User:TarkusAB/sandbox/Apollo13

Apollo 13

Framework
Landing target was 3000 feet diameter area north of the large Fra Mauro crater. This was a more difficult landing target after the pinpoint landing of Apollo 12. Scientists hoped that list location would have samples of material ejected from the cosmic collision that created the Imbrium Basin to the north.

The Lunar Module (LM), Aquarius, was named after a song from the rock musical Hair, "Aquarius/Let the Sun Shine In", a version of the song sung by a group called the 5th Dimension, became popular with the crew and control team as symbolic of the energy and momentum in the Apollo program. The lyric "This is the dawning of the Age of Aquarius" symbolized the mission as the first of a new decade and bearing more difficulty and risk. The Command Service Module (CSM) was dubbed Odyssey.

The commander for the mission was veteran astronaut Jim Lovell, who previously has experience on Gemini 7 and 12, as well as Apollo 8, the first mission to orbit the Moon. The remaining crew were rookies. The LM pilot was Fred Haise, a member of the fifth class of astronauts. The command module pilot was originally slated to be Ken Mattingly, but two days before the launch he was exposed to measles, and thus was replaced by Jack Swigert from the backup crew. The backup crew had been present during pre-mission meetings, and so were known well by the Mission Control Center (MCC) team. After a couple days of refreshing training, Swigert was ready for the mission.

The lead flight director was Gene Kranz. The other flight directors were Griffin, Frank, and Windler who were preparing to take lead responsibility in later Apollo missions. Windler and Kranz were jet fighter pilots, Griffin flew as a radar operator. Lunney was a flight dynamics officer.

Milt Windler served as launch flight director. He was previously a test director in Kraft's recovery division.

Sy Liebergot served as EECOM for Kranz. He moved up to the front line position during Apollo 8.

Launch
Liftoff occurred at 13:13 Central Daylight Time. The first stage went smoothly, and all five engines of the second stage burned smoothly for five and a half minutes, after which the center engine shut down unexpectedly. Milt's team reviewed the status of the remaining four engines to calculate new engine cutoff times and sent these to the crew. After the second stage shut down, the S-IVB stage successfully ignited and brought the astronauts into orbit. After completing a CSM orbital check-out and updating trajectory parameters, Windler have the go ahead for translunar injection. The controllers thought they had made it through the most difficult part of the mission.

Before Accident
The crew found Swigert was performing well as a stand-in for Mattingly.

For a brief period, the CSM high-gain antenna did not work in either automatic modes and needed to be positioned manually. When the crew later performed a roll maneuver, the antenna locked up.

Two days in
The crew ran a live TV broadcast which ran until just before 8:00PM Houston time. Lovell's and Haise's familiess were at mission control to watch the broadcast.

Shift handover began at mission control to Lunney's Black Team. The crew was getting prepared for a sleep period, so mission control was having the crew prepare the craft so mission control could monitor its status and not need to wake up the crew. The antenna that had previously ceased to work was working properly again suddenly. Kranz's team did not have enough time to troubleshoot the glitch, so it was left as an open item to Lunney.

The crew continued preparing for the sleep period. They terminated the commend module battery charge. During the previous sleep period, the crew had been awakened by an alarm monitoring the pressure in a hydrogen tank. Mission control decided to not reset this alarm out of concern that it may trigger again and wake up the crew. Because of this, a cryo pressure warning light stayed illuminated in the spacecraft and on Sy Liebergot's console. Sy watched the pressures from the ground when the crew slept.

Liebergot was working through another glitch. The telemetry gauge for oxygen tank 2 had been reading normal at 80% for the mission, but had gone through four rapid up/down cycles before failing and sticking at 100%, making this sensor invalid.

Electrical power was provided by mixing cryogenic oxygen and hydrogen in the three fuel cells in the service module. The reaction of mixing this oxygen and hydrogen also created water for drinking and cooling the CSM systems. The only other source of power for the command module were the three reentry batteries planned for use in the final two hours of the mission. The oxygen and hydrogen was maintained in a liquid state below -300 degrees farenheit in spherical tanks, insulated by a vacuum between the outer and inner walls. The liquids gradually changed to gas as the mission progressed.

The cryogenics were now a "thick soupy vapor" part liquid/part gas. Fans in the tanks were periodically activated by the crew at the request of mission control to stir up the mixture to allow for more precise tank quantity measurements. Heaters were also located in the tanks to raise the tank pressure, and could be activated automatically or manually by the crew.

With the oxygen pressure management being a concern, and wanting to avoid an alert during the sleep period, Liebergot requested the crew stir the tanks before the sleep period. Swigert started the stir at 55:53, and Liebergot watched his monitors to record when the stir began.

Sixteen seconds after the stir initiation, there was a spark between the wires of the heater circuit inside tank 2. This caused a rapid rise in pressure in the tank. Liebergot was preoccupied with monitoring the fuel cell currents and did not notice the oxygen flow measurements on all three fuel cells slowly fluctuating for eighteen seconds. The pressure in tank 2 continued to rise rapidly, but did not set off the high-pressure alarm because it has been disabled. It suddenly began a rapid drop, and the temperatures in the spherical tanks began to rise quickly. One minute and 53 seconds after the stir began, there was a three second telemetry data loss. When data returned, the tank 2 pressure read 19 psi, temperature +84 degrees. The normal pressure reading is 865-935 psi. Time was now 55 hours 55 minutes and 4 seconds.

MCC noticed there was a computer restart at that time. Swigert say "We have a problem". A few moments later, Lovell said "Okay, Houston, we have a problem!" Haise reported that the voltage was looking good but there was a "pretty large bang" associated with the caution and warning alerts. Controllers were relaying related problems to the flight director, and Lovell was relaying a list of warning indicators they received in the spacecraft. The data suggested an electrical glitch and Kranz thought they would be able to fix the issue and get past it, but was wrong.

