It is also a big factor in the design of the Apollo architecture, as we shall cover briefly.

This nonlinearity is why rockets and spacecraft are typically not accounted in terms of liters or gallons of fuel remaining, but rather in ΔV remaining: how much more change in velocity do we have in reserve?

But the flip-side of this is that the spacecraft gets vastly lighter as it burns that fuel, while the engines remain just as powerful. This means that by the time the spacecraft is on its way to the Moon, for example, and has burned most of its fuel, that little bit of fuel left can cause, percentage-wise, an immense amount of change in spacecraft velocity.

There is one very important thing to understand about rocketry itself: the fuel is most of the weight you carry into orbit. If you want to go a bit further, you have to add some fuel. But then you also have to carry that fuel to the new, further point you wish to burn it, so you have to add even more fuel just to carry that added fuel—and so on. This game hits diminishing returns pretty quickly, and it's why the Saturn V is as incredibly gigantic as it is.

Our last note will be that nothing is ever so clean as presented here. In reality, any object orbiting anywhere in the Solar System is affected by a multitude of gravitational forces, the Earth is not actually spherical nor is its weight distributed evenly, and no burn is ever purely prograde or retrograde or plane change. Many, many factors go into actual orbital and burn calculation. For Apollo, these factors were all calculated on massive computers on the ground over the course of the mission.

These burn examples illustrate the third thing to understand, which is that much like orbits, burns can be described by two basic parameters: the point in orbit of the burn and the change in velocity (commonly referred to as ΔV). Because rocket engines do not instantaneously modify a spacecraft's speed by tens or hundreds of km/h and because it is easier to keep an eye on a clock than a position in the universe, this is more practically delivered to the astronauts and executed upon with three primary datapoints: clock time of burn, attitude of the spacecraft during the burn, and how long to burn for. (In reality, there are additional parameters for the computer's use, for checking star alignments, and other details.) These figures would be read up and written down on a pre-printed PAD form.

There are other types of burns that do different things—we'll cover just one more. Prograde and retrograde burns modify the orbit, but only within the 2D plane in 3D space that the spacecraft is already travelling within. If that plane itself needs to change, this can be done by burning orthogonally to it. But recall again our second observation, that changing our immediate path is really difficult. Changing our plane necessarily involves changing our entire path, including our immediate path. So this is really expensive to do, fuel-wise.

When you listen to the astronauts worry about small details like the particular set of thrusters they are using to point the spacecraft in different directions, it is this effect that they are keenly aware of—particularly with a close approach to the Moon coming up.

The final example ( figure 4 ) demonstrates just how profoundly small changes in velocity can affect the orbit. From an orbit that just reaches the Moon, we'll decelerate by a mere 20m/s—not even highway car speed. It may not look like much on this extreme scale, but that small change is the difference between passing comfortably over the surface of the Earth by a margin of ~1,200,000km (~740,000mi) and smashing into the Earth while trying to pass ~270,000km (~168,000mi) below its surface.

We can invert this effect by turning around so that instead our engines point in the direction of our travel, and burning. This is called a retrograde burn ( figure 3 ).

It doesn't matter much today, but this is known as a prograde burn. Of course, if we wanted to go to the Moon, we'd want to do exactly the same thing but on the other side of Earth.

That was more interesting. By burning in the same direction as our travel, we modified the opposite side of our orbit by moving it outwards significantly. Remember again: we can change the shape of our orbit by changing our speed, but most changes we can make don't really have much effect on our immediate local path. So all that change goes elsewhere in the orbit: in this case, to the opposite side.

Let's try working with the speed we already have, then. We'll burn exactly the same amount, just in our direction of travel ( figure 2 ).

That didn't work at all. In fact, despite going faster we are now destined to crash back into Earth. This is because we forgot about our second observation, that our burns are relatively small percentages of the spacecraft's base speed. We're not going to be able to overwhelm the momentary velocity taking us parallel to the Moon by adding a small percentage of it towards the Moon.

Instead, what a burn has far more impact on is the overall shape of the orbit. Let's try this out ( figure 1 ). On the left is a typical Apollo orbit just after launch: the numbers described just above. The orbit and planet are to scale, while the spacecraft is blown up so you can see which way it's burning. Notice how close the orbit is to the surface of the planet, despite the spacecraft being well into space. We want to go to the moon, so let's wait until we're as close as possible, point at it, and burn for a little bit. We will increase our speed by 5,400 km/h to 32,400 km/h.

The reason this is important to understand is because one must realize how little impact maneuvering or even full engine burns have on a spacecraft's immediate location or trajectory. A typical Apollo mid-course correction burn might modify its speed by somewhere between 20km/h and 150km/h: these changes are minuscule adjustments to the incredibly fast speeds described above, and have next to no impact on the spacecraft's immediate path.

The second thing to understand is just how fast orbital speed is. In Earth orbit roughly 100nm (115mi/185km) above the surface, the Apollo spacecraft would typically be travelling at over 28,000km/h (~17,500mph). Most of a rocket's launch efforts are not invested in pushing the spacecraft up, but rather in hurling it sideways.

The first thing to understand is that given any instantaneous velocity (speed and direction) and position of an object above Earth, we can definitively (with some handwaving) calculate its entire orbit. Somewhat simplistically, this follows from calculating basic Newtonian physics, such as the Universal Law of Gravitation, over time. This observation isn't terribly intuitive or informative on its own, but it helps us think about what happens when we change the two parameters involved: velocity and position. As an example, it is not possible to speed up or slow down without profoundly affecting the shape of one's orbit; this is commonly misunderstood and incorrectly depicted in popular films.

Much has been written about this popularly misunderstood and rather counterintuitive topic. We can avoid most of the details here, and instead focus on developing a basic-enough grasp to understand what is happening in these six hours.

Lastly, sometimes redundancy simply wasn't practical. The Command/Service Module had two main DC electrical buses (A and B) that circulated electricity around the spacecraft. With hundreds or thousands of total sensors and components to wire, you can imagine that sending two entire loops of wiring to every single piece of electronics was not only infeasible, it would mean a greater chance of mistakes or accidents, and a far heavier spacecraft. In some cases, this meant that some instruments or components were only available on one bus or the other. In other cases, a hybrid approach was taken: of the three Command Module inverters that converted DC to AC power, for example, the first could only pull electricity off the A bus, the second only the B bus, and the third inverter could draw from either A or B.

Another example is the Abort Guidance System (AGS) on board the Lunar Module. It served as the backup to the Apollo Guidance Computer and some of its associated sensor systems (collectively known as the Primary Guidance, Navigation, and Control System, or PGNCS), in case it failed during a landing. In that case, the landing would be called off and the focus moved to getting back to orbit and rendezvousing with the still-orbiting Command/Service Module for the trip home: a much simpler task. Thus, the AGS had far fewer features than the AGC—and simplicity is often a recipe for greater robustness. You'll hear discussion of using the less power-hungry AGS in lieu of the AGC for the trip around the Moon in the final stages of the audio recording.

The backups to the IMU, then, were known as Body Mounted Attitude Gyros, or BMAGs. There were two of them in the Command Module, and rather than turning about freely on gimbals, they were locked down rate gyros . This meant they could only measure the rate of change of orientation rather than measure the absolute orientation. This is a bit like telling how far you've driven down a highway by sampling your speedometer over time and doing some math: it ought to work, but tiny imprecisions in measurement can throw you off. A really long tape measure will give you an absolute answer with far more confidence, and so the IMU was the preferred instrument. But the BMAGs were lighter, and because no rotating gimbals were involved they were not susceptible to gimbal lock.

Both Apollo spacecraft, for example, had one primary navigational sensor: the Inertial Measurement Unit. The IMU was a big powered gyroscope that tracked orientation, much like your smartphone today can detect how it's being tilted and rotated around. The IMU gyroscope was mounted on three freely rotating gimbal axes; it's a lot like turning about while holding a compass, except instead of magnetic force it is the rotational inertia of the spinning gyro that holds the "needle" still, and instead of one axis around which to rotate there are three. This allowed it to read the spacecraft's absolute orientation relative to its static reference angle, much like you can always read your bearing relative to magnetic North on a compass. This allowed great precision and confidence, but it also created a problem state known as gimbal lock, as the three gimbals together couldn't quite follow the spacecraft across certain extreme angles.

The most robust way to deal with failure is to increase the safety factor by introducing redundant systems. Each Space Shuttle Main Engine, for example, had two computers with two processors each, and a system that would redelegate control if errant calculations were detected. But in the Apollo days, redundancy didn't always mean identical backups. Often, to save weight, money, or complexity, the redundant systems were actually entirely independent designs. Sometimes this could actually be an advantage, as different designs will have different strengths and weaknesses, and thus different failure points.

Sending humans into space is a big deal, and it's dangerous. While the basic principles and science behind many aspects of spaceflight may be independently simple, the engineering reality is that things fail. Nearly every NASA mission at this point had a major quirk or two to deal with.

There are a few other elemental concepts to understand before diving in:

While Apollo was, in aggregate, an immensely complex system comprised of countless components, miles of wiring and circuitry, and cutting-edge-for-the-time technology, we can vastly simplify our effort to understand the spacecraft by approaching it at a high level from these three fundamental problem areas. Each is covered in detail in the Overview section.

Getting to the Moon and home again involved a small number of broad, basic tasks:

Jack Lousma serves as CAPCOM throughout all available audio here. He later flew aboard the Skylab 3 mission, and commanded one of the very first Space Shuttle missions, STS-3.

CAPCOM was, with exceedingly rare exception, the only person allowed to talk directly to the crew. This allowed him to ensure the consistency, coherency, and accuracy of instructions and information transiting to and from the crew, and to translate to and from terms and descriptions more-familiar to the astronauts. The latter effort was aided by a convention that CAPCOMs were drawn from the astronaut pool.

During Kranz's shift, CONTROL was Larry Strimple. He was relieved by Hal Loden for Lunney's shift.

Where TELMU is effectively the EECOM of the Lunar Module, CONTROL is effectively the GNC. In addition to overseeing the navigation and propulsion systems during powerup and the lunar-bound correction burn following the accident, the heavy debate had by Lunney's team on maintaining platform control on a low electricity budget hinged on the navigation systems overseen by CONTROL.

Kranz's TELMU was Bob Heselmeyer, and Lunney's TELMU was Merlin Merritt.

TELMU was effectively the EECOM of the Lunar Module, responsible for many of the respective systems aboard the LM. As the Lunar Module lifeboat plan becomes increasingly real and correspondingly pressing, TELMU has to oversee an emergency startup of the LM, working with the crew on board to safely power up the spacecraft in literal record time. Later, TELMU is a key player in determining a low-power configuration that can bring the crew safely home while maintaining navigation.

The White team INCO was Alan Glines, and the Black team INCOs were Gary Scott and Ed Fendell.

INCO pipes up quite a bit in the audio to ask for antenna changes as the spacecraft attitude is somewhat out of control following the accident; INCO is also a key player and communicator in identifying and resolving the LM/S-IVB communications issues that occur midway through the Black team shift.

INCO was in change of communications for both spacecraft. These included the telemetry systems, and the various omnidirectional and steerable antennas upon each craft. In addition to managing the on-board equipment to ensure quality of signal and successful data operations, INCO worked with NETWORK and PROCEDURES to coordinate appropriate related reconfigurations of the ground-air link from both ends of the connection.

Bill Stoval is FDO for Kranz's White team, and Bill Boone and Maurice Kennedy take over at shift change.

Down in the spirited Trench of the room, FDO managed spacecraft trajectory, both present and into the future. Where GNC and CONTROL managed the propulsion and attitude control hardware and software systems of the CSM and LM, respectively, and GUIDO was in charge of their actual, immediate use, FDO worked one level above that, formulating and overseeing the navigation and maneuver plans required to deliver the spacecraft where it needed to go. FDO collaborated with a variety of people, both on and off campus, to determine and calculate the necessary orbital maneuvers required to achive mission success.

Bill Fenner and Ray Teague serve as White team GUIDO, while Gary Renick and Will Presley take over as part of Black team.

The Guidance Officer was in charge of the spacecraft position and attitude at all times, and the appropriate use of the attitude adjustment and propulsion systems to ensure smooth operations. As an example, you will hear GUIDO crop up when the spacecraft nears gimbal lock, a condition which would invalidate all available understandings of spacecraft orientation until a lengthy recalibration could be performed. You'll also hear him talk about some of the various control modes of the spacecraft that translate crew input into thruster firings.

Said appearances are made by Bill Strable, who is then relieved by Jack Kamman with Lunney's Black team.

GNC managed all of the go-there systems: the propulsion hardware, the RCS attitude thrusters, the propellant to be burned, and the navigation instruments and software, including the guidance computer. The explosion broke many things loose, jarred many valves open or shut, and knocked electrical buses offline, and so GNC makes frequent appearances in the first hour or so following the incident to try to find a combination of RCS thrusters that are trustworthy to put on the working electrical bus, and to shut down errant thrusters which were pushing the craft about or wasting power while failing to fire.

