Apollo 13's damaged service module, as photographed by the crew from the command module
|Mission type||Crewed lunar landing attempt|
|Mission duration||5 days, 22 hours, 54 minutes, 41 seconds|
|Launch mass||101,261 pounds (45,931 kg)|
|Landing mass||11,133 pounds (5,050 kg)|
|Start of mission|
|Launch date||April 11, 1970, 19:13:00UTC|
|Rocket||Saturn V SA-508|
|Launch site||Kennedy LC-39A|
|End of mission|
|Recovered by||USS Iwo Jima|
|Landing date||April 17, 1970, 18:07:41UTC|
|Landing site||South Pacific Ocean|
|Flyby of Moon (orbit and landing aborted)|
|Closest approach||April 15, 1970, 00:21:00 UTC|
|Distance||254 kilometers (137 nmi)|
|Docking with LM|
|Docking date||April 11, 1970, 22:32:08 UTC|
|Undocking date||April 17, 1970, 16:43:00 UTC|
Left to right Lovell, Swigert, Haise, 12 days after their return.
Apollo 13 was the seventh crewed mission in the Apollo space program and the third intended to land on the Moon. The craft was launched on April 11, 1970, from the Kennedy Space Center, Florida, but the lunar landing was aborted after an oxygen tank exploded two days later, crippling the service module (SM) upon which the command module (CM) had depended. Despite great hardship caused by limited power, loss of cabin heat, shortage of potable water, and the critical need to make makeshift repairs to the carbon dioxide removal system, the crew returned safely to Earth on April 17, 1970, six days after launch.
The flight passed the far side of the Moon at an altitude of 254 kilometers (137 nautical miles) above the lunar surface, and 400,171 km (248,655 mi) from Earth, a spaceflight record marking the farthest humans have ever traveled from Earth. The mission was commanded by James A. Lovell with John L. "Jack" Swigert as Command Module Pilot and Fred W. Haise as Lunar Module Pilot. Swigert was a late replacement for the original CM pilot Ken Mattingly, who was grounded by the flight surgeon after exposure to German measles.
The story of the Apollo 13 mission has been dramatized multiple times, most notably in the 1995 film Apollo 13.
Crew and key Mission Control personnel
Fourth and last spaceflight
|Command Module Pilot||Jack Swigert|
|Lunar Module Pilot||Fred Haise|
Lovell was born March 25, 1928 in Cleveland, Ohio. He initially attended the University of Wisconsin for two years but was appointed to the United States Naval Academy at Annapolis, Maryland, from which he graduated in 1952 with a Bachelor of Science degree. Becoming a naval aviator and test pilot, Lovell was selected as part of the second group of astronauts in 1962. A naval captain at the time of Apollo 13, he flew alongside Frank Borman in Gemini 7 and Buzz Aldrin in Gemini 12 before flying in Apollo 8 in 1968, the first spacecraft to orbit the Moon. Swigert was born on August 30, 1931 in Denver, Colorado. He earned a B.S. in mechanical engineering from the University of Colorado in 1953, later gaining a Master of Science degree in Aerospace Science from RPI in 1965, and in 1967 an MBA degree from the University of Hartford. He served in the Air Force and in state air national guards, and was an engineering test pilot prior to his selection as one of the fifth group of astronauts in 1966. Haise was born in Biloxi, Mississippi on November 14, 1933. He received a B.S. degree from the University of Oklahoma in 1959. He served in the Oklahoma Air National Guard and the United States Air Force, and was a civilian research pilot for NASA when he was selected alongside Swigert as a Group 5 astronaut.
According to the standard crew rotation in place during the Apollo program, the prime crew for Apollo 13 would have been the backup crew for Apollo 10 with Mercury and Gemini veteran L. Gordon Cooper in command. That crew was composed of Commander L. Gordon Cooper Jr., Command Module Pilot Donn F. Eisele and Lunar Module Pilot Edgar D. Mitchell. Deke Slayton, NASA's Director of Flight Crew Operations, never intended to rotate Cooper and Eisele to another mission, as both were out of favor with NASA management for various reasons (Cooper for his lax attitude towards training, and Eisele for incidents aboard Apollo 7 and an extra-marital affair). He assigned them to the backup crew simply because of a lack of flight-qualified manpower in the Astronaut Office at the time the assignment needed to be made. Slayton felt Cooper had no more than a very small chance of receiving the Apollo 13 command, if he did an outstanding job with the assignment, which he did not. Despite Eisele's issues with management, Slayton always intended to assign him to a future Apollo Applications Program mission rather than a lunar mission, but this program was eventually cut down to only the Skylab component.
