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| Preparations for Launch | Journal Home Page | Earth Orbit, Rev 1 |
[Apollo 10 was classified as an 'F' type mission, to test all elements of the Apollo spacecraft, both the CSM and LM in the lunar environment. Demonstrate performance of LM and CSM in lunar gravitation field. Evaluate CSM and LM docked and undocked lunar navigation.The mission would follow the same basic flight plan as the first lunar landing, with the exception of the final descent and landing, the surface activities and the ascent from the lunar surface. Additionally visual observations and stereoscopic strip photography of Apollo Landing Site 2 (first planned lunar landing site) was untaken.]
[During seperate operations the CSM used the call sign "Charlie Brown" and the LM "Snoopy", after the characters of the popular comic strip Peanuts© by Charles M. Schulz.]
[The Saturn V launch vehicle designated AS-505 (the fifth launch of the Apollo Saturn V stack-third manned), launched CSM-106 and LM-4 from launch complex 39-B at the Kennedy Space Center on May 18th 1969. This represented the only use of Pad 39-B during the Apollo lunar missions. Apollo 10 was crewed by Thomas P. Stafford, Commander(CDR), John W. Young, Command Module Pilot (CMP), and Eugene A. Cernan, Lunar Module Pilot (LMP). This was the first of only two all veteran crews to fly during Apollo (the other being the first lunar landing mission Apollo 11).]
[For over two months, the space and launch vehicle was tested on the pad and its explosives systems (pyrotechnics) prepared for launch. Then, on May 2 1969, the huge propellant tanks of the S-IC first stage were filled with RP-1, a refined kerosene fuel for the first stage of flight. For five days, commencing on the 5 May 1969, KSC personnel performed the Count Down Demonstration Test (CDDT), essentially a complete rehearsal of the count, including the filling of the cryogenic tanks. This proved the readiness of the launch crew and all the ground support systems that prepare the Saturn V and the Apollo spacecraft for flight. Steps were taken to ensure that the range safety explosives could not be detonated and that the vehicle's engines could not be accidentally ignited, the launch teams brought the count all the way to the point where, in a real launch, the engines of the first stage would be ignited. On completion of the CDDT, the huge quantities of super-cold liquid hydrogen (LH2) and liquid oxygen (LOX) were drained from the launch vehicle. The final preparation of the vehicle for launch then commenced.]
[The terminal countdown was commenced at 01:00:00 GMT on 17 May 1969 and proceeded with no unscheduled holds. During the automatic replenish operations of the RP-1 propellant, at approximately T minus 12 hours, the fast fill valve "open" indication dropped out causing system shutdown. Replenish operations were reinitiated in the manual_ mode and were completed satisfactorily. The problem was subsequently traced to improperly adjusted fast fill valve limit switches. Although attempts at readjustment were unsuccessful, there was no significant impact on remaining RP-1 operations. The fast fill valve is not used during the countdown after replenish is completed. If unscheduled replenish had been required, it could have been accomplished, as before, in the manual mode.]
[At six predetermined points in the count, the countdown clock is put on hold to give the launch teams an opportunity to fix problems and to allow those tasks subsequently delayed to get back on track.]
[A failure occurred during fill line chilldown on the primary LOX replenish pump during its start up procedure at approximately T minus 8 hours due to a blown fuse in the pump motor starter circuit. Troubleshooting of the faulty pump resulted in the replacement of the fuse which delayed the beginning of LOX loading by 50 minutes. However it was completed by T minus 4 hours, 22 minutes. The built-in 1-hour hold at T minus 3 hours 30 minutes precluded a launch delay. The respective tanks are purged of contaminants with nitrogen gas, then precooled. Loading is done slowly at first to get the tank walls down to the -183°C temperature of the LOX. The tanks are filled in just over three hours and, prior to launch, only need to have their contents replenished. Heat, leaking in from the ambient surroundings, causes LOX to boil away, creating the distinctive plumes of white vapour seen drifting from a loaded Saturn V.]
[The two upper stages of the vehicle, the S-II and the S-IVB, use LH2 as their fuel. To make it liquid, LH2 has to be extremely cold, presenting particular difficulties both for the construction of the rocket and the loading of fuel. In the S-IVB, an internal insulation was used so that its adhesive wouldn't have to endure the temperatures of -253°C, only 20° above absolute zero. For Apollo 10's S-II, panels of insulation were affixed to the outer surface of its tank, as explained by journal contributer Mike Jetzer in his article on S-II insulation. Its designers wished to exploit a characteristic of a special aluminum alloy (2014-T6), which increased in strength at cryogenic temperatures. Later S-II stages, Apollo 13's onward, were built using insulation that was sprayed onto its exterior.]
[Before loading, the tanks must be conditioned as this supercold fuel will solidify almost any contaminant gas within. This process begins at T minus 7 hours, 42 minutes and takes 2 hours, 40 minutes. Helium, which will not freeze in the presence of LH2, is passed through the tank repeatedly to remove air (nitrogen and oxygen) and water vapour. Then, to begin cooling the tanks, cold gas is pumped through them. Also, grooves had to be provided next to the insulation's adhesive through which helium was pumped to purge any voids of air, lest the air liquifies and causes loosening of the panels.]
[At T minus 4 hours, 49 minutes, the final chilldown of the S-II stage began by filling the tank with fuel, slowly at first. Though already cold due to the presence of LOX on the underside of the two tanks' common bulkhead and the passage of cold gas, the structure is still very warm in comparison to the LH2, which furiously boils, taking heat away as it does. It takes 46 minutes to get all the fuel required for launch into the tank, after which the level is maintained until launch to compensate for continuing boil-off. Once the S-II is full, loading the S-IVB commences in a similar manner, and it reaches launch mass at T minus 3 hours, 30 minutes.]
