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Apollo 13

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This article is about the Apollo mission. For the film based upon it, see Apollo 13 (film).
Apollo 13
COSPAR ID1970-029A Edit this at Wikidata
SATCAT no.04371Edit this on Wikidata
Crew
Members3, named James A. Lovell, John L. Swigert, and Fred W. Haise.
File:GPN-2000-001167.jpg

Apollo 13 was the fourth manned lunar-landing mission, part of Project Apollo under NASA in the United States. The crew members were James A. Lovell Commander, John L. "Jack" Swigert Command Module pilot, and Fred W. Haise Lunar Module pilot. The original Command Module pilot for this mission was Thomas "Ken" Mattingly but due to exposure to German measles he was replaced by his backup, Command Module pilot John L. Swigert. It launched on April 11, 1970. Two days after the launch, the Apollo spacecraft was crippled by an explosion, caused by a fault in the 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 systems remained functional, but were deactivated to preserve the vehicle's capability to reenter Earth’s atmosphere. Despite severe constraints on power, cabin heat, and potable water, the crew endured great hardship and successfully returned to Earth.

Crew

The original Command Module pilot for this mission was Thomas "Ken" Mattingly but due to exposure to German measles he was replaced by his backup, Command Module pilot John L. Swigert.

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

Flight directors

Mission parameters

Oxygen tank explosion

Closest approach to Moon

  • April 14, 1970, 00:21:00 UTC
    • 254.3 km above far side of Moon
    • 400,171 km from Earth (possibly a record distance; see Mission notes below)

Quote

Famous misquote: "Houston, we have a problem."
Actual quote: "Okay, Houston, we've had a problem here",[5] uttered by Swigert to ground. Lovell then uttered this similar phrase: "Houston, we've had a problem."

"Houston, we've had a problem"
Lovell reporting the explosion on April 13, 1970
Problems playing this file? See media help.

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 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.[6] 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 3 inches. However, the oscillations caused a sensor to register excessively low average pressure, and the computer shut the engine down automatically.[7] 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.[8] 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

Apollo 13 damaged Service Module as photographed from the Command Module after being jettisoned.

As the spacecraft was on its way to the Moon, at a distance of 321,860 kilometers (199,990 mi) from Earth, the number two oxygen tank, one of two tanks contained in the Service Module (SM), exploded. Mission Control had requested that the crew stir the oxygen tanks, a task required to prevent the oxygen ‘slush’ from stratifying. The Teflon-insulated wires that provided electricity to the stirrer motor were damaged, causing a large fire when electricity was passed through them. The fire heated the surrounding oxygen, increasing the pressure inside the tank above its nominal 1,000 PSI (7 MPa) limit, and causing the tank to explode. The cause of the explosion was unknown at the time, however, and the crew and Houston conjectured that a meteoroid had struck the SM or even the Lunar Module (LM).

This explosion caused damage to other parts of the Service Module, including, critically, the number one oxygen tank. Because the Command/Service Module (CSM) relied on the oxygen tanks to generate electricity, damage to number one tank meant that very little power was available for the spacecraft. The Command Module (CM) contained batteries for use during re-entry, after the SM was jettisoned, but these would only last about ten hours. Because this power needed to be saved for re-entry, the crew survived by using the LM, still attached to the CSM, as a "lifeboat". The LM "lifeboat" procedure had actually been created during a training simulation (in the simulator) not long before the flight of Apollo 13.[9](Lovell and Kluger 83-87)

The damage done to the CSM meant that the planned Moon-landing at the Fra Mauro Highlands had to be scrubbed. To return the crew to Earth as quickly and safely as possible, only a single pass around the Moon was made, in what is called a free return trajectory, which uses the Moon's gravity to "slingshot" the spacecraft back to Earth. To enter this trajectory, a significant course correction was required. This would normally have been a simple procedure, using the SM propulsion engine, but the flight controllers did not know exactly how much damage the service module had taken, and did not want to risk firing the main engine. Therefore the course correction was performed by firing the LM's descent engine, an option settled upon after extensive discussion among the engineers on the ground. The initial maneuver to change 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) in order to accelerate the spacecraft's return to Earth. Afterwards, only one more descent engine burn was required, for a minor course correction.

Considerable ingenuity under extreme pressure was required from both the crew and the flight controllers to work out how to jury rig the craft for the crew's safe return, with much of the world watching the developing drama on television. (Because of the severe electrical power limitations following the explosion, no live TV broadcasts were made from the craft for the remainder of the mission; network commentators used models and animated footage to illustrate their coverage).

Interior of the Lunar Module, showing the "mailbox" built to adapt the Command Module's Lithium Hydroxide canisters to fit the LM's environmental systems.

A major challenge in keeping the crew alive was that the LM "lifeboat" was only equipped to sustain two people for two days, but had to sustain three people for four days. The lithium hydroxide canisters available for the LM's carbon dioxide scrubbers would not last for all four days. The CM had an adequate supply of replacement canisters, but they were the wrong shape to fit the LM's receptacle. An adapter then had to be fabricated from materials in the spacecraft. The astronauts called it the "mailbox."[10]

As the time for re-entry into Earth's atmosphere approached, NASA took the unusual step of jettisoning the Service Module before the Lunar Module, so pictures of the SM could be taken for later analysis. When the crew saw the damaged service module, they reported that the access panel covering the oxygen tanks and fuel cells, which extended the entire length of the Module's body, had been blown off.

