Human Spaceflights

International Flight No. 36

Apollo 13


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Launch, orbit and landing data

Launch date:  11.04.1970
Launch time:  19:13 UTC
Launch site:  Cape Canaveral (KSC)
Launch pad:  39-A
Altitude:  184 - 186 km
Inclination:  32,55°
Landing date:  17.04.1970
Landing time:  18:07 UTC
Landing site:  21° 63' S, 165° 37' W

walkout photo

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alternate crew photo

alternate crew photo


No.   Surname Given names Position Flight No. Duration Orbits
1  Lovell  James Arthur, Jr. "Shaky"  CDR 4 5d 22h 54m  1,5 
2  Swigert  John Leonard, Jr. "Jack"  CMP 1 5d 22h 54m  1,5 
3  Haise  Fred Wallace, Jr. "Pecky"  LMP 1 5d 22h 54m  1,5 

Crew seating arrangement

1  Lovell
2  Swigert
3  Haise
1  Swigert
2  Lovell
3  Haise

Backup Crew

No.   Surname Given names Position
1  Young  John Watts  CDR
2  Swigert  John Leonard, Jr. "Jack"  CMP
3  Duke  Charles Moss, Jr. "Chuck"  LMP

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alternate crew photo


Launch from Cape Canaveral (KSC); landing in the South Pacific between New Zeeland and Samoa.

This miision was the third lunar landing attempt. The mission was aborted after rupture of service module oxygen tank.

En route to the Moon, approximately 200,000 miles (320,000 km) from Earth, Mission Control asked John Swigert to turn on the hydrogen and oxygen tank stirring fans, which were designed to destratify the cryogenic contents and increase the accuracy of their quantity readings. Approximately 93 seconds later, just under 56 hours since launch, the astronauts heard a "loud bang", accompanied by fluctuations in electrical power and firing of the attitude control thrusters. The crew initially thought that a meteoroid might have struck the Lunar Module (LM).
In fact, the number 2 oxygen tank, one of two in the Service Module (SM), had exploded. 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 pounds 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 Sector 4 outer aluminum skin panel, which as it blew off probably caused minor damage to the nearby high-gain S-band antenna used for translunar communications. Communications and telemetry to Earth were lost for 1.8 seconds, until the system automatically corrected by switching the antenna from narrow-band to wide-band mode.
Mechanical shock forced the oxygen valves closed on the number 1 and number 3 fuel cells, which left 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.
Because the fuel cells combined hydrogen and oxygen to generate electricity and water, the remaining fuel cell number 2 finally shut down and left the Command Module (CM) on limited-duration battery power. The crew was forced to shut down the CM completely and to use the LM as a "lifeboat". This 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.

The damage to the Service Module made safe return from a lunar landing impossible, so Lead Flight Director Gene Kranz aborted 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 Module Propulsion System (SPS) engine to achieve a large change in velocity. Though a successful SPS firing would have landed the crew one day earlier (at 118 hours GET), the maneuver required that the LM be jettisoned first and crew survival depended on the LM's presence during the coast back to earth, making that option "out of the question". Apollo 13 was close to entering the lunar sphere of 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. There also was concern about "the structural integrity of the Service Module", so mission planners were instructed that the SPS engine would not be used "except as a last ditch effort".
For these reasons, Kranz chose the circumlunar option, using the Moon's gravity to return the ship to Earth. However, Apollo 13 had left its initial free return trajectory earlier in the mission, as required for the planned lunar landing at Fra Mauro. Therefore, the first order of business was to re-establish the free return trajectory with a small burn of the LM descent propulsion system. 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, but this was deemed unnecessary given the rates at which consumables were being used. One more descent engine burn was later required for a minor course correction.
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 LM "lifeboat" 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 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 re-entry, 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.
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. The astronauts called the jury-rigged device "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 Thomas Mattingly and many engineers and designers, had to invent a new protocol 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 considerably. The un-powered 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.

As Apollo 13 neared Earth, the crew first jettisoned the Service Module so pictures could be taken for later analysis. It was then that the crew were surprised to see for the first time that the 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, leaving the Command Module Odyssey to begin its lone re-entry through the atmosphere. The re-entry on a lunar mission normally was accompanied by four minutes of communications blackout caused by ionization of the air around the Command Module. The possibility of heat shield damage from the O2 tank rupture heightened the tension of the blackout period, which took 33 seconds longer than normal. The crew was in good condition except for Fred 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. A misunderstanding prompted the crew to store all urine for the rest of the flight. The recovery ship was the USS Ivo Jima.

Photos / Drawings




Last update on October 05, 2012.