Thus, the original assignment Slayton submitted to his superiors for this flight was Commander Alan B. Shepard Jr. Command Module Pilot Stuart A. Roosa and Lunar Module Pilot Edgar D. Mitchell. For the first time ever, Slayton's recommendation was rejected by management, who felt that Shepard needed more time to train properly for a lunar flight, as he had only recently benefited from experimental surgery to correct an inner ear disorder which had kept him grounded since his first Mercury flight in 1961. Thus, Lovell's crew, backup for the historic Apollo 11 mission and therefore slated for Apollo 14, was swapped with Shepard's crew and the original crew selection for the mission became:
|Commander||James A. Lovell Jr.|
|Command Module Pilot||T. Kenneth Mattingly II|
|Lunar Module Pilot||Fred W. Haise Jr.|
|Commander||John W. Young|
|Command Module Pilot||John L. "Jack" Swigert|
|Lunar Module Pilot||Charles M. Duke Jr.|
Ken Mattingly was originally intended as the Command Module Pilot. Seven days before launch, the backup lunar module pilot, Charlie Duke, contracted rubella from one of his children. This exposed both the prime and backup crews, who trained together. Mattingly was found to be the only one of the other five who had not had rubella as a child and thus was not immune. Three days before launch, at the insistence of the Flight Surgeon, Swigert was moved to the prime crew.
Mattingly never contracted rubella and was assigned after the mission as command module pilot to Young's crew, which later flew Apollo 16, the fifth mission to land on the Moon.
- Gene Kranz (lead) – White team;
- Glynn Lunney – Black team;
- Milt Windler – Maroon team;
- Gerry Griffin – Gold team.
The CAPCOMs were Kerwin, Brand, Lousma, Young and Mattingly.
The Apollo 13 mission insignia depicts the god Apollo, the Sun god, with three horses pulling his chariot across the face of the Moon, with the Earth seen in the distance. This is meant to symbolize the Apollo flights bringing the light of knowledge to all people. The motto, Ex luna, scientia means "From the Moon, knowledge".
The mission insignia was sculpted as a medallion, Steeds of Apollo by Lumen Martin Winter, and was painted as a mural on the wall of a Chicago-area restaurant owned by one of Lovell's children. That representation shows four horses, one for each member of the crew who flew, and the fourth for Mattingly.
Hardware and mission parameters
Launch vehicle and spacecraft
The Apollo 13 spacecraft consisted of Command Module 109 and Service Module 109 (together CSM-109) and Lunar Module 7 (LM–7). Also considered part of the spacecraft were the Launch Escape System which would propel the CM to safety in the event of a problem during launch, and the Spacecraft–LM Adapter (SLA) which was to house the LM during the first hours of the mission.
Concerned about how close Apollo 11's LM, Eagle, had come to running out of fuel during its lunar descent, mission planners decided that beginning with Apollo 13, the CSM would bring the LM to the low orbit from which the landing attempt would commence. This was a change from Apollo 11 and 12, on which the LM made the burn to bring it to the lower orbit. The change was part of an effort to increase the amount of hover time available to the astronauts as the missions headed into rougher terrain.
ALSEP and other equipment
Apollo 11 had left a seismometer on the Moon, but the solar-powered unit did not survive its first two-week-long lunar night. The Apollo 12 astronauts also left one as part of its ALSEP installation of nuclear-powered scientific instruments. At the First Lunar Science Conference in January 1970, it was revealed that while there were almost daily impacts of objects onto the Moon, none had been as large as the impact of Apollo 12's LM, Intrepid, which had been deorbited after being jettisoned. In the hope larger impacts would allow scientists on Earth to probe the structure of the Moon's crust, it was decided that beginning with Apollo 13, the launch vehicle's S-IVB stage would be crashed into the Moon instead of being sent into solar orbit as in earlier missions.
Apollo 13 carried a similar seismometer as part of its ALSEP package, which was placed in the LM descent stage's scientific equipment bay. That seismometer was to be calibrated by the impact, after jettison, of the ascent stage of Apollo 13's LM, an object of known mass and velocity impacting at a known location.
Other ALSEP experiments included a Heat Flow Experiment, which would involve the astronauts drilling two holes 10 feet (3.0 m) deep. A Charged Particle Lunar Environment Experiment (CPLEE) measured the protons and electrons of solar origin reaching the Moon. The package also included a Lunar Atmosphere Detector and a Dust Detector, to measure the accumulation of debris on the ALSEP.
To power the ALSEP, the SNAP-27 radioisotope thermoelectric generator was flown. Developed by the U.S. Atomic Energy Commission, SNAP-27 was first flown on Apollo 12. The device contained about 8.36 pounds (3.79 kg) of plutonium oxide. The cask placed around the fuel was built with heat shields of graphite and of beryllium, with structural parts of titanium and of Inconel materials. Thus, it was built to take the heat of re-entry into the Earth's atmosphere without coming apart, as the Apollo 13 Press Kit put it, "in the unlikely event of an aborted mission".
Like Apollo 11 and 12, Apollo 13 flew the Solar Wind Composition Experiment, a windowshade-like device that would be deployed on the lunar surface and then be folded up and brought back by the astronauts. It also flew the Lunar Stereo Closeup Camera, intended to show the fine structure of lunar rocks and soil. A United States flag was also taken, to be erected on the Moon's surface. For Apollo 11 and 12, the flag had been placed in a heat-resistant tube on the front landing leg; it was moved for Apollo 13 to the Modularized Equipment Stowage Assembly (MESA) in the LM descent stage. The structure to fly the flag on the airless Moon was improved from Apollo 12's.