It took fifteen minutes to capture the full scope of the crisis. MCC realized at this time that there would not be a lunar mission, and would need to become a mission of survival.

It appeared to MCC that they were losing oxygen and, with it, the fuel cells, the spacecraft's main source of power. If that occurred, they would lose the main propulsion system. They had never practiced for this type of incident in simulations.

The ship's crew remained calm and continued to feet meter readings and other information to MCC. MCC had no sense of the big picture. Both electrical buses were in an undervolt condition and the crew was working to restore power to the craft, independent of the control team.

At the time of the initial power problem, Gary Scott of INCO (instrumentation and communications) reported that the antenna has switched to wide beam at that exact moment. Kranz felt the ship had an electrical short caused by an antenna glitch.

Five minutes after the event, GNC Buck Willoughby reported to Kranz that he suspected the bang shook the Quad D helium valves shut, cutting off fuel to the attitude thrusters, and wanted the crew to verify they were open. This reminded Kranz of when he served as Flight Director of Apollo 9, and a pyrotechnic shock occasioned while the CSM separating from the Saturn S-IVB booster closed the fuel valves.

No pattern could be identified. Two, possibly three fuel cells were down, both oxygen tanks were depleted, and there was an attitude control problem pushing the spacecraft around. Liebergot, CapCom Jack Lousma, and Kranz worked through electrical options with the crew while the remaining controllers made occasional inputs to CapCom correcting small problems.

INCO Gary Scott recommended falling back to the less powerful but adequate Omni antennas. There are four Omni antennas on the spacecraft. Some force was pushing the spacecraft around but they didn't know what.

Kranz realized he needed to notify top management about the problem. He called and spoke with Kraft, who got out of the shower, and Kranz told him to come to mission control.

GNC and GUIDO, Willoughby and Will Fenner, had been watching the spacecraft's attitude to avoid "gimbal lock". Gimbal lock is when rings that support the spacecraft's gyroscope align in the same position, they lock, and then no one can derive usable readings from the gyroscopic platform. They would be unable to maneuver or point the spacecraft. This could be fixed by realigning the gyros to certain stars. Whenever the crew got close to gimbal lock, Willoughby told Lousma at CapCom who advised the crew to use the CSM hand controllers and attitude jets to move away from disaster.

EECOM, Liebergot, was responsible for the system's that support life, power, water, oxygen, and pressure. After about 14 minutes, the control team was still unable to stop the learking of fuel cell oxygen reactants.

The pieces of the puzzle started coming together when Lovell reported seeing that the spacecraft was venting a gas into space. Kranz realized that an oxygen tank had exploded and caused collateral damage to the cryogenics and fuel cells. Lunar mission was now NoGo, needed to just get the crew home safe.

After calculating resources, team determined the power and oxygen in CSM could keep crew alive but the LM was the only safe haven, even though it was designed to accommodate only two men for two days.

Kranz was preparing to hand over the situation to flight director Lunney's team, and take his team into a back room to start a plan to rescue the crew. Kranz's team (White Team) was the lead team, so was their responsibility to manage the crisis.

Clint Burton taking over for Sy. Ed Fendell joined Gary Scott at communications after hearing news on the radio. Together they would ensure communications stayed operational through the crisis and transfer to the LM.

Kraft arrived as the control team was starting the second phase of the power down of the CSM. They began powering up the LM at this time. Lousma told the crew to secure the command module entry oxygen system, a small oxygen bottle used during the final two hours of the mission. They would use the LM as a lifeboat.

Liebergot told Kranz that he thought they had lost fuel cells 1 and 3. Kranz believed at the time that fuel cell 2 and one of the oxygen tanks may still be salvageable.

At the time of the explosion, Apollo 13 was 200,000 miles from Earth and 45,000 miles from the surface of the Moon. They were entering a phase of the mission where the Moon's gravity becomes a stronger influence than Earth's, the "lunar sphere of influence".

Glynn was working with "the Trench" working on abort options. The team reviewed abort maneuvers three hours in the future and came up with two options, a direct abort or one looping around the Moon. The fastest direct abort would get the crew home in 34 hours. The crew would fly in front of the moon, but would jettison the LM and use all the main engine fuel. There were several options with flying around the moon, the best one of which took two days longer than the direct abort. However, they would not use the main engine and could keep the LM. The LM was only designed to hold two men for two days. Looking at the power-down checklists, the path around the moon left the team short of 36 hours of battery power.

Windler, leader of the Maroon Team, preferred the direct abort as the shortest/fastest possible path back to Earth. Lunney and Kranz disagreed, not wanting to jettison the LM as they had not nailed down the exact cause of the explosion or extent of damage. The main engine or control systems may have been damaged, so needed time to work on return procedures.

Keeping the LM buys time, jettisoning it would cut off many options, per Lunney. Kranz wrapped up the discussion, saying to hold on to the LM and take chances going around the Moon. Kranz did not trust the SCM service propulsion system, believing it may have been damaged by the explosion and they wouldn't now if it worked until trying it. The LM would buy time.

53 minutes after the explosion, the plan was becoming clear. The retreat to the LM was in progress with a trajectory path chosen, and Lunney was now in the flight director seat. Kranz signed off 1 hour and 10 minutes after the explosion, "the longest hour in [his] life".

When Kranz left the control room, the remaining cryo oxygen tank pressure was down to 100 pounds per square inch. The command module would die in under two hours. Lunney oversaw the retreat to the LM, saving resources from the CSM. After transferring the navigational data to the lunar module computer, Glynn told the crew to turn off the CSM systems and computer.

