Apollo 16

This is Apollo Control; 98 hours, 5 minutes Ground Elapsed Time into the mission of Apollo 16. Three minutes and 50 seconds to Acquisition of Signal; that is, [for] the two spacecraft come around the Moon on the 13th lunar revolution. Some 29 minutes, 24 seconds until ignition for the landing phase. Ignition time for PDI or Powered Descent Initiate is 98:35:04. The descent engine will burn for approximately 12 minutes and 53 seconds, according to the nominal plan, for a total velocity change from orbital velocity all the way down to zero, or landing at the lunar surface of 6,698 feet per second [2,041 metres per second]. The Lunar Module Orion will slim down at a rate that would make a calorie counter envious for at the start of PDI, the Orion will weigh some 18 tons. By landing, she'll only weigh 9 tons. All of this weight loss, of course, is propellant. During the descent, the Lunar Module Pilot will be calling out numbers that the computer display has displayed for him. He will call them out to the Commander. Both men will be in what is called a Vox mode, or voice actuated communications so that those on the ground can hear their conversation. The Lunar Module Pilot will call out these numbers for the angle at which the Commander can see the landing site on a grid on his window called the Landing Point Designator. During the final descent phase of the touchdown, the Lunar Module Pilot will be calling out the landing radar readouts of H and H-dot, that is, altitude and descent rate respectively. The so-called low level of propellant quantities will be called out when the propellant quantities reach 5.8 percent. At that time, the burn time remaining will be approximately 111 seconds. 91 seconds into this margin, there's a point called 'Bingo'. This is the point where the Commander has to make the decision to go ahead and land or to begin vertical motion and then abort stage in case it's a No-Go situation on the landing. He has approximately 20 seconds to make this decision to land. The CapCom, in this case, Jim Irwin, or the Orion, will be make this call of level and Bingo to the crew at the appropriate times. Some 19 seconds away from predicted acquisition as Orion and Casper come around the Moon and Casper meanwhile will have circularized. 25 minutes, 47 seconds from ignition. We should have acquisition now. We're standing by for that.

It remains to be seen whether the steerable antenna on the Orion is functioning properly as we come around on Revolution 13. In any case, whether it works or not, we're still Go for landing at this point. Displays here in Mission Control have switched from the lunar orbit background projection plotters to the X-Y plotters of altitude, velocity and so on. Colored lines that are driven by radar, for the descent and landing phase. We have AOS on Lunar Module Orion. Let's switch on to air-ground.

This is Apollo Control. Aboard the Command Module Casper, Ken Mattingly is troubleshooting the SCS, reading out what his onboard indications are. Let's listen to that for a while, and switch away from Orion.

This is Apollo Control, 99 hours and 1 minute Ground Elapsed Time. Flight Director Gerry Griffin is instructing the two spacecraft communicators to brief the crew on the current situation. And which apparently we have as long as five lunar orbits to make a determination on the feasibility of continuing with the landing, or whether we'll have to rendezvous with the two spacecraft back together, and do an immediate return to Earth, assuming that the Service Propulsion System would be inoperative. We're some 14 minutes away from Loss of Signal with the Command Module. We'll monitor the discussion between the spacecraft communicator, and the crew of Orion, and Mattingly in Casper.

This is Apollo Control at 99 hours, 11 minutes into the mission of Apollo 16. To recap the current situation, the crews of both vehicles, Casper and Orion, have been instructed to station-keep as they come to their closest approach during the next pass behind the Moon, with the Command Service Module being active in the rendezvous. We have some five hours to resolve the current problem which consists of difficulty by Ken Mattingly in getting the Thrust Vector Control System, which keeps the Service Propulsion Engine aligned through the center of gravity on the Command Service Module. At the same time people on the ground, here in Mission Control and over in the Training Building are running simulations to attempt to develop a bypass or a workaround for the situation that Ken Mattingly has encountered and as preparations for the circularization burn. Some three minutes away from Loss Of Signal.

This is Apollo Control. One slight correction. We have five revolutions which amounts to ten hours in which to make the decision before the geometry of the two spacecraft orbits would dictate no landing, would be out of plane with the landing site beyond the capability of the Descent Propulsion System to steer into the landing site. To repeat again, that is five revolutions instead of five hours.

Lunar Module Orion has been advised of the possibility of a wave-off for landing on this revolution. It seems that the circularization burn on the Command Module Casper was unsuccessful.

This is Apollo Control. We are going around at least one more rev before attempting the Power Descent Initiation for Lunar Module Orion. Ken Mattingly in Command Module Casper encountered some problems in preparing for the Service Propulsion System burn for the circularization maneuver. Seems that a secondary circuit on the Thrust Vector Control System apparently did not come up to specifications. So the circularization burn was aborted, and we have a wave-off. We'll stand by for the remainder of this front-side pass as a new circularization burn maneuver is calculated, and troubleshooting continued for Ken Mattingly and his problem aboard Casper.