During Kranz's shift and the initial incident, you will hear EECOM Sy Liebergot, who at one early point was described as staring at his telemetry readouts with a two-handed death grip on the handles of his display. Clint Burton takes over as part of Lunney's team—he oversees most of the power-down procedure of the CSM.

As the poor sap in charge of the electrical and cryogenic gas systems that got literally blown up during Apollo 13, EECOM is the flight controller from whom you will hear the most in the early stages of diagnosis. EECOM's purview included both electrical power and life support systems, as these systems were intertwined in their reliance upon the same cryogenic gases. These systems included gas storage and distribution, the fuel cells, batteries, alternators, and electrical buses, and the various life support and regulator valves that maintained a habitable atmosphere within the spacecraft. As implied by the name, monitoring and managing the consumption of the consumable gas (and therefore electrical) resources were also EECOM's charge.

One of the tools Flight had in managing their relatively sizable team was a set of manually toggled status lights, one for each flight controller. In addition to their use during go/no go calls, Flight would often call for their use as a status indicator for various critical room-wide issues, such as shift changes and status updates.

The Flight Director was the ultimate authority during an active mission, charged with ensuring, in order, crew survival and mission success. There were actually multiple teams of flight controllers during any mission, each of which was led by its own Flight Director. You will hear from two today: Gene Kranz and Glynn Lunney. As the center of the room, both figuratively and literally, each Flight Director defined their own style of leadership and set the tone of the room. The differences between Kranz's and Lunney's styles are immediately apparent in the loop audio presented here.

Below, we review the controller positions you'll hear from most in the audio. For further information on the other equally important roles, please refer to one of the references linked above.

It is important to note that the flight controllers in the main Mission Operations Control Room (MOCR) were far from the sole engineers and problem-solvers on hand during this or any other mission. There were the Staff Support Rooms (SSRs) in which internal teams backed up each flight controller, each on their own private team audio loop, as well as the Spacecraft Analysis (SPAN) room, in which engineers and other representatives from the various private contractors that actually designed and built the components of the spacecraft were on hand to offer data and analysis. In addition, there were stations all over the world, on sea and on land, which tracked the spacecraft and in doing so provided valuable information and analysis on top of the telemetry they received. Before the time of Apollo, much of this data was not networked back to Houston, and so flight controllers would actually have to be deployed to the various remote stations to directly perform their duties on-site.

There are many fantastic, complete references on the various flight controllers, their roles, and the people involved. The Ars Technica article is a great, free place to start; the book Go, Flight! goes much deeper into the controllers' history throughout the early years of NASA. Here, we seek to provide enough information such that the real-time audio experience may be fully appreciated.

If you have feedback or questions, please don't hesitate to send me a tweet or file a GitHub issue .

Hopefully, you have not only enjoyed these six hours of audio, but as well gained a new appreciation and tactile understanding of what it was like to hurl Apollo through the heavens. If you wish to delve yet further into Apollo and spaceflight, please take a look at the further reading section.

Over the next many hours and days, many more problems need to be solved: the LiOH canisters mentioned briefly by Glynn Lunney deplete, and a makeshift adapter has to be fashioned for spares from the Command Module to be used in order to prevent a buildup of carbon dioxide; extensive resource planning is done to stretch consumables far past their designed limit; the crew deals with hypothermic conditions and dangerously scant water rations while demanding tasks continue to be required; an entirely new hours-long Command Module power-up procedure must be developed, tested, and successfully read over voice to an exhausted Jack Swigert to ensure a successful re-entry, a process that by all rights should take weeks rather than days.

Following the PC+2 past the far side of the Moon, even Aquarius would be powered down completely apart from COMM and life support, in order to conserve power. When a final midcourse correction was required after this, the infamous manual burn dramatized in the film was performed, as power could not be spared to power up the entire computer system.

After six hours of continual crisis, Apollo 13 is now safely back on a trajectory towards Earth, with a stable configuration and no immediate dangers. The Command Module is completely dark, and the crew is preparing to bring Aquarius down to a minimal state. It would eventually transpire, after some on-board experimentation with different solutions, that because of the added cost of the inverter required to keep the navigation eight-ball running, it was cheaper in total to leave the whole PGNS system running in Attitude Hold mode to prevent gimbal lock rather than having the crew watch the drift manually. For thermal control, the crew were simply instructed every so often to manually move the stack around to different attitudes.

Up Left Right Down

CAPCOM Okay FLIGHT, you read his pitch and yaw and his high-gain meter.

FLIGHT That's affirmative.

CAPCOM And now you want roll right to 060?

FLIGHT Might as well do that. And we'll try and get Comet Bennett, I'd still like the verification on the docking angle because that's what we'll be using for computation for alignments and everything else. Let's see if there's anything else.

EECOM FLIGHT, EECOM.

FLIGHT Go ahead, EECOM.

EECOM Okay, let's terminate the battery B charge at 55 +50.

FLIGHT Okay.

EECOM And at the same time, I'd sure like to have a cryo stir, all 4 tanks.

FLIGHT Let's wait until they get settled down a little more.

EECOM Roger.

GNC FLIGHT, GNC.

FLIGHT Go, GNC.

GNC They would still like to enable the other two quads for the maneuver.

FLIGHT Okay. When rolling to 060 you want them to enable C and D, right?

GNC Right.

FLIGHT Do you want them to disable A and B?

GNC No.

FLIGHT Okay. All four quads.

GNC They have a coupled jet maneuver -

FLIGHT Roger. Copy, CAPCOM?

CAPCOM Got it.

INCO FLIGHT, INCO.

FLIGHT Go, INCO.

INCO I'd like to confirm their configuration on their high-gain now.

FLIGHT Okay.

INCO I'd like to know what track mode they're in and what SERVO electronics they're in.

FLIGHT Okay, let's just standby 1 there. Now we'll C and D for roll to 060, terminate battery B charge.

FLIGHT Okay, the third thing we want up there, CAPCOM, is to verify their high-gain configuration. And I assume what you want from there is you want to know their tracking, position of track - BEAM WIDTH you don't need, do you? Do you want the whole works?

INCO Yeah, the whole works.

FLIGHT Okay.

FLIGHT CAPCOM, we want the configuration of the CSM high-gain.

INCO That's good.

FLIGHT Okay.

FLIGHT Good report.

GNC FLIGHT, GNC.

FLIGHT Go, GNC.

GNC Can we verify that they reenabled C-4 thruster?

FLIGHT Okay. Verify that they re- - you're showing that disabled, yes?

GNC Yes.

FLIGHT CAPCOM, we're still seeing CM C-4 thruster disabled.

EECOM FLIGHT, EECOM.

FLIGHT Go EECOM.

EECOM We've got 40 amp-hours back in battery B now.

FLIGHT Okay.

CONTROL You got it, FLIGHT. Likely in response to seeing C-4 thruster enabled.

FLIGHT Okay.

FLIGHT Okay, all flight controllers. I want to go around the horn and pick up anything you need configuration-wise. TELMU -

TELMU Go ahead, FLIGHT.

FLIGHT - you still worried about any configuration items?

TELMU Negative. The LM heater current indicates that the LM was properly closed out. They apparently have not closed the LM hatch yet.

FLIGHT Okay. So you're happy that you don't need them to verify that - what was it, Activation 2-3, those pages we were on?

TELMU That's right. It was TLC 2, and we're happy.

FLIGHT Okay.

GUIDO FLIGHT, GUIDANCE.

FLIGHT Go, GUIDANCE.

GUIDO Can we ask about the docking index again?

FLIGHT CAPCOM will get that for me.

FLIGHT Okay. Got your answer, GUIDANCE?

GUIDO Roger, FLIGHT.

FLIGHT Okay, go with it.

FLIGHT Okay. GNC, you got any configuration items here?

GNC Negative, FLIGHT.

FLIGHT CAPCOM, looks like the last item we need here is a stir on H₂ and O₂ at their convenience. The fateful but inevitable request.

CAPCOM Okay.

GUIDO FLIGHT, GUIDANCE.

FLIGHT Go, GUIDANCE.

GUIDO We finally got a ∆H update. Do you want to just read it up to the crew or uplink it?

FLIGHT Let's see, now. Can we collapse deadbands and do all that good stuff if we uplink here?

GUIDO Uh. Yeah. That - why don't we just read it up to them?

FLIGHT If they enter it through the DSKY are they gonna do it?

GUIDO Standby 1.

FLIGHT Now, we haven't stabled out in that attitude yet, so I don't think we're gonna have any problems.

GNC FLIGHT, I don't think there's any problem, they haven't opened up deadbands yet.

FLIGHT Yeah, that's just what I'm saying. The time to do it is now, GUIDANCE.

GUIDO FLIGHT, GUIDANCE.

FLIGHT Go, GUIDANCE.

GUIDO As long as he's in P00 and don't reselect it, he can uplink it - enter it himself or we can do it easier. Doesn't matter.

FLIGHT Okay. Why don't - you gotta pass the data for the crew checklist anyway on-board, don't you?

GUIDO Right.

FLIGHT Don't you got a page update? Well, why don't we read it up to them and that'll serve both purposes.

GUIDO Alright.

FLIGHT Both have them enter it as well as why don't you tell them what page you want it in the checklist?

GUIDO Okay.

TELMU FLIGHT, TELMU.

FLIGHT Go, TELMU.

TELMU We show the LM overhead hatch is closed, and the heater current looks normal.

FLIGHT Okay.

GUIDO FLIGHT, GUIDANCE.

FLIGHT Go, GUIDANCE.

GUIDO We've had a hardware restart. I don't know what it was.

FLIGHT Okay. GNC, you want to look at it? See if you see any problems?

FLIGHT Roger. We're copying it, CAPCOM. We see a hardware restart.

FLIGHT You see an AC BUS UNDERVOLT there, GUIDANCE? Err - EECOM?

EECOM Negative, FLIGHT.

FLIGHT I believe the crew reported it.

CAPCOM We've got a MAIN B UNDERVOLT.

FLIGHT Oh, MAIN B.

EECOM Okay, FLIGHT, we've got some instrumentation funnies, let me add them up. Having missed the pre-explosion pressure spike on tank 2, all EECOM has to work with now is a Christmas tree of bad data readout. So many numbers were off whack all of a sudden that EECOM assumes it has to be instrumentation. Lengthy discussion ensues on the EECOM loop.

Poor Sy had a "two-handed deathgrip" on his console by now.

FLIGHT Roger.

EECOM We may have had an instrumentation problem, FLIGHT.

FLIGHT Roger.

INCO FLIGHT, INCO.

FLIGHT Go, INCO.

INCO We switched to WIDE BEAM width about the time we had the problem. A red herring, but a believable one if the problem were instrumentation or telemetry.

FLIGHT Okay.

FLIGHT INCO, you say you went to WIDE BEAM width there?

INCO Yes.

FLIGHT Let's see if we can correlate those times. Get the time when you went WIDE BEAM, INCO.

INCO Okay.

CAPCOM Do we have the floodlights off right now?

TELMU That's affirmative, FLIGHT.

FLIGHT Yeah, we can determine that from the LM current.

FLIGHT Roger, we copy that also.

FLIGHT EECOM, you were seeing any AC problems? Looks like -

EECOM FLIGHT, EECOM.

FLIGHT - we have a lot of instrumentation problems here. Go ahead.

EECOM That's affirm. He's flipping out fuel cells around, FLIGHT. This ended up being a problem for the flight controllers. The astronauts were doing their own problem solving and configuration changes, so every time the controllers on the ground had a recommendation for them something would get changed and they'd have to start over.

FLIGHT Well, let's get some recommendation here, Sy, if you've got any better ideas.

FLIGHT Sy, what do you want to do? Hold your own, and -

FLIGHT - Sy, have you got a SIG SENSOR type problem there, or what?

EECOM FLIGHT, EECOM.

FLIGHT Go ahead.

EECOM He's got fuel cells 1 and 3 are offline. We've got MAIN A volts, we have no MAIN B volts. Have them attempt to reconnect the fuel cells. FUEL CELL 1 to MAIN A, FUEL CELL 3 to MAIN B.

FLIGHT Okay.

EECOM Let's just try that -

FLIGHT FUEL CELL 1 -

EECOM - back to MAIN A, FUEL CELL 3 back to MAIN B.

FLIGHT - MAIN A, 3 to MAIN B.

EECOM Let's see what happens.

FLIGHT Okay, now is there - do we have instrumentation problems?

EECOM Well, we've lost - it does appear we've lost AC BUS 2 VOLTAGE. MAIN B is reading - 4 volts. And that effectively takes AC 2 away from us -

FLIGHT Okay.