Kranz's team (the White Team, called Tiger Team by the media), assembled at 10:30 PM CDT in a back room. Along with the team were key managers from Grumman, the LM designer, and North American, the CSM designer. They were reviewing flight data to pinpoint a cause of the explosion.

The command module was the reentry vessel as it had the heat shields, but had limited electrical power. The Lunar Module would be used as a "lifeboat" with its power, life support, and propulsion, although it was designed to only support two men for two days on the lunar surface. The extent of damage to the service module was still unknown. With these pieces, Kranz's team had to build a plan to fly around the moon, perform maneuvers, and support three crewmen for over four days, then separate the pieces to follow different trajectories at reentry.

Electrical power, water, and oxygen were critical resources. These could not be stretched unless "the Trench" came up with options to speed up the return trajectory after the Moon. Return plan split into two phases: first would be to develop a maneuver to use in under 18 hours to speed up the return journey.

Kranz made Aldrich the head of building the integrated checklist for the reentry phase. John Aaron was made in charge of managing the the electrical, water and life support resources. Bill Peters was made in charge of extending the LM's support from 2 days/2men to 4 days/ 3 men.

Kranz addressed his team to work collaboratively on solutions.

Meanwhile, Lunney, in the control room, had completed the evacuation of the crew to the LM and was preparing for a maneuver to put the spacecraft on a return trajectory to Earth.

Lunney was concerned about powering down the navigational system, as he was advised by astronauts Tom Stafford and Gene Cernan of the difficulties performing an alignment while docked and using the LM optics, because sunlight reflecting off the CSM made it difficult to recognize navigational stars. The crew had also reported that they could not recognize stars due to the cloud of debris around the spacecraft. Lunney decided to keep the LM computer and display systems on until the maneuver was done, then power down after. Difficult choosing between saving electrical power or risking navigational issues.

New estimates showed 20 hours short in electrical power and 36 hours short in water.

Flight control teams shifted every eight hours.

Kranz had to decide how aggressively to return to earth after looping around the moon. Most aggressive option required jettisoning the service module, and using all the LM descent propellant. WOuld cut 24 hours. Several other options available. Griffin wanted any option with splashdown in Pacific, where we had full recovery capabilities. After ten hours since the crisis began, Lunney handed over the contorl room to Griffin. And Lunney and Kranz and now settled on maneuver options that would bring the crew back to the Pacific at 142 hours MET. This was a middle of the road option, cutting 12 hours of return journey. This option was chosen because they had doubts about crews ability to use LM navigations systems, and it gave them a greater margin of error in maneuvers, and reserved propellant for corrections if needed.

April 14

Kranz's White Team arrived and briefed the crew on the return strategy, maneuvers, consumables, etc. in the remote change they lose communication during return.

Kranz stressed that the burn start time was not critical. Already on the return path, so could NoGo burn until everyone confident. The burn maneuver was a variation to one performed on Apollo 9.

The systems controllers had been watching LM temperatures closely since started using it as a lifeboat. The teams agreed that they needed to execute a passive thermal control (PTC) maneuver before powering down LM and sending crew to sleep. A PTC is a rotisserie like maneuver that slowly spins spacecraft so sun heats all sides. This procedure of initiating the PTC had never been done in a docked configuration using the LM jets, whcih were not favorably located.

Kranz decided to do the PTC first before sleep or power down. Trying to set up PTC was "like trying to thread a needle with bad eyesight." After 40 minutes, fired thrusters to start roll, and it started wobbling within minutes. They had to do it again. The second spin-up worked, and then they initiated complete power down of spacecraft. Now 26 hours after explosion. Crew could now sleep.

Aaron's plan had the crew powering down to a 12 amp load (about a quarter of the power consumed by a household vacuum cleaner). This power down would make the spacecraft and crew very cold. Still tight on water with plan. Plan was if ran out of LM water, use waste water and urine for cooling if needed.

The crew's breathing was slowly poisoning the atmosphere in the cabin with carbon dioxide. Ran out of cylindrical lithium hydroxide air scrubbers used in the LM, and so the engineering team developed an adapter for the square command module canisters. It was built from cardboard, duct tape, a plastic bag, a sock, a hose from a pressure suit. The hose ran down to a small fan which fulled air through the scrubber, sending it through the sock which served as a filter.

Several men got to work in the SPAN (spacecraft analysis) room to solve many problems. Including Aaron Cohen and Owen Morris (NASA spacecraft program chiefs), Dale Myers from North American, and Tom Kelly from Grumman, engineers Don Arabian and Scott Simpkinson.

The low LM water available for cooling dictated the low power levels. As a result, the team soon realized they could make it home on LM battery power, and they would have some battery power to spare to recharge the command module batters. The three CM batteries would be the sole power source for the final hours of reentry. Since some of the battery power had been used in the moments following the CSM explosion, Aaron wanted to find a way to charge them back to maximum capacity. Both spacecraft were never designed for a need to charge the CM batters from the LM, so controllers began looking at ways to use the LM heater cable in the reverse direction to charge the batteries for the final entry phase.

Aaron decided to charge the CSM batteries, but first wanted to test the set up to verify procedures and measure the power loss from charging. SPAN set up a test rig to prove the procedure. Astronauts tested the entry procedures in simulators.

Crew was cold, tired, and dehydrated. This would affect their cognitive and motor responses.

It was now in the final 36 hours, reviewing plan. LM would provide attitude control until jettisoned, then control would switch th CM. Without heat since the explosion, the CM thrusters were cold and the propellant valves sluggish. GNC officer Buck WIlloughby wanted a "hot fire" test to make sure they were working before separating from LM. They added this to the plan.

