With the celebration of the anniversary of the Apollo 13 mission, there have been many stories published about the efforts to return the crew back home following the oxygen tank explosion in the Service Module which deprived them of their primary source of oxygen and power. While these stories have largely focused on the accident and its aftermath, what about the original mission of America’s third attempt to land on the Moon?

The Mission Crew & Hardware

Building on the experience of the previous two lunar landing missions, the main objectives of Apollo 13 were:

Inspect, survey and sample material from a preselected lunar landing site

Deploy an ALSEP (Apollo Lunar Science Experiments Package)

Further develop capabilities to work in the lunar environment

Obtain orbital photography of potential future Apollo landing sites

NASA officially announced the crew of the Apollo 13 mission on August 9, 1969. The primary crew consisted of US Navy Captain James A. Lovell, Jr. as the Commander, US Navy Lt. Commander Thomas K. Mattingly II as the Command Module Pilot (CMP) and civilian Fred W. Haise, Jr. as Lunar Module Pilot (LMP). Jim Lovell, 42 years of age, was an Annapolis graduate who had an impressive military career as a pilot and instructor before being selected with the second group of NASA astronauts in September 1962. Lovell had previously flown as the pilot on the Gemini 7 mission in December 1965 (see “Gemini 7: Two Weeks in the Front Seat of a Volkswagen”), the command pilot on Gemini 12 flown in November 1966 (see “The Grand Finale: The Mission of Gemini 12”) and as the CMP on the Apollo 8 mission to orbit the Moon in December 1968 (see “Apollo 8: Where No One Has Gone Before”). At this point, Lovell held the cumulative spaceflight record with almost 24 days logged in space. The Apollo 13 mission would make Jim Lovell the first person to fly into space four times and to the Moon twice. Lovell’s last assignment was as the backup Commander of the Apollo 11 mission.

Ken Mattingly, 34 years old, was a carrier-based fighter pilot before being selected as part of NASA’s fifth astronaut group in April 1966. He had yet to make his first spaceflight and had previously served a backup CMP for the Apollo 11 mission. Rookie astronaut Fred Haise, 36 years of age, was a civilian test pilot for NASA before being selected as an astronaut along with Mattingly. His previous assignment was as the backup LMP for the Apollo 11 mission.

The backup Commander for the Apollo 13 mission was US Navy Captain John W. Young. Selected as part of NASA’s second astronaut group along with Lovell, Young had previously flown as the pilot of the Gemini 3 mission in March 1965 (see “The Mission of Gemini 3”), as the command pilot on Gemini 10 in July 1966 (see “Gemini 10: Dual Rendezvous in Orbit”) and as the CMP on the Apollo 10 mission to test the LM in lunar orbit in May 1969 (see “Apollo 10: The Adventure of Charlie Brown & Snoopy”). The backup CMP was 38 year old John L. Swigert, Jr. who was a civilian test pilot at North American Aviation before becoming an astronaut. The backup LMP was USAF Major Charles M. Duke, Jr.. Both Swigert and Duke had been part of NASA’s fifth astronaut group, along with Mattingly and Haise, and neither had yet to fly in space.

The launch vehicle for the Apollo 13 mission was the Saturn V designated SA-508. Aside from minor modifications based on previous flight experience, SA-508 was essentially identical the rockets used on the earlier lunar landing missions. The spacecraft assigned to the mission were CSM-109 and LM-7. For this lunar mission, CSM-109 carried a full propellant load for its SPS (Service Propulsion System) and had a launch mass of 28,790 kilograms. LM-7, with a fueled mass of 15,185 kilograms, was the heaviest LM flown to date. With a total docked mass of 43,975 kilograms, the CSM-109/LM-7 combination was the most massive crewed spacecraft ever launched until this time as well as the largest payload ever sent to the Moon (beating Apollo 12 on both counts by 69 kilograms).