EECOM - the - yeah and he reported barber poles on the -

FLIGHT Roger.

EECOM - on the fuel cell on-board, too, FLIGHT.

FLIGHT (unintelligible) yeah.

GNC FLIGHT, GNC.

EECOM Let's see if we can get our DC back.

FLIGHT Roger. Go ahead, GNC.

GNC Verify that the Quad Delta HELIUM VALVES are open.

FLIGHT You seeing an attitude problem or you seeing some BI-levels that are giving you problems?

GNC No, it's some low pressures in the fuel and oxidizer which would be symptomatic of the HELIUM VALVE closing and firing some jets. Here he means these two things both happening, not that the valve closing would cause jet firing. Helium is used as an inert gas to maintain pressure in many propellant tanks even today. If the helium isn't coming in, propellant gas exits the tank without anything re-entering to keep the pressure up. Kranz notes that this was a moment of realization for him; the reported bang must have been pretty strong to have jarred shut the valve. He'd seen something similar on Apollo 9 during CSM/S-IVB separation.

FLIGHT Quad number 2 HELIUM VALVE open?

GNC Quad Delta.

FLIGHT Quad Delta - HELIUM VALVE open, right?

GNC Right.

FLIGHT CAPCOM, do you want to verify the Quad Delta HELIUM VALVE is open, please.

FLIGHT Any other problems in the RCS, Buck?

CAPCOM Okay, is that all we've come up with for them; have we got any other recommendations? CAPCOM is anxious.

FLIGHT Yeah, we wanted to get FUEL CELL 1 configured to MAIN A, FUEL CELL 3 to MAIN B. Did you pass that up?

EECOM Let's attempt that, FLIGHT.

FLIGHT INCO, this seems to be an AC type problem, it may be tied into that high-gain thing you got.

INCO We went to WIDE BEAM WIDTH - FLIGHT - at 55:55:04, best we can tell.

FLIGHT Okay.

EECOM I copy, FLIGHT.

EECOM Let me commiserate on that.

CAPCOM Is there any kind of leads we can give them? Are we looking at instrumentation or have we got a real problem, or what? The lack of answer here is telling. At some point here, steely-eyed missile man and NASA legend EECOM John Aaron had gotten called at home. He asked for some numbers to be read out, and while bolting out the door warned them that whatever it was, it wasn't instrumentation.

EECOM Roger. FLIGHT, EECOM.

FLIGHT Go, EECOM.

EECOM Let's reverse the configuration request -

FLIGHT Okay, but wait a minute. We've got a good MAIN A BUS, let's make sure that whatever we do doesn't screw up MAIN A. MAIN A -

EECOM FUEL CELL 2 is on MAIN A, FLIGHT -

FLIGHT Okay.

EECOM - and I'm not going to ask to change that.

FLIGHT Okay, what do you want to do?

EECOM Let's try to put FUEL CELL 1 on MAIN B, FUEL CELL 3 on MAIN A. We'll use the other sensing circuitry.

FLIGHT FUEL CELL number 1 on MAIN B -

EECOM - FUEL CELL 3 on MAIN A.

EECOM We're not going to touch FUEL CELL 2, FLIGHT.

FLIGHT Okay, but if we got any problems in the system I want to make sure that we don't blow the voltage off MAIN A, then we're not going to be able to see anything.

FLIGHT Can we review our status here, Sy, and see what we've got from a standpoint of status. What do you think we've got in the spacecraft that's good?

EECOM MAIN BUS A is reading 25 volts.

FLIGHT Okay. MAIN A -

EECOM And that's reflected by the fact - FUEL CELL 2 is putting out 53 amps, which is just about the most it can and keep our voltage up.

FLIGHT Okay.

EECOM So that's bona fide. AC BUS 2 is 0, which is reflected by the fact that we lost MAIN B.

FLIGHT AC BUS -

EECOM Standby, FLIGHT.

FLIGHT - zero output.

EECOM FLIGHT, EECOM.

FLIGHT Go ahead, EECOM.

EECOM Okay. If we want to keep - - standby, he's changed configuration, we've got BATTERY A on MAIN A.

FLIGHT Go ahead.

EECOM That's what I was going to ask you for, to put the battery on, FLIGHT.

INCO FLIGHT, INCO.

FLIGHT Go, INCO.

INCO We need OMNI Bravo. Our high-gain won't drive without AC 2. The steerable antenna needed AC BUS 2 to power its servos.

FLIGHT Okay. You want OMNI Bravo?

INCO Right.

FLIGHT You don't think we're going to be able to get HIGH BIT RATE data here, do you? On the OMNIs.

INCO We may be. We've got the 210s.

FLIGHT You've got the 210s -

INCO Right.

FLIGHT Okay, that'll save a bit of power. CAPCOM, recommend selection of OMNI Bravo, please -

INCO It's Charlie now.

FLIGHT Okay, Charlie.

INCO He's maneuvering.

CAPCOM OMNI Charlie?

INCO Roger.

FLIGHT That's affirmative.

INCO Okay, FLIGHT, we've got OMNI Charlie and HIGH BIT RATE.

FLIGHT Okay. You have HIGH BIT RATE now off the 210s, right? OMNI -

INCO Right.

FLIGHT Okay.

EECOM FLIGHT, EECOM.

FLIGHT Go, EECOM.

EECOM Okay. Let's get a readout on a couple of fuel cell pressures here -

FLIGHT Okay.

EECOM - FUEL CELL 1 N₂ pressure. FUEL CELL 3 O₂ pressure. We're reading 0 N₂ pressure on FUEL CELL 1 and 13psi on FUEL CELL 3 O₂ pressure. Nitrogen was used to pressurize the electrolytes in the fuel cell through a diaphragm, as well as the reactant feed systems. Feedback loops are set up with the cryogenic oxygen to regulate the relative pressures.

FLIGHT Okay, you want FUEL CELL 1 -

EECOM N₂ pressure.

FLIGHT - N₂ pressure. FUEL CELL 3, what do you want there?

EECOM O₂ pressure.

FLIGHT O₂ pressure. CAPCOM, let's get those as a start.

GUIDO FLIGHT, GUIDANCE.

FLIGHT Go, GUIDANCE.

GUIDO When his hardware restart he was doing a crew-defined maneuver, and that should have killed it, but we're still moving. We ought to stop it.

FLIGHT Are we using RCS now, Buck?

FLIGHT GNC, from FLIGHT.

FLIGHT GNC, from FLIGHT.

GNC GNC.

FLIGHT Did you see any problems in Quad D HELIUM VALVE? Does that look like that's cleared up?

GNC Roger, that's cleared up, FLIGHT, we're in good shape.

FLIGHT Okay. Now, are we using RCS now?

GNC That's affirmative, we're going to have to switch some thrusters to MAIN A to hold attitude here. Because the thrusters required electrical power to operate and MAIN B was dead, a lot of them had to be switched around to the other bus to maintain operation.

FLIGHT Okay. How much RCS are we using?

GNC Oh, we've used - our guess 25 pounds.

FLIGHT Okay. Give me minimum fuel usage configuration that'll keep me attitude.

GNC Roger.

TELMU FLIGHT, TELMU.

FLIGHT Go, TELMU.

TELMU The LM heater current's become essentially static.

FLIGHT Roger. Let's solve one problem at a time. Come back to me later on on it.

CAPCOM We confirming those numbers?

FLIGHT Buck, I need that RCS stuff as soon as you can get it.

GNC Roger, FLIGHT. He's turned off all jets now.

FLIGHT Okay.

CAPCOM Okay, we came up with those numbers, FLIGHT.

FLIGHT Okay, Sy. Give me your next best thing to try.

FLIGHT EECOM, from FLIGHT.

EECOM FLIGHT, EECOM.

FLIGHT Go ahead.

EECOM Why don't we try - leave FUEL CELL 2 alone, and just make sure that 1 and 3 are disconnected from both buses. And make sure that there's abs - that there won't be any load on them at all. And let's see what happens to those cells. n.b. this is shutting off the output electrical circuit of the fuel cells, not the fuel cells themselves, which remain on.

Since the fuel cell electricity was produced via a chemical reaction, reducing the electrical output load would reduce the reaction rate, which could have an impact on the problem.

FLIGHT Okay, what do you want to do? Open-circuit FUEL CELL 1 and 3?

EECOM That's affirm, flight.

FLIGHT Okay. CAPCOM, let's recommend we open-circuit FUEL CELL number 1 and number 3 and leave FUEL CELL number 2 as-is.

CAPCOM Okay, 1 and 3 open-circuit, 2 as-is. And earlier we got a report from them that 1 and 3 were reading grey but zero flow. Connected to the circuit. An open circuit would yield a barber pole.

FLIGHT Yeah - CAPCOM, let's amend that. EECOM, from FLIGHT.

EECOM FLIGHT, EECOM.

FLIGHT Why don't we just open-circuit 1 and make sure we don't have any problems getting that back onto the bus -

EECOM Okay, FLIGHT.

FLIGHT - and just watch it for a while before we make any further moves with 3. FLIGHT's caution is probably well-advised here, but the last-minute change is dropped by EECOM; later he still thinks both 1 and 3 have been open-circuited.

EECOM Roger.

FLIGHT Okay, CAPCOM. Let's just open-circuit one of those right now.

GNC FLIGHT, GNC.

EECOM That's roger, FLIGHT. That's the AC problem.

FLIGHT Roger.

FLIGHT Crew thinks they're venting something.

EECOM I heard it, FLIGHT.

CAPCOM Copy that, FLIGHT? Pretty much as worked-up as the room gets.

FLIGHT Roger.

FLIGHT Okay, let's everybody think of the kinds of things that we'd be venting. GNC, you got anything that looks abnormal in your system?

GNC Negative, FLIGHT.

FLIGHT How about you, EECOM? You see anything that - with the instrumentation you've got that could be venting?

EECOM That's affirm, FLIGHT.

EECOM Let me look at the system, FLIGHT, as far as the venting is concerned.

FLIGHT Okay. Let's start scanning. I assume you've called in your backup EECOMs?

FLIGHT EECOM?

EECOM FLIGHT, say again?

FLIGHT Have you called in your backup EECOMs now? See if we can get some more brain power on this thing?

EECOM We got one here.

FLIGHT Roger.

INCO FLIGHT, INCO.

FLIGHT Go, INCO.

INCO He's - he's - never mind, he's straightening up a little bit.

FLIGHT Okay.

FLIGHT Okay, now, let's everybody keep cool. We've got the LM still attached, the LM spacecraft is good, so if we need to get back home we've got a LM to do a good portion of it with. Okay? Let's make sure we don't do anything that's going to blow our CSM electrical power with the batteries, or that will cause us to lose the MAIN - the FUEL CELL number 2. We want to keep the O₂ and that kind of stuff working, we'd like to have RCS. But we've got the Command Module system , so we're in good shape if we need to get home. Let's solve the problem, but let's not make it any worse by guessin'. Note the repeated use of "if" here. The severity of the problem was not yet fully understood.

As noted elsewhere, FLIGHT likely meant LM here.

GNC FLIGHT, GNC.

FLIGHT Go, GNC.

GNC I have some jet configurations for you whenever you need them.

FLIGHT Okay.

FLIGHT Give them to me.

GNC Okay. Charlie 3, Charlie 4 to MAIN A. Bravo 3 and Bravo 4 to MAIN A. Charlie 1 and Charlie 2 to MAIN A -

FLIGHT Standby.

GNC Yeah; it's all of quad Charlie on MAIN A.

FLIGHT Okay.

GNC Plus Bravo 3 and Bravo 4.

FLIGHT Now, what are we going to be doing with these, GNC?

GNC That'll give us one jet in each direction on each axis.

FLIGHT Okay.

GUIDO FLIGHT, GUIDANCE.

FLIGHT Go, GUIDANCE.

GUIDO He's getting close to gimbal lock.

FLIGHT CAPCOM - okay, CAPCOM, recommend he bring up C-3, C-4, B-3, B-4, C-1, C-2 on MAIN A and advise him he's getting close to gimbal lock.

FLIGHT GUIDANCE, from FLIGHT.

GUIDO Go ahead.

FLIGHT Could we go to a coarse align on the platform here, so we don't have to use any gas if we need to? We could reorient if necessary.

GUIDO Roger. I was going to recommend a P52 in a little bit anyway -

FLIGHT Well, it's going to take a while before we get to the point we're even thinking of a P52.

GUIDO Yeah.

FLIGHT Yeah, it'll coarse align itself there, won't it?

GUIDO It'll coarse align at -

FLIGHT Roger.

GUIDO - any time itself.

FLIGHT Okay, EECOM. I'm coming back to you.

EECOM FLIGHT -

FLIGHT Go ahead.

EECOM - I think the best thing we can do right now is start a power down.