Lovell starting to ask for specifics, showing his exasperation.

April 16

Vance Brand began the final read up of procedures 18 hours prior to entry. He had started a half hour earlier, but had to stop when they realized they needed to make copies of the procedures for the other controllers. The read up was completed 6 and a half hours before the entry procedures were to start.

With a surplus of power now, Windler ordered to start up power two hours early to get heat into the spacecraft to help the crew warm up.

April 17

Had to run a final maneuver to get back on return trajectory.

A few hours before reentry, the crew jettisoned off the SM. They were able to observe the damage to the module as it floated away.

Kranz concerned about potential damage to heat shields, but nothing could be done about it now.

Blackout, cannot communicate with crew. Intense heat prevents comms. The aerodynamic braking slowed the CM down from five miles a second to under 100 miles per hour.

Blackout time was predicted, when it hit zero, Kranz asked Joe to call. No response. 1:28 past expected acquisition time when a aircraft reported acquisition. Relief in the room, then relief again when they hear voice from 13. Then relief again when they see chutes on TV.

Accident
Treating two docked spacecraft as one system was one of the most important lessons learned in Gemini 8 and was important to how problems with Apollo 13 were approached.

Aftermath
Day following landing, Kranz and other flight directors received Presidential Medal of Freedom on behalf of the mission operations teams, from Nixon.

Two weeks later, May 1, FLight directors and wives flew to Chicago fro luncheon and ticket-tape parade. Lovell awarded the city's Medal of Merit and everyone given key to Chicago by Mayor Richard Daley. Rest of crew there too, except Fred Haise, still recovering from Flight.

Investigation
There was a design flaw in the heater circuit for the cryogenic tanks. During pre-launch testing, the heater thermostat switch closed and, due to the flaw, the Teflon insulation on the wiring was damaged. Before the mission, the bare copper wires in the tank's electrical system were serviced by submerging them in liquid oxygen. Two days after liftoff, there was enough gaseous oxygen that could create an explosion, and the damaged insulation made it possible for a spark to initiate an explosion.

Apollo 13 debriefing. Learned that the tank failure was due to a combination of a design flaw, mishandling during change-out, a draining procedure after a test that damaged the heater circuit, and a poor selection of the telemetry measurement range for the heater temperatures.

No more missions in 1970. Downtime needed to redesign service module.

Lovell, Kluger
Prologue

If the crew had perished at the time of the accident, the spacecraft’s trajectory would have looped around the farside of the moon and back towards Earth, but it would have missed Earth by about 40,000 miles. The spacecraft would have entered a egg-shaped loop of slingshotting around the Earth and Moon permanently.

The American public was losing interest in spaceflight.

ABC was airing the Dick Cavett Show when Houston began sending reports to ABC correspondents about the Apollo 13 accident. They interrupted the show with a brief special report, explaining that there was an accident, the lunar landing would be aborted but the astronauts were “in no immediate danger”. Several minutes later, they were given a better prognosis and understood that the lives of the astronauts were indeed endangered.

Chapter 2

Lovell, Mattingly and Haise were named as backup crew for Apollo 11 and prime crew for Apollo 14. Apollo 13 was originally planned to be flown by Shepard, Roosa, and Edgar Mitchell. Problem was, Shepard had an innear-ear problem affecting his balance that had grounded him since his first flight in 1961. Shepard had recently underwent sugery to correct the issue, but needed more time to train before the mission. Deke Slayton asked Lovell if he wouldn’t mind trading Apollo 14 for 13 with Shepard, which Lovell obliged.

Chapter 3

Sy Liebergot was in charge of the Electrical and Environmental Command Console, or EECOM. He was responsible for overseeing the life-support and power systems of the command-service module.

Mission Control had gained confidence from previous missions, 4 to the moon, two of which landed on the lunar surface.

The landing spot for Apollo 13 was Fra Mauro, a mountainous region which held a potentially more interesting geological makeup of. Previous missions 11 and 12 landed in flat plain areas, the Sea of Tranquility and Ocean of Storms which held roughly the same geological material of the same age. This new unlevel region would prove a good test to the astronauts’ skills and the capabilities of the lunar module.

All of NASA’s pervious lunar missions were launched on free-return trajectories, that is, trajectories that would guarantee an automatic return trip home should the service module engine fail during their journey. Apollo 13 would not be on a free-return trajectory. This is because the crew needed to make a short burn on their trip to the moon so they could land when the angle of the sun was such that the shadows of the hills were more visible in the Fa Mauro region to make for an easier landing. WIthout the shadows, it would be difficult to distinguish geological features. This new trajectory would still ship it around the moon but it would miss Earth by around 40,000 miles.

Gene Kranz was lead flight director.

The concept of using the LEM as a lifeboat in the event of a crippled command module had been studied since the early days of the Apollo program. A few weeks before the launch of Apollo 13, Mission Control and the astronauts in their training mockups were running a simulated lunar excursion when the orbiting command module experienced a sudden depressurization. The solution the controllers devised was to have the astronauts on the moon launch with the LEM back to the command module and use the LEM as a lifeboat to return to Earth. Such a scenario occurring was considered a low probability.

American interest in the Apollo program was dropping. Two days before the scheduled launch, the New York Times made no mention of the mission. The first significant mention of the mission in the paper was the day before the flight, on page 78 with the weather.

Seven days before the mission, backup LEM pilot Charlie Duke got sick with the German measels from one of his children. He had unknowingly also exposed the rest of the backup and prime crew. Blood tests proved that all others had been exposed to the disease before and were immune to it, except Mattingly. Lovell fought to keep Mattingly on the mission, but NASA ultimately replaced him with the backup CM pilot Jack Swigert.