In order to avoid confusion during communications while the CSM and LM were flying independently, the two spacecraft were given callsigns. CSM-109 used the callsign Odyssey, not as a reference to the classic Greek epic poem by Homer, but as an homage to Stanley Kubrick’s 1968 sci-fi classic, 2001: A Space Odyssey. LM-7 went by the callsign Aquarius after the zodiacal sign of the water carrier (as well as the title of a hit song by the Fifth Dimension from the popular counterculture musical, Hair, released in 1969).

The Mission Plan

On December 10, 1969, Apollo program managers officially selected the landing site for the Apollo 13 mission. It was located in the Fra Mauro Formation 40 kilometers north of the 95-kilometer, basalt-flooded lunar crater by the same name (which itself is named after the 15th century Italian cartographer, Fra Mauro) on the eastern edge of Oceanus Procellarum. The area was first imaged at high resolution by Lunar Orbiter 3 in February 1967 as a site of scientific interest (see “Lunar Orbiter 3: Preparing for Apollo”). The area is dominated by hummocky terrain believed to be ejecta from the giant impact event which created the 1,200-kilometer wide Imbrium Basin. Samples from this area would allow analysis of material excavated from the lower crust of the Moon and help date this key lunar nearside stratigraphic unit. While rougher than the mare landing sites for the Apollo 11 and 12 missions, exploring this region was given a high priority by lunar scientists and had been the backup landing site for the Surveyor 7 unmanned lunar landing mission in January 1968 if its primary target, Tycho, could not be reached safely (see “Surveyor 7: Mission to Tycho”).

The coordinates for the center of the Apollo 13 landing ellipse were 3.669° S, 17.451° W on a relatively flat plain 1.8 kilometers west of the 330-meter crater informally dubbed “Cone Crater”. Geologists selected this site because it provided access to a variety of geological units but they were especially interested in landing within walking distance of Cone Crater which would have punched a hole in the local strata allowing the material beneath to be sampled. Following the analysis of supplemental photography of the area acquired during the Apollo 12 mission in November 1969, the site was deemed safe enough for landing.

Given the restrictions on launch, tracking and lighting conditions, there was a single launch window available on April 11, 1970 running from 2:33 to 5:37 PM EST (19:33 to 22:37 GMT). This launch window would result in the Sun being 9.9° above the horizon at the scheduled landing time of 9:55 PM EST on April 15 (02:55 GMT on April 16), assuming an on time launch at the beginning of the window. A day earlier and the Sun would have yet to rise at the landing site but a day later, the solar elevation angle would be too high to safely observe potential hazards during landing. Unlike the previous lunar landings, Apollo 13 would not have an alternate landing site and therefore no backup launch date for that month.

In case the April launch window was missed, three launch windows on May 9, 10 and 11 existed which could support 24 or 48-hour post-scrub recycling of the countdown. The launch windows on May 10 and 11 would allow a landing with solar elevation angles of 7.8° and 18.5°, respectively. For a launch on May 9, an extra day would be spent in lunar orbit to allow a landing after local dawn.

Heading for the Moon

Launch of Apollo 13 would take place from Pad A of Launch Complex 39 at Cape Kennedy, Florida – the seventh Saturn V launch from LC-39A. The first two stages of the Saturn V along with an initial 143-second burn of its S-IVB third stage would place Apollo 13 into a temporary 190-kilometer parking orbit around the Earth. All systems of the spacecraft would then be checked out during the following two hours before the final decision to proceed to the Moon would be made. Assuming all was well, the S-IVB stage would reignite 2.6 hours after launch about halfway through its second revolution for the 351-second Trans Lunar Injection (TLI). This burn would place Apollo 13 into an extended geocentric orbit which would intercept the Moon during the outbound leg. Following TLI, the CSM would extract the LM from the S-IVB stage and move away from the spent stage for the remainder of the 75-hour trip to the Moon.