This is Apollo Control. Here in Mission Control, all of the...

This is Apollo Control. Here in Mission Control, all of the options are being considered with the current situation in which the Thrust Vector Control portion of the Stabilization and Control System, which in turn controls the firing and gimbaling of the Service Propulsion System engine. It's being mulled over. The other options would be rendezvous over the next couple [of] revolutions and possibly using the Descent Propulsion System onboard Orion for injecting the spacecraft back into a trans-Earth trajectory. Over the next several hours this consideration should sort itself out.

This is Apollo Control at 98:37. The current situation in Apollo 16 is a wave-off. That is another revolution before attempting a landing.

However as mentioned earlier other options are being looked at in case the trouble shooting on the Command Module - Command Service Module Stabilization and Control System fails to pan out to where the circularization burn or any other Service Propulsion System burns could be conducted successfully.

This is Apollo Control. There's a rather busy huddle around the Flight Director's console here in Mission Control as all the options for the current situation in the mission are considered. Shall we continue trying to troubleshoot the problem with the Command Service Module Stabilization and Control System or shall we proceed with re-rendezvous and a Trans-Earth Injection burn at several hours hence. The possibility is still open for troubleshooting and fixing the problem with the system that controls the Service Propulsion System, and just landing at a later time. We are hopeful that before Loss of Signal on this 12th revolution of Apollo 16 that the decision will be made. At 98:46, this is Apollo Control.

This is Apollo Control. Spacecraft communicator Jim Irwin in the next few moments should pass up to the crew of Orion what the current thinking is here in the Control Room on attacking the problems that have arisen in the Apollo 16 mission.

This is Apollo Control. We've had Loss of Signal at the end of the - near the end of the 13th lunar revolution as both spacecraft go around the back of the Moon. Flight Director Gerry Griffin is having what he calls a 'tag up' with all of the console positions here in the Control Center for a discussion of the current situation in Apollo 16. We've had a wave-off so far. That is the current posture of the mission. Crew will rendezvous at the next closest approach time and station-keep until such time as the resolution is made here on the ground whether or not to continue the mission or to re-rendezvous, dock and do an immediate Trans-Earth Injection burn. They're attempting to work around the problem in the Command Service Module Thrust Vector Control circuitry, which apparently bombed out on Ken Mattingly when he was preparing for his circularization burn. We have some five revolutions in which the decision can be made before it would be a definite No-Go for landing. At 99:18, and 46 minutes away from acquisition on Rev 14, this is Apollo Control.

This is Apollo Control, 99 hours, 31 minutes Ground Elapsed Time into the mission of Apollo 16. To recap the current situation here in Mission Control Center, various considerations are underway on whether or not to continue the mission with a later landing or to have the two spacecraft, Orion and Casper, rendezvous, dock and do a Trans-Earth Injection burn using the Lunar Module's Descent Propulsion System. This would assume of course that the Service Propulsion System on the Command Module is inoperative, because of the apparent problem in the SCS or Stabilization Control System, which in turn drives and controls the SPS system, aboard the Command Service Module. We have something in the neighborhood of five revolutions or about 10 hours in which to reach the decision on the outcome of the lunar landing. As Orion came around the east limb of the Moon this last revolution in preparation for Powered Descent Initiation, they were prepared for the landing. However Casper, piloted by Ken Mattingly, reported that he had not made the Circularization Burn. Since that time there have been many huddles here in the Control Room; engineers are going over drawings in the back rooms, simulations are underway here at the Manned Spacecraft Center to determine the nature of the Service Propulsion System control problem and hopefully by the time the crew comes around the corner again some 31 minutes from now, at least some clarity will come out of the situation. But as mentioned earlier, it may take the entire five revolutions. The limit of five revolutions has to do with the orbital geometry because after that time the orbital plane of the Lunar Module would be - would have drifted so far away from the landing site that the - there's not ample propellant to steer into the Descartes landing area from the present orbit without a [orbital] plane change. At 99:34, and 30 minutes and 30 seconds from Acquisition of Signal [from] both spacecraft, this is Apollo Control.

