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Apollo 13

Apollo 13 was the third manned lunar-landing mission, part of Project Apollo under NASA in the United States. The crew members were Commander James A. Lovell, Command Module pilot John L. "Jack" Swigert, and Lunar Module pilot Fred W. Haise. It launched on April 11, 1970 at 13:13 CST. Two days after the launch, the Apollo spacecraft was crippled by an explosion, caused by a fault in an oxygen tank. The explosion damaged the Service Module, resulting in a loss of oxygen and electrical power. The crew used the Lunar Module as a “lifeboat” in space. The command module remained fully functional on its internal batteries, but they were needed for re-entry and landing so it was shut down shortly after the accident. Despite great hardship caused by severe constraints on power, cabin heat, and potable water, the crew successfully returned to Earth. The mission was thus called a "Successful Failure".

Crew

Number in parentheses indicates number of spaceflights by each individual prior to and including this mission.

Ken Mattingly was originally slated to be the Command Module pilot. After being exposed to rubella (German measles) a disease to which Mattingly was not immune contracted by backup Lunar Module pilot Charles Duke, Mattingly was grounded shortly before launch. He was replaced by Jack Swigert, and later flew with the Apollo 13 backup crew as CMP of Apollo 16. Mattingly never contracted rubella.

Backup crew

Support crew

Flight directors

Mission parameters

Oxygen tank leak

Closest approach to Moon

Mission highlights

The Apollo 13 mission was scheduled to explore the Fra Mauro formation, or Fra Mauro highlands, named after the 80-kilometer-diameter Fra Mauro crater, located within it. It is a widespread, hilly geological (or more properly, selenological) area covering large portions of the lunar surface around Mare Imbrium, and is thought to be composed of ejecta from the impact which formed the mare. With the failure of the mission, the flight to Fra Mauro was done on Apollo 14.

The flight's problems began during the liftoff with a lesser-known malfunction: during the second-stage burn, the center engine shut down two minutes early. The four outer engines were run for longer than planned, to compensate for this. Engineers later discovered that this was due to dangerous pogo oscillations which might have torn the second stage apart; the engine was experiencing 68g vibrations at 16 hertz, flexing the thrust frame by . However, the oscillations caused a sensor to register excessively low average pressure, and the computer shut the engine down automatically. Smaller pogo oscillations had been seen on previous Apollo missions (and had been recognized as a potential problem from the earliest unmanned Titan-Gemini flights), but on Apollo 13 they had been amplified by an unexpected interaction with the cavitation in the turbo-pumps. Later missions included anti-pogo modifications, which had been under development since before Apollo 13. Those modifications solved the problem. They entailed (a) the addition of a helium gas reservoir in the center engine’s liquid oxygen line to dampen pressure oscillations, (b) an automatic cutoff for the center engine in case this failed, and (c) simplified propellant valves on all five second-stage engines.

Explosion

As the spacecraft was on its way to the Moon, at a distance of 321,860 kilometers (200,000 mi) from Earth, the number two oxygen tank, one of two in the Service Module (SM), exploded. (The report of the Apollo 13 review board does not refer to this incident as an "explosion", instead detailing how the oxygen tanks were designed with rupture disks and other safeties to prevent a catastrophic explosion.) Mission Control had requested that the crew stir the hydrogen and oxygen tanks to keep the contents from stratifying and interfering with tank quantity readings. The Teflon-insulated wires that powered the stirrer motor in oxygen tank 2, damaged before launch, had shorted. When energized they ignited the Teflon. The fire increased tank pressure above its nominal 1,000 PSI (7 MPa) limit and the tank failed. This was unknown at the time and the crew initially thought that a meteoroid might have struck the Lunar Module (LM).