FLIGHT Okay -

EECOM Let's go down the emergency 1-5.

FLIGHT You want to power down, let us look at the TM and all that good stuff, and then come back up.

EECOM That's affirm.

INCO FLIGHT, INCO. OMNI Bravo.

FLIGHT You want OMNI Bravo again?

INCO Right.

FLIGHT On board. OMNI Bravo.

FLIGHT CAPCOM, recommend OMNI Bravo.

FLIGHT Okay. What - you want to go to - power down - give me the page.

EECOM Emergency 1-5, FLIGHT, we'll go down - try to get a delta of 10 amps reduction.

INCO Okay, we've got OMNI Bravo, FLIGHT.

FLIGHT EECOM, do you want to go through that again? What do you want to power down to?

EECOM I want to power down a total of 10 amps, FLIGHT.

FLIGHT A total of 10 amps. You can hear someone (FLIGHT, perhaps?) whistle in amazement at this.

EECOM That's affirm.

FLIGHT Okay.

FLIGHT CAPCOM, we'd recommend emergency power down checklist 1-5, we want to power down a total - a delta of 10 amps from where we are now.

GNC FLIGHT, GNC.

FLIGHT Go, GNC.

GNC Can we afford to do a PTC first, and then we can shut off all of that stuff with no problems. As FLIGHT notes later, this is not a possible request.

FLIGHT Why? You think you're going to have a thermal problem here?

GNC Well, we could have - if we stay there too long, or we -

FLIGHT Okay, we'll run into that one later, Buck -

GNC Okay.

FLIGHT - I want to get our major problems sorted out now.

CAPCOM You want - you still want 1-5 down to 10 amps?

FLIGHT 1-5 power down a delta of 10 amps, CAPCOM.

FLIGHT EECOM, from FLIGHT.

EECOM Go, FLIGHT.

FLIGHT You don't want to get fuel cell pumps off, do you?

FLIGHT Optics power is already off, I believe.

EECOM We can do that on FUEL CELL number 1, FLIGHT.

FLIGHT Okay, well let's make sure we don't blow the whole mission. Kranz himself writes that he realized within fifteen minutes that an oxygen tank had exploded and therefore the "mission" referred to here was now survival, not a lunar landing. But it is not clear if the entire room was on this page quite yet.

EECOM FLIGHT, EECOM.

FLIGHT Go, EECOM.

EECOM Would you not want to consider going to PTC? Echoing GUIDO's suggestion earlier. Still not possible, as FLIGHT points out later.

FLIGHT Well, why don't we get this problem here resolved, right now -

EECOM This will aid our power down, I think -

FLIGHT Pardon?

EECOM - this should aid our power down, I'd hope - wouldn't it?

FLIGHT Well, do you expect that we're going to be in a thermal problem for the next many hours? EECOM?

EECOM Well, I don't know where to say the sun is right now, FLIGHT.

GNC Well, it's pretty close to quad A right now.

EECOM Are we - by 90 degrees?

GNC I don't know exactly where. It's between A and B, mostly on A. He's likely deducing this from temperature sensors in the RCS thruster packages.

FLIGHT GNC, from FLIGHT.

FLIGHT GNC, from FLIGHT.

GNC GNC.

FLIGHT Buck, I'd prefer not making any unnecessary maneuvers now, or try to use any of the equipment's on board the spacecraft, such things as CMC, that type of stuff until we nail down what our problem is.

GNC Well, that's why I was recommending PTC because we don't need any of that stuff then; heaters or anything else. The RCS system involved warming heaters to ensure everything fired as expected.

FLIGHT Yeah, but you gotta get the CMC on, and keep it online. And you need a rather precise period of time for redamping there.

GNC In the order of about 20 minutes to damp out and then spin up and then we can do without any of that.

GNC If we get a good spinup going then we're stable -

FLIGHT Okay, that might be a good idea. That would buy us some more time from a standpoint of reviewing the data. And it would get us back into the - as close to the normal flight plan as we could. How far are we out of attitude right now?

GNC He's a fair ways out right now, FLIGHT. He'd have to do another VERB 49 and fly back and then stabilize there.

EECOM FLIGHT, EECOM.

FLIGHT Go, EECOM.

EECOM Okay, I need one thing right now. He's powering down, he's down to 41 amps, total spacecraft. I'd like to get my AC 2 BUS back so I can look at O₂ TANK 2 PRESSURE. I have no insight into that.

FLIGHT Okay.

EECOM Let's get - I guess we can put INVERTER 3 to MAIN A. AC 2.

EECOM And let's just do it temporarily -

FLIGHT Now, let me ask you a question - before you do that would you like to make sure you've got all AC load you don't need isolated from the bus?

EECOM Nah, it - let's not do that right now, FLIGHT. I think we're in good shape that way. The MAIN A is up high enough where it can handle the inverter.

FLIGHT Well, the thing that concerns me is starting - is throwing equipment - we had a problem, we don't know the cause of the problem, and -

EECOM FLIGHT, I've got a feeling we've lost two fuel cells. I hate to put it that way, but - I don't know why we've lost them. It doesn't all tag up. And it's not an instrumentation problem, the best I can tell right now. The other shoe drops. 27 minutes past the accident, and the picture is becoming clearer. The situation is dire. Only one fuel cell remains, and the gas for it is leaking slowly out to space.

FLIGHT Okay, I'll tell you what. Let's discuss this for just a little bit longer there, Sy. CAPCOM, start them moving back towards a PTC attitude, let's start him going into his rate damping. I feel it's going to be a relatively long period of time to try and nail down the problem. Go ahead. What Sy is saying is highly consequential. This is dramatized in the film for the sake of informing the audience. But the decision hasn't been made to irreversibly close the reactant valves and thus shut down the fuel cells yet.

CAPCOM He's asking how do we like his amperage setup right now?

FLIGHT Are you happy with his power level right now, EECOM?

INCO FLIGHT, INCO.

FLIGHT Go ahead.

INCO I'd like to - for him to secure the high-gain before he starts getting into PTC.

GNC That's affirmative, FLIGHT.

FLIGHT GNC? What's firing now? You got something firing?

GNC Well, we've seen quite a bit of thruster activity.

FLIGHT Okay, I guess this kills the PTC, too, because we're not going to get into PTC as long as we've got something venting.

GNC Roger, FLIGHT. That agrees with what we're seeing here.

EECOM FLIGHT, EECOM.

FLIGHT Go, EECOM.

EECOM I've got a little correction. Let's put INVERTER 1 on both AC buses, please. Earlier he asks for INVERTER 3. Only 1 and 3 could pull power off of MAIN A, and MAIN B is dead.

FLIGHT INVERTER 1 on both AC. Why?

EECOM That's affirm, so I can get some AC BUS power back so I can have some insight into my AC BUS 2 telemetry, especially my cryos, maybe - the venting may be coming from that. And also, I think that the FUEL CELL 2 pumps are on AC 2, and this will take care of it without switching the pumps yet. Presumably, he needed the pumps back on.

FLIGHT Say that again. You think your fuel cell pumps -

EECOM Yeah. FUEL CELL 2 pumps I think are on AC 2.

FLIGHT Okay, but according to the checklist, he should have powered - he should have turned those off, right? Now, he said he was down to BMAG number 2 is in WARM UP, so he's already gone through the fuel cell pump stuff.

EECOM Okay. Good enough.

FLIGHT Okay, so you want to configure INVERTER 1 on both AC buses.

EECOM That's affirm, FLIGHT.

CAPCOM FLIGHT, I didn't - I was listening to the spacecraft and I didn't pass up INVERTER 3 to MAIN A to AC 2, did you delete that?

FLIGHT No, we deleted that.

CAPCOM Alright.

FLIGHT You want to put INVERTER 1 on both AC BUSES. EECOM and CAPCOM, let's do it.

CAPCOM Okay.

FLIGHT EECOM, from FLIGHT.

EECOM FLIGHT, EECOM.

FLIGHT Monitor this bear when we switch again -

EECOM With you.

FLIGHT TELMU and CONTROL, from FLIGHT.

TELMU Go, FLIGHT.

FLIGHT Will you -

CONTROL Go, FLIGHT.

FLIGHT - take a look at the prelaunch data and go through your systems and see if there's anything you've got that may have started venting here?

CONTROL Roger, FLIGHT.

TELMU We'll look.

FLIGHT Okay. And I want a report on that in about the next fifteen minutes. Quick look type stuff.

CONTROL Okay.

FDO FLIGHT, FDO.

FLIGHT Go, FDO.

FDO We're definitely seeing a vent in the data.

FLIGHT Okay.

FLIGHT Roger. We copy that, CAPCOM.

EECOM Fuel cell - FLIGHT, EECOM.

FLIGHT Go ahead.

EECOM FUEL CELL 2 PUMPS to AC 1.

FLIGHT You want FUEL CELL 2 PUMP to AC 1.

EECOM Affirmative.

FLIGHT CAPCOM, FUEL CELL 2 PUMP to AC 1.

FLIGHT EECOM, from FLIGHT.

EECOM FLIGHT, EECOM.

FLIGHT Have you got anybody getting a delog on this thing downstairs? The beginnings of an effort to trace back the data through the accident and piece together what actually happened.

FLIGHT NETWORK, from FLIGHT.

NETWORK FLIGHT, NETWORK.

FLIGHT Bring me up another computer in the RTCC, will you?

NETWORK We got one machine on the RTCC and we got dual CPs downstairs.

FLIGHT Okay, I want another machine up in the RTCC and I want a bunch of guys capable of running delogs down there.

NETWORK Roger that.

CAPCOM FLIGHT, did you hear him say he's getting some rates? We want to know if he's firing any thrusters?

FLIGHT Roger. GNC, watch those thrusters, will you?

GNC GNC. Say again?

FLIGHT Have you got any thrusters firing?

GNC We're looking at that C-3 thruster, FLIGHT. It looks like it stays on most of the time.

FLIGHT Well, can we turn them all off and see if we've still got the rates or any build-up in rates?

GNC Well, the rates that we're seeing is opposite to the direction of that thruster, so if anything it's just trying to hold and not quite up to it. In other words, the venting is pushing in the opposite direction to C-3's firing so they're fighting, but the venting is stronger and winning.

FLIGHT Okay, but -

CAPCOM He's been trying to counteract the rates with DIRECT. He's been getting a negative pitch and a negative roll.

FLIGHT Okay.

CAPCOM But he asked if we were getting some thruster firings that were not being made by him.

FLIGHT I'll tell you what, GNC can you get somebody in the back room to try to figure out what the equivalent ∆V is we're getting? So that we can see if we can backtrack to see if we can figure out what's venting. An elegant physics solution, albeit one that would take some time to pull off. In space, absent any external forces and by basic three-laws Newtonian physics, locating single sources of acceleration is a simple matter of running the numbers through basic physics equations.

FLIGHT In other words, do - it would seem we could equate that to effective thrust and an axis and then deduce what's venting. A vector, in other words, like you remember from grade school.

GNC Roger, we'll give that a try, FLIGHT. He sounds impressed.

FLIGHT Okay. And that might be of interest to the LM guys. TELMU and CONTROL.

CAPCOM He also said it was coming past window number 1.

INCO FLIGHT, INCO.

FLIGHT Roger, we got that.

INCO Need OMNI Charlie.

FLIGHT OMNI Charlie, CAPCOM.

FLIGHT EECOM, from FLIGHT. What did - okay, we've got two good AC buses. What did all that tell you, now?

EECOM It tells me that - well, just give me about 2 more minutes, FLIGHT.

FLIGHT Okay. Take your time.

FLIGHT Roger. Concur, CAPCOM.

TELMU FLIGHT, TELMU. We copy.

FLIGHT Roger.

FDO FLIGHT, FDO.

FLIGHT Go, FDO.

FDO Two machines in the RTCC.

FLIGHT Okay.

GNC FLIGHT, GNC.

FLIGHT Go, GNC.

GNC We would like to turn thruster Alpha 3 on MAIN A and see that'll help control that pitch and at the same time we can turn off Charlie 3 because -

FLIGHT Okay. Get me some real-time plotting on how we're using RCS here, will you?

GNC Roger, FLIGHT. And in the pitch axis we really don't seem to be using any. And that's why we'd like to go to Alpha and see if that changes it any.

FLIGHT Okay, now what do you want again?

GNC Thruster Alpha 3 to MAIN A.

FLIGHT Alpha 3 to MAIN A.

FLIGHT CAPCOM, do you want to pass that up to the crew, please?

FLIGHT Give me a gross amount of RCS propellant consumed so far, GNC.

GNC Roger, FLIGHT. It'll take 30 seconds.

FLIGHT Okay.

GNC That's affirmative, FLIGHT. We're still below the limits.

EECOM Flight, EECOM.

FLIGHT Go, EECOM.