For the first time, red stripes were placed on the helmet, arms and legs of the commander's spacesuit. This was done as after Apollo 11, those reviewing the images taken had trouble distinguishing Armstrong from Aldrin, but the change was approved too late for Apollo 12. The Apollo 12 moon walkers had gotten thirsty during their lunar surface activities; the new drink bags that could be placed inside the helmets and sipped from as the astronauts explored were demonstrated by Haise during Apollo 13's final television broadcast before the accident.
Landing site selection; astronaut training
Apollo 12 had shown that lunar astronauts could perform a precision landing. Thus, mission planners for Apollo 13 were able to seek a smaller landing target someplace other than the lunar mares, or seas, upon which Apollo 11 and 12 had set down. Apollo 11 and 12 each had a backup site for landing in case of launch delays; this requirement also was scrubbed for Apollo 13. This did not open up the whole Moon to planners—sites still had to be in the equatorial region of the near side —but they could be more flexible and could seek a site of greater scientific interest.
In anticipation of successful lunar landings, the Site Selection Board met in June 1969 to plan Apollo 13, and a site near Fra Mauro crater gained consensus. The Fra Mauro formation was believed to contain much material spattered by the impact that had filled the Imbrium basin, early in the Moon's history. Dating it would provide information not only about the Moon, but about the Earth's early history. The landing site was about 26 miles (42 km) north of Fra Mauro crater itself, near what was dubbed Cone crater, a site where an impact was believed to have drilled deep into the lunar regolith. Due to the roughness of the terrain, the selected landing site was over a mile (two kilometers) from Cone crater, but Lovell, who as commander was to perform the landing, had the option of setting down closer if he believed he could do so safely. NASA initially had few high-quality photographs of the landing site, but after Dick Gordon, CMP of Apollo 12, took more from orbit in November 1969, Fra Mauro was confirmed as Apollo 13's landing site.
A month before the planned landing, Lovell and Haise undertook a traverse at Arizona's Verde Valley, over a landscape made to look as much like the lunar surface as possible. The Apollo 13 prime crew undertook over 1,000 hours of mission-specific training, more than five hours for every hour of the mission's ten-day planned duration. Each member of the prime crew spent over 400 hours in simulators of the CM and of the LM at KSC and at Houston, some of which involved the flight controllers at Mission Control. Specialized simulators at other locations were also used.
Lovell and Haise wore their spacesuits for some 20 walk-throughs of EVA procedures, including sample gathering and use of tools and other equipment. The astronauts flew in the "Vomit Comet" in simulated microgravity or lunar gravity, including practice in donning and doffing spacesuits. To train for the descent to the Moon's surface, Lovell flew the Lunar Landing Training Vehicle (LLTV). Despite the fact that four of the five LLTVs and similar Lunar Landing Research Vehicles crashed during the course of the Apollo program, mission commanders considered flying the LLTV invaluable experience.
- Mass: CSM Odyssey 63,470 pounds (28,790 kg); LM Aquarius 33,490 pounds (15,190 kg);
- Perigee: 99.3 nautical miles (183.9 km);
- Apogee (parking orbit): 100.3 nautical miles (185.8 km);
- Inclination (Earth departure): 31.817°;
- Period: 88.19 min.
The Apollo 13 mission was to explore the Fra Mauro formation, or Fra Mauro highlands, named after the 80-kilometer (50 mi) diameter Fra Mauro crater located within it. It is a widespread, hilly selenological area thought to be composed of ejecta from the impact that formed Mare Imbrium.
The next Apollo mission, Apollo 14, eventually made a successful flight to Fra Mauro.
- Oxygen tank explosion: 03:07:53 UTC (55:54:53 Ground Elapsed Time); 173,790.5 nmi (321,860 km) from Earth
- CSM power down, LM power up: 05:23 UTC (58:10 Ground Elapsed Time)
Closest approach to Moon
April 15, 1970, 00:21:00 UTC; 137 nmi (253.7 km)
April 17, 1970, 18:07:41 UTC (142:54:47 Ground Elapsed Time). Crew was on board USS Iwo Jima 45 minutes later.
Launch and translunar injection
The mission was launched at the planned time, 02:13:00 PM EST (19:13:00 UTC) on April 11. An anomaly occurred when the second-stage, center (inboard) engine shut down about two minutes early. The four outboard engines and the third-stage engine burned longer to compensate, and the vehicle achieved very close to the planned circular 100 nautical miles (190 km) parking orbit, followed by a normal translunar injection about two hours later. The engine shutdown was determined to be caused by severe pogo oscillations measured at a strength of 68 g and a frequency of 16 hertz, flexing the thrust frame by 3 inches (76 mm). The vehicle's guidance system shut the engine down in response to sensed thrust chamber pressure fluctuations. Pogo oscillations had been seen on previous Titan rockets, and also on the Saturn V during the uncrewed Apollo 6 mission, but on Apollo 13, they were amplified by an unexpected interaction with turbopump cavitation. Later missions implemented anti-pogo modifications that had been under development. These included addition of a helium-gas reservoir to the center engine liquid oxygen line to damp pressure oscillations, an automatic cutoff as a backup, and simplification of the propellant valves of all five second-stage engines.
The crew performed the separation and transposition maneuver to dock the CM Odyssey to the LM Aquarius, and pulled away from the spent third stage, which ground controllers then sent on a course to impact the Moon in range of a seismometer placed on the surface by Apollo 12. They then settled in for the three-day trip to Fra Mauro.