After the CSM/LM moves off, the S-IVB stage would turn and vent its residual cryogenic propellants to deflect itself further away from Apollo 13 and towards an impact on the lunar surface (unlike earlier Apollo lunar missions where the S-IVB was sent into solar orbit). The ullage engines in the S-IVB’s pair of Auxiliary Propulsion System (APS) pods could be fired about six hours after launch to fine tune its trajectory. Assuming an on-time launch, the S-IVB stage would impact the lunar surface at 7:59 PM EST on April 14 (00:59 GMT April 15) about 200 kilometers west of the Apollo 12 landing site. The impact, with the equivalent kinetic energy of one ton of TNT, would provide a seismic impulse of known location and size that could be observed using the ALSEP seismometer left by Apollo 12.

Like the earlier Apollo 12 mission, Apollo 13 would follow a hybrid trajectory to the Moon. After TLI, Apollo 13 initially would be following a free-return trajectory which would allow the spacecraft to swing around the Moon passing as close as 389 kilometers above the surface and return to Earth without any major propulsive maneuvers in case of a mission ending problem. A course correction was scheduled for 9 hours after launch to ensure that Apollo 13 was safely in this free-return trajectory. If all systems checked out, the Service Propulsion System (SPS) main engine would be used to perform a midcourse correction with a delta-v of about 4.5 meters per second at about 8:54 PM EST on April 12 (01:54 GMT on April 13) which move from the safety of the free-return path and into a new trajectory that would pass 109 kilometers above the Moon. This new course would minimize the delta-v required to enter the desired lunar orbit for landing and help optimize communications.

Assuming all went well during the coast to the Moon, Apollo 13 would perform its Lunar Orbit Insertion (LOI) burn at 7:38 PM EST on April 14 (00:38 GMT on April 15) using the SPS as the CSM/LM passed behind the Moon. The nominal 858 meter per second retrograde burn would then place Apollo 13 into an initial 106 by 311 kilometer lunar orbit. In earlier Apollo lunar missions, the SPS made a second burn after two revolutions to enter a circular 111-kilometer orbit. The next day, the LM would then perform a Descent Orbit Injection (DOI) burn following separation from the CSM which would lower the perilune to about 15 kilometers as the initial step towards landing. On the Apollo 13 mission, however, the SPS would be used for the DOI with a delta-v of 65 meters per second 4¼ hours after LOI to place the CSM/LM combination into 13 by 106 kilometer orbit. Using the SPS for this maneuver (which had ample excess delta-v capacity) instead of relying on the LM’s Descent Propulsion System (DPS) helped to increase the LM’s propellant margins during landing as well as improve navigation accuracy.

After spending the next day in lunar orbit checking out the LM, Lovell and Haise would transfer to Aquarius to ready for descent. Mattingly would then undock the CSM, Odyssey, at 5:29 PM EST (22:29 GMT) on April 15 and use a brief burn the Reaction Control System (RCS) to move off. Odyssey would now be in an equi-period orbit that would allow the two spacecraft to reach a maximum separation of 4.6 kilometers a half orbit later. If a problem developed with Aquarius, orbital motion would bring the two spacecraft back together a half orbit afterwards.

As Odyssey approached its first apolune 79 minutes after undocking, Mattingly would fire the SPS for a delta-v of 21 meters per second to enter a more circular 96 by 115 kilometer orbit where it would remain until the return of Aquarius. At 9:44 PM (02:44 GMT on April 16), Aquarius would fire its DPS to begin its powered descent as it approached perilune. If all went according to plan, the landing at Fra Mauro would take place at 9:55 PM EST (02:55 GMT).

Lunar Surface Operations

Safely on the surface, Lovell and Haise would begin a post landing checkout of the LM’s systems. Aquarius was scheduled to spend 33½ hours on the lunar surface – slightly longer than the 31½ hours Apollo 12 spent on the Moon. Considering the tight schedule, every activity was mapped out on a detailed timeline starting with a hour-long meal break followed by preparations for the first surface EVA.