EECOM We've really got to get that battery off the line and power down some more. And we've got to get some MAIN B power back so we can build our pressure back up in O₂ TANK 1. It's down to 318psi. Nominal O₂ pressure is around 900psi. Normally, an automated pressure sensing switch would activate a heater as the tank depleted to heat the O₂ and keep the pressure around that number. 100psi is a bit of a redline mark, at which point even at minimal load only about 2 hours of useful power could be expected.

FLIGHT BATTERY -

EECOM With MAIN B down, we have no heaters in O₂ tanks. Heaters could be used to increase the pressure even with less gas (good old PV=nRT ). But EECOM thinks they are on the dead DC MAIN B bus.

FLIGHT Okay, what do you want to power down?

EECOM Well, where'd he say he got down to? BMAG 2 OFF? Not inclusive?

FLIGHT That's affirmative. BMAG 2 is in WARM UP.

EECOM I think we'll go ahead and turn that down - we still have the LM with us, right?

FLIGHT That's affirmative.

EECOM So - if we shut down the SCS we ought to be a little better off, perhaps. I think we ought to press on and go down through BMAG 2 OFF, and get those lights minimum.

FLIGHT Okay. How much you want to power down? Another 10 amps?

EECOM Let's get the BMAG off and get the lights down to a minimum. Let's go down two more steps.

FLIGHT Okay. CAPCOM, we want to power down a little bit more. Want to get the BMAG off and the lights minimum there.

FLIGHT Okay, Sy. Now, how long do you want to leave this battery online?

EECOM I want to try and get it off as quick as I can -

FLIGHT Okay.

EECOM - but I need to get powered down. The spacecraft is currently drawing too much power for the one healthy fuel cell to supply, so the battery is currently required.

EECOM The crew did report they removed FUEL CELL 3 - they open-circuited it also, didn't they? Here's that last-minute change FLIGHT requested earlier that EECOM missed.

FLIGHT I don't believe so.

EECOM FUEL CELL 1 and FUEL CELL 3 should be open-circuited.

CAPCOM We just had our last call for FUEL CELL 1 open-circuit, and we left FUEL CELL 3 as it was.

EECOM Let's take this open-circuit, FUEL CELL 3.

FLIGHT Open-circuit FUEL CELL 3.

EECOM Get it off the bus.

GNC FLIGHT, GNC.

FLIGHT Calling, FLIGHT. Say again?

GNC This is GNC, FLIGHT.

FLIGHT Go ahead.

GNC Yeah, we've used a total of about 70 pounds RCS. We'd like to change the jet configurations, see if that'll help us out any.

FLIGHT Okay, what do you want to try now?

GNC They would like to turn the Bravo jets all to be OFF, and all Delta to MAIN A.

FLIGHT Turn all Bravo OFF, and Delta to MAIN A, right?

GNC Roger. That will verify that it isn't a Bravo thruster that's causing the problem with attitudes.

FLIGHT Okay. CAPCOM, we'd like to turn all Bravo jets OFF and all Delta jets to MAIN A.

CAPCOM Roger.

EECOM FLIGHT, EECOM.

FLIGHT Go, EECOM.

EECOM Let's take BATTERY A off the MAIN.

FLIGHT We can support the -

EECOM That's affirm.

FLIGHT - MAIN now on the one fuel cell even with the cryo O₂ going down?

EECOM That's affirm, FLIGHT.

FLIGHT Okay. What's your worry level on cryo O₂?

EECOM Say again, FLIGHT?

FLIGHT Okay. You want to -

EECOM I want to save the battery, FLIGHT.

FLIGHT Okay. Let's see, what battery have we got online, Sy?

EECOM Say again?

FLIGHT What battery have we got online?

EECOM BATTERY Alpha, FLIGHT.

FLIGHT BATTERY A, okay.

EECOM And next step, of course, we'll then think - we've got to worry about getting some power on MAIN B to get the pressure back up in O₂ TANK 1.

FLIGHT Roger. Turn BATTERY A OFF, CAPCOM.

EECOM FLIGHT, EECOM.

FLIGHT Go, EECOM.

EECOM Let's have them isolate the surge tank also, and save it. We'll use the cryo as much as we can. The surge tank provided additional O₂, and was located in the Command Module, so it stayed with the crew for the whole flight.

FLIGHT Say that again?

EECOM Let's isolate the surge tanks -

FLIGHT Why that?

EECOM - in the Command Module.

FLIGHT I don't understand that, Sy.

EECOM I don't want to - I want to use the cryo as much as possible.

FLIGHT But that would seem to be the opposite, if you want to keep the fuel cell going.

EECOM The fuel cells are fed off the tanks in the Service Module, FLIGHT. The surge tank is in the Command Module. We want to save the surge tank which we need for re-entry. You can find a detailed diagram of the O₂ system, including the Surge Tank, here

FLIGHT Okay, I'm with you. I'm with you.

EECOM Roger.

FLIGHT CAPCOM, let's also isolate the surge tank.

CAPCOM Okay, you want to isolate the surge tank.

FLIGHT Yeah.

CAPCOM O₂ surge tank, right?

FLIGHT Yeah. What we're really doing is securing our entry systems right now.

FLIGHT Yeah, we're trying to figure out some way to get power on BUS B. Recall that the tank heaters, which are needed to raise the pressure, are thought to be on BUS B, which is currently dead.

FLIGHT EECOM, from FLIGHT.

FLIGHT EECOM, from FLIGHT.

EECOM FLIGHT, EECOM.

FLIGHT Would you consider putting a battery on BUS B long enough to get the pressure up?

EECOM Well, I'm trying - I want to determine whether or not the - the 5 amps is going to hurt us any. That's going to be on MAIN A, incidentally. I made a mistake. O₂ TANK 1 HEATERS are on MAIN A. Good news, since MAIN B appears to be shot.

FLIGHT Well, we've got MAIN A with us, haven't we?

EECOM FLIGHT, EECOM.

FLIGHT Go, EECOM.

EECOM Okay. Since O₂ TANK 1 HEATERS are on MAIN A, and we've got them off now, we'll be able to stand the 5 amps temporarily for manual pressurization. Let's have them turn the heaters on manually in O₂ TANK 1. As noted previously, the heaters are normally controlled automatically off a pressure sensor. That automated switching highlights the simplicity of the spacecraft's systems; no computers needed to monitor and react to the sensor: it just plugged right into the activation circuit.

FLIGHT O₂ -

EECOM And we'll watch the pressure.

FLIGHT - TANK 1.

EECOM That's CRYOGENIC O₂ HEATER 1, FLIGHT.

GNC FLIGHT, we copy that. No problem.

FLIGHT No problem, CAPCOM.

FLIGHT CAPCOM, we want to get CRYO O₂ TANK number 1 HEATER ON.

FLIGHT You can stand the 5 amps on MAIN A?

EECOM That's affirm. We think so, FLIGHT.

FLIGHT Did you see your 5 amp increase in current there, EECOM?

EECOM That's affirm, FLIGHT.

FLIGHT Okay.

EECOM 26.7 volts, looks good -

FLIGHT Okay.

EECOM - we'll watch the pressure.

EECOM FLIGHT, to be consistent we ought to isolate the REPRESS package also. The repressurization package, like the O₂ surge tank, was a reserve of pressurized oxygen gas in the Command Module.

FLIGHT Okay, you want to isolate REPRESS pack.

FLIGHT AFD, from FLIGHT.

AFD Go ahead, FLIGHT.

FLIGHT Get one of your guys full-time in the back room keeping track of the spacecraft configuration as we pass it up to the crew. You might use Larry. Why don't you stay on, get Larry in the back room to keep track of configuration stuff we give to the crew?

AFD Okay, FLIGHT.

FLIGHT Okay?

AFD And we've got the voice recorder and we're starting to transcribe that.

FLIGHT Okay, now has anybody started the delog of the initial problem? You've got a delog going? Have you got people that are going to be in a position to evaluate it?

FLIGHT Okay.

FLIGHT TELMU and CONTROL, from FLIGHT.

CONTROL Go, FLIGHT.

FLIGHT Roger. I want LM manning around the clock.

CONTROL Roger.

EECOM FLIGHT, EECOM.

FLIGHT Go ahead, EECOM.

EECOM I want the fans on in O₂ tank 1, we're not seeing a pressure increase. We can stand it.

FLIGHT You can stand it?

EECOM That's affirm.

FLIGHT Fans on in TANK 1, right?

EECOM Affirmative, FLIGHT.

FLIGHT CAPCOM, do you want to bring the fans on in TANK 1?

EECOM It's just 1 amp, FLIGHT.

FLIGHT Okay.

EECOM Okay, he's got an MC&W for - varied reasons.

GNC FLIGHT, GNC.

FLIGHT Go ahead, GNC.

GNC It looks like the vehicle has stabilized considerably over the last few minutes.

FLIGHT Okay. That could mean one of two things. Either whatever was venting has stopped venting, it's empty; or do you feel it could also be associated with the thruster Quad Bravo we just isolated?

GNC It's possible, FLIGHT. We really don't know yet, though.

FLIGHT Okay. Are we essentially in a - can you figure out what orientation we are from a standpoint of thermal control? Assume - what's our rate right now? He's referring to the heat and shadow of the Sun.

GNC Right now he has a -0.10 of a degree in pitch. And yaw and roll are very close to 0.

FLIGHT Okay.

EECOM FLIGHT, EECOM.

FLIGHT Go ahead, EECOM.

EECOM The pressure in O₂ TANK 1 is all the way down to 297 , we'd better think about getting in the LM, or using the LM systems. I'm going to have to power way down; I don't know if I'm going to be able to save the O₂ for the third fuel cell - for FUEL CELL 2, rather. PSI. At 56:32:37 it was reported at 312psi.

FLIGHT The heaters aren't working, now let's start thinking circuit breakers. You got any circuit breakers you want to check, there? In other words, FLIGHT is wondering if the heater circuit breaker popped, so despite flipping the switch on, the heaters weren't actually running.

EECOM We saw the current, FLIGHT. EECOM doesn't think the circuit breaker theory is likely, since he saw the load on MAIN A increase by the expected amount for a heater to be running.

FLIGHT You saw the current - okay, look -

EECOM Let's check it anyway, FLIGHT, you're right. But that could be a coincidence or something else could be wrong, so he comes around.

FLIGHT It looks like it's cycling up a PCM count from 297 to 302. Give me some circuit breakers to check. The telemetry refreshed and the pressure increased - by a hair.

EECOM Okay, panel 226. CRYOGENIC O₂ HEATER 1, MAIN A circuit breaker.

FLIGHT I'm sorry, I didn't catch you there. CRYO O₂ TANK 1? Panel 226?

EECOM CYRO O₂ HEATER 1, MAIN A, panel 226.

FLIGHT Roger.

EECOM Also, FLIGHT, let's check the FAN MOTOR circuit breakers TANK 1, on panel 226 also.

FLIGHT FAN MOTOR.

EECOM CRYO FAN MOTORS TANK 1. There are three circuit breakers - three phase. Three-phase alternating current. Motors are easier built on three-phase AC. Unlike the two-phase AC your house gets, three-phase AC works with three wires.

FLIGHT Get that, CAPCOM?

CAPCOM I've got the 226 CRYO O₂ HEATER 1 MAIN A, and CRYO FAN MOTORS TANK 1, three of them on -

FLIGHT That's right. All three phases.

FLIGHT EECOM, I don't think we're going to come to any solution here until we get back to the initial set of conditions, so I hope you got a set of guys looking at the delog pretty soon.

FLIGHT TELMU, from FLIGHT.

TELMU Go ahead, FLIGHT.

FLIGHT I want you to get some guys figuring out minimum power in the LM to sustain life. The first mention of this critical problem and need on the loop, but it's nearly certain that the back rooms were working on this already.

TELMU Roger.

CAPCOM We got the circuit breakers. All in, FLIGHT. The circuit breakers popped out when broken and pushed in when the circuit was closed.

FLIGHT Roger. Copy, all circuit breakers in.

EECOM FLIGHT, EECOM.

FLIGHT Go ahead, EECOM.

EECOM Don't we have both BMAGs OFF?

FLIGHT CAPCOM, would you verify that both BMAGs are OFF, please?

FLIGHT You want to bring it off, right EECOM?

EECOM Affirmative, FLIGHT.

FLIGHT CAPCOM, let's get it off.

FLIGHT CAPCOM, from FLIGHT.

CAPCOM Go, FLIGHT.

FLIGHT Will you get a cockpit panel 1, 2 layout and have the crew - just get the thing and have the crew read across all instruments, all gauges, and write down exactly what they read in those things? Panel 3 contained fuel cell readings, which were already being closely monitored, and propellant readings for the SPS, which FLIGHT did not want to use. So there was no need for a survey.

CAPCOM Okay. You want a survey of panels 1 and 2 on gauges?