[During the automatic RP-1 level adjust at about T minus 50 minutes, an anomaly occurred which caused the level adjust valve to close slightly late. As a result the RP-1 flight mass percentage (which can normally be adjusted to 100 ±0.02 percent) was adjusted to 99.81 percent, but was still within Launch Mission Rules requirements of 100 ±0.2 percent. The same problem occurred during Countdown Demonstration Test (CDDT), however post CDDT troubleshooting revealed no problems with the Propellant Tanking Control System (PTCS). Further postlaunch investigation has isolated the problem to a defective printed circuit card in the PTCS.]
[The backup CMP Donn Eisele and astronaut Joe Engle went onboard the CM early in the countdown to verify the lift-off configuration, checking each switch, circuit breaker, knob and talkback indicator to ensure they were all correctly set prior to the flight crews arrival and ingress. He remained inside the CM during the flight crew ingress to assist them connecting the environment umbilicals and communications links between the spacecraft and the astronauts' space suits.]
[The crew were all onboard the CM by T minus 2 hours, 33 minutes to perform their pre-launch checks.]
[Partial overcast obscured some of the ascent, with lift-off occuring at 12:49:00 p.m. EDT]
[The transcript begins over an hour before launch. The Apollo 10 spacecraft sits atop its Saturn V launch vehicle on Pad 39B. Statements on the progress of the countdown are made by the Public Affairs Officer (PAO) Jack King, the 'Voice of Apollo'. In this transcript the record of communications between the crew and the Mission Control Center, through 'CapCom' (the Capsule Communicator, Charlie Duke at launch) starts just prior to lift-off, continues through the ascent, including both staging events of the Saturn V launch vehicle, and insertion into Earth orbit about 12 minutes later. This first section of the transcript concludes with the confirmation of orbital parameters.]
-001:26:00 PAO: This is Apollo Saturn Launch Control; one hour, 26 minutes and counting; we are proceeding with the Apollo 10 countdown at this time. The closeout crew at the 320-foot level have now essentially completed their work and they are about to secure the White Room, the arm that attaches to the spacecraft hatch itself. They begin to break up the White Room in preparations for the departure, and also preparations a little later for retracting the complete swing arm, swing arm number 9, to a standby position. We are a good bit ahead in the countdown as far as these preparations are concerned, probably in the area of some 20 minutes ago or so. We anticipate that the closeout crew will be ready to depart in about 10 minutes from this time. Spacecraft Test Conducter made another check with Houston Flight, just on a contingency basis, at this time in the countdown, to check the flight since we are on the same launch time as planned. The flight azimuth of 72 degrees is already aboard the spacecraft computer and no changes are required. This is strictly for contingency purposes in case we - the window changed or we were launching a little later than the planned lift-off time. All still going well at this time; 1 hour, 24 minutes, 42 seconds and counting. This is Launch Control.
[Any delay in the launch time would require an amendment to the launch azimuth to compensate for the rotation of the Earth in the time beyond the original scheduled launch.]
-001:16:00 PAO: This is Apollo/Saturn Launch Control T minus 1 hour, 16 minutes and counting. We are Go on the countdown for the Apollo 10 lunar mission at this time. Astronaut Tom Stafford, the spacecraft commander, is in the spacecraft going through some checks with the Spacecraft Test Conductor of the stabilization and control system of this spacecraft, at this time. All the propellants are aboard the three-stage Saturn V launch vehicle, and all looks well at this time. We are G at T minus 1 hour, 15 minutes, 30 seconds and counting. This is Launch Control.
-001:06:00 PAO: This is Apollo/Saturn Launch Control at T minus 1 hour, 6 minutes and counting. Still aiming at our planned lift-off at 12:49 pm Eastern Daylight Time. All aspects of the countdown, both with the Saturn V launch vehicle, the Apollo spacecraft, and the Lunar Module, all are Go at this time. The close-out crew, which has been up to the 320-foot level at the end of the swing arms, swing arm number 9, working with the Apollo 10 crew in the spacecraft, now is departing the area. Once the crew has left, this will permit us to go into preparations to move the swing arm away from the spacecraft hatch. We move the swing arm 12 degrees from the hatch in a parked position, where it remains until the T - 5 minute mark in the count, when it comes all the way back to its full-back position of about 60 feet. The purpose of course, is in the event of an emergency, we could bring that swing arm on back in a hurry and the astronauts would egress. They have a high-speed elevator that's locked at the 320-foot level standing by, in case of such an emergency. This elevator is operated by Jack Lousma, the capsule communicator, the astronaut capsule communicator here in the firing room. We are still Go at 1 hour, 4 minutes, 42 seconds and counting. This is Launch Control.
Swing arm 9
-001:00:00 PAO: This is Apollo/Saturn Launch Control. We are coming up on 60 minutes and counting. Mark, T minus 60 minutes and counting, T minus 60 minutes; we are proceeding at this time. The 363-foot Apollo/Saturn V space vehicle is Go as are the tracking elements, weather, all conditions ready for a launch at 12:49 pm Eastern Daylight Time. At this point in the countdown we are beginning some final telemetry checks and we are bringing up the various radio frequencies concerned with the launch vehicle. These include 2 key tracking beacons located in the Instrument Unit which give us back tracking information during the powered phase of flight. All still well with the Apollo 10 astronauts; Tom Stafford, John Young and Gene Cernan aboard the spacecraft at the 320-foot level. This is Launch Control.
