully, putting Odyssey under its own power once again. Figuring out a way to power-up a dead command module had been one of ground control's hardest problems, and it was time to test the hastily-written procedures. There could be no second chance. But Jack laughed with joy now, as Odyssey hummed into life, reborn out of its own ashes like the legendary phoenix.

9:45 AM: The most important task for Jack now was to do a position check. This would have to be done on a couple of bright stars, since they were now too close to Earth to use the shadow method. He still had the nagging problem of the "false stars," those ice crystals that were still following them. Ground control suggested dimming the cabin lights, so he might be able to locate his guide star, Altair. Lovell, who was watching the Earth grow larger by the minute, shouted to Jack, "Hurry up!" Dimming the lights seemed to help, and Jack suddenly found the star centered in his scope. He quickly entered its position into the computer, to compare it to their present heading. Any errors in the trajectory would now flash on the screen in front of him as a series of five numbers, and he would have to adjust the craft's direction manually. Jack couldn't believe his eyes; The screen read five zeros. He quickly shifted the eyepiece to the second star, Vega, and entered its position. Again, he saw five zeros. 13 was coming in exactly on course. Swigert breathed a sigh of relief. He now felt that they just might make it, after all.

10:25 AM: The time had come to bid Aquarius goodbye. The ship that had served them so well had to be cut free, to sail alone to its fiery fate. Everyone would be sorry to see it go, for it had done so much more for its crew than it had ever been designed to do. Fred Haise later wrote, "I was proud of her. She was magnificent. I wished that Aquarius had a heat shield, too. I'd like to have that LM sitting in my backyard right now."

10:30 AM: Fred's backyard was now only a few thousand miles away, and Apollo 13 was hurtling in to meet it at 15,000 mph. The order came from the ground and Aquarius was cast off, pushed away by the burst of air trapped in the connecting tunnel. Lovell said, "Farewell, Aquarius, and we thank you." Fred watched his ship fade into the distance, snapping some final pictures until it was only a tiny gold speck on the horizon.

10:50 AM: Apollo 13 was coming in now as if nothing out of the ordinary had happened, except that they were four days early. There was still the unspoken worry about possible damage to the heat shield, and Fred wished that he could have gone out and looked at it. This was out of the question, since entry interface (contact with the outermost fringes of the atmosphere) was just an hour away.

11:00 AM: RETRO was facing a problem as serious as any they had had up to now. 13's drift, the same motion that had been nudging them off course all along, was still present. The capsule was still safely within the entry corridor, but the angle of the trajectory was slowly dropping towards 6.08 degrees. If it went lower than 6.08 degrees, RETRO would have to recalculate the maneuvers the astronauts would perform during interface.

11:20 AM: The crew was getting anxious to learn these final procedures, and RETRO found himself on the spot. The information they wanted was on the screen in front of him, assuming they would not go lower than 6.08 degrees. He made his choice, and sent the data in front of him up to 13. If he was wrong, and it did drop lower than 6.08 degrees, the timing would be all off, the parachutes would open at the wrong height, and he didn't even want to think about the crew. He knew he would have one last chance to change his mind, when the astronauts performed their final position check, by carefully noting the exact time and place that the Moon disappeared as they swung around the Earth, just a few minutes away. RETRO had been the one to come up with this method of verification, but there was no time to pat himself on the back. He was already busy computing the alternate maneuvers the crew would need if his guess was wrong. He did have one thing to be thankful for, however. The weather at the splashdown site was beautifully clear, and tropical storm Helen was currently raging over the alternate landing site the weathermen had wanted to switch to two days earlier.

11:42 AM: Swigert rolled the capsule to get the best view of the Moon's disappearance. Shortly, he saw it blink out behind the dark side of the planet, the first time in six days it was out of his view. Luckily, the drift was not bad now that they had dumped the LM (which, they found later, had been causing the drift all along), and the position checked. It was none too soon, as they whipped around the night side of their planet at 21,000 mph.

11:47 AM: Mission Control was growing quiet now, as 13 plunged towards interface at 22,000 mph. Swigert tried to break the tension by telling the ground, "I know all of us here want to thank all you guys down there for the very fine job you did." "That's affirm," said Lovell. CAPCOM replied on behalf of the many people who worked so hard to bring them home, "Tell you—we all had a good time doing it."

11:49 AM: As the crew received their final instructions, the Flight Director went down the line of controllers, getting a "go" from each. He finished with RETRO, who was staring at his screen. He saw that Odyssey's angle of entry had leveled out at 6.13°, just 1/20th of a degree from the maneuver shift. There was only one thing to say: "GO!"

11:50 AM: CAPCOM told Lovell, "We just had one last time around the room, and everybody says you're looking great." "Thank you," came the reply.

11:52 AM: Apollo 13 was finally home. At entry interface it reached its maximum velocity of 24,000 mph before the friction of the ocean of air began slowing it down. It was 76 miles above the Earth's surface, and about 1,400 miles downrange from the splashdown site in the South Pacific.