FLIGHT Yeah.

CAPCOM Okay. And talkbacks, huh?

FLIGHT That's affirmative. Figure out some code that you can use and - I think that's something we should have gotten started a while ago.

FDO FLIGHT, FDO.

FLIGHT See that juice is still going down there, EECOM. You got any more suggestions?

EECOM FLIGHT, EECOM.

FLIGHT Any more suggestions in trying to pump up O₂ TANK 1 pressure?

EECOM No. FLIGHT, we're gonna hit 100psi in 1 hour and 54 minutes. That's the end, right there.

FLIGHT Okay, 100psi -

EECOM Less than 2 hours, now.

FLIGHT FDO, from FLIGHT.

FDO Go ahead, FLIGHT.

FLIGHT Whatever planning you do, I want to do assuming that we're going around the Moon and we're using the LM for performing maneuvers, because in the present configuration, unless we get a heckuva lot smarter I think we're wasting our time planning and using the SPS.

FDO Okay, FLIGHT.

FLIGHT So I think all of our return-to-Earth type planning should be assuming the use of the LM DPS and/or RCS. And I think third priority down the line should be CSM RCS.

FDO Okay, and I'm assuming that you want fast-as-possible return.

FLIGHT Yeah, I think that's the case.

FDO Okay. We'll work on it from that sideline, FLIGHT -

FLIGHT Okay.

FDO Should be no problem.

GUIDO I copy that, FLIGHT.

EECOM FLIGHT, EECOM.

FLIGHT Go ahead, EECOM.

EECOM Okay, listen. There is a possibility that we blew a O₂ line in one of the fuel cells, and it's effectively manifolded there , of course. Now, I'm - I want to shut off one of the reactant valves to one of the fuel cells. And that would be FUEL CELL 3, since its O₂ pressure is gone. Now, FUEL CELL 1's O₂ pressure is trying to stay up there, at 45psi. Maybe the problem is in FUEL CELL 3. In other words, both tanks run into this line.

FLIGHT That sounds like a good assumption, right there.

EECOM Yeah. FUEL CELL 3 is lost anyways, for us.

GNC FLIGHT, GNC.

FLIGHT Go ahead, GNC.

GNC Turn Charlie 1 thruster OFF.

FLIGHT You want to turn Charlie 1 OFF? Why?

GNC Well, looks like we're getting a lot of firing out for no reason.

FLIGHT Okay, CAPCOM, recommend THRUSTER C-1 to OFF.

CAPCOM Say again, FLIGHT?

FLIGHT THRUSTER C-1 to OFF.

CAPCOM C-1 and -2 OFF.

FLIGHT No. C-1. OFF. I added a word in there. Turn THRUSTER C-1 OFF.

FLIGHT EECOM, from FLIGHT.

EECOM FLIGHT, EECOM.

FLIGHT Why don't you show me where you think that problem is?

EECOM Okay. Clint's coming up.

EECOM FLIGHT, EECOM.

FLIGHT Go ahead, EECOM. This is actually Glynn Lunney responding, who was preparing for his shift. He spent some time before his team came on circulating the consoles and issuing a single critical question to each that had to be answered in the following half hour.

EECOM We need to get the - make sure the inline heaters for FUEL CELLS 1 and 3 are OFF.

FLIGHT EECOM, from FLIGHT. You want to shut off both reactant valves to FUEL CELL number 3?

EECOM It's dead anyway, FLIGHT.

FLIGHT Okay.

EECOM And the inline heaters OFF in FUEL CELLS 1 and 3, please.

FLIGHT What we're proposing here - supposing here, CAPCOM, is we may have a - had some problem in FUEL CELL number 3 since that's the one that's reading no O₂ right now. And we may be losing our O₂ through FUEL CELL number 3, the O₂ manifold - inasmuch as they're manifolded together commonly. Looks like the O₂ in FUEL CELL 1 and 2 seem to be trying to stay up there. And FUEL CELL 3 looks like it's the oddball here.

FLIGHT CAPCOM, let's close the REACTANT VALVE to FUEL CELL number 3.

CAPCOM Okay, close REACTANT VALVE to FUEL CELL number 3.

CAPCOM And you're saying that 1 and 2 look okay?

FLIGHT Well, what it looks like - looks like the pressure's trying to stay up there and this is the best guess we've got right now because we've got to stop this O₂ flow.

CAPCOM Okay.

GNC FLIGHT, GNC.

FLIGHT GO, GNC.

GNC Some more jet reconfigurations to see if we can hold the attitude.

FLIGHT Okay.

GNC We'd like to turn Charlie 2 OFF -

FLIGHT Wait, why are we interested in holding attitude? If we're not venting why not drift for a while? That would probably be better from a standpoint of thermal control anyway, wouldn't it?

GNC I'd think we'd like to get into a controlled drift rather than just some random thing, FLIGHT.

FLIGHT Standby.

FLIGHT Do you want them to go through that whole smash for fuel cell shutdown, Sy? I assume you do - heaters and all?

FLIGHT EECOM?

EECOM That's affirm, FLIGHT. He's gone through much of it already, got the pumps off.

FLIGHT Okay. You want them to go through the whole fuel cell shutdown. Heaters and all.

EECOM Roger. Heaters, reactant valves, and the pumps of course he's already got.

FLIGHT Okay. Have them go ahead, CAPCOM.

EECOM And get the inline heaters OFF on FUEL CELL 1 also, FLIGHT.

FLIGHT Inline heaters OFF on FUEL CELL 1.

EECOM Roger, it'll cut the current requirement down that way.

CAPCOM Their COMM holding up? Sounds like he's going out.

FLIGHT How you doing there, INCO? From a standpoint of OMNI-switching?

INCO We might be a little better on Bravo.

FLIGHT Okay. Can you figure me out some way to keep communications and yet cut down a bit on the load? You might talk to EECOM on it.

INCO Okay. We can turn the tape recorder OFF.

FLIGHT EECOM, from FLIGHT.

EECOM FLIGHT, EECOM.

FLIGHT You don't need the tape recorder, do you?

EECOM Heck, no. Get it off.

FLIGHT Let's get it off.

INCO It may be already off, but that's one thing we don't need.

EECOM Let's go down the list as much of that INCO stuff as we can get, FLIGHT. I think that's about the one biggie right there.

INCO I think that's about the only thing we can give up. We turn the POWER AMPL OFF, we won't get HIGH BIT RATE.

FLIGHT CAPCOM, from FLIGHT.

CAPCOM Go.

FLIGHT Let's also verify tape recorders OFF, please.

CAPCOM Okay, I think we -

FLIGHT I don't think we got down that far on the list, did we? We went through the BMAGs and that was lights - BMAGs and lights, and I think we stopped right there.

CAPCOM Yeah.

EECOM Yeah, that's affirm, FLIGHT. Tape record - we'll skip a step and go tape recorder OFF.

RECOVERY AFD, meet RECOVERY. RECOVERY loop.

FLIGHT What was that, CAPCOM?

GUIDO We copy, FLIGHT.

FLIGHT What was that, GUIDANCE?

GUIDO He had an 06 18 he couldn't get rid of; he's gotten rid of it now.

FDO FLIGHT, FDO.

CAPCOM Okay, FLIGHT. I had them reading off a lot of gauge readings, and we got over to FUEL CELL 3. And I hope your people were copying all this down.

FLIGHT Did you get some kind of master? We got it on tape, I'm sure we can get it off the tape.

CAPCOM Alright. That's affirm. I'd say I have 95% of the ones he read.

FLIGHT Okay.

FDO FLIGHT, FDO.

FLIGHT Go, FDO.

FDO When the systems men can stand it, I need two minutes for a checkpoint to save all this data.

FLIGHT I don't see why we couldn't - EECOM, GNC, can you stand a checkpoint right now?

EECOM It only takes a minute, I guess I'll have to if we need it, FLIGHT.

GNC Go ahead, FLIGHT.

FLIGHT Yeah, I think it'd be good to get a checkpoint. Go ahead.

FLIGHT EECOM, have you deduced anything - have you seen your REACTANT VALVES go off? You seen flow cease?

EECOM Can't tell, FLIGHT.

FLIGHT Yeah.

EECOM They were open-circuited, and the pressure - still appears to be going down.

FLIGHT Yeah.

FDO Negative, FLIGHT.

EECOM FLIGHT, EECOM.

FLIGHT Go, EECOM.

EECOM We'd better confirm that the FUEL CELL 3 REACTANT VALVE circuit breaker on panel 226 was closed when he shut those.

FLIGHT FUEL CELL 3 REACTANT circuit breaker on what panel?

EECOM 226.

EECOM They're normally open. To avoid accidental shutoff of the reactant valves, the electrically activated shutoff valves were normally open-circuited and had to be closed in order for the shutoff switch to actually do anything.

FLIGHT Okay, good idea.

CAPCOM You want them - close the circuit breaker -

FLIGHT Yeah.

CAPCOM - on the valve, and then -

FLIGHT Yeah.

EECOM Yeah, FLIGHT; he should have gotten a barber pole on that.

FLIGHT Yeah, wouldn't he get a barber pole when he turned the reactants off? EECOM?

EECOM Affirm, FLIGHT.

FLIGHT Even with the circuit breaker open?

EECOM No -

FLIGHT No. Okay, so he ought to know that. We can just verify that he got a - The rest of the sentence here would have been "barber pole."

FDO Okay, FLIGHT. We have our checkpoint.

FLIGHT Okay. All flight controllers, I'd suggest you start handing over, because I think a fresh team's probably going to be thinking clearer. I think the rest of us can continue working in some other function in support of the new team coming on.

GNC Go on thruster A-4, FLIGHT.

FLIGHT Okay. Go on thruster A-4, CAPCOM.

INCO OMNI Charlie, FLIGHT.

FLIGHT Roger. And OMNI Charlie.

CAPCOM FLIGHT, he wants to bring on A-4, he hasn't got any way to stop the pitch rate in DIRECT or AUTO.

FLIGHT Go.

GNC He has it on, FLIGHT.

CAPCOM I never got a call for OMNI Charlie, you want it?

INCO Yes.

EECOM Copy.

FLIGHT Okay. All flight controllers, I'm handing over to Glynn. I assume the majority of all the team guys are pretty much briefed and up to speed as best we can. Now what I'd suggest is the white team do two things: they go over the delogs - okay - let me go back over this again. We're handing over to Glynn. I'd suggest the white team goes back and starts going through the delog of the data. In other words, let's see if we can go back to the initial conditions and work on that problem to see if we can find out what happened and we may find some better clues as to what to do and let the fresh guys come on and try to figure out where do we go from here. Kranz's team was the white team. Glynn headed up black team.

FLIGHT And the delog is in way now. Roger.

FLIGHT Okay, EECOM. Tell me about the latch. Do you think you've got the reactants latched? FLIGHT is following up on the possibility that the reactant valve didn't close. There was, in addition to the breaker, a latch that could wedge it open to prevent it from closing in case of heavy vibration, as could happen during a burn.

EECOM FLIGHT, EECOM.

FLIGHT Go.

EECOM The crew reported he got barber pole whenever he threw the reactant switch, so that implies that he did all the right things and he really got it shut off. And it looks like that didn't help us any - the pressure's not improving any.

FLIGHT Okay, now the next question is: are you willing to do that on FUEL CELL number 1?

EECOM That's the question we're pondering, FLIGHT. We've got to come up with an answer on that one. Soon.

FLIGHT FUEL CELL 2 is working okay.

EECOM That's affirmative.

FLIGHT Unless we do something to get that oxygen, it's not going to do us any good to save fuel cells. In other words, there's no reason to be reluctant to shut off another fuel cell if there won't be any oxygen to feed into the working one anyway. You can already see how much more Lunney opines on debates.

EECOM That's affirmative.

FLIGHT Okay - okay. GNC, FLIGHT.

GNC GNC.

FLIGHT You stabilized now? - standby.

FLIGHT Here comes configuration, I think it's yours.

FLIGHT I didn't copy all those; did you, GNC?

GNC Roger, FLIGHT. We concur.

FLIGHT Is that good? How are the rates?

CAPCOM You copy those, GNC?

GNC It's holding down around a tenth of a degree per second, FLIGHT. Oscillating, he's in ACCEL CMD, so -

FLIGHT ACCEL CMD?

GNC Right.

FLIGHT Alright.

CAPCOM FLIGHT, did you copy all those thrusters?

FLIGHT Go ahead. Who's calling?

CAPCOM CAPCOM. Did you copy all those -

FLIGHT I didn't copy them all, Jack. GNC, did you copy them all?

GNC That's affirmative, FLIGHT.

FLIGHT Do you like that configuration for right now?

GNC Yes.

FLIGHT As best you can tell - best you can tell, the rates are okay. And he's flying ACCEL CMD.