The extra time Apollo 13 would spend on the surface allowed the pair of EVAs to be lengthened from a nominal 3½ hours originally planned for Apollo 12 to four hours on this mission. And like on Apollo 12, the Apollo 13 surface EVAs could be extended by up to an hour if needed provided enough consumables remained. For their EVA, Lovell and Haise would use the same A7L spacesuits they wore at launch and during other key parts of the flight. Their suits differed from the 16-kilogram intravehicular variant worn by Mattingly in lunar orbit on board Odyssey with the addition of an outer thermal micrometeoroid garment integrated with the suit to provide additional protection during the EVA.

For the EVA, the astronauts would also don lunar overshoes to provide better traction and protect their suits’ boots as well as a lunar extravehicular visor fitted with a moveable sunshade (introduced for Apollo 12) attached to their bubble-like pressure helmets to help shield the astronauts from the Sun’s rays. Life support during the EVA would be provided by the Portable Life Support System (PLSS) backpack which also supplied power, communications and cooling water. Atop of the PLSS was an Oxygen Purge System (OPS) which would provide at least a half an hour’s worth of oxygen during an emergency. The OPS could also be used if the astronauts needed to perform an EVA to return inside the CM in case of an issue during docking in lunar orbit. These spacesuits were identical to those worn by the Apollo 12 crew except for the addition of a 225-milliliter water bag inside the suit’s neck ring which the astronauts could drink from using a three-millimeter diameter straw. The complete Extravehicular Mobility Unit (EMU), as it was called, had a total mass of 83 kilograms. Lovell’s EVA suit also included red stripes below the elbows and knees to help differentiate him from Haise in images of the EVAs.

The EVAs

The first EVA would begin with the depressurization of the LM’s cabin starting at 2:13 AM EST (07:13 GMT) with Lovell scheduled to exit the spacecraft first and step foot on the Moon 16 minutes later. Like the earlier lunar landings, the EVA would be broadcast live using an improved version of the color television camera used on Apollo 12. But with these events taking place in the early morning hours in the US, there would be few people watching this EVA live. In case the color television camera was damaged as happened early during the first EVA on Apollo 12, a backup black and white camera similar to that carried by Apollo 11 was available. After Lovell familiarized himself with the environment and gathered a contingency sample, Haise would join him at about 2:40 AM EST (07:40 GMT).

The first hour or so of the EVA would be spent erecting the S-band antenna, repositioning the TV camera about 15 meters from Aquarius to record EVA activities, inspecting the LM and, at 3:17 AM EST (08:17 GMT), planting the American flag on the surface. About an hour and a half would then be spent deploying the ALSEP about 90 meters away from the LM. Similar to the one left by Apollo 12 four months earlier, the ALSEP consisted of four instruments and a central station which would radio data back to Earth after Apollo 13 left. These instruments would study charged particles, the thin lunar atmosphere, heat flow from the interior and lunar seismic activity. Power for the ALSEP would be provided by a SNAP 27 RTG (Radioisotope Thermoelectic Generator) which would convert the heat generated from the decay of its plutonium-238 fuel into 63 watts of electricity.

Following deployment of the ALSEP, Lovell and Haise would make a geologic traverse west of the LM to “Star Crater” and visit “Doublet Craters” on the return gathering samples and recording their context along the way. The total traverse distance was expected be about 1.5 kilometers. Before reentering Aquarius, Haise would deploy the Solar Wind Composition (SWC) experiment at 5:47 AM EST (10:47 GMT). Similar to the experiment flown on Apollo 11, it consisted of a 30 by 140 centimeter sheet of ultra-pure aluminum foil on a telescopic pole exposed to the Sun. Ions from the solar wind would embed themselves in the foil. Provided the EVA was not extended, Lovell and Haise would then reenter the LM and close its hatch at 6:12 AM EST (11:12 GMT) to end EVA 1. After a post-EVA checkout and debriefing, the crew would eat another meal and settle down for a well deserved 9.6-hour rest period.