Due to reduced temperatures on the return leg of the mission, there was extensive water condensation in the CM. There was some fear that this condensation could seriously damage the electronics of the Command Module by causing a short circuit. Until the electronics were activated, it was impossible to know whether this would occur. The equipment worked normally when activated, however, partly due to the extensive design modifications made to the CM after the fire aboard Apollo 1.

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The crew returned unharmed to Earth, although Haise had a urinary tract infection, as a result of the scarcity of potable water on the damaged ship and the difficulty of urine disposal (the crew was instructed to store urine and other waste products on board instead of dumping them into space, to avoid altering the trajectory of the spacecraft).[11]

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 a 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.[12]

Cause of the accident

The crew of Apollo 13 onboard the USS Iwo Jima following splashdown.

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.

Supercooled gases, 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 (much like freezing water will shatter even the strongest sealed container). However, Apollo’s liquid oxygen tanks were 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 100 degrees Fahrenheit. As a result, higher temperatures registered at only 100 °F. 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.
  • During assembly, the structure carrying the tank that failed was dropped about 2 inches (5 cm). The exterior was undamaged, but the pipes that directed flow within the tank became misaligned.
  • 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 100 °F. The current recorder in the power supply showed that the heater was not cycling on and off, as it should have if the thermostat was functioning correctly, but no one noticed it at the time. Because the thermometer did 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 high temperatures 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 close 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

Two days before the launch, Charlie Duke contracted the measles from one of his children, exposing the main crew. Although Lovell and Haise had obtained the measles 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 the measles, and later flew on Apollo 16 and several Space Shuttle flights, while none of the Apollo 13 astronauts flew in space again.

Plaque that was to be attached to Aquarius

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 2007; 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 stated in the book Lost Moon that apart from the plaque and a couple of other pieces of salvage, the only other item he has, regarding this mission, was a letter from Charles Lindbergh.)

The splashdown point was 21°38′S 165°22′W / 21.633°S 165.367°W / -21.633; -165.367, 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, the seventh lunar landing is slated to be flown by 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 there was confusion by Mission Control personnel on them distinguishing the Apollo 12 landing team (before they accidentally destroyed the vidicon tube in the camera when it was exposed to direct sunlight), which had no distinguishing marks for the commander, and 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 Shuttle and ISS astronauts.

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 the only time it was flown. 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).[13]

Insignia

The Apollo 13 logo featured three flying horses of Apollo's chariot across the sky, the motto “Ex luna, scientia” (from the Moon, knowledge), 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

A view of the controls in the command module on display at the Cosmosphere.

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 2000 years, it does not appear to be releasing any of its 3.9 kg of radioactive plutonium.[14] NASA has expressed a wish that the RTG be recovered.

Depiction in fiction

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—was released in 1995. It was directed by Ron Howard and starred Tom Hanks, Bill Paxton, and Kevin Bacon as the astronauts, with Ed Harris as flight director Gene Kranz, and Kathleen Quinlan and Gary Sinise in supporting roles. Jim Lovell, Gene Krantz, 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 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. In a letter to the magazine TV Guide, astronaut Jim Lovell criticized the movie, saying it would have been safer on the stricken spaceship.

Games

Notes

  1. ^ Richard W. Orloff. "Apollo by the Numbers: A Statistical Reference (SP-4029)". NASA.
  2. ^ Ken Mattingly was originally slated to be the Command Module pilot. He was grounded shortly before launch after being exposed to rubella, a disease to which he was not immune. He was replaced by Jack Swigert, and later flew with the Apollo 13 backup crew as CMP of Apollo 16. Mattingly never contracted rubella.
  3. ^ NASA: The Flight of Apollo 13
  4. ^ NASA: The Flight of Apollo 13
  5. ^ Detailed Chronology of Events Surrounding the Apollo 13 Accident
  6. ^ Apollo 14 Launch Operations (comments on Apollo 13 pogo), Moonport: A History of Apollo Launch Facilities and Operations, NASA
  7. ^ Pogo, Jim Fenwick, Threshold - Pratt & Whitney Rocketdyne’s engineering journal of power technology, Spring 1992
  8. ^ Mitigating Pogo on Liquid-Fueled Rockets, Aerospace Corporation Crosslink magazine, Winter 2004 edition
  9. ^ Lovell, Jim, and Jeffrey Kluger. Apollo 13. Boston: Houghton Mifflin, 2000.
  10. ^ "Interior View of the Apollo 13 Lunar Module and the "Mailbox"". Jan 16, 2007.
  11. ^ Account of Apollo 13 by James Lovell, NASA website
  12. ^ "THE STIR THAT SAVED THE LIVES OF APOLLO 13's CREW", Jerry Woodfill, retrieved 27 January 2007
  13. ^ http://www.myspacemuseum.com/alsepu1.htm
  14. ^ "General Safety Considerations" (pdf lecture notes). Fusion Technology Institute, University of Wisconsin-Madison. Spring 2000.

References

Wikimedia Commons has media related to Apollo 13.
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