Apollo 13 Mission

Background Information Michelle Nichols, Master Educator – NASA Forum Programs

Information modified from http://www-pao.ksc.nasa.gov/kscpao/history/apollo/apollo-13/apollo-13.htm

The Apollo 13 mission was supposed to have been the 3rd manned Moon landing mission. Because of an oxygen tank explosion while the spacecraft was headed to the Moon and located 200,000 miles from any sort of rescue, the mission became a NASA and industry team effort to return the astronauts safely. Apollo 13 accomplished almost none of its lunar landing objectives, but it was, instead, a triumph of teamwork and ingenuity. Thanks to the popular Apollo 13 movie directed by Ron Howard and starring Tom Hanks, many more people now know about – and respect - this “successful failure” mission. EVENT DATE & TIME MISSION ELAPSED TIME (Central Standard Time) (hours: minutes: seconds) Launch April 11 01:13:00 p.m. 00:00:00 Earth orbit insertion April 11 01:25:40 p.m. 00:12:40 (EOI is when the spacecraft reached Earth orbit after launch) Translunar injection April 11 03:54:47 p.m. 02:41:47 (TLI is when the spacecraft engines fired to head to the Moon) LO2 tank anomaly April 13 09:07:53 p.m. 55:54:53 (LO2 tank anomaly is the time of the liquid oxygen tank explosion) Trans-Earth injection April 14 08:40:39 p.m. 79:27:39 (TEI is when the spacecraft engines fired to head back to Earth) Splashdown April 17 12:07:41 p.m. 142:54:41 Crew Captain James A. Lovell, Jr. Mission Commander, was born March 25, 1928, in Cleveland, Ohio. He received a bachelor of science degree from the U.S. Naval Academy (1952) and was chosen with the second group of astronauts in 1962. He was back-up pilot for Gemini 4, pilot of Gemini 7, back-up command pilot for Gemini 9, command pilot for Gemini 12, command module pilot of Apollo 8, back-up commander for Apollo 11, and commander of Apollo 13. In May 1971, he became Deputy Director of Science and Applications at the Johnson Space Center. He retired from NASA and the Navy in March 1973.

John L. Swigert, Jr., Command Module Pilot, was born August 30, 1931 in Denver, Colorado. He received a bachelor of science degree in mechanical engineering from the University of Colorado (1953), a master of science in aerospace science from Rensselaer Polytechnic Institute (1965), and a master of science in business administration from the University of Hartford (1967). He was chosen in the fifth group of astronauts in 1966. He was scheduled to be the back-up command module pilot for Apollo 13 but was moved to the prime crew 72 hours before the launch in place of Ken Mattingly who had been exposed to measles. Swigert took a leave of absence from NASA in April 1973 to become Executive Director of the Committee on Science and Technology, U.S. House of Representatives. He resigned from NASA and the committee in August 1977. Astronaut Swigert died of bone cancer on December 27, 1982.

Fred W. Haise, Lunar Module Pilot, was born November 14, 1933, in Biloxi, Mississippi. He received a bachelor of science degree in aeronautical engineering from the University of Oklahoma (1959) and was chosen in the fifth group of astronauts in 1966. He was back-up lunar pilot for Apollo 8 and Apollo 11, lunar module pilot for Apollo 13, and backup commander for Apollo 16. He was commander of one of the crews who flew shuttle approach and landing tests and had been selected as commander of one of the shuttle orbital flight tests but resigned from NASA in June 1979.

Spacecraft The Apollo 13 spacecraft was made up of the same components as all Apollo landing missions, consisting of the two-part Command and Service Module Odyssey and the two-part Lunar Module Aquarius. Abbreviations used below will include CM – Command & Service Module and LM – Lunar Module. Original plan The Apollo 13 mission was supposed to have landed in the Fra Mauro region of the Moon. This landing site was later reassigned to the Apollo 14 mission. Fra Mauro is named for a 15th century Venetian monk and mapmaker who in 1457 mapped the then-known Mediterranean world with surprising accuracy. The Fra Mauro region of the Moon, a hilly – and very geologically interesting - area near the Moon’s equator, is named after the 50-mile-diameter Fra Mauro crater within it.