Lovell and Haise had become accustomed to hearing the “nuances and inflections” in Mattingly’s voice. It took the remaining days of simulator drills before NASA and the astronauts felt they could work together as good as the old prime crew.

The commemorative plaque attached on the outside of the LEM had to be milled and replaced with the change in crew.

Swigert had forgotten to file his federal income taxes. The return was due on April 15, when he would be in orbit around the moon. Swigert decided he would worry about it when he returned.

Swigert was a 38 year old bachelor, and was previously known for being the only unmarried man accepted as an astronaut by NASA.

Fred Haise, 36, youngest, former Marine pilot.

Apollo 13 launched on schedule, at 13:13 Houston time on April 11, and blasted out of Earth orbit toward moon 3 hours later.

The name of the LEM, “Aquarius”, was taken by Lovell from the Aquarius of Egyptian mythology that brought knowledge and fertility to the Nile valley. Odyssey was chosen because he liked the word and its dictionary definition. Some press erroneously reported that he took Aquarius from the musical Hair.

LEM was designed to support two men for two days.

Loss of interest. No television stations planned to air the planned live TV show broadcast from the spacecraft a couple days into the mission. Nevertheless, NASA still decided to go ahead with the show in case any stations wanted to records pieces for their later news broadcast. When Apollo 13 ran the live broadcast, only the Houston mission control center watched the program.

As Apollo 13 was running the live broadcast, the controllers were busy preparing for maneuvers and operations to be done after the broadcast.

One of these exercises, requested by EECOM LIbergot, was a stir of the cryogenic tanks, a routine operation.

The service module was equipped with two hydrogen tanks and two oxygen tanks which held the gases in a cold cryogenic state. The material inside is not solid, not liquid, not gas, but somewhere “slushily” in between.

The cryo tanks are connected to fuel cells, devices equipped with electrodes. When the oxygen and hydrogen flowed into the fuel cells, the gases would combine and produce electricity, water, and heat.

The oxygen tanks were also important because they contained breathable air for the crew.

The cryo tanks each is 26 inches in diameter, holds 320 pounds of oxygen at pressures up to 935 pounds per square inch. Inside each tank was a probe to measure gas quantity, a thermostat, a heater, and a fan. The heater would be used in case the pressure in the tank dropped too low, and the fans would be used to stir the gas, at least once a day at EECOM’s request, as the gases would stratify and the probes would get misreadings.

After 27 minutes, the broadcast was drawing to a close. As they were getting prepared to sign off, Haise activated the repress valve which jerked the spacecraft and made a sudden noise. Lovell believed that Haise was activating the valve more than necessary to mischievously scare Lovell and Swigert.

After the end of the broadcast, a yellow warning light flashed on the CM pilot’s side of the console, indicating their might (MIGHT) be a problem with the pressure in the cryogenic system. Concurrently, a corresponding alert appeared on Libergot’s console. Liebergot noticed that the alarm was from a low pressure reading in one of the hydrogen tanks. The tank had had intermittent problems for the past two days. Warnings like this were usually indicators that the tanks (all) should be stirred.

After the warnings were diagnosed, Houston radioed instructions to roll, check C4 thrusters, and stir up cryo tanks. At this time, Haise had just finished closing down the LEM and was drifting into the CM. Lovell was preparing for the thruster adjustment, and Swigert through a switch to stir all four tanks. On the ground, Libergot and his backroom team were monitoring the pressures, anticipating stabilization in hydrogen pressure.

16 seconds following the initiation of the cryo stir, a large bang shook (literally) the ship.{{sfn|Lovell, Kluger|1994|p=94}

Lovell thought this might have been Haise messing with the repress valves again, and looked at him down in the tunnel. Haise appeared frightened to Lovell and said “It wasn’t me”. Lovell looked at Swigert, who looked equally confused.

Above Swigert an amber warning light flashed, and another warning light flowed on the right side of the panel that monitored electrical systems, and a warning alarm sounded in Haise’s headphones. Swigert read the warnings and determined that there appeared to be a sudden loss of power to main bus B. Main bus B was one of two main power distribution panels that provided power to all the hardware in the CM.

Swigert said “Hey we’ve got a problem here”. Lovell said “Houston, we’ve had a problem...We’ve had a main B bus undervolt”

On the ground, Libergot and his backroom noticed their tank data readouts were abnormal. Liebergot noticed that the second O2 tank (spacecraft had two O2 tanks) was reading zero on all data. He also noticed they lost fuel cell 1 and 2. According to this data, it appeared that Odyssey was having problems with most of its power system, and half of its atmospheric system. Liebergot considered it possible to be an instrumentation problem, and potentially nothing was wrong with the fuel cells or O2 tanks. He reported to Kranz it might be an instrumentation problem and that he was examining the data.

Haise reported that the main B bus voltage was now looking good, and reported there was a “pretty large bang” associated with the warning lights.

Lovell followed by saying that they were going to button up the tunnel. All three astronauts were thinking that it was probably a meteor. Since the CM seemed to be in good shape, a meteor may had likely hit the LEM. They wanted to seal the hatch quickly to prevent any possible depressurization.

Swigert tried three times to lock the hatch but was unable to get it locked. Lovell tried a couple of times and also could not get it to lock. After this they gave up. If the spacecraft had truly been hit by a meteor, it would have been depressurized by now. They tied the hatch down elsewhere.

Now back at his instrument panel, Lovell noticed that the quantity for the O2 tank two was so high it was off the top of the scale. This was opposite of the zero read they were getting in Houston. Lovell reported this to Houston.