11:53 AM: The friction began heating the capsule and the air around it, and the crew had the eerie sensation of watching the colored flames begin flickering around the windows. Swigert said, "The colors match the mood I'm in." It was the last message from Apollo 13 before radio communications were blacked out by the intense heat of re-entry, and it would be at least three minutes before the ground could regain radio contact. There was no way on Earth to know how the crew was faring until then.

11:57 AM: When Odyssey's radio blackout passed the three minute mark, the ground controllers grew frantic. No two blackouts were exactly the same, but this was too long. CAPCOM called up again, "Odyssey, Houston. Standing by." There was silence for a few seconds and everyone started to fear the worst, when they suddenly heard a familiar voice say, "OK, Joe." The words he said hardly mattered; the sound of Jack Swigert's voice said it all.

12:02 PM: At 24,000 feet, the small drogue chutes opened, and the capsule was so close to the TV cameras on the recovery ship that the crew in Houston saw the drogues come out for the first time.

12:04 PM: The three main parachutes billowed open and a triumphant cheer echoed throughout the world. Never before in the history of space travel had so many people around the globe felt so close to America's space travelers. Lovell was absolutely amazed at the worldwide reaction to their flight. He had had no idea they were commanding headlines everywhere.

12:07 PM: Odyssey neared the water at about 20 mph, 1/1000th of its speed at interface, just 15 minutes before. Then, in the words of Jim Lovell, "We splashed down gently in the Pacific Ocean near Samoa, a beautiful landing in a blue-ink ocean on a lovely, lovely planet." Odyssey touched the water just four miles from the recovery ship, which was not a bad job for a bum spacecraft.

12:15 PM: The first frogmen to reach the capsule were chilled by a blast of cold air when the hatch opened. In spite of the 81 degree South Pacific water, they noticed that they could see the crew's breath. The astronauts eagerly jumped into the recovery raft, and in a few minutes they were hoisted onto a waiting helicopter.

12:53 PM: Less than one hour after splashdown, three tired, cold, and thirsty spacemen stepped off the helicopter and set foot on the carrier Iwo Jima, to the resounding cheers of her crew. The captain said to them, "Glad you boys could make it." Fred Haise replied, "It’s nice to be warm." After a brief moment of silent prayer, the astronauts immediately went below decks to be examined by a team of nine doctors. They soon found out just how close to total collapse these men really were. Fred Haise had developed a kidney infection which would keep him in the hospital for three weeks. But aside from that, there was nothing wrong with them that food, water, and rest couldn't cure. Before drifting off to sleep, one of the astronauts told a doctor, "I don't know how much longer we could have kept going." Judging by their physical condition, they would not have made it one more day.

Lucky 13

So now it's up to you to decide if the number 13 was unlucky for Jim Lovell, Fred Haise, and Jack Swigert. Fred and Jim lost their chance to be members of the select few who walked the lunar surface, and all three had very nearly lost their lives, definitely bad luck. But the crew of Apollo 13 had much to feel lucky about, for it could have been worse, much worse. If it had happened to Jim Lovell two years earlier on Apollo 8, he, Frank Borman, and Bill Anders would have died, for they carried no lunar module to limp home in. The same would have been true if it had happened to 13 on the homeward part of the mission, after leaving the LM on the Moon. If it had happened while Aquarius was on the Moon, Jack would have died alone in lunar orbit, and Jim and Fred would have had no way to return to Earth. If the explosion had happened while they were sitting atop the giant Saturn V rocket before launch, the whole rocket might have blown up. The list could go on forever. This mission may have had more than its share of rotten luck, but in the end, through sheer courage and determination, the crew of Apollo 13 had made their own luck.

Alan Bean, Is Anyone Out There, 2000, Textured Acryllic with Moon Dust on Aircraft Plywood

Congratulations to Apollo 10

The potential bomb known as oxygen tank #2 had originally been installed in the SM of Apollo 10, but was later removed for modification and transferred to 13’s SM. Jim Lovell wrote, "I have to congratulate (the crew of Apollo 10) Gene Cernan, Tom Stafford, and John Young, the lucky dogs, for getting rid of it." The transfer may have been the cause of the initial damage leading to the accident, but it can never be known for sure whether it would have exploded on the flight of Apollo 10 or not. Perhaps the fates, in their mysterious way, made certain that it could only happen on number 13.

Recommended Reading

The tale of Apollo 13 can only be made more intense and suspenseful when told by those who didn't know the ending as events unfolded. Read a first hand account of the mission in Apollo 13 by James Lovell and Jeffrey Kluger.

Apollo 13 by James Lovell and Jeffrey Kluger

Written thirty years after the launch of the mission, Apollo 13 contains never-before-seen photographs from Apollo 13. Jim Lovell and coauthor Jeffrey Kluger delve into America's on-again-off-again love affair with space exploration, which culminated when Apollo 13 was returned to the US after a lengthy consignment to an aviation museum outside Paris.

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