At about 6:00 PM EST (23:00 GMT) on April 16, Lovell and Haise would end their rest period, eat and prepare for their second EVA. The LM cabin would be depressurized starting at 9:58 PM EST (02:58 GMT on April 17) and both astronauts would be on the surface about 22 minutes later. Once again, the EVA would be televised live during the evening hours back in the US for what would have been a larger audience back home.

The main objective for EVA 2 was to perform a 2.7-kilometer, three-hour long geologic traverse to the east of Aquarius towards Cone Crater. During this traverse, a series of sites identified by geologists from orbital photography would be visited, surface and core sample gathered, photographs taken along with other measurements. After returning to Aquarius at about 1:17 AM EST (06:17 GMT) on April 17, Lovell and Haise would work together to stow their samples and gear in the LM as well as the foil from the SWC for return to Earth. Assuming that there was no extension, the EVA would end with the closing of the LM’s hatch at 1:54 AM EST (06:54 GMT). Lovell and Haise would then stow their equipment, be debriefed and begin preparations for launch.

The Return Home

About 5½ hours after the scheduled end of the second EVA, the LM ascent stage’s Ascent Propulsion System (APS) would be ignited to liftoff from the descent stage at 7:22 AM EST (12:22 GMT) on April 17. The planned 7-minute, 8-second burn of the APS would place Aquarius’ ascent stage into an initial 17 by 81 kilometer orbit about 494 kilometers behind and 94 kilometers below Odyssey. Over the next 3½ hours as the distance between the two spacecraft begins to close, Aquarius would use its RCS engines to perform a series of maneuvers to raise its orbit and rendezvous with the Odyssey. Docking would take place at 10:58 AM EST (15:58 GMT).

Following the transfer of the crew, an expected 43 kilograms of lunar samples and other equipment to the LM over the next 2⅓ hours, the ascent stage would be jettisoned leaving Odyssey to fly solo for the balance of the mission. The unmanned ascent stage would then be deorbited by remote control and targeted for an impact on the lunar surface at 3:13 PM EST (20:13 GMT) 67.6 kilometers west northwest from the Apollo 13 landing site as a further test of the just-deployed ALSEP seismometer.

One of mission’s objectives was to photograph potential future Apollo landing sites and other targets of scientific interest. While this task had been performed during earlier Apollo lunar missions using one of the 70 mm Hasselblad 500-series cameras used to document the flights, a special 29-kilogram Hycon lunar topographic camera (LTC) was carried for this job for the first time. Using 4.5-inch, large format photographic film, LTC could resolve objects as small as 5 to 8 meters from an altitude of 111 kilometers or as small as 1 to 1½ meters during low perilune overpasses at 13 kilometer altitude.

One of the targets of interest, the fresh four-kilometer crater Censorinus, would be photographed from Odyssey’s initial orbit. At 12:26 AM EST (05:26 GMT) on April 18, the SPS would be fired for an out-of-plane delta-v of 251 meters per second to rotate Odyssey’s orbital plane by 8.8° and increase the orbit inclination to 11.4° (actually, since Apollo 13 was in a retrograde orbit, the inclination would have been decreased to 168.6°). From this new orbit, Davy Rille and Descartes (which would be the future landing site of the Apollo 16 mission) could be photographed using the LTC for evaluation.

With all their tasks completed, Trans Earth Injection (TEI) would take place at 1:42 PM EST (18:42 GMT) on April 18. The burn, with a delta-v of 959 meters per second, would allow the CSM to break free of the Moon and set on a trajectory towards the Earth with a 73½-hour transit time. During the coast back home, up to three mid-course maneuvers would be made to ensure that Apollo was headed for its narrow entry corridor. At 2:47 PM EST (19:47 GMT) on April 21, the SM would be jettisoned in preparation for the start of reentry 16 minutes later. After reentry and the deployment of the parachutes, the CM would splashdown at 3:17 PM EST (20:17 GMT) in the central Pacific Ocean at 1.6° S, 157.5° W where the primary recovery ship, the aircraft carrier USS Iwo Jima, would be waiting. Assuming an on time launch on April 11, the total mission length would be 10 days, 1 hour and 4 minutes.