-000:56:00 PAO: This is Apollo/Saturn Launch Control at 56 minutes and counting. 56, and we're proceeding satisfactorily. Weather conditions still Go for a launch attempt at this time. All still well with the crew in the spacecraft. We're going through some telemetry checks with the launch vehicle. We've also taken a look at that RP-1 fuel in the first stage that's been in there for a little while. We've checked its status and the status is reported back as good. We're proceeding; 55 minutes, 33 seconds and counting. We'll be prepared within a matter of minutes to bring the swing arm back from the spacecraft at the 320-foot level. This is the top swing arm, Apollo access arm, identified as swing arm number 9. It will be retracted initially to a parked position some 12 degrees from the spacecraft. This is about 5 feet. It will remain in that position until a 5-minute mark in the count when it will be brought to its complete fallback position some 60 feet from the spacecraft. Coming up on 55 minutes, this is Launch Control.
-000:50:52 PAO: This is Apollo Saturn Launch Control; T minus 50 minutes, 52 seconds and counting. All still going well with the countdown at this time. Here in the firing room, the launch team gearing up for two key tests at this time. One, a check of the range safety command destruct system aboard the Saturn V launch vehicle. The other, some attitude command checks to assure that the engines will swivel in response to commands from the guidance system during flight. The astronauts in the spacecraft still busy with some of their final preparations at this time, and all is proceeding satisfactorily. T minus 50 minutes, 18 seconds and counting; this is Launch Control.
-000:46:00 PAO: This is Apollo/Saturn Launch Control at 46 minutes and counting; T minus 46 minutes and counting. All is still proceeding very satisfactorily for the countdown of the Saturn V Apollo space vehicle. The swing arm number 9 now has been retracted to the 12-degree position. This is a position some 5 feet away from the spacecraft. Once this was accomplished, we then proceeded to arm the pyrotechnics, the busses for the pyrotechnics aboard the spacecraft, particularly the Launch Escape Tower. From here on down during the count, if an emergency was so critical that it would be necessary, the astronauts could activate that escape tower now that the swing arm has been moved away from it. The range safety command checks are still continuing at this time. All is going well. Still aiming for that planned lift-off time of 12:49 pm Eastern Daylight Time. This is Launch Control.
-000:41:00 PAO: This is Apollo Saturn Launch Control, T minus 41 minutes and counting. T minus 41; all going well. Little quieter from the spacecraft now; the astronauts are still busy but they are not sending back as many reports as they had up to about 10 minutes ago. The countdown still proceeding very satisfactorily at this time. Coming up in about 5 minutes will be a key test of the launch vehicle power transfer, where we will switch from external power to the flight batteries aboard the three stages; and the Instrument Unit of the Saturn V to assure themselves that they will operate properly when called on during the flight. Over the final portion of the countdown, that swing arm number 9 will come back to its fully retracted position at 5 minutes in the count. We'll go on an automatic sequencer at 3 minutes and 6 seconds in the countdown; from that point on down, all activities during these final moments of the countdown will be automatic, run by the ground base master computer here in the control center. If anything does go wrong, the computer will automatically shut down and stop the count; would go into a Hold in those conditions. Once the automatic sequence does occur, we will begin to pressurize the various tanks in the three stages of the Saturn V. We'll go to transfer to internal power with the launch vehicle at the 50-second mark, the five engines in the first stage will ignite at 8.9 seconds; we'll have all engines running at 2 seconds in the count and should get lift-off at zero. Still aiming towards a final liftoff - 12:59; correction, 12:49 pm, Eastern Daylight Time. This is Launch Control.
-000:36:00 PAO: This is Apollo/Saturn Launch Control at T minus 36 minutes and counting. T minus 36. All still going well with the Command Module, Service Module, Lunar Module for the flight as well as the three stages of the Saturn V launch vehicle. We are Go for the mission at this time. The following are some of the highlights that have occurred since last evening. We went into a built-in hold at 4 pm Eastern Daylight Time yesterday afternoon. Following the start of the built-in hold we did move the 9.8 million pound [Mobile] Service Structure from the pad. The [Mobile] Service Structure was moved to its fallback position which is some 17,000 feet away from pad B. Astronauts Donn Eisele and Joe Engle boarded the Apollo 10 spacecraft last evening to go through some switch list checks to assure that all would be ready for the countdown when it was picked up today. We picked up our countdown at T minus 9 hours and counting at 2:49 am Eastern Daylight Time this morning. We were a little late starting our propellant loading because of some minor problems at the launch pad concerned with ground support equipment. However, we then did proceed into our propellant load and loaded a little more than three quarters of a million gallons of liquid oxygen and liquid hydrogen aboard the vehicle. We were then ready by the time we resumed our countdown at 3 hours and 30 minutes to have a full propellant supply aboard. The Apollo 10 astronauts Tom Stafford, John Young and Gene Cernan were awakened this morning with Stafford and Young being awakened at 7:34 AM. Their teammate Gene Cernan got up a little earlier. He was awakened at 6:50 AM. They had breakfast with some 10 of their colleagues, donned their suits, and then came to the pad. They were declared physically fit during their brief examination by Dr. John Teegen and Dr. Alan Harter before coming to the launch pad. The breakfast menu included the normal astronaut fare of steak and eggs, coffee, orange juice. The crew came aboard the spacecraft with the Commander first at 10:06 AM. He was followed by the Lunar Module Pilot Gene Cernan, who sits in the right-hand seat, at 10:11 am; and finally John Young, the man in the middle seat, the Command Module Pilot, at 10:16. Since the crew has come aboard we've really been ahead in the countdown. Since that time, all has gone well. We're proceeding at this time. We have just satisfactorily completed our power transfer with the launch vehicle. Tom Stafford aboard the spacecraft giving some readouts back to Test Conductor Skip Chauvin at this time. All aspects of the mission, including weather, Go as we approach the 33-minute mark in the count. Now 33 minutes, 10 seconds and counting; this is Launch Control.