Apollo landing sites by mission number. Credit: http://science.nasa.gov

Adler exhibit connection: Visitors can get an up-close view of the Apollo 14 landing site - which was to have been the Apollo 13 landing site - on the Moon Wall in the Shoot for the Moon gallery. The image was taken by the Lunar Reconnaissance Orbiter in 2009. Prior to launch Days before the mission, backup LM pilot Charlie Duke inadvertently exposed the crew to rubella (also called “German measles”). The original command module pilot, Ken Mattingly, turned out to have no immunity to measles and was replaced by backup command module pilot Jack Swigert. Mattingly never came down with rubella, and he later flew as CM pilot for the Apollo 16 mission. On the Service Module, oxygen tank No. 2 had been previously installed in the service module of Apollo 10, but was removed for modification and was damaged in the process of removal. The tank was fixed, tested at the factory, installed in the Apollo 13 service module, and tested again during the Countdown Demonstration Test at the Kennedy Space Center beginning March 16, 1970. The tanks normally were emptied to about half full, and No. 1 emptied well. But No. 2 dropped to only 92 percent of capacity, instead of 50 percent. Gaseous oxygen was sent through the vent line to expel, or push out, the liquid oxygen, but this did not work. A report was written, and on March 27, two weeks before launch, the process was tested again. No. 1 again emptied normally, but No. 2 did not. After a conference with contractor and NASA personnel, the test director decided to "boil off" the remaining oxygen in No. 2 by using the electrical heater within the tank. The technique worked, but it took eight hours of power to the heater to boil off the super-cold liquid oxygen. This turned out to severely damage the internal heating elements of the tank, but this fact was unknown until after the Apollo 13 accident was investigated. Launch The launch itself was smooth. At five and a half minutes after liftoff, Swigert, Haise, and Lovell felt a little vibration. Then the center engine of the Saturn V rocket’s second stage shut down two minutes early, after computers detected a dangerous level of up-and-down flexing in the metal frame structure holding the engine in place. This caused the remaining four engines to burn 34 seconds longer than planned, and the third stage had to burn nine seconds longer to put Apollo 13 in orbit. This had no impact on the mission, as the rocket’s systems were designed to handle problems like this. During the first two days the crew ran into a couple of minor surprises, but generally Apollo 13 was initially looking like the smoothest flight of the program. At 46 hours, 43 minutes Joe Kerwin, the CapCom (Capsule Communicator, the astronaut responsible for communicating directly with the crew) on duty, said, "The spacecraft is in real good shape as far as we are concerned. We're bored to tears down here." At 55 hours, 46 minutes, as the crew finished a 49-minute TV broadcast showing how comfortably they lived and worked in weightlessness, Lovell stated, "This is the crew of Apollo 13 wishing everybody there a nice evening, and we're just about ready to close out our inspection of Aquarius and get back for a pleasant evening in Odyssey. Good night." Nine minutes later, oxygen tank No. 2 blew up, causing the No. 1 tank also to fail. The crew felt a sharp bang and vibration. Jack Swigert saw a warning light that accompanied the bang, and said, "Houston, we've had a problem here." The time was almost 9:08 p.m. Central Time on April 13, 1970.

Next, the warning lights indicated the loss of two of Apollo 13's three fuel cells. The spacecraft used the combination of oxygen and hydrogen to produce electricity. With warning lights blinking on, one oxygen tank appeared to be completely empty, and there were indications that the oxygen in the second tank was rapidly being depleted. Without oxygen for the fuel cells in the CM, the crew might not have enough electricity to power the spacecraft systems. Thirteen minutes after the explosion, Lovell happened to look out of the left-hand window, and saw the final evidence pointing toward potential catastrophe. "We are venting something out into the…into space," he reported to Houston. Jack Lousma replied, "Roger, we copy you venting." Lovell said, "It's a gas of some sort." It was oxygen gas escaping at a high rate from the second, and last, oxygen tank. The pressure in the No. 1 oxygen tank continued to drift downward. When the pressure reached 200 psi (pounds per square inch), the crew and ground controllers knew that they would lose all oxygen from the tank, which meant that the last CM fuel cell, the electricity generating capability, would stop working. NASA made the decision to have the crew get into the LM, using its own battery-powered (non-fuel cell) electrical systems and other resources as a “lifeboat” until the spacecraft returned to Earth. Ground controllers in Houston faced a formidable task. Problems had to be solved in minutes or hours, not days, weeks or months, and only the resources on board the spacecraft could be used to get the crew home safely. Completely new operating procedures had to be written and tested in the simulator before being passed up to the crew. With only 15 minutes of power left in the CM, CapCom told the crew to make their way into the LM, keeping the CM attached. The first concern was to determine if there were enough consumables to get home:

• The overall working lifetime of the Lunar Module was in question. LM was built for only a 45-hour lifetime (used only when near and at the Moon), and that needed to be stretched to 90 hours to allow enough time to get the crew to the Moon, swing around, and return to Earth.

• Oxygen to breathe and use wasn't a problem in the LM. The full LM descent tank alone would suffice, and in addition, there were two LM ascent-engine oxygen tanks (the ascent engine was normally used to lift the top of the LM off of the surface of the Moon), and two spacesuit backpacks whose oxygen supply would now not be used on the lunar surface. Two emergency bottles on top of those packs were also available.

• Power was a concern. Controllers carefully worked out a procedure where the CM batteries were charged with LM power. All non-critical systems were turned off and energy consumption was reduced to a fifth of normal.

• Water was the main consumable concern. It was estimated that the crew would run out of water about five hours before Earth reentry. However, data from the Apollo 11 mission showed that its mechanisms could survive seven or eight hours in space without water-cooling. The crew conserved water. They cut down to six ounces each per day, a fifth of normal intake, and drank fruit juices; they ate hot dogs and other wet-pack foods when they ate at all. The crew became dehydrated throughout the flight and set a record that stood up throughout Apollo: Lovell lost fourteen pounds, and the crew lost a total of 31.5 pounds, nearly 50 percent more than any other crew. Those stringent measures resulted in the crew finishing the mission with 28.2 pounds of water left over (~3 gallons), about 9 percent of the total available when the mission began.

• Removal of carbon dioxide was also a concern. There were enough lithium hydroxide canisters, which remove carbon dioxide from the spacecraft, but the square canisters from the CMwere not compatible with the round openings in the LM environmental system. There were four cartridges from the LM, and four from the backpacks, counting backups, and all had different sizes and

shapes. However, the LM was designed to support two men for two days and was being asked to care for three men nearly four days. After a day and a half in the LM a warning light showed that the carbon dioxide had built up to a dangerous level. Mission Control devised a way to attach the CM canisters to the LM system by using materials that were available on board: plastic bags, cardboard, and tape.

Adler exhibit connection: There is a logbook in the Shoot for the Moon gallery case that contains several of Captain Lovell’s artifacts. Look for the ring-bound book on the top shelf that has a somewhat-strange drawing of an astronaut on the front. The cover of the logbook is missing. Where is it? The astronauts tore off the cover of the logbook to help provide some of the material to help construct the mechanism to get the various CM and spacesuit lithium hydroxide canisters (with their varying shapes & sizes) to work with the carbon dioxide removal system in the LM. In other words, the cover of that logbook was used to construct the “fix” to remove CO2 from the air so the astronauts wouldn’t suffocate. One of the big questions was, "How to get back safely to Earth?" The LM navigation system wasn't designed to help in this situation. The job of aligning the spacecraft correctly so it was in the right direction was transferred to the LM but verifying alignment was difficult. Ordinarily the alignment procedure used an onboard sextant device, called the Alignment Optical Telescope, to find a suitable navigation star. However, due to the explosion, a swarm of debris from the ruptured service module made it impossible to sight real stars. An alternate procedure was developed to use the sun as an alignment star. Lovell rotated the spacecraft in the direction Houston had requested and when he looked through the AOT, the Sun was just where it was expected. The alignment with the Sun proved to be less than a half a degree off. Adler exhibit connection: The telescope and the joystick used to align the spacecraft correctly for a return to Earth is located in the main Shoot for the Moon artifact case. The trip was marked by discomfort beyond the lack of food and water. Sleep was almost impossible because of the cold. When the electrical systems were turned off, the spacecraft lost an important source of heat. The temperature dropped to 38 F and condensation formed on all the walls. A most remarkable achievement of Mission Control was quickly developing procedures for powering up the CM after its long cold sleep. Flight controllers wrote the documents for this innovation in three days, instead of the usual three months. The Command Module was cold and clammy at the start of power up. The walls, ceiling, floor, wire harnesses, and panels were all covered with droplets of water. It was suspected conditions were the same behind the panels. The chances of short circuits caused apprehension, but thanks to the safeguards built into the command module after the disastrous Apollo 1 fire in January 1967, no electrical arcing (pronounced “ARK-ing”) took place. The droplets furnished one sensation as the crew decelerated in the Earth’s atmosphere: it rained inside the CM. Four hours before landing, the crew shed the service module where oxygen tank No. 2 had exploded; Mission Control had insisted on keeping it attached to the CM crew capsule until then because everyone feared what the cold of space might do to the uncovered CM heat shield. Photos of the Service Module showed one whole panel missing, and wreckage hanging out. Three hours later, the crew left the Lunar