Approaching 56 hours into the mission, Apollo 13 was approximately 205,000 miles (330,000 km) from Earth en route to the Moon. Approximately six and a half minutes after the end of a live TV broadcast from the spacecraft, Haise was in the process of closing out the LM, while Lovell was stowing the TV camera. Houston flight controllers asked Swigert to turn on the hydrogen and oxygen tank stirring fans in the service module, which were designed to destratify the cryogenic contents and increase the accuracy of their quantity readings. Two minutes later, the astronauts heard a "pretty large bang", accompanied by fluctuations in electrical power and the firing of the attitude control thrusters; the crew initially thought that a meteoroid might have struck the lunar module. Communications and telemetry to Earth were lost for 1.8 seconds, until the system automatically corrected by switching the high-gain S-band antenna, used for translunar communications, from narrow-beam to wide-beam mode.
Immediately after the bang, Swigert reported "Okay, Houston, we've had a problem here", which Lovell repeated and clarified as a "main B bus undervolt", a temporary loss of operating voltage on the second of the spacecraft's main electrical circuits. Oxygen tank 2 immediately read quantity zero. About three minutes later, the number 1 and number 3 fuel cells failed. Lovell reported seeing out the window that the craft was venting "a gas of some sort" into space. The number 1 oxygen tank quantity gradually reduced to zero over the next 130 minutes, entirely depleting the SM's oxygen supply.
Because the fuel cells generated the command and service module's electrical power by combining hydrogen and oxygen into water, when oxygen tank 1 ran dry, the remaining fuel cell finally shut down, leaving the craft on the command module's limited-duration battery power and water. The crew was forced to shut down the CM completely to save this for reentry, and to power up the LM to use as a "lifeboat". This situation had been suggested during an earlier training simulation, but had not been considered a likely scenario. Without the LM, the accident would certainly have been fatal.
Crew survival and return journey
The damage to the service module made safe return from a lunar landing impossible, so Lead Flight Director Gene Kranz ordered an abort of the mission. The existing abort plans, first drawn up in 1966, were evaluated; the quickest was a Direct Abort trajectory, which required using the service propulsion system (SPS) engine to achieve a 6,079-foot-per-second (1,853 m/s) delta-v.p. III-14 Although a successful SPS firing at 60 hours ground elapsed time (GET) would land the crew one day earlier (at 118 hours GET, or 58 hours later), the large delta-v was possible only if the LM were jettisoned first,p. II-1 and since crew survival depended on the LM's presence during the coast back to Earth, that option was "out of the question."p. III-17 An alternative would have been to burn the SPS fuel to depletion, then jettison the service module and make a second burn with the LM Descent Propulsion System (DPS) engine. It was desired to keep the service module attached for as long as possible because of the thermal protection it afforded the command module's heat shield. Apollo 13 was close to entering the lunar sphere of gravitational influence (at 61 hours GET), which was the break-even point between direct and circumlunar aborts, and the latter allowed more time for evaluation and planning before a major rocket burn.p. B-5 There also was concern about "the structural integrity of the Service Module,"p. III‑23 so mission planners were instructed that the SPS engine would not be used "except as a last-ditch effort."p. III-14
For these reasons, Kranz chose the alternative circumlunar option, using the Moon's gravity to return the ship to Earth. Apollo 13 had left its initial free-return trajectory earlier in the mission, as required for the lunar landing at Fra Mauro. Therefore, the first order of business was to re-establish the free-return trajectory with a 30.7-second burn of the DPS. The descent engine was used again two hours after pericynthion, the closest approach to the Moon ("PC+2 burn"), to speed the return to Earth by 10 hours and move the landing spot from the Indian Ocean to the Pacific Ocean. A more aggressive burn could have been performed at PC+2 by first jettisoning the service module, returning the crew in about the same amount of time as a direct abort,p. III-20 but this was deemed unnecessary given the rates at which consumables were being used. The 4-minute, 24-second burn was so accurate that only two more small course corrections were subsequently needed.
Considerable ingenuity under extreme pressure was required from the crew, flight controllers, and support personnel for the safe return. The developing drama was shown on television. Because electrical power was severely limited, no more live TV broadcasts were made; TV commentators used models and animated footage as illustrations. Low power levels made even voice communications difficult.
The lunar module consumables were intended to sustain two people for a day and a half, not three people for four days. Oxygen was the least critical consumable because the LM carried enough to repressurize the LM after each surface EVA. Unlike the command and service module (CSM), which was powered by fuel cells that produced water as a byproduct, the LM was powered by silver-zinc batteries, so electrical power and water (used for equipment cooling as well as drinking) were critical consumables. To keep the LM life-support and communication systems operational until reentry, the LM was powered down to the lowest levels possible. In particular, the LM's Abort Guidance System was used for most of the coast back to Earth instead of the primary guidance system, as it used less power and water.pp. III‑17,33,40
Availability of lithium hydroxide (LiOH) for removing carbon dioxide presented a serious problem. The LM's internal stock of LiOH canisters was not sufficient to support the crew until return, and the remainder was stored in the descent stage, out of reach. The CM had an adequate supply of canisters, but these were incompatible with the LM. Engineers on the ground improvised a way to join the cube-shaped CM canisters to the LM's cylindrical canister-sockets by drawing air through them with a suit return hose. NASA engineers referred to the improvised device as "the mailbox".