The failure also damaged the number one oxygen tank. Its contents slowly leaked out over the next several hours, leaving the SM completely without oxygen. Because the fuel cells in the service module needed oxygen to generate electricity, the loss of all SM oxygen left only the command module's own batteries, needed for re-entry after SM jettison. These would only last about ten hours. The crew survived by turning the CM completely off and using the LM, still attached to the CSM, as a "lifeboat". This possibility had been conceived during a training simulation before the flight but had been considered an unlikely scenario. Without the LM, the accident would certainly have been fatal. The damage done to the CSM canceled the planned Moon-landing at the Fra Mauro Highlands. To return the crew to Earth as quickly and safely as possible, a pass around the Moon was made without entering orbit in a free return trajectory that used the Moon's gravity to return the spacecraft to Earth. Apollo 13 had been launched on a free-return trajectory, but to permit landing at Fra Mauro it left this trajectory earlier in the mission. Restoring it meant a significant course correction. This would normally have been a small burn with the SM service propulsion system engine, but the flight controllers did not know its condition and did not want to take the risk. Therefore the course correction was performed with the LM's descent engine, an option reached after extensive discussion on the ground. This return to a free return trajectory was made within hours of the accident. After passage around the Moon, the descent engine was fired again for a PC+2 burn (PeriCynthion + 2 hours) to speed the return. One more descent engine burn was later required for a minor course correction.

Considerable ingenuity under extreme pressure was required from both the crew and the flight controllers for the crew's safe return. Much of the world watched the developing drama on television. Because electrical power was severely limited, no more live TV broadcasts were made; TV commentators used models and animated footage as illustrations. Even voice communications were often difficult due to minimal power levels.

The major challenge was that the consumables in the LM "lifeboat" were intended only to sustain two people for two days, not three people for four days. Oxygen was the least critical consumable. Repressurizing the LM after each EVA took considerable oxygen, and with no EVAs there would be plenty for the return trip. Electrical power and especially water were the real problem. The LM was powered entirely by batteries during independent flight and by an umbilical from the CSM during translunar coast. To keep the LM life support and communication systems going until entry, the LM was powered down to the lowest levels possible. This also conserved water, an even more scarce resource, needed for drinking and to cool the LM systems by evaporation into space.

Another serious limitation was lithium hydroxide (LiOH) for removing carbon dioxide. The LM's internal stock of LiOH canisters would not support the crew until return, and the remainder was stored outdoors in the descent stage, out of reach. The CM had an adequate supply of canisters, but they were cubical while the LM canisters were cylindrical. An ad-hoc method to use the CM canisters was fabricated from available materials; the astronauts called it the "mailbox.

Low power levels (zero in the CM, bare minimums in the LM) caused the spacecraft interior to cool considerably. Water condensed in the CM, causing concern this might cause damage when it was reactivated. This turned out to be unwarranted, partly due to the extensive CM design modifications after the fire aboard Apollo 1.

As Apollo 13 neared Earth, the crew jettisoned the Service Module before the Lunar Module so pictures of the SM could be taken for later analysis. The crew reported that the access panel covering the oxygen tanks and fuel cells, extending the entire length of the SM, was missing.

The crew returned unharmed to Earth, although Haise had a serious urinary tract infection as a result of the scarcity of potable water on the damaged ship and the difficulty of urine disposal; he had allowed it to build up in his collection bag. The crew had been instructed to store urine and other waste products on board instead of dumping them into space to avoid altering the trajectory of the spacecraft. Mission Control had intended this to be temporary, but because of a misunderstanding the crew avoided urine dumps for the remainder of the mission.

Although the explosion forced the mission to be aborted, the crew was fortunate that it occurred on the first leg of the mission, when they had maximum of supplies, equipment, and power. If the explosion had occurred while in orbit around the Moon or on the return leg after the LM had been jettisoned, the crew would have had a significantly smaller probability of survival.

Ironically, the crew's lives may have been saved by another failure in the oxygen tanks. At around 46 hours and 40 minutes into the mission, the oxygen tank 2 quantity gauge went "off-scale high" (reading over 100%) and stayed there. As a result of this failure, and to assist in determining the cause, the crew was asked to perform cryo-tank stirs more often than originally planned. In the original mission plan, the stir which blew out the tank would have occurred after the lunar landing.