GNC Roger, FLIGHT.

FLIGHT No rate damping, then, right?

GNC Roger.

FLIGHT Are both BMAG packages off?

GNC Yes, they are.

FLIGHT Okay.

FLIGHT Standby. EECOM, you need anything?

EECOM Roger, FLIGHT. We'll take those.

CAPCOM We want those?

EECOM Roger.

FLIGHT What do you want?

EECOM Get him to go through the meters -

FLIGHT Okay.

EECOM - on FUEL CELL 1 and 3.

FLIGHT Okay. Just FUEL CELL 1 and 3, Jack.

FLIGHT EECOM, I don't like the way that O₂ pressure's going down. If you want to do something about these other reactant valves, let's make up our mind.

EECOM Okay.

FLIGHT Don't you think?

EECOM Let me get that for you in a minute, FLIGHT. Let's standby on these readouts.

FLIGHT Yeah, okay. Anybody can copy the readouts. Be sure you're discussing these reactants.

CAPCOM Hey, FLIGHT. CAPCOM. Long time ago I heard someone mention something about closing the REPRESS package and then we never made a decision on that. Do you want to do that, too?

FLIGHT EECOM? - he's busy.

EECOM Go, FLIGHT.

FLIGHT Do you want to close out the REPRESS pack? I think that came on for them before.

EECOM We indicated earlier that we'd like to get it closed off -

FLIGHT Yes, Jack.

EECOM FLIGHT, EECOM.

FLIGHT Go ahead.

EECOM Okay, on the reactants for FUEL CELL 1. Seems to me we have no choice but to go ahead and do it. The pressure continues to drop. We're not going to have anything left soon anyway. So, looks like the next best thing to try is to go ahead and turn the reactants OFF on FUEL CELL 1.

FLIGHT Yeah. What is this pounds on your display, Clint?

EECOM On O₂?

FLIGHT Yup.

EECOM That's - that's invalid.

FLIGHT Okay.

EECOM And of course, you'll want to make sure that his circuit breaker is closed for FUEL CELL 1 when he starts to close the reactant valves.

FLIGHT Which circuit breaker is that? The one on 226?

EECOM Roger.

FLIGHT That's FUEL CELL number 1.

EECOM That's right, FUEL CELL reactants number 1.

FLIGHT Alright.

FLIGHT Is he done with that readout yet?

EECOM I didn't copy the last part of it there, FLIGHT -

FLIGHT EECOM, FLIGHT.

EECOM Go, FLIGHT.

FLIGHT Is there any chance that I'm just looking at a bad pressure reading here? I'm going to shut off the second fuel cell now, is there any data you can correlate that says that yeah, that pressure is going down?

EECOM On the O₂ tank?

FLIGHT Yes.

FLIGHT You understand my question?

EECOM I understand your question. The temperatures are also dropping. Let me get a verification on that - standby just a minute. The ideal gas law PV=nRT can help verify the two readings against each other.

FLIGHT Alright.

FLIGHT Yeah, we copy that. Tell them we're debating shutting off the reactants on 1.

EECOM FLIGHT, EECOM.

FLIGHT Go ahead.

EECOM The temperature is the only thing we have.

FLIGHT And does it correlate?

EECOM Pretty closely.

FLIGHT You're saying that I'm looking at a valid pressure in that tank, and it's still going down.

EECOM That's the way it looks, FLIGHT.

FLIGHT Therefore?

EECOM Therefore we need to go to FUEL CELL 1 and turn off the reactants.

FLIGHT CAPCOM, FUEL CELL 1 reactants. Circuit breaker and a switch.

CAPCOM Okay - you want them to go through the fuel cell shutdown procedure on 1?

FLIGHT EECOM?

EECOM Say again, FLIGHT?

FLIGHT Do you want them to go through the fuel cell shutdown procedure on 1?

EECOM That's affirmative.

FLIGHT Yes, Jack.

CAPCOM Because -

FLIGHT Because the tank 1 is still going down. Pressure and temp - pressure going down, temperature confirms it.

CAPCOM Okay.

FLIGHT EECOM, FLIGHT.

EECOM Go ahead, FLIGHT.

FLIGHT Of course, you want to ask yourself if you want to open 3. Open-circuit FUEL CELL 3, perhaps?

EECOM Open 3?

FLIGHT Yeah. You don't want to do that?

EECOM Negative, let's leave 3 like it is.

GNC FLIGHT, GNC.

FLIGHT Standby.

FLIGHT What MAIN BUS do you want up?

EECOM MAIN A.

FLIGHT Just like we -

EECOM Just like it is.

FLIGHT Just like it is. FUEL CELL 2's on MAIN A.

EECOM That's affirm.

INCO FLIGHT, INCO.

FLIGHT Go.

INCO OMNI Bravo.

FLIGHT OMNI Bravo, too, Jack.

FLIGHT EECOM, FLIGHT.

EECOM Go ahead, FLIGHT.

FLIGHT How long can I leave that stuff off and still turn it back on? Any time at all?

EECOM Negative, FLIGHT. It's like it wipes it out. As dramatized in the film, once the fuel cells are shut off they're done for good.

FLIGHT Alright.

FLIGHT EECOM, FLIGHT.

FLIGHT I don't know. That's what I'm asking, but we've got that shut off now.

FLIGHT Okay. When you can.

EECOM That's right, FLIGHT.

FLIGHT You're ready for that now. Sure, absolutely, huh EECOM?

EECOM That's it, FLIGHT.

FLIGHT It's still going down and it's not possible that thing is sort of bottoming out, is it?

EECOM Well, the rate is slower but we have a little less pressure too, so we would expect it to be a little bit slower.

FLIGHT You are sure, then; you want to close it.

EECOM Seems to me we have no choice, FLIGHT.

FLIGHT Well.

EECOM Standby one minute; I'll poll my back room.

FLIGHT It went down again. One more.

EECOM We're go on that, FLIGHT.

FLIGHT Okay. That's your best judgement; we think we ought to close that off, huh?

EECOM That's affirmative.

FLIGHT It's dropping down to 234 . Yeah. Okay. FUEL CELL number 1 REACTANTS coming OFF. psi.

GNC FLIGHT, GNC.

FLIGHT Go ahead.

GNC I think we can help the CMP a bit if we can tell them to enable B/D ROLL in the DAP . He's got A/C turned OFF and he's got A/C selected in the DAP . Can we tell him to - To instruct the DAP that it was allowed to use RCS packages B and D for roll control.

The A/C ROLL thrusters were disabled entirely, but the DAP was being asked to use them for roll control.

FLIGHT Is he under DAP control?

GNC Well, he goes to it occasionally -

FLIGHT Okay.

GNC - he's in - RATE CMD right - ACCEL CMD right now, but -

FLIGHT Okay. Okay. He's got A/C off, huh?

GNC Right.

FLIGHT CAPCOM, when you get a spare minute there, Jack needs to enable B/D ROLL in the DAP if he wants to use it.

FLIGHT If he wants to use the DAP, that is.

FLIGHT Jeez, it's really going down.

EECOM FLIGHT, EECOM.

FLIGHT Go.

EECOM Okay, is the - LM gotten all set up for using LM systems for supporting the CSM?

TELMU That's affirmative.

FLIGHT Yes.

EECOM Okay. We'll get you time as to what it looks like we'll have for power here, shortly.

FLIGHT TELMU and CONTROL, FLIGHT.

CONTROL CONTROL here.

FLIGHT Keep reminding me of that heater; now I don't want to let that thing go too long.

CONTROL Okay. We're still trying to get some data - substantiating data on that, FLIGHT. My own personal opinion is the sooner we can take care of that, the better off I'm going to feel about it.

FLIGHT Yeah, okay, Hal. Go get 'em.

TELMU Okay; and FLIGHT, TELMU. We're working on a procedure right now that powers the LM internally from its own power.

FLIGHT Yes. Fine.

INCO FLIGHT, INCO.

FLIGHT Go.

INCO Save you a little more power to turn the HIGH GAIN antenna switch to OFF.

FLIGHT HIGH GAIN antenna OFF?

INCO POWER switch OFF.

FLIGHT POWER switch. You're doing okay on the OMNIs, huh?

INCO Yes. We've got the 210s.

FLIGHT Okay. CAPCOM, he can turn the HIGH GAIN antenna POWER switch OFF; we're doing fine on the OMNIs. We've got the big dish.

EECOM FLIGHT, EECOM.

FLIGHT Go.

EECOM Like to charge BATTERY A.

FLIGHT Yeah, I was wondering about that. Do you - let me get the HIGH GAIN POWER off first, okay? Clint?

EECOM Okay.

FLIGHT How much - how many amps will that give us, EECOM?

EECOM About 1.3, 1.4 amps - - amp-hours per hour . The cost is about 1.5 amps. The rate of battery charge.

FLIGHT So it's no big deal on the amps.

EECOM That's right. And we'd like to use whatever time we have to put energy back into the battery.

FLIGHT Yeah, and I see O₂ tank 1 pressure is 217.

EECOM That's affirmative. It's still coming down.

FLIGHT CAPCOM, FLIGHT.

CAPCOM Go, FLIGHT - standby.

FLIGHT GUIDANCE, you want anything done with the CMC right now?

GUIDO FLIGHT, we would like a VERB 74 before they power it down.

FLIGHT VERB 74, CAPCOM.

CAPCOM You ready for it now?

GUIDO Standby, FLIGHT, let me the flight - site configured.

FLIGHT EECOM, FLIGHT.

EECOM Go ahead, FLIGHT.

FLIGHT Does the temperature in tank 2 correspond with the pressure reading?

EECOM Let me see how close it is, FLIGHT.

GUIDO FLIGHT, GUIDANCE -

FLIGHT Go.

GUIDO - we're ready.

FLIGHT Yeah; VERB 74 you want?

GUIDO Roger.

FLIGHT VERB 74.

EECOM FLIGHT, EECOM.

FLIGHT Go.

EECOM Temperature and pressure correspond - they verify that the pressure reading's right.

FLIGHT In tank 2?

EECOM Tank - standby.

EECOM That's right, FLIGHT. Tank 2.

FLIGHT Okay. Now, is it possible that we still have that tank and it's good? And we could somehow get power on B and use it? MAIN DC BUS B

EECOM It's not likely, FLIGHT.

FLIGHT What's not likely, Clint?

EECOM Not likely to be able to - actually have anything left in the tank.

FLIGHT You don't think so?

EECOM I don't think so, but let's - we'll pulse (??) that one to you.

FLIGHT Alright.

EECOM Let me get you a time it looks like we've got on tank 1 here.

FLIGHT Alright.

FLIGHT TELMU, FLIGHT.

TELMU Go, FLIGHT.

FLIGHT Is there anything simple that we can refer the crew to to get them thinking about using the LM here? Have you got anything in the checklist, paperwork that'll describe to them what your intentions are?

TELMU Negative, there's nothing documented in contingency. We're thinking about using the LM as a lifeboat, we have some procedures here. On the ground, though.

FLIGHT I'm sure you do. What do they amount to? Flying with the tunnel open?

TELMU Roger. Just a LM, low power - low - supplying power to the CSM.

FLIGHT Supplying power to the CSM?

TELMU Yes; about 5 amps.

FLIGHT To what?

TELMU To their MAIN BUS B . Which hasn't actually functioned since the accident.

FLIGHT Okay. Where did - well, MAIN B is in bad shape. We don't have anything on MAIN B right now. What's that power for? TELMU?

TELMU Just anything they might need it for.

FLIGHT GNC and EECOM?

EECOM Go, FLIGHT.

GNC Go, FLIGHT.

FLIGHT What power do you need from the LM?

EECOM Okay, we'll -

FLIGHT That's right.

EECOM We confirm that here.

EECOM FLIGHT, EECOM. Looks like we've got about 40 minutes left in that tank.

EECOM That's affirmative.

FLIGHT Yes.

EECOM Like to get battery A on charge, FLIGHT.

FLIGHT Now -

FLIGHT CAPCOM, just for his information we're not going to do a DPS burn until we hook around the Moon. Let them know that. And that's at about 79 +30. This later turns out to be incorrect. FLIGHT is thinking of the PC+2 burn to send the spacecraft home from the far side of the Moon, but one correction burn ends up happening before then to get the spacecraft back on a return trajectory as early as possible.

GUIDO FLIGHT, GUIDANCE.

FLIGHT Go ahead.

GUIDO We didn't get a good recording on that VERB 74, we'll need them to do it again.

EECOM FLIGHT, EECOM.

FLIGHT Go ahead.

EECOM We'd like to get BATTERY A on charge, and we'd like to go ahead and get some more power off if we can. I'm not sure what the situation is on getting the computer up -

FLIGHT Clint, let me ask you now, is there anything you want to do - trying to pump up the other tank? Anything? Are you satisfied that both of these tanks are going down and we're past helping them? Even with batteries? That's what I'm getting at.