Technically, a problem in an O2 tank, a fuel cell, and a bus simultaneously could occur (tanks feed O2 to fuel cells, fuel cells power the bus), but it was statistically unlikely. The O2 tanks were built with the fewest number of part possible, making the likelihood of a breakdown as slim as possible. Even if one tank failed, the other tanks would be more than adequate to power all three cells. And if all three buses continued to operate, so would the busses. The probability of any one component failing was extremely low, The probability of one tank, two cells, and one bus failing was nearly impossible.

Immediately after the jolt, Bill Fenner, guidance officer (GUIDO), responsible for planning spacecraft’s trajectory, reported a “hardware reset”. This would occur when the computer onboard identified an undefined glitch and needed to set out on a data hunt to figure out the source of the problem. Hardware resets were not unexpected, but this meant that the problem was probably within the ship, rather than a meteor hitting them.

Also, after Odyssey reported the problem, INCO (instrumentation and communications officer) reported that they switched to wide beam at the time of the jolt. What this means is, at the time, the spacecraft stopped transmitting through high-gain antenna, and switched to four smaller omnidirectional antennas mounted on the SM. This seemed to indicate to Houston that an instrumentation problem was more likely. Kranz asked INCO to get the times they want to wide beam.

EECOM had doubts about the low O2 tank pressure reading they saw on their consoles. Since the ship crew had reported the bus and O2 tank read fine on their panels, why should they believe the bad data on their consoles?

Around this time, Haise noticed main bus B had crashed again on Odyssey’s on board panel. Bus A’s readings were falling too. Lovell now also noticed on the readings in front of him that the O2 tank two was now showing empty. The fuel cell readings on the panel were also now matching EECOM’s screen, two of the three cells were not outputting anything.

Swigert radios the bad news to Capcom Lousma. He reported: main bus A undervolt at about 25 and a half, main bus B is reading zip, fuel cell 1 and 3 are showing gray flags, but zip on the flows, and O2 cryo two is reading zero.

The ship was still wobbling and swaying over ten minutes after the explosion. The thrusters would fire to automatically counteract the motion and try to stabilize the ship, but the spacecraft could not settle. The rotation of the ship was important. It’s known as passive thermal control (PTC), a position and constant rotation of the ship to keep it evenly heated by the sun. Should one side get all the heat and the other side not, it could damage the ship’s equipment or skin. Lovell tried taking on manual control of the ship, but he was also unsuccessful.

Lovell looked out the left hand window and saw a thin white gassy cloud surrounding the craft. He reported the venting to Capcom. Kranz probed EECOM if something within his readings might be venting, to which he replied yes, but requested time to review the numbers.

“OK everybody let’s keep cool…”[kranz quote 56:10:45 GET, 15:52 minutes after accident]

One tank of air and one cell was enough to bring the crew around the moon and back home safe.

Lovell looked at the O2 tank one quantity to see how much margin of error it would provide them. Lovell saw that the quantity needle was below full and *visibly* dropping. Force of the leak was most likely responsible for the change in the ship’s attitude. Positive was once it was empty, Odyssey would stop oscillating. Downside was inability to sustain life.

Lovell estimated he had a couple hours before the oxygen was gone. When that O2 tank one pressure was depleted, all that would be left for air and electricity in Odyssey were the three compact batteries and a single small oxygen tank in the CM, all to be used for re-entry. Those small pieces of equipment could only run for a couple hours. At this point Odyssey, could keep the crew alive only until between midnight and 3AM Houston time. It was a little after 10pm at this time.

Aquarius was only built to sustain two people for ~45 hours it would take to descent to the surface, stay for a day and a half, then rendezvous. Only enough air and power for 45 hours, only for two men. Third person reduces that. Water was also limited. Lovell knew that from this point in space, a return to Earth would take around 100 hours.

Lovell told his crew that they will have to use Aquarius to get home.

Bob Heselmeyer, EECOM for LEM.

Wally Schirra was helping Cronkite to cover all the Apollo landings with CBS.

Schirra was whisked onto the set and made aware of the accident immediately before going on air with Cronkite.

Marilyn Lovell was made aware of the accident when she received a call from Jerry Hammack at Mission Control, after returning home from viewing the live TV broadcast.

Pete Conrad and his wife visited the Lovell house when Marilyn returned. They were also made aware of the accident at the house. Conrad helped to explain to Marilyn the problems with the spacecraft.

With the spacecraft still not able to be steadied, the crew became more cautious of hitting gimbal lock. The crew noticed this, as did mission control. GUIDO told Capcom to relay instructions to bring up a set of thrusters and advise they were getting close to gimbal lock.

Many problems still being reported. INCO reporting having trouble aligning antennas on the jerky ship, GNC advising of coming close to thermal imbalance (one side of the ship getting more sun), and EECOM’s power and oxygen problems.

EECOM Sy and his support team reviewing options. To prevent a complete shutdown of electrical system, they could connect the reentry batteries. Although these wanted to be saved for reentry, it had to be considered. Should the craft run dry of oxygen in the SM tanks, the craft would automatically begin taking O2 from the surge tank, used for reentry. Surge tank would normally compensate for fluctuations in the main two tanks during the flight, and before SM jettisoning, it would be topped off. Seeing as the SM would soon be out of Oxygen and run the surge tank dry, the only option they had was to connect the batteries briefly to power the dying busses and begin powering down the CM.

Sy recommended to Kranz to start powering down, first by a total (delta) of 10 amps. The spacecraft was pulling about 50 amps, so this was a roughly pulling the plug on 20% of the systems. Capcom relayed it to the crew, Swigert found the emergency checklist in the spacecraft and began a power down.