Another problem to be solved for a safe return was accomplishing a complete power-up from scratch of the completely shut-down command module, something never intended to be done in-flight. Flight controller John Aaron, with the support of grounded astronaut Mattingly and many engineers and designers, had to invent a new procedure to do this with the ship's limited power supply and time factor. This was further complicated by the fact that the reduced power levels in the LM caused internal temperatures to drop to as low as 4 °C (39 °F). The unpowered CM got so cold that water began to condense on solid surfaces, causing concern that this might short out electrical systems when it was reactivated. This turned out not to be a problem, partly because of the extensive electrical insulation improvements instituted after the Apollo 1 fire.
The last problem to be solved was how to separate the lunar module a safe distance away from the command module just before reentry. The normal procedure was to use the service module's reaction control system (RCS) to pull the CSM away after releasing the LM along with the command module's docking ring, but this RCS was inoperative because of the power failure, and the useless SM would be released before the LM. Grumman called a team of six University of Toronto engineers, led by senior scientist Bernard Etkin, to solve the problem within a day. The team concluded that pressurizing the tunnel connecting the lunar module to the command module just before separation would provide the force necessary to push the two modules a safe distance away from each other just prior to reentry. The team had 6 hours to accurately compute the pressure required, using slide rules. Too high a pressure could damage the hatch and its seal, endangering the astronauts on reentry; too low and the lunar module would not be sufficiently separated. Grumman relayed their calculation to NASA, and from there in turn to the astronauts, who used it successfully.
Reentry and splashdown
As Apollo 13 neared Earth, the crew first jettisoned the service module, using the LM's reaction control system to pull themselves a safe distance from it, instead of the normal procedure which used automatic firing of the SM's RCS. They photographed it for later analysis of the accident's cause. It was then that the crew were surprised to see for the first time that the entire Sector 4 panel had been blown off. According to the analysts, these pictures also showed the antenna damage and possibly an upward tilt to the fuel cell shelf above the oxygen tank compartment.
Finally, the crew jettisoned the lunar module Aquarius using the above procedure worked out at the University of Toronto, leaving the command module Odyssey to begin its lone reentry through the atmosphere. The reentry on a lunar mission normally was accompanied by about four minutes of typical communications blackout caused by ionization of the air around the command module. The blackout in Apollo 13's reentry lasted six minutes, which was 87 seconds longer than had been expected. The possibility of heat-shield damage from the O
2 tank rupture heightened the tension of the blackout period.
Odyssey regained radio contact and splashed down safely in the South Pacific Ocean, American Samoa and 6.5 km (3.5 nmi) from the recovery ship, USS Iwo Jima. The crew was in good condition except for Haise, who was suffering from a serious urinary tract infection because of insufficient water intake. To avoid altering the trajectory of the spacecraft, the crew had been instructed to temporarily stop urine dumps, which forced them to invent ways of storing all urine for the rest of the flight., southeast of
The lunar module and service module reentered the atmosphere over the South Pacific between the islands of Fiji and New Zealand.
The crew of Apollo 13 on board the USS Iwo Jima following splashdown
The Apollo 13 lunar module Aquarius is jettisoned above the Earth after serving as a lifeboat for four days. It reentered Earth's atmosphere over Fiji and burned up during reentry
Public and media reaction
Analysis and response
NASA Administrator Thomas Paine and Deputy Administrator George Low sent a memorandum to NASA Langley Research Center Director Edgar M. Cortright on April 17, 1970, (date of spacecraft splashdown) advising him of his appointment as chairman of an Apollo 13 Review Board to investigate the cause of the accident.
The second memorandum to Cortright from Paine and Low on April 21 established the board as follows:
- Robert F. Allnutt (Assistant to the Administrator, NASA Hqs.);
- Neil Armstrong (Astronaut, Manned Spacecraft Center);
- Dr. John F. Clark (Director, Goddard Space Flight Center);
- Brig. General Walter R. Hedrick Jr. (Director of Space, DCS/RED, Hqs., USAF);
- Vincent L. Johnson (Deputy Associate Administrator-Engineering, Office of Space Science and Applications);
- Milton Klein (Manager, AEC-NASA Space Nuclear Propulsion Office);
- Dr. Hans M. Mark (Director, Ames Research Center).
- George Malley (Chief Counsel, Langley Research Center)
- Charles W. Mathews (Deputy Associate Administrator, Office of Manned Space Flight)
- William A. Anders (Executive Secretary, National Aeronautics and Space Council; ex-astronaut);
- Dr. Charles D. Harrington (Chairman, NASA Aerospace Safety Advisory Panel);
- I. I. Pinkel (Director, Aerospace Safety Research and Data Institute, Lewis Research Center).
- Gerald J. Mossinghoff (Office of Legislative Affairs, NASA Hqs.)
