2.3 See also

• Splashdown

3 Quote

Famous misquote: "Houston, we have a problem"
Actual quote: "Okay, Houston, we've had a problem here" [1], uttered by Swigert to ground. Lovell then uttered this similar phrase: "Houston, we've had a problem."

4 Mission Highlights

The crew's understated radio message to Mission Control was "Okay, Houston, we've had a problem here." Within 321,860 kilometers of Earth, an oxygen tank in the service module exploded. The only solution was for the crew to cancel their planned landing, swing around the Moon and return on a trajectory back to Earth. Since their command module "Odyssey" was severely damaged, however, the three astronauts had to use the lunar module "Aquarius" as a crowded lifeboat for the return home. The four-day return trip was cold, uncomfortable, and tense. But Apollo 13 proved the program's ability to weather a major crisis and bring the crew back home safely.

4.1 Problem

As the spacecraft was on its way to the Moon, the number two oxygen tank in the Service Module exploded when Mission Control requested that the crew perform a "cryo stir", in which the oxygen "slush" is stirred to prevent it from stratifying. Faulty wires connecting to the stirrer motor caught fire when power was applied. The fire caused a pressure increase above the tank's nominal 1,000 lb/in² (7 MPa), and the tank exploded. The explosion damaged other parts of the service module, including the number 1 oxygen tank. At the time of the explosion, however, the true cause was not known, and was conjectured to be a meteor impact.

The loss of both Service Module oxygen tanks and the oxygen required to create electrical power for much of the spacecraft meant that the moon-landing mission had to be aborted; a single pass around the Moon was made and the spacecraft returned to Earth. Considerable ingenuity under extreme pressure was required from both the crew and the ground controllers to figure out how to jury-rig the craft for the crew's safe return, with much of the world watching the drama on television. Central to the survival of the crew was the use of the Lunar Module (still attached to the Command Module) as a "lifeboat". One of the major stumbling blocks in this was that the LM was equipped to sustain two people for two days, and it would now have to sustain three people for four days. The carbon dioxide filters in the LM could not handle the extra load and the CM's spare filters were the wrong shape for the LM's filter receptacle; an adapter had to be fabricated from materials in the spacecraft. The crew had to use the LM as a lifeboat because the explosion had damaged the craft's electrical systems, precluding the generation of enough power to keep the Command Module operational. The emergency batteries would only last about ten hours, and needed to be saved for reentry.

In order to accomplish a safe return to Earth, a significant course correction to place the spacecraft on a free return trajectory was required. This would normally be a simple procedure using the service module propulsion engine. However, the mission's ground 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 would have to be performed by firing the lunar module's descent engine. After extensive thought and discussion, engineers on the ground found it was possible. The descent engine was fired after passage around the Moon in order to accelerate the spacecraft's return to Earth, and once again for a minor course correction. This created concern, as the LM was designed to be fired once and permanently shut down.

Reentry in Earth's atmosphere required the unusual step of undocking and jettisoning the lunar module, which had been retained for the flight back to Earth, in addition to the separation of the damaged service module. There was some fear the reduced temperatures during the return leg would cause condensation that could seriously damage the electronics of the Command Module upon activation, but the equipment worked perfectly under the circumstances.

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. When the crew saw the damaged service module, they reported that the access panel covering the O2 tanks and fuel cells was blown off.

It was noted later that while the crew was unfortunate to have this kind of major malfunction, they were still extremely 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 occurred on the return leg after the moon landing, they likely would never have survived, especially if the LEM had already been jettisoned.

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.

Jim Lovell and Jeffrey Kluger's book about the mission, Lost Moon, was later turned into a successful movie, Apollo 13, starring Tom Hanks.

5 Mission notes

• Swigert was a replacement for Ken Mattingly, who later flew to the Moon aboard Apollo 16. Mattingly was reportedly exposed to German measles prior to the mission, and NASA officials insisted upon removing him from the flight so as not to endanger the mission. He never contracted the sickness and played a critical role in the crisis working on the simulator to help devise a means for the crew to return home safely.

• 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, as of 2004 not even superseded later, but this may well not be the case: the variation in distance between Earth and the Moon owing to the eccentricity of the Moon's orbit about Earth is much larger than this 100 km.

• The splashdown point was 21 deg 38 min S, 165 deg 22 min W, SE of American Samoa and 6.5 km (4 mi) from the recovery ship, USS Iwo Jima.

• There was another not quite so famous failure on this mission which could have been equally catastrophic. During second stage burn the center engine shut down. It was later discovered that this was due to dangerous POGO oscillations which might have torn the second stage apart. Luckily the oscillations caused a low pressure reading to register, and the computer shut the engine down automatically.

6 Insignia

The Apollo 13 logo featured three flying horses, and the motto Ex luna, scientia (from the moon, knowledge), and the name of the mission in Roman numerals.

7 Statistics

Launched: April 11, 1970 from Pad 39A

Returned: April 17, 1970

Crew members: Jim Lovell, commander; Jack Swigert, command module pilot; Fred Haise, lunar module pilot.

Command module: Odyssey

Lunar module: Aquarius

Intended lunar landing site: Fra Mauro highlands

8 Relics

The command module is currently displayed at the Kansas Cosmosphere and Space Center, Hutchinson, Kansas. It was formerly at the Musee de l'Air , Paris. The lunar module burned up in Earth's atmosphere 17 April, 1970.

Preceded by: Apollo 12

Project Apollo

Followed by: Apollo 14

9 Dramatization

• Apollo 13 - a 1995 movie directed by Ron Howard and starring, as the astronauts, Tom Hanks, Bill Paxton, and Kevin Bacon, with Ed Harris, Kathleen Quinlan , and Gary Sinise in supporting roles.

10 Board game

• Apollo 13 - a 1995 board game released by Universal Games and based on the popular 1986 space-age Monopoly variant, Solarquest.

11 External link

• Apollo 13 entry in Encyclopedia Astronautica

11.1 Reference

• NASA NSSDC Master Catalog
• APOLLO BY THE NUMBERS: A Statistical Reference by Richard W. Orloff (NASA)
• The Apollo Spacecraft: A Chronology
• Apollo Program Summary Report
• Apollo 13 Characteristics - SP-4012 NASA HISTORICAL DATA BOOK

Lunar spacecraft Human spaceflights Apollo program

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