Apollo 13

This is Apollo Control. Flight Director Milton Windler has completed checking the status with each of his flight controllers at this time, and the general tenor all the way around was that we're in very good shape at the present time. A couple of the significant items discussed, the surgeon reported that the lithium hydroxide, the makeshift lithium hydroxide canister appears to be doing an excellent job. We're presently reading a carbon dioxide level of 1.2 millimeters of mercury. The LM TELCOM, reported that they're beginning to see the effects of the engine burn heat soak back into the helium tank and related rise in pressure in the helium, which would indicate that the burst disk may go a bit earlier than originally predicted, although the heat soak back had been expected. The plot that we have on the pressure rise in the helium tank would indicate the burst disk going sometime between 107 and 108 hours, ground elapse time. The range on the burst disk is 1,881 pounds per square inch to 1,970 pounds per square inch and somewhere between this pressure range we would expect the burst disk to go relieving the pressure on the super-critical helium tank. The flight dynamics officer reported that when we get the burst disk rupture, they will be observing what they call Doppler shift, to see what effect the venting from the helium tank has on the trajectory. If there is no effect on the trajectory, we would expect to have a preliminary data on the effects of the midcourse correction within about 2 hours. That would be about 2 hours after the burst disk ruptures. If on the other hand, there is some change in velocity as a result of the burst disk rupture, the flight dynamics officer said that it would be at least 5 hours before we had a preliminary estimate on the trajectory, the new trajectory. We've noted that the communications has gotten somewhat noisier. This is related to the power down of the lunar module. One of the items that is turned off in the power down is the communications power amplifier. This increases the noise with respect to the signal and we do expect the communications to remain more or less noisier than they have been. This condition will vary as the spacecraft attitude changes and as the position of the antennas changes with respect to the tracking antennas on Earth. The Flight Plan at this time calls for the Command Module pilot Jack Swigert and the Lunar Module Pilot Fred Haise to get about 6 hours of rest. Jim Lovell will stay on the watch in the lunar module. At 106 hours, 16 minutes, Apollo 13 is 149,706 nautical miles from Earth, traveling at speed of 4,509 feet per second. And the clock in Mission Control counting down to entry shows that we have 36 hours, 24 minutes until Earth entry. This is Apollo Control at 106 hours, 17 minutes.

This is Apollo Control at 106 hours, 45 minutes. The...

This is Apollo Control. The participants for the Change of Shift Press Briefing are leaving Mission Control now. We estimate that the briefing will begin in about 10 minutes, in the MSC main auditorium in the News Center.

While we're waiting for the information which Jack Swigert requested on the expected lifetime of the two current lithium hydroxide canisters, we might recap some of the conservation between Swigert and CapCom Jack Lousma. Jack Swigert reported the crew had taken no medication and he said as far as rest they're no more tired than normally in this situation. He said they planned to switch to a rest cycle as indicated in the Flight Plan as soon as it's convenient. Now we passed up a consumable status to the crew. Also the status on the super critical helium tank burst disk we expect will be within the range where the disk could rupture within a matter of minutes. We're presently showing the super critical helium tank pressure at 1,874 pounds per square inch. We'll hit the lower limit of 1,881 pounds per square inch shortly and we'll be advising the crew when that level is reached. Jack Lousma advised them that they likely will hear the disk rupture and may see something from the LM at the time it ruptures.

This is Apollo Control at 107 hours, 11 minutes. Our displays based on telemetry information from the spacecraft currently show that we have pressure in the supercritical helium tank of about 1,889 pounds per square inch. This is within the range where the burst disk on the tank could rupture. The range is roughly between 1,881 pounds per square inch and 1,970 pounds per square inch. During the last 10 or 15 minutes there's been a huddle around the Flight Director's console. The subject of the discussion is what procedure we use if the burst disk does not rupture as expected. The pressure in the tank should not go above about 2,000 pounds per square inch. If the burst disk does not rupture, we would need to use an alternative method of depressurizing the tank. These alternatives involve either depressurizing by venting all at once or by venting in stages, a little at a time. And a decision has not been made at this time on how the tank will be vented in the event it is necessary. But those are the options that we have as it appears right now. You've also heard Jack Swigert aboard the LM reporting the relative position of the Earth and the Moon and the Sun as the spacecraft rotates in the Passive Thermal Control mode. As these bodies come into view through the windows, we've asked him to give a relative position of the Earth and Moon on the Landing Point Designator, the grid on the LM window which is calibrated and will give us a bit more precise information on how the spacecraft is maintaining it's Passive Thermal Control attitude. At the present time now we show Apollo 13 to be 147,186 nautical miles from the Earth.

This is Apollo Control at 107 hours, 31 minutes. We're presently reading a pressure on the supercritical helium tank of 1,897 pounds per square inch. Our LM Control officer just advised the Flight Director that he expects the most likely time for the burst disk on the supercritical helium tank to rupture would be within the next 15 minutes or so. At that time our indication in Mission Control that the disk has ruptured would be a drop in the tank pressure to zero. We presently show a current on the spacecraft Electrical Power System of anywhere from 10 to 12 amps. This is well below the minimum that we'd like to stay under. We'd like to keep it down to at least 14 amps and since the spacecraft is then powered down, we've been well below that figure.