- Brian Duff (Public Affairs Officer. Manned Spacecraft Center)
Activities and report
The board exhaustively investigated and analyzed the history of the manufacture and testing of the oxygen tank, and its installation and testing in the spacecraft up to the Apollo 13 launch, as documented in detailed records and logs. They visited and consulted with engineers at the contractor's sites and the Kennedy Space Center. Once a theory of the cause was developed, elements of it were tested, including on a test rig simulation in a vacuum chamber, with a damaged tank installed in the fuel cell bay. This test confirmed the theory when a similar explosion was created, which blew off the outer panel exactly as happened in the flight. Cortright sent the final Report of Apollo 13 Review Board to Thomas Paine on June 15, 1970.
The failure started in the service module's number 2 oxygen tank. Damaged Teflon insulation on the wires to the stirring fan inside oxygen tank 2 allowed the wires to short-circuit and ignite this insulation. The resulting fire rapidly increased pressure beyond its 1,000-pound-per-square-inch (6.9 MPa) limit and the tank dome failed, filling the fuel cell bay (Sector 4) with rapidly expanding gaseous oxygen and combustion products. It is also possible some combustion occurred of the Mylar/Kapton thermal insulation material used to line the oxygen shelf compartment in this bay.
The resulting pressure inside the compartment popped the bolts attaching the 13-foot (4.0 m) Sector 4 outer aluminum skin panel, which as it blew off probably caused minor damage to the nearby S-band antenna.
Mechanical shock forced the oxygen valves closed on the number 1 and number 3 fuel cells, leaving them operating for only about three minutes on the oxygen in the feed lines. The shock also either partially ruptured a line from the number 1 oxygen tank, or caused its check or relief valve to leak, causing its contents to leak out into space over the next 130 minutes, entirely depleting the SM's oxygen supply.
The board determined the oxygen tank failure was caused by an unlikely chain of events. Tanks storing cryogens, such as liquid oxygen and liquid hydrogen, require either venting, extremely good insulation, or both, in order to avoid excessive pressure buildup due to vaporization of the tanks' contents. The service module oxygen tanks were so well insulated that they could safely contain supercritical hydrogen and oxygen for years. Each oxygen tank held several hundred pounds of oxygen, which was used for breathable air and the production of electricity and water. The construction of the tanks made internal inspection impossible.
The tank contained several components relevant to the accident:
- a quantity sensor;
- a fan to stir the tank contents for more accurate quantity measurements;
- a heater to vaporize liquid oxygen as needed;
- a thermostat to protect the heater;
- a temperature sensor;
- fill and drain valves and piping.
The heater and protection thermostats were originally designed for the command module's 28-volt DC bus. The specifications for the heater and thermostat were later changed to allow a 65-volt ground supply, in order to pressurize the tanks more rapidly. Beechcraft, the tank subcontractor, did not upgrade the thermostat to handle the higher voltage.
The oxygen shelf carrying the oxygen tanks was originally installed in the Apollo 10 service module, but was removed to fix a potential electromagnetic interference problem. During removal, the shelf was accidentally dropped about 2 inches (5 cm) because a retaining bolt had not been removed. The tank appeared to be undamaged, but a loosely fitting filling tube was apparently damaged, and photographs suggested that the close-out cap on the top of the tank may have hit the fuel cell shelf. The report of the Apollo 13 review board considers the probability of tank damage during this incident to be "rather low." After the tank was filled for ground testing, it could not be emptied through the normal drain line. To avoid delaying the mission by replacing the tank, the heater was connected to 65-volt ground power to boil off the oxygen. Lovell signed off on this procedure. It should have taken a few days at the thermostatic opening temperature of 27 °C (81 °F). When the thermostat opened, the 65-volt supply fused its contacts closed and the heater remained powered. The board confirmed by testing that the thermostats welded themselves closed under the higher voltage. This raised the temperature of the heater to an estimated 540 °C (1,000 °F). A chart recorder on the heater current showed that the heater was not cycling on and off, as it should have been if the thermostat was functioning correctly, but no one noticed it at the time. Because the temperature sensor was not designed to read higher than the 27 °C (81 °F) thermostat opening temperature, the monitoring equipment did not register the true temperature inside the tank. The gas boiled off in hours rather than days.
The sustained high temperatures melted the Teflon insulation on the fan power supply wires and left them exposed. When the tank was refilled with oxygen, it became a bomb waiting to go off. During the "cryo stir" procedure, fan power passed through the bare wires which apparently shorted, producing sparks and igniting the Teflon. This in turn boiled liquid oxygen faster than the tank vent could remove it.
In June 1970, the Cortright Report provided an in-depth analysis of the mission in an extremely detailed five-chapter report with eight appendices. It included a copy of established NASA procedures for alleviating high pressure in a cryogenic oxygen tank, to include:
- Turning the four tank heaters and fans off;
- Pulling the two heater circuit breakers to open to remove the energy source;
- Performing a 2-minute purge, or directly opening the O2 valve.
This procedure was designed to prevent hardware failure so that the lunar landing mission could be continued. The Mission Operations Report Apollo 13 recounts how the master caution and warning alarm had been turned off for a previous low-pressure reading on hydrogen tank 2, and so it did not trigger to call attention to the high oxygen pressure reading.