Alternate Mission Plans

Like the earlier Apollo missions, there were a number of abort options and potential alternate mission plans available if problems were encountered. If there was a problem with the CSM upon reaching parking orbit that required an immediate return, Odyssey would separate from the S-IVB and use its SPS or, if the SPS was not functioning, the RCS to deorbit and return to Earth. If a problem with the S-IVB stage or other issue prevented Apollo 13 from going to the Moon but the CSM was otherwise functional, an alternate Earth orbital mission would be flown. Odyssey would dock with Aquarius and extract it from the S-IVB stage. The crew would then enter the LM to retrieve cameras then deorbit Aquarius over the Pacific to minimize the threat of debris or the SNAP-27 RTG it was carrying (which was designed to survive reentry intact avoiding the spread of the dangerous plutonium-238 fuel into the environment). Odyssey would then use the SPS for a plane-change maneuver which would raise the inclination to 40° to support an Earth photography mission.

A number of abort options also existed during the coast to the Moon following TLI. If a return to Earth was required and the CSM was still functional, the LM would be jettisoned and the SPS would then be used to set a course for a return back to Earth. If there were problems with the SM, the LM could remain attached to the CSM and act as a lifeboat with the LM’s DPS used to perform maneuvers needed for a return home.

If problems were encountered approaching the Moon or once in lunar orbit, Apollo 13 would jettison the LM to clear the view from the CM windows and perform a photographic mission. As in the primary mission, targets like Censorinus, Davy Rille and Descartes would be photographed using the LTC for consideration as future Apollo landing sites.

Preparing for Launch

The first piece of Apollo 13 mission hardware to arrive at Kennedy Space Center (KSC) was the S-IVB-508 stage of the SA-508 launch vehicle on June 13, 1969. This was followed by the delivery of the S-IC-8 first stage three days later allowing its erection on Mobile Launch Platform 3 (MLP-3) inside the Vertical Assembly Building (VAB) on June 18. On June 26, CSM-109 arrived at KSC followed by the LM-7 ascent then descent stages over the next two days. The S-II-8 second stage was delivered to KSC on June 30. After the arrival of the Instrument Unit (IU) on July 7, all the launch vehicle components had been delivered. With the addition IU-508 to the stack on August 1, the SA-508 launch vehicle was powered up to begin its long series of tests.

Meanwhile, the CSM and the LM stages were integrated on June 30 and July 15, respectively, to begin their testing. CSM-109 completed its high altitude chamber tests including procedures with both the primary and backup crews’ participation. LM-7 finished its high altitude chamber tests a month later. CSM-109 and LM-7 were integrated with SLA-16 (Spacecraft Launch Adapter #16) on December 10. The completed stack was then transferred from the VAB to LC-39A on December 15.

With the decision in January 1970 to push out the launch of Apollo 13 from March to April (partly for budgetary reasons), the pace of launch preparations eased up somewhat. On February 26, the space vehicle flight readiness test was completed. On March 18, the wet Countdown Demonstration Test (CDDT) started following the loading of RP-1 fuel into the S-IC-8 stage two days earlier. One of the issues encountered during the CDDT was with the emptying of cryogenic LOX tank #2 in the SM which provided oxygen for life support and as a reactant to the power-producing fuel cells. When the time came in the test to empty the two tanks to the 50% level, tank #2 only emptied to 92% due to an undetected displacement of the fill tube assembly caused by rough handling during construction of the tank. Eventually the decision was made to boil off the remaining LOX by running the tank’s heater. This untried procedure caused a pair of thermostatic switches to weld shut over the 8-hour operation because they were never upgraded to run on the 65 VDC ground supply in addition to the 28 VDC spacecraft power supply as specified. As a result of this failure, components in tank #2 reached temperatures as high as 540° C causing significant damage to the Teflon coating on the tank’s fan assembly wiring. This undetected damage was literally a time bomb waiting to go off.