-000:30:40 PAO: This is Apollo/Saturn Launch Control; T-30 minutes, 40 seconds and counting. We are proceeding at this time and aiming for a planned lift-off 49 minutes after the hour. Coming up shortly, the Apollo 10 Lunar Module will go on internal power. This is on power of 2 batteries in the ascent stage and 4 batteries in the descent stage. Most of the preparation work in the Lunar Module had been taken care of before we got into the final count, but it will go internal shortly. For a status report on operations at the Mission Control Center we will now switch to Houston.
PAO: This is Mission Control, Houston. The prime team of flight controllers, headed by Glynn Lunney, is on station prepared to support this mission. The Manned Space Flight Network reports it is green, ready to support the mission. One minor problem with the telemetry computer at Carnarvon, but it will not hold the mission up, there is a backup computer there. Recovery forces report all on station. Among those in the viewing room here in the Control Center are Senator and Mrs. Barry Goldwater. We have three astronauts at the CapCom console; Charlie Duke, Bruce McCandless, and the backup spacecraft Commander for Apollo 10, Gordon Cooper. Taped to the CapCom console are 2 dolls, one Charlie Brown, one Snoopy, replete with spacesuit. This is Mission Control, Houston.
-000:26:00 PAO: This is Apollo Saturn Launch Control; T minus 26 minutes and counting. All aspects of the countdown for the Apollo 10 lunar mission are Go at this time. At this point in the count, the astronauts in the spacecraft have completed the pressurization of the Reaction Control System for the Service Module. These are those four thrusters, those four quad thrusters around the Service Module, 100-pound thrust each, which they use for maneuvers once the astronauts have separated from the launch vehicle and are on their way to the Moon. In addition to this, Astronaut Tom Stafford is getting a new setting for his altimeter in the spacecraft; he uses this to change different abort modes during the powered phase of flight. The new settings given to him from Houston Flight by the Spacecraft Test Conducter here. Vice President Agnew has arrived at the control center; he has been here for some 25 minutes at this time, and he is viewing the operations from a room adjacent to firing room 3, from where the overall countdown is being handled. We are 24 minutes, 53 seconds and counting; this is Launch Control.
-000:21:00 PAO: This is Apollo/Saturn Launch Control at 21 minutes and counting. All still going well, aiming for our planned lift-off at 49 minutes past the hour. We are making some final checks of the second stage of the Saturn V launch vehicle. At this time starting a chill-down sequence in which we introduce cold helium into the engine chamber, the five engines in the second stage, to condition it for later, during the powered flight, when that extremely cold hydrogen and oxygen meet in the engine chamber. We condition them for these extremely low temperatures over the final portions of the countdown itself. As a matter of interest, the target of the Apollo astronauts, the moon, at launch time will be a distance of 218,528 miles, 218,528 nautical miles. We are coming up on T minus 20 minutes and counting. All aspects of the mission Go. This is Launch Control.
-000:16:00 PAO: This is Apollo/Saturn Launch Control; T minus 16 minutes and counting, T minus 16. We are proceeding satisfactorily. Astronaut Tom Stafford in the Apollo 10 spacecraft had completed some final checks of the spacecraft Stabilization and Control System. Coming up in the next minute will be a series of busy checks on the part of the astronauts aboard the spacecraft. They will update the spacecraft computer with some central timing feeds from Houston. The spacecraft will go on full internal power. Of course, the fuel cells for power for the spacecraft have been upped, but an external source has been sharing the load. This external source will be removed and will be on full fuel cell power at the 15-minute mark. The astronauts also will switch their Emergency Detection System equipment to the automatic mode for abort purposes during the flight. The rotational hand controllers both for Tom Stafford and John Young will be armed. 15 minutes and counting; this is Launch Control.
-000:11:00 PAO: This is Apollo/Saturn Launch Control; T minus 11 minutes and counting, T minus 11. All aspects are still going well at this time. The astronauts aboard the spacecraft have completed some special communication checks on what we call the astro-comm circuit. It's a special circuit which has the Launch Operations Manager, the Spacecraft Test Conductor, and Astronaut Jack Lousma who has the call sign Stoney, the capsule communicator here in the firing room. This is special communications which can be used particularly for abort contingencies. These are the only people on the circuit and they have performed their final communications checks. In about 5 minutes, we will go on the circuit and keep it up at that time. Mission Control Center in Houston also coming in shortly with some communications checks. All aspects going well, we are proceeding, all aspects of the mission Go. Coming up on the 10-minute mark in the count. This is Launch Control.
-000:06:43 PAO: This is Apollo/Saturn Launch Control at T minus 6 minutes, 43 seconds and counting. Spacecraft Test Conductor Skip Chauvin has just completed Apollo status check of all personnel involved in the spacecraft countdown. He received 'Go' from all participating. Three particularly strong ones from the three astronauts aboard the Apollo 10 spacecraft. The countdown still proceeding very satisfactorily at this time. We'll have final Go/No-Go checks from Launch Director, Houston Flight and Mission Director coming up in about a minute or so. The weather is Go and the complete Saturn V launch vehicle to include the spacecraft and Lunar Module appears to be ready for a launch 49 minutes after the hour for this, the Apollo 10 lunar mission. We've now hit the 6-minute mark. All aspects of the mission Go. This is Launch Control.