This is Apollo Control; 99 hours, 56 minutes Ground Elapsed Time into the mission of Apollo 16. Some seven minutes, 40 seconds away from acquisition on the 14th lunar revolution. To recap again the current situation in the mission, the circularization burn for Command Module Casper was aborted when Ken Mattingly discovered some discrepancies in the backup system which controls the Service Propulsion Engine. We still have a good prime system, that is a Guidance and Navigation system aboard the Command Module. However, we would be one failure away for the very critical Trans-Earth Injection maneuver which requires a fairly lengthy burn and a stable engine bell from the Service Propulsion System; therefore, quite a few people here in Houston and at the spacecraft manufacturer in Downey, California are looking into the ramifications of the backup system having apparently failed. Would this present any structural strain on the spacecraft if the engine bell went to full yaw, and would we be able to do a successful Trans-Earth Injection with this engine? As all of these questions are answered, the decision will be made whether or not to continue with the landing phase or to rendezvous and do a Trans-Earth Injection burn using the Descent Engine on the Lunar Module Orion. We have about five revolutions, or some 10 hours in total time in which to make this decision. This, again, is dictated by the orbital mechanics. The fact that the Lunar Module would drift away from the desired ground track for the landing site at Descartes during any time past these five revolutions. The Gold Team of flight controllers will stay on duty in the Control Center for the landing if the decision is made to land. If the decision is made to rendezvous and do a docked Descent Propulsion System burn to bring the spacecraft home, Pete Frank's Orange Team will take over. Some 4 minutes, 37 seconds now away from acquisition and at 100 hours even, this is Apollo Control.

This is Apollo Control; 100 hours, 3 minutes Ground Elapsed Time. Less than a minute now away from acquisition of Orion and Casper coming around the east limb of the Moon on the 14th lunar revolution. Standing by for acquisition here half a minute away. The atmosphere here in the control room is reminiscent of the period just after the cryogenic oxygen tank incident on Apollo 13. Ten seconds. We're waiting confirmation from the network controller that we've had acquisition.

We have AOS, Lunar Module. Let's stand by now for resumption of communications between the control center, Jim Irwin CapCom, and the crew of Casper and Orion.

This is Apollo Control at 100 hours, 21 minutes. Still standing by here for a resolution of the apparent problem with the Stabilization and Control System aboard the Command Service Module. Meanwhile the two spacecraft are making the necessary maneuvers for rendezvous. Or I should qualify that to say station-keeping. Right now the Rendezvous Radar display shows a separation of some one nautical mile [1.85 km].

The maneuver Mattingly was attempting was a 5-foot-per-second line-of-sight RCS maneuver toward the Lunar Module. Right now, he's ahead and below the Lunar Module by about one nautical mile [1.85 km], straight-line distance. We would like to re-emphasize that this will be strictly for station-keeping. Lunar landing is still not positively ruled out at this time depending on what decision is made on the reliability of the Stabilization and Control System to control the SPS engine on the Service Module. Continuing to monitor air/ground for both spacecraft, this is Apollo Control [at] 100 hours, 24 minu...

This is Apollo Control. Flight Director Gerry Griffin has instructed the CapCom to tell the crew that at Acquisition of Signal on Rev 15 - that's in spite of the next revolution - they'll be given a Go/No-Go for a landing on Rev 16. Hopefully by that time the situation will have resolved itself on the Thrust Vector Control System which drives the SPS. Apparently there is a problem in the yaw gimbal actuator in the Service Propulsion System. The decision has not yet been made, and hopefully will be made prior to the time of Acquisition of Signal on Revolution 15. Some 19 minutes remaining in this 14th revolution. Add to that 47 minutes of backside pass, and at start of that rev we'll either be Go for landing or for immediate rendezvous, docking, and subsequent return home. This is Apollo Control at 100 hours, 51 minutes.

This is Apollo Control. We have had Loss Of Signal with both vehicles as they pass behind the Moon during the end of revolution number 14. At the start of Revolution 15, the crew of Apollo 16, still at this time station-keeping in the two vehicles, will be given a Go/No-Go decision for powered descent and landing during Rev 16 which will be some 4 hours from now. If the decision is Go, and all of the maneuver timelines will have to be read up to the crew during the front-side pass of revolution number 15. If the decision is [for] no landing, then the crew would proceed to rendezvous, dock, and prepare the spacecraft for return home. To recap the situation, the - the planned circularization maneuver by the Command Service Module back prior to AOS on Revolution 13 was aborted by Ken Mattingly when he discovered that the backup system, the Stabilization and Control System which in turn controls the gimbal actuators on the Service Propulsion System, apparently had a malfunction in the yaw direction - in other words the driver that moves the engine bell left and right apparently had some excursions of several degrees and fairly rapid amplitude - fairly rapid succession. Simulations are underway here at - in Houston and with the Command Module simulator and some structural tests are underway at this time at the manufacturer's plant, Downey, California to determine if indeed the problem would present any structural hazard to the spacecraft should the backup SCS system have to be used in SPS burns. Keep in mind, please, that the primary system - the G&N system - is still in perfect condition, but the mission rules call for both systems being operational before we have a 'Go' for landing. Some 44 minutes remaining now until acquisition on Rev 15. During the next three quarters of an hour, the decision should be firmed up on a Go for landing - Go/No-Go decision. And at 101 hours, 14 minutes Ground Elapsed Time into the mission of Apollo 16; this is Apollo Control.