With the completion of the CDDT on March 26, all was set for the start of the long countdown ten days later. But as the countdown started on April 5, a problem with the crew was encountered with just six days to go until launch. Backup LMP Charlie Duke had possibly contracted rubella (also known as German Measles) and then exposed the primary crew of Apollo 13 to the disease. Subsequent medical tests showed that Lovell and Haise already had immunity but not Mattingly. After much deliberation, it was decided to substitute the backup CMP, Jack Swigert, into the primary crew. This was only the second time that a crew member of an American spaceflight had been substituted with a backup (the first time was when the original primary crew for the Gemini 9 mission, Elliot See and Charles Bassett, were killed in a plane crash 2½ months before launch – see “The Angry Alligator and the Snake: The Mission of Gemini 9”). Because of his mission training in parallel with the primary crew and his professionalism, Swigert was able to quickly integrate with Lovell and Haise to everyone’s satisfaction. The mission could proceed.

Mission Aborted

At midnight EST (05:00 GMT) on April 10, 1970, the terminal countdown for launch started at the T-28 hour mark. The countdown proceeded with no unplanned holds and lifted off at the beginning of the launch window at 2:13:00 PM EST (19:13:00 GMT) on April 11. The only major problem encountered during ascent was excessive longitudinal vibration (called pogo) while under power of the S-II-8 second stage forcing a shutdown of the center J-2 engine 132 seconds earlier than planned to relieve the problem. The remaining four J-2 engines burned 34 seconds longer than originally planned before the S-IVB-508 stage ignited. With an extra nine seconds added to the burn time of this stage’s J-2 engine, Apollo 13 had made it into a 183.9 by 185.8 kilometer parking orbit – just a bit lower than planned but still well within mission requirements.

S-IVB-508 reignited for TLI at 4:48:46 PM EST (21:48:46 GMT) to send Apollo 13 on its way to the Moon. An hour and a half later, Odyssey had extracted Aquarius from S-IVB-508 and the two went their separate ways. All was going more or less as planned until late in the day of April 13 after Apollo 13 had performed its SPS burn to turn from the safety of the free-return trajectory. At 10:06:18 PM EST (03:06:18 GMT), Swigert turned on the fan in LOX tank #2 in the SM while Lovell and Haise were performing a checkout of Aquarius. Unknown to everyone at the time, a short circuit occurred inside the tank with the resulting arcing igniting the damaged fan wiring. A cascade of events followed resulting in the explosion of tank #2 after about 95 seconds. In the minutes that followed, it was discovered that the crew was in immediate danger and the Apollo 13 lunar landing was scrubbed.

The rest, as they say, is history. Odyssey was powered down while Aquarius was reconfigured to act as a lifeboat. Through the ingenuity and courage of the crew and ground teams, Lovell, Swigert and Haise made it safely back to Earth with a splashdown taking place in the Pacific four days earlier than planned at 1:07:41 PM EST (18:07:41 GMT) on April 17. While the cause of the Apollo 13 failure was being investigated, NASA placed further Apollo flights on hold. It would be left to Apollo 14 to explore Fra Mauro when flights resumed in February 1971.

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Related Video

This is a short video of Jim Lovell explaining the goals of the Apollo 13 mission before its launch.

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Here is an excellent NASA documentary on the Apollo 13 mission:

Related Reading

Articles on other Apollo missions can be found on this site’s Apollo Program page.

General References

David Baker, The History of Manned Space Flight, Crown Publishers, 1981

Alan Lawrie & Robert Godwin, Saturn V The Complete Manufacturing and Testing Records, Apogee Books, 2005

Richard W. Orloff and David M. Harland, Apollo: The Definitive Sourcebook, Springer-Praxis, 2006

Prelaunch Mission Operation Report – Apollo 13 (AS-508), NASA Office of Manned Space Flight, Report No. M-932-70-13, March 31, 1970

Apollo 13 Press Kit, NASA Press Release 70-50K, April 2, 1970