-000:04:30 PAO: This is Apollo Saturn Launch Control; T minus 4 minutes, 30 seconds and counting. The Apollo access swing arm number 9 now fully retracted to its fallback position, some 60 feet away from the spacecraft. At lift-off we will still have some five swing arms still attached; they will move back automatically at first motion, some three-quarters of an inch after the vehicle takes off. Astronaut Tom Stafford has completed his checks with the Spacecraft Conducter. The Mission Director George Hage and the Launch Director Rocco Petrone have given a Go for the flight as has the Range. We have now passed the 4-minute mark and proceeding satisfactorily; we are Go; this is Launch Control. We have just passed the 3 minute mark; we've had the firing command; that's the signal that the automatic sequence is now in, and the remainder of the count will he handled by the Master Computer here in the firing room as various events click off leading up to the ignition of the five engines in the first stage of the Saturn V at the - with lift-off at the zero mark in the count. The actual ignition of those five engines will come at 8.9 seconds in the count. We'll have a report of all engines running at the 2-second mark, and at that time, and over the next few seconds, those engines will be specially checked to assure that we have proper thrust. Once that occurs we will get Commit, meaning that the hold-down arms can release and we will get lift-off of the Saturn V launch vehicle atop 7½ million pounds of thrust. We are now coming up toward the 2-minute mark in the count; at this point the tanks in the vehicle pressurizing; 2 minutes and counting. Our status board indicates here in the control room that all aspects involved are ready. Tom Stafford has just reported back that they want to thank everybody for all the help. We are now at T minus 1 minute, 45 seconds and counting.
[MP3 Audio of PAO (with recording breaks).][MP3 Audio of air-ground, no PAO (and no recording breaks).]
PAO: We'll go on internal power with the launch vehicle at the 50-second mark. At 17 seconds in the count, the guidance system goes internal - this is guidance reference release.
[At T minus 17.3 seconds, the Saturn V's inertial guidance platform in the IU is released from the systems which have up to now been holding it in the correct orientation for the flight. This also represents the start of timebase 0.]
PAO: We already have the proper flight azimuth in, now 90 seconds and counting. Now 90 and counting. The astronauts have turned off their ground communication at this time however they are on VHF, and of course the S-band circuits, as well as the special astronaut communication circuit. One minute, 12 seconds and counting. The vehicle tanks beginning to pressurize at this time; our status board indicates the first stage tanks are now pressurized. We're coming up on the 60-second mark; 60 seconds and counting; we are Go for a mission to the Moon at this time. The second stage now pressurizing and we are coming up on power transfer. Fifty seconds and counting, we have now switched to internal power satisfactorily on the batteries of the first stage, all three stages of the Saturn V vehicle. Forty seconds and counting, Tom Stafford making a final check of his computer. The vehicle, all stages pressurized at this time. We are waiting for the swing arms to come back. One should be coming back at this time, the second one at 17 seconds. Tom Stafford reports they are Go. We are coming up on the 20-second mark. T minus 20 seconds and counting. Guidance internal. 15, 14, 13, 12, 11, 10, 9, we have ignition sequence start, engines on, 5, 4, 3, 2, all engines running, launch commit, lift-off. We have lift-off, 49 minutes past the hour.
[Photograph S69-35107HR shows the Apollo 10 space vehicle just after lift-off.]
000:00:00 CapCom: 10, 9, 8, 7, 6, 5, 4 - Ignition - 3, 2, 0.
[Start of timebase 1.]
000:00:01 CapCom: Lift-off.
000:00:02 Stafford: We have a lift-off.
000:00:03 CapCom: Roger. Lift-off.
000:00:05 Stafford: Yaw - yaw maneuver.
000:00:07 CapCom: Roger.
000:00:08 Stafford: Clock is started.
PAO: Stafford reports the clock has started. The tower is clear.
000:00:09 CapCom: Roger.
[Photograph KSC-69PC-170HR shows Apollo 10 just as it clears the LUT.]
000:00:11 Stafford: And the...
000:00:13 Duke: ...are off.
000:00:14 Stafford: Roger.
000:00:15 Cernan: We're going!
000:00:16 Stafford: And, roll program right on time.
[Stafford is reporting that the IU has commanded the intiation of the maneuver to roll the complete space vehicle onto the desired launch azimuth. Both launch pads at LC-39 are aligned with the flame trench running due north-south. This therefore means that at launch, the vehicle's frame of attitude reference is in an azimuth that is 90° east of north. The roll maneuver will adjust this to the desired azimuth of 72.028° east of north.]
000:00:17 Duke: Roger, Tom.
000:00:19 Stafford: She's looking good, Charlie.
000:00:20 Duke: Beautiful.
PAO: Tom Stafford acknowledges the roll and pitch program to put Apollo 10 on the proper course.
[The Public Affairs Officer commentary has now transferred to Houston.]
000:00:26 Stafford: Okay. Pitch is tracking. Looking good.
000:00:29 Duke: Roger.
000:00:34 Stafford: Roll complete. ELS Manual.
[ELS is the Earth Landing System, the system of parachutes and their deployment systems that bring the CM to a safe splashdown in the sea.]
000:00:36 Duke: Roger. Roll.
000:00:41 Duke: 10, Houston. Mark. Mode 1 Bravo.
[The initial 42 seconds, to an altitude of about 10,000 feet, are flown in abort Mode 1A (one alpha). If an abort situation occurs within this time period, the CM would rapidly separate from the SM using the Launch Escape Tower (LET), the solid-fuelled rocket mounted on top of the CM, which would carry it up from the malfunctioning launch vehicle. A small 'pitch control' motor at the top of the LET would pitch the LET/CM assembly east out over the Atlantic Ocean and away from the booster below which will likely be breaking up and possibly exploding. The tower stays attached for 14 seconds after the initiation of the abort. The highly dangerous hypergolic propellants of the Command Module's RCS would quickly and automatically be dumped overboard as they would be harmful to the recovery forces. The CM would then follow a standard descent on parachutes to a normal splashdown.]