Kranz called in his boss Chris Kraft to Mission Control.

Tanks needed pressure of at least 100 psi, otherwise, pressure not great enough to feed fuel cells. Falling pressure of tank 1 caused the predicted use of the surge tank to begin. EECOM suggested isolating the surge tank, this was relayed up to Swigert who isolated the surge tank.

Pressure dropping at a rate of 1.7 pounds per minute. EECOM team estimated 1 hour 54 minutes of O2 remaining before critical 100 psi. Then fuel cells would be done.

Liebergot’s final alternative to slow the dropping pressure was to close the reactant valves on fuel cells 1 and 3. Perhaps the O2 leak was further downstream around there. This however, was final, no turning back from shutting reactant valves. Since mission rules required three fuel cells for lunar landing, he knew this was formal acknowledgement of mission abort.

First, Sy asked for closing react valve on fuel cell 3. This was relayed to the crew, and it was this moment that made it official for them that they would not be landing on the moon. EECOM noticed the leak was continuing, next they closed fuel cell 1 react valve, but the leak continued. (ANTHONY NOTE: I doubt this, the next team closed FC 1 reactants per flight loop recordings) Sy then told Kranz that O2 was under 300 and they better start thinking of going into the LEM.

Kranz asked TELMU and CONTROL to start determining minimum power needed in the LEM to sustain life.

Temp in CM had fallen to 58 degrees.

Capcom told crew that they were thinking of the LEM lifeboat.

As Lovell and Haise entered the LEM and started the power up procedure, Swigert started the power down procedure in the CM. They needed to power down the CM one switch or system at a time to preserve the calibration and configuration of the instruments. Around this time Glynn Lunney’s Black Team was coming into rotation to replace Kranz’s White Team. Clint Burton was EECOM to take over for Sy.

Oxygen leak rate was accelerating to 3 pounds per minute. EECOM > Flight > Capcom > Crew to make way to LEM. Swigert acknowledged that Fred and Jim were in LEM already. Swigert remained in CM to finish power down. Part of the LEM power up procedure called for the CM pilot to call off the orientation and coordinates of the guidance system to the commander in the LEM. The commander would then need to convert the computations to reflect the slightly different orientation of the LEM, and then type into the LEM’s computer. If these calculations were not made before the Odyssey lost all its power, the information would be lost forever.

Lovell, momentarily doubting his math, asked for Houston to double-check the math.

Swigert was able to finish powering down the CM and drifted down to the LEM.

Sitting flight director at the time was Glynn Lunney. While he was concerned about life support capabilities in the LEM, the more immediate concern was the ship’s trajectory.

Few ways to bring ship back home in lunar missions. One option, a direct abort, would have the crew turn the spacecraft with the tail facing the moon then fire the SPS for five minutes, changing its velocity in the opposite direction at the same speed. The alternative to this is the circumlunar abort, or free-return trajectory. The ship would loop around the moon and get a gravity assisted slingshot path back home. Advantage was it required no engine burn, no mid-course turning, but it would take longer than a direct abort. All previous lunar missions were on free-return trajectorys.

Irregular course to Fra Mauro had Apollo 13 off the slingshot route, it would miss Earth by 40,000 miles. Because Apollo 13 was not on a free return directory, the flight plan included a procedure known as a PC+2 burn. When done two hours after pericynthion (closest approach to moon backside), the craft would fire its engine to change its course enough to put it on a path to Earth.

Problem was this, all these plans required the availability of the SPS engine. The SPS was probably out of commission. If the bang that shook the ship had not destroyed the engine, the power problems would make it impossible to fire. LEM descent and ascent stage engines would need to be considered.

Tom Kelly works for Gumman, the LEM manufacturer.

At the time Kelly was in Cambridge at MIT on sabbatical (sent by Gumman) to study industrial management. Grumman crews were crewed around the country to watch LEM data during the mission. Kelly, an engineering manager, knew he’d get a call if any problems.

One of Kelly’s Grumman colleagues, Howard Wright, called Kelly, notified him of the problem. The two went to Logan to fly to (ANTHONY NOTE: I can't remember and I returned the book, either Bethpage (Grumman HQ) or Houston).

Lots of Kranz’s white team was still hovering around in the auditorium after Lunney’s black team took over.

Lunney asked TELMU to work on long term LEM consumable problems (O2, water, power). He asked Control to determine the LEM’s attitude and motion, as it would be needed before an engine burn. Asked Recovery to start identifying possible splashdown sites.

Time was of essence. Ship speed was climbing and distance increasing the closer they got to the moon. PC+2 burn would require significant planning, but would need to be down earlier in the lunar circumnavigation to use less fuel.

No one knew condition of SM. Kraft was convinced to not use SPS because all that power could collapse the SM and send the ship tumbling.

Kraft determined that using the LEM’s engine was the best bet. It would be a long time before PC+2, so Kraft wanted to fire the engine now to put the ship on a free-return trajectory, and use the PC+2 milestone opportunity to execute any maneuvers to refine trajectory or increase speed.

Kranz did not trust the SPS either. Kranz and Kraft agreed on the method above. (Was not just Kraft’s idea, both Kranz and Kraft determined this together)

Inside spacecraft, cold conditions. Hatch between LEM and CM still not sealed. Collective respiration of crew and cold temps caused condensation to build on walls.

Swigert went into the CM to get food and fill up drink bags with potable water.

Star seeing problem. The thick cloud of junk from the explosion made it difficult to see stars. In order to accurately calculate the LEM’s attitude and program it into the computer, they would need to use the alignment optical telescope (AOT). With only a 60 mile clearance between ship and moon, a small miscalculation could be fatal.