Cause of the accident

The explosion on Apollo 13 led to a lengthy investigation of the underlying cause. Based on detailed manufacturing records and logs of mission problems, the oxygen tank failure was tracked to a combination of multiple faults. Individually, they were not critical problems; but together they led to near disaster for Apollo 13.

Cryogens, such as liquid oxygen or liquid hydrogen, require great care in handling, and most storage containers holding them are unsealed so that pressure from expanding gas will not cause the container to fail. The Apollo’s liquid oxygen tanks were made capable of safely holding liquid oxygen at supercritical pressures for years before it evaporated, because of their design and insulation. Each tank was able to hold several hundred pounds of the highly pressurized liquid to supply the craft with oxygen, fuel for electricity, and water from the byproducts of the fuel cells. However, the very characteristics that made the tank useful made internal inspection impossible.

The tank was made of several basic components that were relevant to the accident:

  • a thermostat to control the heater within the tank, used to speed the evaporation of the liquid into gas;
  • a thermometer to determine the temperature of the heater;
  • valves and piping that were designed to allow the tank to be completely emptied of liquid, by forcing gas into the tank;
  • an interior coating of Teflon that protected the wiring from the extremely cold gas; and
  • an internal fan to stir the liquid oxygen (which will turn into a “slush” at these pressures if it is allowed to sit for a long period of time).

These were the basic design, manufacturing, and operational problems that led to the accident:

  • The thermostat was originally designed to handle the 28-volt supply that would be used in the command module. However, the specification for the tank was changed, so that it had to handle 65 volts on the launch pad. Most of the wiring was changed to handle the higher voltage, but the thermostat was not. Engineers at Saturn V subcontractor Beechcraft later admitted they knew they had put 65 volts on a line designed for only 28 volts. The tank then made it into the Apollo 13 Service Module which crippled the mission.
  • The thermometer was designed to read out at the highest operational temperature of the heater, about . As a result, higher temperatures registered at only . At the time, this was not an issue, because the thermostat was supposed to cut out at 80 °F (27 °C), making higher temperatures impossible.
  • The oxygen shelf carrying oxygen tanks no. 1 and 2 was originally destined to fly in the Apollo 10 mission. Due to potential electro-magnetic interference problems, it was removed from Apollo 10. During removal, the shelf was accelerated upwards then dropped a distance of about 2 inches (5 cm). The exterior was undamaged, but calculations of the force of the impact showed that a loosely fitting filling tube could have been displaced by this event. In addition, photographs suggested that the close-out cap on top of tank no. 2 may have hit the fuel cell shelf (installed above the oxygen shelf) during the initial upward acceleration. The report of the Apollo 13 review board considers the probability of tank damage during this incident to be "rather low".
  • For ground-testing, the tank was filled. However, when it came time to empty it, the problem with the piping was discovered. As such, the tank could not be properly emptied except by running the heater to evaporate the liquid gas. Not using this tank would have delayed the mission, and there was no alternate tank available. Lovell was aware of the decision to use the heater to evaporate the oxygen, which was calculated to take a few days at the highest operational temperature of 80 °F (27 °C).
  • However, when the heater was turned on continuously:
    • The higher 65-volt supply fused the thermostat, which was only designed to handle 28 volts.
    • This malfunction eliminated the thermostat's ability to switch off the heater, which in turn allowed the heater to keep heating up past 80 °F (27 °C), and eventually past .
    • The electrical current recorder in the power supply 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 thermometer could not register temperatures higher than 100 °F (38 °C), the monitoring equipment did not register the true temperature inside the tank -- an estimated 800 degrees Fahrenheit (430 °C). Instead of taking several days, the gas evaporated in hours.
    • The protracted high temperatures then burned off the Teflon coating, leaving the wires inside the tank exposed.
  • When the tank was refilled with oxygen, it became a bomb waiting to go off. During the "cryo stir" procedure, the electricity needed to run the fans passed through the exposed wires inside the tank, setting off sparks which led to the explosion.
  • The proximity of the two oxygen tanks exacerbated the situation. Although the remaining tank survived the explosion, its valves were damaged, allowing the oxygen within to leak out. In subsequent Apollo missions, the two oxygen tanks were situated farther apart, while a third tank was installed in an isolated location.