Oxygen tank 2 was not the only pressure vessel that failed during this mission. Prior to the accident, the crew had moved the scheduled entry into the lunar module forward by three hours. This was done to get an earlier look at the pressure reading of the supercritical helium (SHe) tank in the LM descent stage, which had been suspect since before launch. After the abort decision, the helium pressure continued to rise and Mission Control predicted the time that the burst disc would rupture. The helium tank burst disc ruptured at 108:54, after the lunar flyby. The expulsion reversed the direction of the passive thermal control (PTC) roll (nicknamed the "barbecue roll").
While the investigation board did recreate the oxygen tank failure, it did not report on any experiments that would show how effective the Cryogenic Malfunctions Procedures were to prevent the system failure by de-energizing the electrical heater and fan circuits.
The oxygen tank was redesigned, with the thermostats upgraded to handle the proper voltage. The heaters were retained since they were necessary to maintain oxygen pressure. The stirring fans, with their unsealed motors, were removed, which meant the oxygen quantity gauge was no longer accurate. This required adding a third tank so that no tank would go below half full.
All electrical wiring in the power system bay was sheathed in stainless steel, and the oxygen quantity probes were changed from aluminum to stainless steel. The fuel cell oxygen supply valves were redesigned to isolate the Teflon-coated wiring from the oxygen. The spacecraft and Mission Control monitoring systems were modified to give more immediate and visible warnings of anomalies.
Because Apollo 13 followed the free-return trajectory, its altitude over the lunar far side was approximately 100 km (60 mi) greater than the orbital altitude on the remaining Apollo lunar missions. The Moon was almost at apogee during the mission (as it also was during the flights of Apollo 10 and Apollo 15), which also increased the distance from the Earth. The combination of the two effects ensures that Apollo 13 holds the absolute altitude record for a crewed spacecraft, reaching a distance of 400,171 kilometers (248,655 mi) from Earth on 7:21 pm EST, April 14, 1970.
The A7L spacesuit intended to be worn on the lunar surface by Lovell would have been the first to feature red bands on the arms, legs, lunar EVA helmet assembly, and the life-support backpack. This came about because Mission Control personnel watching the video feeds of Apollos 11 and 12 had trouble distinguishing the astronauts while both had their helmet sunshades down. The red bands were used for the remaining Apollo flights, the Space Shuttle program, and in the International Space Station.
The Apollo 13 mission was called a "successful failure" by Lovell, because of the successful safe return of the astronauts, but the failed lunar landing. It has also been termed "NASA's finest hour."
President Nixon flew to Houston to award the Apollo 13 Mission Operations Team the Presidential Medal of Freedom on April 18. Because the Medal of Freedom was presented as a group award, the members of the Apollo 13 team have the distinction of being the only individuals ever presented with the honor without being given the actual medal itself. He then flew to Honolulu to award the crew the Presidential Medal of Freedom for their actions during the mission.
The Cold Cathode Gauge Experiment (CCGE) which was part of the ALSEP on Apollo 13 was never flown again. It was a version of the Cold Cathode Ion Gauge (CCIG) which featured on Apollo 12, Apollo 14, and Apollo 15. The CCGE was designed as a standalone version of the CCIG. On other missions, the CCIG was connected as part of the Suprathermal Ion Detector (SIDE). Because of the aborted landing, this experiment was never deployed. Other experiments included on Apollo 13's ALSEP included the Heat Flow Experiment (HFE), the Passive Seismic Experiment (PSE), and the Charged Particle Lunar Environment Experiment (CPLEE).
Plaque and insignia
The original lunar plaque affixed to the front landing leg of Aquarius bore Mattingly's name, so a replacement plaque with Swigert's name was carried in the cabin, for Lovell to place over the other after he descended the ladder. He kept the plaque as a souvenir. In his book Lost Moon (later renamed Apollo 13), Lovell stated that, apart from the plaque and a couple of other pieces, the only other memento he possesses is a letter from Charles Lindbergh.
The Apollo 13 crew patch featured three flying horses as Apollo's "chariot" across space. Given Lovell's Navy background, the logo also included the mottoes "Ex Luna, scientia" ("From the Moon, knowledge"), borrowed from the U.S. Naval Academy's motto, "Ex scientia tridens" ("From knowledge, sea power"). The mission number appeared in Roman numerals as Apollo XIII. The patch did not have to be modified after Mattingly's replacement since it is one of only two Apollo mission insignia—the other being Apollo 11—not to include the names of the crew. It was designed by artist Lumen Martin Winter, who based it on a mural he had done for The St. Regis Hotel in New York City. The mural was later purchased by actor Tom Hanks, who portrayed Lovell in the movie Apollo 13, and now is on the wall of a restaurant near Chicago owned by Lovell's son.
Despite Apollo 13's failure to land on the Moon, several experiments were conducted successfully because they were initiated before or conducted independently of the oxygen tank explosion.
- Several experiments to study electrical phenomena were conducted prior to and during the launch of Apollo 13. This information was used to better understand hazards of launching in less than ideal weather conditions.
- Eleven photographs of Earth were taken at precisely recorded times, to study the feasibility of using geosynchronous satellites to study cloud height.
- Apollo 13's S-IVB third stage was the first to be purposely crashed into the lunar surface, as an active seismic experiment which measured its impact with a seismometer left on the lunar surface by the crew of Apollo 12. (The S-IVBs from the previous four lunar missions were sent into solar orbit by ground control after use.)