Module Aquarius and climbed into the CM capsule. They then discarded the LM lifeboat that had helped to save their lives. During reentry, as the crew capsule was traveling at high speed through the Earth’s atmosphere, Apollo 13 experienced a prolonged period of communication blackout (or LOS: Loss of Signal). Approximately 4 minutes was a normal LOS period; Apollo 13 experienced 6 minutes of LOS, as recorded in Flight Director Gene Krantz’s mission logbook. LOS is caused by the capsule’s friction with the Earth’s atmosphere, which creates ionization of the air around the capsule. Ionization blocks radio communication signals, and LOS was a normal part of Apollo missions. Apollo 13’s LOS was longer due to a more shallow reentry angle, which created a longer path that the capsule had to travel through the atmosphere and a longer time that it experienced the friction & heating that caused LOS. On April 17, 1970, the crew splashed down gently in the Pacific Ocean near Samoa. The crew was picked up by the U.S.S. Iwo Jima. What happened? After an intensive investigation, the Apollo 13 Accident Review Board identified the cause of the explosion. The oxygen tanks were highly insulated spherical tanks which held a "slush" of liquid oxygen, with a fill line and heater running down the center. In 1965 the CM had undergone many improvements, which included raising the permissible electrical voltage to the heaters in the oxygen tanks. Unfortunately, the switches on these heaters weren't modified to match the change. During the final test on the launch pad, the heaters were on for 8 hours, which was a long period of time. This subjected the wiring in the vicinity of the heaters to very high temperatures (1000 degrees F), which had been subsequently shown to severely degrade their Teflon insulation and expose the wires. The switches tried to open when they detected a temperature in the tank that was at 80 degrees F, but they were probably welded shut due to the excessive heat. The gauges measuring the temperature inside the tank were designed to measure only to 80 degrees F, so the extreme heating was not noticed. (Side note: It was also 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 and emptying the No. 1 tank, even though the No. 2 tank was the one that ruptured.)

The crew's lives may have been saved by the malfunction. At around 46 hours 40 minutes into the mission, the oxygen tank No.2 quantity gauge went "off-scale high" (reading over 100%) and stayed there, possibly due to the damaged internal insulation. To assist in determining the cause, the crew was asked to perform more frequent “cryo-tank stirs”, where the liquid oxygen in the tank was stirred around using fans. The exposed fan wires inside the tank shorted and the remaining Teflon insulation caught fire in the pure oxygen environment. This fire rapidly heated and increased the pressure of the oxygen inside the tank, and may have spread along the wires to the electrical conduit in the side wall of the tank, which weakened and ruptured under pressure, causing the No. 2 oxygen tank to explode. In the original mission plan, the stir that ruptured the tank would not have been done until after the lunar landing. Although the explosion aborted the mission, it fortunately happened on the way to the moon when the LM was still available with its full complement of consumables. Had the explosion occurred after the landing or on the return to Earth after the LM had been discarded, the crew would not have had enough resources to survive.