Mission notes

Following the established protocol for crew rotation on Apollo missions the original prime crew for Apollo 13 was the back up crew for Apollo 10 that would have seen Mercury veteran Gordon Cooper command the mission with Lovell's crew being Apollo 14 (as they were the backup crew for the historic Apollo 11 mission). Deke Slayton, the Director of Flight Crew Operations ("Chief Astronaut") bumped Cooper from the position in favor of Mercury 3 veteran Alan Shepard, who recovered from an experimental, yet successful operation to correct an inner ear disorder. In addition to Shepard's reinstatement, Cooper was also bumped due to his criticism toward the NASA management, criticisms that go back to the days of his preparation for the Mercury 9 mission that almost led to him being grounded and replaced by Shepard due to an unauthorized low-level flyby ("flathatting") of the Mercury Operations office at Cape Canaveral. In a change from the usual procedure, the prime crews of 13 and 14 were swapped, to afford Shepard more time to prepare.

Two days before the launch, backup Lunar Module pilot Charlie Duke contracted rubella (German measles) from one of his children, exposing the main crew. Although Lovell and Haise had had rubella as children, command module pilot Ken Mattingly had not, and the flight surgeons grounded him, replacing him with Swigert. This may have been a blessing in disguise for him – Mattingly never developed rubella, and later flew on Apollo 16, STS-4, and STS-51-C, retiring from both NASA and the U.S. Navy with the rank of Rear Admiral. Mattingly was also able, using the simulator, to map out a plan for the astronauts to get the module going again using the limited power supply they had left.

There was no time to properly replace the original lunar plaque on Aquarius (which bore Mattingly’s name), so Jim Lovell was given a replacement (with Swigert’s name) to put over the original plaque once they landed on the moon. However, because the lunar landing was never made, Lovell kept the plaque, which is one of the few mementos from the mission that he has on display at his home.

As a result of following the free return trajectory, the altitude of Apollo 13 over the lunar far side was approximately 100 km greater than the corresponding orbital altitude on the remaining Apollo lunar missions. This could mean an all-time altitude record for human spaceflight, not even superseded as of 2008; however, the variation in distance between Earth and the Moon, owing to the eccentricity of the Moon's orbit about Earth, is much larger than 100 km, so it is not certain whether the actual distance from Earth was greater than that of all other Apollo missions. The Guinness Book of Records listed this flight as having the absolute altitude record for a manned spacecraft, and Lovell should have received a certificate from them attesting to this record. (Lovell wrote in the book Lost Moon — later renamed Apollo 13, that apart from the plaque and a couple of other pieces of salvage, the only other item he possessed regarding the Apollo 13 mission was a letter from Charles Lindbergh.)

The splashdown point was , SE of American Samoa and 6.5 km (4 mi) from the recovery ship, USS Iwo Jima.

Superstitious people have associated the belief that 13 is an unlucky number with the mission, due to the fact that the mission began on April 11, 1970 (4/11/70, digits summing to 13) at 13:13 CST from Complex 39 (three times thirteen), the problems began on April 13, and the mission is called Apollo 13. Other coincidental appearances of the number 13 connected to the mission included the explosion occurring at 19:13 CST, and a post-flight estimate that, had the explosion occurred on the ground, repairing the damage would have cost $13 million. In a feature on the making of the Apollo 13 film, Jim Lovell pointed out that NASA has never had another spacecraft numbered 13. However, in NASA's preliminary schedule for the return to the moon, an upcoming spaceflight is to be called Orion 13.

The A7L spacesuit worn by Lovell would have been the first to feature red bands on the arms and legs of the suit, as well as on the life-support backpack and lunar EVA helmet assembly, to easily distinguish him from Haise. This was done because during the Apollo 12 mission, Mission Control personnel watching the video feed had trouble distinguishing the two astronauts while both Charles Conrad and Alan Bean had their side sunshades extended down. The red bands were a feature for the remaining Apollo flights, and are used on the Extravehicular Mobility Units worn by the astronauts of the Space Shuttle program and on the International Space Station (ISS).

