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Apollo 13

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This article is about the Moon mission. For the film, see Apollo 13 (film).
Apollo 13
Mission insignia
Apollo 13 insignia
Mission statistics
Mission name: Apollo 13
Call sign: Command module: Odyssey
Lunar module: Aquarius
Number of
crew: 		3
Launch: April 11, 1970
19:13:00 UTC
Kennedy Space Center
LC 39A
Lunar flyby:
(Pericynthion) 		April 15, 1970
00:21:00 UTC
254.3 km from Moon
400,171 km from Earth
Splashdown: April 17, 1970
18:07:41 UTC
21° 38' 24" S - 165° 21' 42" W

Duration: 5 d 22 h 54 min 41 s
Mass: CSM 28,945 kg;
LM 15,235 kg
Crew picture
Apollo 13 crew portrait (L-R: Lovell, Swigert, and Haise)
Apollo 13 crew portrait
(L-R: Lovell, Swigert, and Haise)
Apollo 13 Crew
Apollo 13 was the third American manned lunar landing mission, part of the Apollo program. Two days after launch, the Apollo Spacecraft was crippled by an explosion, causing the Service Module portion of the Apollo Command/Service Module to lose its 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 its capability to re-enter earth's atmosphere upon return to the earth. The crew endured difficult conditions due to severe constraints on power, cabin heat, and drinkable water, but successfully returned to Earth.

Contents

Crew

Backup Crew

Support crew

Changes

Ken Mattingly, who was slated to be command module pilot, was grounded shortly before launch due to exposure to Rubella, which he was not immune to (yet never ended up contracting). He was replaced by John Swigert, for Apollo 13 and he later flew with Young and Duke (Apollo 13 back-up crew) as command module pilot on Apollo 16.

Mission parameters

Oxygen tank explosion

Closest approach to Moon

See also

Quote

Famous misquote: "Houston, we have a problem"
Actual quote: "Okay, Houston, we've had a problem here" [Detailed Chronology of Events Surrounding the Apollo 13 Accident], uttered by Swigert to ground. Lovell then uttered this similar phrase: "Houston, we've had a problem."

Mission highlights

The Apollo 13 mission began 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.[Apollo 14 Launch Operations (comments on Apollo 13 pogo)], Moonport: A History of Apollo Launch Facilities and Operations, NASA 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. Luckily the oscillations caused a sensor to register excessively low average pressure, and the computer shut the engine down automatically. [Pogo], Jim Fenwick, Threshold - Pratt & Whitney Rocketdyne's engineering journal of power technology, Spring 1992 Smaller pogo oscillations had been seen on previous Apollo missions (and had been recognised 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 turbopumps.[Mitigating Pogo on Liquid-Fueled Rockets], Aerospace Corporation Crosslink magazine, Winter 2004 edition Later missions had anti-pogo modifications, which had already been under development since before Apollo 13, and which solved the problem. The modifications were the addition of a helium gas reservoir in the center engine's liquid oxygen line to dampen pressure oscillations in the line, plus an automatic cutoff for the center engine in case this failed and simplified propellant valves on all five second stage engines.

Problem

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 in the Service Module (SM) exploded. Mission Control requested that the crew stir the oxygen tanks, a task required to prevent the oxygen "slush" from stratifying. Damaged Teflon-insulated electrical wires powering the stirrer motor caught fire when power was applied. The fire caused a pressure increase above the tank's nominal 1,000 Psi (7 MPa), causing the tank to explode. The true cause of the explosion was unknown at the time. One conjecture was that a meteoroid had impacted the SM or even the LM.

This explosion damaged other parts of the service module, primarily the number one oxygen tank. As a result the Command/Service Modules (CSM) lost its entire oxygen supply. The oxygen in the service module was required to create electrical power for the CSM, meaning that after the explosion very little power was available for the spacecraft. The Command Module (CM) contained batteries for use during re-entry, after the Service Module 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 Lunar Excursion Module (LEM) - still attached to the CSM - as a "lifeboat". The LEM "lifeboat" procedure had actually been worked on/created during a training simulation (in the simulator) not long before the flight of Apollo 13.Lovell, Jim, and Jeffrey Kluger. Apollo 13. Boston: Houghton Mifflin, 2000.(Lovell and Kluger 83-87)

Apollo 13 damaged Service Module (NASA)
Enlarge
Apollo 13 damaged Service Module (NASA)

The damage to the CSM meant that the Moon-landing at the Fra Mauro Highlands had to be abandoned. To return the crew 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 effectively "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 service module propulsion engine. However, the flight controllers did not know the extent of the damage the service module had suffered, and did not want to risk firing the main engine. Instead, the course correction was performed by firing the lunar module's descent engine, an option selected after extensive discussion amongst 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 (PeriCynthion + 2 hours) burn in order to accelerate the spacecraft's return to Earth. Only one more descent engine burn was required later, 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. One of the major stumbling blocks was that the LEM "lifeboat" was only equipped to sustain two people for two days, yet it was now required to sustain three people for four days. One of the most critical problems was that the lithium hydroxide canisters available for the LEM's carbon dioxide scrubbers would not last for all four days. Although the CM had an adequate supply of replacement canisters, they were the wrong shape to fit the LEM's receptacle; an adapter had to be fabricated from materials in the spacecraft.

As re-entry to 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 Service Module's body—had been blown off.

There was some fear that the extensive water condensation in the CM, due to reduced temperatures during the return leg, might have seriously damaged the electronics of the Command Module, which would only become apparent upon activation. But the equipment worked perfectly when activated, at least partly due to the extensive design modifications made to the CM after the Apollo 1 fire.

A successful splashdown (NASA)
Enlarge
A successful splashdown (NASA)

The crew returned unharmed to Earth, although Haise had a urinary tract infection resulting from the scarcity of potable water on the damaged ship and the difficulty of disposing of urine, and had to be treated in an infirmary.

The crew were instructed to store urine and other waste products onboard instead of dumping it into space to avoid disturbing the trajectory which might have required an additional course correction.[Account of Apollo 13 by James Lovell], NASA website

While the crew was unfortunate to have this kind of major malfunction, they were lucky that it occurred on the first leg of the mission when they had a maximum of supplies, equipment, and power to use in the emergency. 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 probably not have survived.

Paradoxically, 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 were asked to perform cryo tank stirs more often than planned: in the original mission plan the stir which blew out the tank would have occurred after the lunar landing... Lovell and Haise would have walked on the Moon, but would never have walked on Earth again.

After the completion of the mission, there was a full investigation of the incident and the craft was modified to prevent future occurrences of the fault.

Cause of the accident

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

Supercooled gases such as liquid oxygen or liquid hydrogen are very difficult to handle, 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). Apollo's liquid oxygen tanks, though, 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 highly pressurized liquid gas to supply the craft with oxygen, fuel for electricity, and water from the by-products of the fuel cells. Unfortunately, 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:

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

Mission notes

Insignia

The Apollo 13 logo featured three flying horses of Apollo's chariot across the sky, and the motto Ex luna, scientia (from the Moon, knowledge), and the number of the mission in Roman numerals. It is one of two Apollo insignias (the other being Apollo 11's) not to include the names of the crew (which was fortunate, considering one of the original crew was replaced not long before the mission began). It was designed by artist Lumen Winter. He 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 a 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, 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 17 April, 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 reentry (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. [link] NASA has expressed a wish that the RTG be recovered.

Dramatization

Games

External links

References

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