[Abort Mode 1B (one bravo) extends from 42 seconds into the flight to an altitude of 16.5 nautical miles. With the space vehicle now being further downrange and tilted over, the pitch control motor on the LET, would not be required in the event of a 1B abort. A pair of canards would be deployed automatically to force the LET/CM combination into an attitude where the base of the CM is facing the direction of travel, ready for the safe deployment of the drogue and main parachutes. While the canards have little effect in a low altitude abort, they become increasingly important as the Saturn V gains speed through the 1B mode.]
000:00:44 Stafford: Roger. One Bravo.
PAO: One bravo is a - an abort mode dealing with altitude, function of altitude.
000:00:52 Stafford: Starting to rattle a little bit in here.
000:00:54 Duke: Roger.
000:00:55 PAO: Plus 55 seconds.
000:00:56 Stafford: Cabin is relieving.
000:00:58 Cernan: Cabin is relieving.
000:01:01 Duke: Roger. Copy.
PAO: Cabin pressure is relieving. Downrange 1 mile, 3.3 nautical miles high.
[Photograph KSC-69PC-188HR shows Apollo 10 during S-IC powered flight.]
000:01:05 Stafford: 2 gs, Charlie.
000:01:07 Duke: Roger. Looking good at 1 minute.
000:01:18 Cernan: What a ride, Babe, what a ride!
000:01:20 Duke: Roger. You're looking good, 10; you're looking real good.
PAO: That's Gene Stafford - Cernan reporting, "what a ride"
000:01:26 Stafford: Roger. Going through Max Q.
000:01:30 Duke: Roger.
000:01:35 Duke: 10, you're through the Max Q. You're looking good.
000:01:39 Stafford: Two and a quarter g's. She's looking beautiful.
000:01:44 PAO: One minute, 44 seconds downrange, 7, 12 miles high.
000:01:51 Stafford: Okay. Two and a half g's.
000:01:53 Duke: Roger. Copy, Tom.
000:01:58 Duke: Okay. And, Mark. Mode 1 Charlie. You're looking great.
[Mode 1C is used for aborts occurring between 16.5 nautical miles and the jettison of the tower. As the air is now very thin, the airflow over the pair of canards at the top of the tower would have little aerodynamic effect during an abort, so the CM RCS would be used to control the orientation of the spacecraft until the canards become effective.]
000:02:01 Stafford: Roger. One Charlie and 3 gs; it feels great.
Ascent acceleration profile
000:02:06 Duke: You're Go for staging, 10.
000:02:08 Stafford: Roger. 10 is GO.
[John Young from the 1969 Technical Debrief: - mentioned that he had been warned that they may have trouble reaching the EDS switch whilst being subjected to 3 to 4 g. However no problem was encountered.]
000:02:16 Stafford: Inboard shutdown.
[Start of timebase 2.]
000:02:19 Duke: Roger. Inboard.
PAO: Inboard engines are out.
000:02:24 Stafford: They're a little Pogo. Pogo damps.
000:02:26 Duke: Roger. Copy, Tom. EDS Off, 10,
PAO: Charlie Duke asking the crew to turn off their Emergency Detection System.
000:02:47 Stafford: Got staging lights out.
[Tom Stafford from the 1969 Technical Debrief - mentioned that they thought they would encounter a single pulse of negative G at staging as the S-IC cutoff and the crew would be thrown forward in their straps, before the S-II ignited and recommenced the acceleration. However they actually encountered was a form of pogo which continued for 4 cycles, during which they were "slammed forward, back, forward, back, forward and back" (direct quotation) and the instrument panel appeared blurred during this time.]
[Start of timebase 3.]
000:02:51 Duke: Roger.
PAO: Good ignition on the second stage.
[MP3 Audio of PAO (with recording breaks).][MP3 Audio of air-ground, no PAO (and no recording breaks).]
000:02:54 Stafford: And it looks like we got a good S-II...
000:02:57 Duke: Roger [Garble] 10, on the S-II. It's looking good. Confirm EDS [Emergency Detection System] Off.
000:03:05 Stafford: EDS is Off [Garble.]
000:03:07 Duke: Roger.
000:03:16 Stafford: Plane Sep.
[The interstage ring or skirt has been jettisoned.]
[Staging of the S-IC and S-II is technically described as a "dual plane separation", as the vehicle is cut across two geometrical planes. The first plane is between the skirt and the S-IC, with the S-II engines starting 1.1 seconds later. The second plane separation, when the second stage loses the skirt, occurs at 3 minutes, 10.7 seconds; 30.0 seconds after the S-IC separation. This time allows the S-II's attitude to stabilise because if either part of the launch vehicle were to be yawing or pitching excessively, there would be a danger of the engine bells striking the S-IC and skirt as the two great metal cylinders coast along before ignition of the S-II. The skirt provides clearance above the first stage's LOX tank for the five J-2 engines of the S-II stage.]
000:03:16 Duke: Roger.
000:03:18 Stafford: There goes the tower.
[A single, small, solid-propellant motor near the top of the LET fires for one second, jettisoning the entire LES (Launch Escape System) and the checklist moves to abort mode II.]
[The LES consists of the tower, with all its rocket motors, instrumentation and canards; and the BPC (Boost Protective Cover), which is a shroud over the entire Command Module. The BPC protects the spacecraft from the heat generated by the friction of ascent, and from the exhaust of the Launch Escape Motor should the tower be used for an abort.]
Click on above image to enlarge
[John Young from the 1969 Technical Debrief - "Just - prior to tower jett, I could see - the only way I can describe it is - aerodynamic heating smoke coming across the hatch window and also the right-hand window underneath the BPC before it was jettisoned. There was no question about it. It was coming between the window and the BPC and it was aerodynamic heating. I could see it on both my right window and on the hatch window".]