FLIGHT I'm trying to be sure that you're satisfied that there's nothing else we can do.

EECOM About all we can do is power down and let heat leak help us some - which is probably going to be trivial.

FLIGHT Okay. There's nothing else you want to try.

FLIGHT That's the only reason I'm delaying on this BATTERY A charge, Clint; to be sure you've gone through everything and you don't have any other tricks up your sleeve.

EECOM Sure don't, FLIGHT.

FLIGHT Okay, what other power do you want to take off before we start the charge?

EECOM Well, looks like we're going to get into the control area. Whatever they can give up we'll have to come up with, here.

FLIGHT Okay, are you ready to go ahead and charge BATTERY A?

EECOM That's affirmative.

FLIGHT CAPCOM, why don't they get all they can in BATTERY A?

CAPCOM Okay, and Jack also asked me if we wanted to get a P52 and get the LM platform up with the -

FLIGHT What do you think of that? GUIDANCE?

GUIDO Go ahead, FLIGHT.

FLIGHT CONTROL. Question is, do you want to do a quick P52 on the CSM so that we can do an align to the LM? I don't know if we want to keep that LM platform up all that time anyway.

CONTROL Negative, that's too much power in my mind, FLIGHT, to keep that thing running for all that time.

FLIGHT Okay, therefore you don't -

CONTROL My vote is not to do that.

FLIGHT Yeah.

GUIDO Mine, too.

FLIGHT Okay, CAPCOM, we don't see any need in doing that, because we wouldn't be using the LM platform until about 79 hours.

CAPCOM Okay, you don't want to worry about the LM platform. We'll align it later with the AOT, huh?

CONTROL FLIGHT, CONTROL.

FLIGHT Yeah.

FLIGHT Did you say BATTERY A charge?

CAPCOM Yup.

FLIGHT Okay. EECOM, we charging A? Watch it, there, okay?

EECOM I'm watching; it's fine.

FLIGHT Okay.

FLIGHT EECOM?

EECOM Go, FLIGHT.

FLIGHT Go one more time around that room. We're letting this thing go down, although I realize we don't have any more thoughts to do, but I want to be sure that if there's anything we can do here, that we're doing it. To keep your -

EECOM Just power down, FLIGHT. All we can power down will put us in that much better configuration.

FLIGHT Okay, I got that part but are there any other things that you can do besides that, is what I'm getting at?

EECOM Negative, FLIGHT.

FLIGHT Okay. GNC, can you help EECOM there as to what else you might power down, if anything? I don't know whether you can or not.

GNC Roger, FLIGHT. We'll work on that, although we're in an ATTITUDE HOLD situation here, and I'd hate to give up the CMC and the IMU right now.

FLIGHT Yeah, well the CMC doesn't matter. The SCS can perform an ATT HOLD without input from the CMC.

GNC Okay, we'll work on it, FLIGHT.

EECOM FLIGHT, we're not going to have anything in about 40 minutes here.

EECOM FLIGHT, EECOM.

EECOM FLIGHT, EECOM.

FLIGHT Go ahead.

EECOM Okay, we've got an update on the time. Looks like we've got about 18 minutes until we get down to 100psi, and that's the cutoff point.

FLIGHT Alright. But we're charging BATTERY A.

EECOM Well, that doesn't mean much in 18 minutes, though. But we're doing all we can do.

FLIGHT Alright. CONTROL and GUIDANCE, one more time.

GUIDO Go ahead.

CONTROL Go, FLIGHT.

FLIGHT Will it do any good at all to - TELMU, FLIGHT -

TELMU Go, FLIGHT.

FLIGHT - join in here. The question is, should we try to do a quick align with the CSM and do an alignment in the LM? Can we keep an alignment in the LM up until 79 hours? Can you keep that kind of power on?

TELMU Standby.

FLIGHT The pilots are reporting it's difficult to do that alignment from scratch in the LM docked. Astronauts were in the MOCR providing advice; in this case the docked configuration occludes vision and reflects light in a way that makes the alignment telescope hard to use.

FLIGHT And we got a tradeoff here as to whether we can stand that kind of power.

TELMU Standby 1, FLIGHT.

FLIGHT Alright. Pronto.

GNC FLIGHT, GNC. We'd save a little power if we turn all the jets off in QUAD C. We're pulsing those jets and we suspect that we've - closed the PROP ISOL VALVES in QUAD C so it's doing us no good right now, so we need to turn off all the jets in the quad. The implication is not that they have chosen to close the valves, but that they have jarred shut. And in this case, to reopen them would require the dead DC MAIN BUS B. Even with the propellant feed lines closed, with the thruster still on power would still be spent powering the solenoids in an attempt to fire.

FLIGHT Oh, okay, you mean RCS SELECT -

GNC That's right.

FLIGHT RCS SELECT AUTO ?? check.

FLIGHT EECOM? Any need to dump water?

EECOM Negative on that, FLIGHT.

FLIGHT No sweat there, Jack . CAPCOM Jack Lousma, still on shift since before the accident.

EECOM FLIGHT, EECOM.

FLIGHT Go ahead.

EECOM They get the POWER AMPL off? I heard them talking about it a while ago. I don't know.

INCO No, they don't.

EECOM We can eliminate that since we're in the 85 foot gainway.

INCO That's not exactly true -

EECOM Okay.

INCO We're looking at it to see how far down we can go.

FLIGHT Alright.

EECOM I believe GNC has got some things we can turn down here.

FLIGHT Yeah, he just - AUTO RCS in Quad Charlie can go off; we've got that Quad PROP ISOL'd. Which I didn't know, but.

EECOM Pardon?

FLIGHT Quad Charlie AUTO RCS - GNC, FLIGHT.

FLIGHT GNC, FLIGHT.

GNC Go ahead, FLIGHT.

FLIGHT Confirm: Quad Charlie is PROP ISOL'd off, right?

GNC Well, we haven't confirmed that, FLIGHT, but it appears that that's the situation we're in. The shock of the O₂ thing, it probably closed those valves -

FLIGHT Oh, you think -

GNC - and we haven't been able to open them because those are powered off of MAIN B.

FLIGHT Mm. Okay.

GNC But A appears to be working okay.

FLIGHT Okay. We think Quad Charlie's PROP ISOL'd off, Jack, so in that case we ought to turn off the AUTO RCS SELECT; that'll save a little power. Probably not much.

CAPCOM Yeah - you want AUTO RCS OFF on Charlie?

FLIGHT Uh huh.

CAPCOM How about antennas? How are we doing? Did I hear them give me some bad COMM there?

INCO We're in pretty good shape right now, FLIGHT.

CAPCOM Okay.

FLIGHT EECOM, FLIGHT.

EECOM Go ahead, FLIGHT.

FLIGHT Let me try one more time. Is it possible that if we got power to MAIN B that we could get TANK 2 powered up and up the pressure?

EECOM We don't feel like that's a possibility, FLIGHT. We might conceivably get power to B but we don't feel like we can get anything out of TANK 2.

FLIGHT Okay, now why is that? Tell me why. I'm just -

EECOM It's because the numbers we're looking at indicate that it's essentially ambient . Pressure-wise.

FLIGHT Hold on.

FLIGHT Okay.

FLIGHT GNC, watch we don't pick up any rates now, will you please?

GNC Okay, FLIGHT.

FLIGHT EECOM, FLIGHT.

EECOM Go, FLIGHT.

FLIGHT How long have we got now in the cell?

EECOM Last account we had 18 minutes, let me get an update.

FLIGHT Okay. TELMU, what have we got to do to power up to get some COMM on the LM?

TELMU Okay FLIGHT, we've got a procedure here that gets power up first on the LM.

FLIGHT Yeah. EECOM, FLIGHT.

EECOM Go, FLIGHT.

FLIGHT Yeah, that gets us power but what do you want up? Just the COMM?

EECOM We'll have to have an environment for the crew, the way this can be -

FLIGHT That's what I'm asking you, EECOM and TELMU. We've got to figure out how - we're just about out of CSM talkin'.

TELMU Okay.

FLIGHT What do you want them to power up in the LM?

TELMU Standby 1.

EECOM FLIGHT, EECOM -

FLIGHT Alright.

EECOM - our input is, here, that we'll have to live out at the LM.

FLIGHT I understand.

EECOM Okay.

FLIGHT We've got a power up procedure here from TELMU but we've got to start thinking about what you want pow - configured in the ECS and the COMM.

EECOM Right.

TELMU That gets power in the LM, and then we'll get you some COMM and TM here.

FLIGHT Yeah - do we need to send any power to the CSM? For the platform, or anything? Or, can we even do that? Sending power back over to the CSM wasn't part of the original design consideration.

EECOM I'm not sure we can do that yet.

FLIGHT Can't do that.

FLIGHT That was a long time ago.

CAPCOM Okay. When do you want them to start working on this procedure?

FLIGHT Well, tell them they gotta start thinking about the power - going over and powering right now because they're going to have lights problem in a little while in the CSM.

CAPCOM Okay, I'll send it up. And they wanted to know if we wanted them to try to reset the PROPELLANT VALVES in the secondaries.

GNC Yeah, roger, FLIGHT.

FLIGHT GNC?

GNC That won't do any good because we lost MAIN B and those valves are powered off of B.

FLIGHT No - no, CAPCOM. It's off MAIN B.

FLIGHT EE - TELMU, FLIGHT.

TELMU Go, FLIGHT.

FLIGHT Does this title - this PG&E (??) page - mean anything more than just power up the LM?

TELMU No. That's all.

FLIGHT Alright.

EECOM FLIGHT, EECOM.

EECOM FLIGHT, EECOM.

FLIGHT Go ahead.

EECOM We'd like to go ahead and power down the CSM all we can except leave that battery charger on. Of course, leave a little light because we're going to be there in 15 minutes anyway.

FLIGHT CAPCOM, we're going to out of power in the CSM in 15 minutes in the fuel cells. We want them to start getting the tunnel clear and get ready and get over there and power up the LM as soon as they can, they ought to send somebody over there. EECOM, what ought they do to leave the cockpit? At this point, the CSM is clearly a lost cause. But in the 15 minutes of power left, the controllers and crew need to ensure that the spacecraft life support, illumination, communications, and navigation are all ready to go in the LM, or the crew will be flying blind in every possible way: unconscious, in the dark, with no support or instructions from the ground, and with no idea which way the spacecraft is pointing.

EECOM Say again?

FLIGHT EECOM and GNC. What ought we do to leave the CSM cockpit? We're going to lose power on the buses, now what do you want to switch off?

EECOM Power it down, FLIGHT. All of it.

GNC The CMC and the IMU, mainly, FLIGHT.

FLIGHT (off loop) That's the problem.

EECOM FLIGHT, EECOM.

FLIGHT Go ahead.

EECOM Last ditch stand on O₂ tank 2, let's turn the fans on.

EECOM That'll cost about 1 amp.

FLIGHT What are they off? MAIN A?

EECOM They're on AC.

FLIGHT Okay. Fans in tank 2 ON.

EECOM Fans, tank 2, ON.

FLIGHT CAPCOM, FLIGHT.

FLIGHT Tell them to try the fans in tank 2. They're off the AC and last ditch stand we'll try the fans in tank 2. Turn the fans on in TANK 2, it only takes 1 amp.

CAPCOM Okay.

FLIGHT TELMU, GUIDANCE, and CONTROL; FLIGHT.

CONTROL CONTROL, here.

GUIDO Go, FLIGHT.

FLIGHT Do you know status of the CSM platform right now?

GUIDO Negative, FLIGHT. It's - good as far as we know.

FLIGHT No, no, no. Do you know its orientation? Do you know its orientation?

GUIDO It's PTC REFSMMAT.

FLIGHT Yeah. You know what you've got, and it's okay.

GUIDO Right.

FLIGHT EECOM?

EECOM Go, FLIGHT.

FLIGHT Did he get it? Fans 2 ON?

EECOM We can't tell, FLIGHT.

FLIGHT He got it, did he, Jack? Number 2 fans?

CAPCOM (off loop) He said he got it.

FLIGHT Okay.

FLIGHT GUIDANCE, CONTROL, and TELMU. The point is, should we, quick - if you guys can't run out the power study, run out - align the - your IMU to the CSM while we study the problem? See what we got in the way of power?

FLIGHT Tom Stafford is concerned that they'll have a hell of a time getting the platform aligned in the LM with AOT. It was already known that sun glare could cause problems finding star positions with the vehicles docked. On top of that, debris would prove a huge issue once this procedure was actually attempted.

GUIDO I agree, FLIGHT.

CONTROL I agree, too, FLIGHT.

FLIGHT Okay. What should we tell them to do?

CONTROL It's going to take about 15, 20 minutes as I understand it to do that proce