Crew determined they needed to change ship attitude to see if they could find a pocket to see stars. As they began working the reaction control system (RCS), the ship was not moving as it was supposed to. Problem was the LEM RCS was designed to work only after the ship had separated from the mothership. Because of this, the ship’s center of gravity was shifted and unfamiliar to the pilots. Lovell had to wrestle with the ship to align it.

Off-duty RETROS, FIDO, GUIDOS worked on devising a burn to bring crew home. They reviewed the block data plans first, pre-made abort plans that had all the information needed to bring the ship back home. Problem was all of these aborts presumed a healthy CSM and a LEM that could be expendable.

They devised a plan for a docked DPS burn (descent propulsion system) to get the ship on a free return trajectory. Present, Aquarius was traveling at abou 3,000 mph (4,400 feet/second). They would need to accelerate the ship by about 16 feet/second to close the gap of missing Earth and instead get splashdown. Because so far away, just a little nudge like this was enough to get ship on course. Waiting longer means burn would need to be longer.

FIDO told Lunney that they’ve devised a free-return burn plan for 61:30. After Lunney consulted with Kranz, Kraft, and others (BOb Gilruth, George Low, Deke Slayton), he asked if FIDO could do 61:00. FIDO said yes. Lunney told the room to plan for a free-return maneuver at 61:00. It was now 59:23.

Capcom paged up to the crew if they could try for 61:00 (in 37 minutes). Crew responded that they would want more time until 61:30.

Normally, the crew would have two hours for descent activation procedure, the ritual to configure the switches and circuit breakers to burn the LEM DPS. Crew would now have half that time.

Around this time, Kranz took his white team downstairs to room 210, a spare data-analysis room ro work out consumable problems. From this point forward, with the exception of recovery, Kranz’s team remained in the room. Kranz renamed his staff the Tiger team. Gold, Maroon, and Black teams would handle the console shifts.

Lunney dispatched Mattingly and John Young (backup commander) to the simulators to see if they could determine maneuvers for Lovell to try to view stars correctly. Young called in Charlie Duke, backup LEM pilot to assist on site. Tom Stafford was with Lousma at the Capcom console..

Lovell gave up trying to navigate with the stars, and would just let the computer navigate for the burn using the numbers typed into the guidance computer when Odyssey was shut down. They would just have to hope for the best with the new numbers.

Plan was that once Haise typed in the numbers, the ship would set itself to the correct attitude for the burn, then Lovell would deploy the landing gear to extend the LEM legs out of the way of the descent engine. Next, the attitude jets would burn for 7.5 seconds forward to force the descent fuel to the bottom of the tanks. After that, the engine would start burn at 10% thrust for 5 seconds automatically. Lovell would then ease forward to 40% and fire for 25 seconds. After 25 seconds, the computer would shut down the engine.

Mostly went according to plan. Engine burned 0.72 seconds longer than expected. Normally a “trim” would be required, small pulse from the jets to refine the trajectory. In this case, the burn was so accurate, no trim was needed.

Crew realized around this time the challenge. Lovell estimated splashdown at 152 hour mark, or in 91 hours. This was twice as long as the LEM was equipped to last for 2 men.

Tiger team TELMU Bob Heselmeyer began researching the consumables. O2 not a problem. More O2 than in previous LEMs. Lots of O2 needed to vent and repressurize cabin twice for two EVAs. Even with three men, there was enough O2 for more than a week.

CO2 was a concern. LEM equipped with Lithium Hydroxide cartridges which trap CO2 and filter it out of air. Ship carried 2 primary and three secondary that could be swapped in. These 5 scrubbers would work for only 53 hours total for two men. Third passenger dropped cartdige lifespan under 36 hours. CM cartridges were square, could not fit in round recepticles for LEM. Crew would asphyxiate from poisonous CO2 in air.

Electricity in short supply. Fully functional LEM ran on 55 amps of current. To conserve power, would need to lower amp consumption to 24.

Water. Water used to cool electric hardware. LEM had 338 pounds of water and consumped 6.3 pounds per hour. That rate would need to be reduced to 3.5 pounds, so electricity would need to be cut further to 17 amps. Same water was used for drinking.

Tom Kelly and Howard Wright arrive at LEM factory in Bethpage and start working with the engineers to get the crew home.

Lots of media at mission control.

Communication problems. S4B still had not hit moon. S4B communicated on same wave length as LEM. Since LEM was originally not going to be powered up until the S4B moon collision, this wasn’t thought to be a problem. But now since using LEM comm, comm was all garbled up. Also had to power down lots of comm equipment and secondary comm hardware. LEM using one antenna for comm at a time.

Flight surgeon radioed up new sleep schedules. Haise was to go to CM to sleep first. Haise tried to sleep but it was too cold and too much noise from LM.

Three PC+2 burn scenarios hashed out by Griffin and Windler, shown to Kraft and NASA heads, Gilruth, Low, Paine.

One theory was to jettison SM and make a long six minute burn, placing the craft into the Atlantic in 36 hours. Very quick. Problem was the SM was protecting the heat shield, and no one knew what would happen if heat shield was exposed. Also, accident could have put hairline crack in shield, which the cold of space could split further.

Second theory was mostly the same but a little longer, and splashed down in Pacific, more heavily trafficked than Antlantic. Still SM jettison.

Third theory, keep SM, make a shorter burn. Ends in Pacific, but 3 days from now, and only 10 hours faster than without PC+2 burn. Best plan per Griffin, but could be tough if consumables an issue.

NASA superiors agreed on the slow burn, to the pleasure of the flight directors. 850 f/s burn for 4.5 min at 79’27”, pacific splash at 142’.