000:03:20 Duke: Roger, on the tower. And we confirm second plane Sep.
000:03:22 Stafford: Okay
PAO: Flight Dynamics reports trajectory Go at 3 minutes, 9 seconds. Downrange, 81 miles. 46 miles high. Second plane separation, that is the skirt around the engines on the second stage. And the Launch Escape Tower has jettisoned.
000:03:25 Stafford: Man, that staging was quite a sequence!
000:03:27 Duke: Roger. Sounded like it.
000:03:30 Stafford: And we have guidance Initiate.
[Up to now, the IU has been steering the vehicle according to a predetermined trajectory which minimises sideways movements though the air while tilting it along its flight azimuth. It has not been using any information about its position and velocity to alter its flight path. The control is open loop. 'Guidance initiate' marks the point where the IU begins the IGM (Iterative Guidance Mode). The control loop is now closed as the IU begins using position and velocity data to help it guide the vehicle to where it wants to get to - an accurate Earth orbit.]
[Eugene Cernan from the 1969 Technical Debrief - "I saw the pitch guidance change about three times, where the horizon went on the bottom of my window and went to the top of my window. And then went to the bottom of my window and then went to the top of my window. It seem to me it was more than hunting, but Tom then verified that the guidance was good and what was happening. Then it had pitched back. It wasn't hunting as in Gemini where you could see the nose hunt. This was definitely a pitch change".]
000:03:31 Duke: We confirm that, 10.
000:03:33 Stafford: Roger.
000:03:35 Duke: The S-II is looking beautiful, Tom. Everything is copacetic.
000:03:37 Stafford: Roger. It looks good to be back up here, Charlie.
000:03:44 Duke: Yes, I bet.
PAO: That's Charlie Duke talking to Tom Stafford.
000:03:45 Young: Just like old times! It's beautiful out there!
000:03:46 Duke: Not bad.
000:03:51 Duke: You guys sound ecstatic.
000:03:55 Stafford: Man, this is the greatest, Charlie.
000:03:57 Cernan: Charlie, babe. It's fantastic, babe, really!
PAO: That's Gene Cernan with fantastic.
000:04:01 Stafford: Okay. Four minutes - -
000:04:01 Duke: Roger. Four minutes. You're Go. Your trajectory and guidance look good.
000:04:07 Stafford: Roger. We look on the line on board.
PAO: 171 miles downrange, 67 miles high at 4 minutes, 15 seconds. Still Go.
PAO: Glynn Lunney taking a status check. Everyone says Go. Four minutes, 50 seconds; 230 miles downrange, 67 miles high.
000:05:01 Duke: 10, Houston. At 5 minutes, you're all Go. All your systems are looking great.
000:05:05 Stafford: Roger. Five minutes, and 10 is GO.
000:05:07 Duke: Roger. You're right on the track.
000:05:09 Stafford: Roger, Charlie.
000:05:58 Duke: 10, Houston. Coming up on 6 minutes. You're looking beautiful.
PAO: We have an estimate of inboard engine cut-off on the second stage at 8 minutes, 15 seconds. Outboard engine cut-off; 9 minutes, 11 seconds. Five minutes, 30 seconds; 299 miles downrange, 83 miles high. All controllers reporting Go. 350 miles downrange, 87 miles high now.
[The SPS gimbal motors are powered up at this time to provide SPS control if needed in an abort. The crew select each of the four gimbal motors On, in the order Pitch 1, Yaw 1, Pitch 2, Yaw 2. Once this procedure is complete, they select the Launch Vehicle/SPS Gimbal Position Indicator (GPI) switch on Panel 1 to GPI which allows them to monitor the position of the SPS gimbals. Up until now, the GPI has been monitoring the Saturn V's propellant tank pressures - another dual use gauge. The GPI scales are in degrees, about a zero midpoint.]
Panel 1
Click the above for full panel diagram.
[The SPS gimbal motors are each selected On at intervals of at least one second to avoid power surges.]
000:06:01 Stafford: Six minutes. Gimbal motors coming On. Pitch 1.
000:06:03 Cernan: That's Go.
000:06:04 Stafford: Yaw 1.
000:06:05 Cernan: That's Go.
000:06:06 Stafford: Pitch 2.
000:06:07 Cernan: That's Go.
000:06:08 Stafford: Yaw 2.
000:06:09 Cernan: You got them all, Tom.
000:06:11 Stafford: Looks good here.
000:06:25 Cernan: Charlie, are you sure we didn't lose Snoopy on that staging?
PAO: Guidance says it's looking real good. Ira's 6 minutes, 23 seconds.
000:06:28 Duke: No, I think Snoopy is still there with you. You're looking good. We copy your gimbal motors On and your trim looks good.
000:06:34 Stafford: ... tracking ... beautiful.
000:06:44 Duke: 10, Houston.
000:06:45 Duke: Mark.
000:06:46 Duke: S-IVB to orbit capability.
[The S-IVB is now capable of placing itself plus the CSM and LM into a safe low earth orbit if problems are encountered with the S-II that require immediate staging. If this abort mode had to be employed the S-IVB would not have sufficient propellant remaining to perform a TLI burn. An alternative mission profile would have to be adopted.]
PAO: Apollo 10 now has the capability to get into orbit on the S-IVB should the second stage malfunction.
000:06:47 Stafford: ...
000:06:55 Duke: 10, Houston. Coming up on 7 minutes. You are all Go. We have nominal level sense arm, 8 plus 15. S-II cut-off, 9 plus 11.