As a joke following Apollo 13's successful splashdown, Grumman Aerospace Corporation pilot Sam Greenberg (who had helped with the strategy for re-routing power from the LM to the crippled CM) issued a tongue-in-cheek invoice for $400,540.05 to North American Rockwell, Pratt and Whitney, and Beech Aircraft, prime and subcontractors for the CSM, for "towing" the crippled ship most of the way to the Moon and back. The figure was based on an estimated 400,001 miles (643,739 km) at $1.00 per mile, plus $4.00 for the first mile. An extra $536.05 was included for battery charging, oxygen, and an "additional guest in room" (Swigert). A 20% "commercial discount," as well as a further 2% discount if North American were to pay in cash, reduced the total to $312,421.24. North American declined payment, noting that it had ferried three previous Grumman LMs to the Moon (Apollo 10, Apollo 11 and Apollo 12) with no such reciprocal charges.
The command module shell was formerly at the Musée de l'air et de l'espace, in Paris. The interior components were removed during the investigation of the accident and reassembled into boilerplate BP-1102A, the water egress training module; and were subsequently on display at the Museum of Natural History and Science in Louisville, Kentucky, until 2000. The command module and the internal components were reassembled, and Odyssey is currently on display at the Cosmosphere in Hutchinson, Kansas.
The lunar module burned up in Earth's atmosphere on April 17, 1970, having been targeted to enter over the Pacific Ocean to reduce the possibility of contamination from a SNAP 27 radioisotope thermoelectric generator (RTG) on board. Intended to power the mission's ALSEP, the RTG survived reentry (as designed) and landed in the Tonga Trench. While it will remain radioactive for several thousand years, it does not appear to be releasing any of its 3.9 kg of radioactive plutonium-238.
A recording of the Apollo 13 S-IVB's impact on the lunar surface as detected by the Apollo 12 Passive Seismic Experiment
LM armrest on display at the Apollo/Saturn V Center in Florida
Popular culture and media
The 1974 movie Houston, We've Got a Problem, while set around the Apollo 13 incident, is a fictional drama about the crises faced by ground personnel when the emergency disrupts their work schedules and places additional stress on their lives; only a couple of news clips and a narrator's solemn voice deal with the actual problems. "Houston... We've Got a Problem" was also the title of an episode of the BBC documentary series A Life At Stake, broadcast in March 1978. This was an accurate, if simplified, reconstruction of the events.
Lovell was approached in 1991 by journalist Jeffrey Kluger about collaborating on a non-fiction account of the mission. The resultant book, Lost Moon: The Perilous Voyage of Apollo 13, was published in 1994.
The next year, in 1995, a film adaptation of the book, Apollo 13, was released, directed by Ron Howard and starring Tom Hanks as Lovell, Bill Paxton as Haise, Kevin Bacon as Swigert, Gary Sinise as Mattingly, Ed Harris as flight director Gene Kranz, and Kathleen Quinlan as Marilyn Lovell. James Lovell, Eugene Kranz, and other principals have stated that this film depicted the events of the mission with reasonable accuracy, given that some dramatic license was taken. For example, the film changes the tense of Lovell's famous follow-up to Swigert's original words from, "Houston, we've had a problem", to "Houston, we have a problem". The film also invented the phrase "Failure is not an option". The film was nominated for several Academy Awards, including Best Picture, Best Supporting Actor (Harris) and Best Supporting Actress (Quinlan).
In the 1998 miniseries From the Earth to the Moon, co-produced by Hanks and Howard, the mission is dramatized in the episode "We Interrupt This Program". Rather than showing the incident from the crew's perspective as in the Apollo 13 feature film, it is instead presented from an Earth-bound perspective of television reporters competing for coverage of the event.
In 2008, an interactive theatrical show titled Apollo 13: Mission Control premiered at BATS Theatre in Wellington, New Zealand. The production faithfully recreated the mission control consoles and audience members became part of the storyline. The show also featured a "guest" astronaut each night: a member of the public who suited up and amongst other duties, stirred the oxygen tanks and said the line "Houston, we've had a problem." This "replacement" astronaut was a nod to Jack Swigert, who replaced Ken Mattingly shortly before the launch in 1970. The production toured to other cities extensively in New Zealand and Australia in 2010–2011. The production was scheduled to travel to the US in 2012.
In the DC's Legends of Tomorrow episode "Moonshot", the oxygen tank explosion is averted when Eobard Thawne disguises himself as Swigert, in order to retrieve a piece of the Spear of Destiny that was hidden in the pole section of the American flag planted on July 21, 1969. Thawne and Ray Palmer crash land the lander on the Moon's surface.
In November 2011, a notebook containing a checklist Lovell used to calculate a trajectory to get the damaged spacecraft, Apollo 13, back to Earth, and handwritten calculations by Lovell, was auctioned off by Heritage Auctions for $388,375. NASA made an email inquiry asking Heritage if Lovell had clear title to the notebook, stating that NASA had "nothing to indicate" the agency had ever transferred ownership of the checklist to Lovell. In January 2012, Heritage stated that the sale had been placed on hold after NASA launched an investigation into whether it was the astronaut's property to sell.
This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration.
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