The Apollo 13 mission has been called “A Successful Failure”, in that the astronauts were successfully brought home despite not landing on the moon.

The Apollo 13 Mission Operations Team was awarded the Presidential Medal of Freedom for their actions during the mission, as were the astronauts.

The Cold Cathode Gauge Experiment (CCGE), which was flown as part of the Apollo Lunar Surface Experiment Package (ALSEP) on Apollo 13, was never flown again. It was a version of the Cold Cathode Ion Gauge (CCIG) which was flown on Apollo 12, Apollo 14, and Apollo 15. The CCGE was designed as a stand-alone 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 actually 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).

Towing fees

Grumman Aerospace Corporation, the builder of the LM, issued an invoice for $312,421.24 to North American Rockwell, the builder of the CM module, for "towing" the crippled ship most of the way to the Moon and back. The invoice was drawn up as a gag following Apollo 13's successful splashdown by one of the pilots for Grumman, Sam Greenberg. He had earlier helped with the strategy for rerouting power from the LM to the crippled CM. The invoice included a 20% commercial discount, as well as a further 2% discount if North American were to pay in cash. North American politely declined payment, noting that they had ferried Grumman LMs to the Moon on three previous occasions with no such reciprocal charges.

Insignia

The Apollo 13 logo featured three flying horses of Apollo's chariot across space, the motto “Ex luna, scientia” (from the Moon, knowledge), borrowed from the U.S. Naval Academy's motto, in which Lovell was a graduate, "Ex scientia tridens," (from knowledge, sea power), and the number of the mission in Roman numerals (APOLLO XIII). It is one of two Apollo insignias (the other being that of Apollo 11) not to include the names of the crew (which was fortunate, considering that Ken Mattingly, one of the original crew members, was replaced not long before the mission began). It was designed by artist Lumen Winter, who based it on a mural he had done for the St. Regis Hotel in New York; 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 in Chicago, owned by Lovell's son.

Relics

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 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. Jim Lovell's lunar helmet is located at the Museum of Science and Industry in Chicago. The command module and the internal components were reassembled, and Odyssey is currently on display at the Kansas Cosmosphere and Space Center, 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. (Had the mission proceeded as planned, the RTG would have been used to power the Apollo Lunar Surface Experiment Package, and then remained on the Moon.) The RTG survived re-entry (as designed) and landed in the Tonga Trench. While it will remain radioactive for approximately 2,000 years, it does not appear to be releasing any of its 3.9 kg of radioactive plutonium. NASA has expressed a wish that the RTG be recovered.

Popular culture

Portions of the events surrounding the Apollo 13 mission (from the perspective of the television reporters covering the mission) are dramatized in the miniseries From the Earth to the Moon episode entitled "We Interrupt This Program".

Apollo 13, a film based on Lost Moon, Jim Lovell and Jeffrey Kluger's book about the event (since retitled Apollo 13), was released in 1995. It was directed by Ron Howard and starred Tom Hanks as Jim Lovell, Bill Paxton as Fred Haise, Kevin Bacon as Jack Swigert, Ed Harris as flight director Gene Kranz, Kathleen Quinlan as Marilyn Lovell and Gary Sinise as Ken Mattingly. Jim Lovell, Gene Kranz, and other principals have stated that this film depicted the events of the mission with reasonable accuracy, though some dramatic license was taken and some technical inaccuracies have been noted. The film is among several to misquote Lovell's famous statement, "Houston, we've had a problem. The film was a critical and box office success - later nominated for several Academy Awards including Best Picture, Best Supporting Actor (Harris) and Best Supporting Actress (Quinlan) - and engendered new interest in the history of the Apollo program and American space flight in general.

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.

The 1983 cassette tape and songbook Minus Ten and Counting: Songs of the Space Age, released by Off Centaur Productions, include a song about the mission, "The Ballad of Apollo XIII," based on the melody of "The Wreck of the Edmund Fitzgerald" by Gordon Lightfoot, new lyrics by William Warren Jr. and performed by Julia Ecklar.

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