[One of the procedures devised to ensure the maximum amount of S-II propellant was consumed prior to the outboard engine cut-off was to use five sensors in each tank to detect when the propellant was nearing depletion. Engine shut down was commanded when at least two of these sensors had detected propellant depletion. To ensure that these sensors did not command a premature engine shut down they are not armed until another independent propellant gauging system had indicated that the tanks were getting close to depletion.]
000:07:03 Stafford: You have the level sense arm, and 9 plus 11 is the S-II.
000:07:07 Duke: Rog.
PAO: Seven minutes, 14 seconds. Downrange now 538 miles and 94½ nautical miles high. Coming up on inboard engine cut-off.
000:07:31 Stafford: 7:30. 10 is good.
000:07:33 Duke: Roger. Looking good here.
000:07:41 Stafford: Inboard's shut down.
[The inboard J-2 engine is shut down early to minimise its tendency to induce low frequency pogo oscillations. This inboard engine shutdown reduced total vehicle thrust by 234,714 lbf to a level of 922,553 lbf.]
000:07:43 Duke: Roger on the inboard's, Tom. We confirm it.
000:07:49 Duke: How's the ride?
000:08:00 Duke: 10, Houston. Eight minutes. You're looking good. How's the ride?
000:08:04 Stafford: Roger. Fantastic, Charlie, fantastic.
000:08:06 Duke: Roger.
000:08:26 Duke: 10, Houston -
000:08:27 Duke: MARK-
000:08:28 Duke: - the level sense arm - -
[Duke is informing the crew that the "level sense arm" signal has been sent to the IU. The engines will be shut down once two probes in one of the tanks have been uncovered by the dwindling propellant. They can expect shutdown shortly.]
000:08:29 Stafford: The level sense arm.
PAO: We are right down the ground track at 8 minutes, 30 seconds. 755 miles downrange, 98 miles high, velocity is 21,499 feet per second. Flight Director is taking a status for staging now.
000:09:01 Stafford: ... everything looks good.
000:09:04 Duke: Roger, Apollo 10. You are Go for staging.
000:09:09 Duke: Mark. Mode IV, Apollo 10. Mode IV.
[Mode IV is the abort mode where the crew have been given a Go decision to continue to orbit using the S-IVB, and should that stage deviate from its allowed limits, the CSM will separate from the Saturn and use the SPS (Service Propulsion System) to continue into Earth orbit.]
000:09:13 Stafford: Through mode Sep IV. Staging.
[Start of timebase 4.]
000:09:14 Duke: Roger.
000:09:17 Stafford: Separation.
000:09:18 Duke: Roger.
000:09:19 Stafford: Appears we got good ignition.
000:09:21 Duke: Roger.
000:09:24 Young (onboard): Yes, it did go out. I think 1 all the way out.
000:09:26 Duke: We confirm your guidance, and your S-IVB looks good, 10.
000:09:29 Stafford: Roger.
PAO: Thrust is good and guidance has initiated on the S-IVB stage, the third stage.
[Just as with the second stage, the third stage is operating the with the same 'Iterative Guidance Mode' where the vehicle is actively steering towards orbit insertion.]
000:09:32 Cernan: Charlie, lots of stuff out the window in staging. We're catching up and passing it now.
000:09:36 Duke: Okay.
000:09:39 Stafford: Okay. Guidance looks right on with the onboard jet, Charlie.
000:09:42 Duke: Roger. We confirm that. Looking great here. You're looking beautiful.
000:09:43 Stafford: Roger.
PAO: 1,037 miles downrange and 102 miles high, and the velocity is 23,400 feet per second.
000:09:46 Young (onboard): Okay. We've got an eighth of a g, old buddy.
000:09:47 Cernan (onboard): (Cough)
000:09:48 Stafford (onboard): An eighth of a g ...
000:09:50 Cernan (onboard): Look at how fast those clouds are.
000:09:53 Young (onboard): ... at 149 ...
000:10:02 Duke: 10, Houston. At 10 minutes you're GO.
000:10:04 Stafford: At 10 minutes, Go. Onboard's good.
000:10:06 Duke: Roger.
000:10:06 Cernan (onboard): Tom, we got everything here so far.
000:10:08 Young (onboard): ... in a 102 .... right on out.
PAO: Predicted cut-off for the Saturn S-IVB stage 11 minutes 47 seconds.
000:10:13 Stafford (onboard): I just can't get over the vibrations ...
000:10:17 Cernan (onboard): Yes, after that first-stage staging, man, it - -
000:10:21 Duke: Apollo 10, Houston. Predicted S-IVB cut-off, 11 plus 47.
000:10:26 Stafford: 11 plus 47.
000:10:28 Young (onboard): ... Come on, baby; keep going ... Right on the line.
PAO: Downrange 1,200 miles now at 10 minutes, 44 seconds, 102½ miles high. The velocity at 24,280 feet per second.
000:10:49 Stafford (onboard): ... and ready to go.
000:10:51 Young (onboard): ... Right on the line, now.
000:10:54 Stafford (onboard): ...
000:10:59 Cernan (onboard): Isn't that something?
000:11:01 Young (onboard): Now, ...
000:11:02 Stafford: 11 minutes, and ...
000:11:03 Duke: ... 10, you're looking ...
000:11:03 Stafford: ... 10 looks good.
000:11:05 Duke: Roger, 10.
000:11:06 Stafford: ...
000:11:08 Stafford (onboard): Sure is right on the line ...
000:11:10 Duke: 10, Houston. At 11:10, you're looking good.
000:11:13 Stafford: Roger, Charlie. The guidance is beautiful.
000:11:15 Duke: Roger.
PAO: Predicted cut-off now 11 minutes, 45 seconds.
000:11:24 Young (onboard): How'd you like that?
000:11:45 Stafford: SECO!
[Start of timebase 5.]
000:11:46 Duke: Roger. SECO.
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