This is Apollo Control at 107 hours, 59 minutes. That report on the relative position of the Earth and Moon through the spacecraft windows is coming from Jim Lovell. That's the first time we've heard from Lovell recently. A check with the Flight Surgeon. As far as we know at this time, all 3 crewmen are still up. However, the fact that Lovell is now on watch might indicate that Jack Swigert and Fred Haise are planning to begin a rest period. In Mission Control, Flight Director Milt Windler has been discussing the situation with the supercritical helium tank and what options we've got if the burst disk does not rupture as it is expected it will. And as we've mentioned before, at that time it appeared the options were either to vent the super crit - vent the pressure from the supercritical helium tank at a series of small vents or to vent it all at once. After looking at the situation, it's been decided that the procedure, should it be necessary to relieve the pressure by venting would be to vent it all at once. In this event it is felt that the fuel in the fuel heat exchanger would be frozen and we would not be able to thaw it out again. This would render the Descent Propulsion System unusable for further maneuvers, however, we have adequate consumables in the LM ascent stage, adequate propulsion in the ascent stage. It's also felt that if a subsequent midcourse was needed probably closer into the Earth entry, we would be able to perform this midcourse using the ascent propulsion stage of the Lunar Module. The present pressure on the supercritical helium tank as read from telemetry data here in Mission Control is 1,913 pounds per square inch. The rise rate has slowed down somewhat. Recapping again the predicted range for the burst disk rupture is between 1,881 pounds per square inch and 1,970 pounds per square inch. We wouldn't begin to get concerned about the pressures on the supercritical helium tank until it got up around 2,000 pounds per square inch. And the LM Control officer anticipates that we would not get up around the 2,000 pounds per square inch in the event the burst disk does not rupture until about 114 or 115 hours Ground Elapsed Time. Experience we've had with ground tests on the supercritical helium burst disk indicates that it should be rupturing around the pressure we've got now, in the low 1,900's. And we're continuing to watch that. The LM power is continuing to run as it has since power-down, between 10 and 12 amps, and we look very good in that respect. There's also been no change in the status of any of the other consumables aboard the spacecraft. They all continue to look quite good at this time. Apollo 13 is presently 144,958 nautical miles from the Earth, traveling at a speed now 4,613 feet per second. We're now 34 hours, 37 minutes until Earth entry. At 108 hours, 4 minutes; this is Mission Control, Houston.

This is Apollo Control at 108 hours, 52 minutes. The Flight Dynamics Officer hopes to have a preliminary set of numbers on the effects of the midcourse correction. At about 109 hours, 30 minutes or a little over 37 minutes from now, the burn was targeted to give the spacecraft a flight path angle of minus 6.52 degrees at Entry Interface. Now we won't have a confirmation of this, of course, until the Flight Dynamics Officer is able to complete the tracking and compilation of data to come up with some preliminary numbers. But the targeted value of that course was to give us a flight path angle of minus 6.52 degrees. The entry corridor which is the width of the flight path angle that we feel we can withstand is about minus 5.25 degrees to about minus 7.4 degrees of flight path angle. We're still watching the supercritical helium pressure aboard the LM descent stage increase gradually. The pressure is now reading 1,937 pounds per square inch. I would like to cover again the procedures which we mentioned have been worked out in the event that the burst disk did not rupture as it is expected to do. The burst disk, of course, is in there to relieve pressure on the tank, on the supercritical helium tank when the pressure gets above a certain specified limits. The disk is designed to rupture at between 1,881 pounds per square inch and 1,970 pounds per square inch. In the event the disk does not rupture, Flight Director Milton Windler as flight controller has worked out a procedure that will be followed to relieve the pressure on the tank, and we see the pressure dropping at this time. The Control Officer reports that the burst disk has ruptured. We - just as we were making this announcement...

While we're waiting for conversation to resume between the CapCom and Jim Lovell aboard Aquarius, we'll summarize the situation as we were talking about the procedure that would be followed in the event the burst disk did not rupture. Lo and Behold the disk ruptured. That occurred at a pressure of about 1,937 pounds per square inch at 108 hours, 54 minutes 40, seconds Ground Elapsed Time. We saw...

That's rotation and communications officer reports we have high bit rate now. We're taking a look at the battery here in Mission Control to see if we see anything unusual. Battery 2 earlier in the - earlier yesterday caused a Master Alarm to go off. We took a look at it at the time and could see nothing wrong with it. The battery was put back on the line and at the time it was felt that the problem was a sensor problem rather than a problem with the battery itself.

This is Apollo Control at 109 hours, 27 minutes. CapCom Jack Lousma was advising Jim Lovell that we'll be handing over from the tracking site at Goldstone, California to the Honeysuckle, Australia site in about 3 minutes. During this handover, for a period of about 30 seconds to a minute, we will not be able to up-link to the spacecraft. At about 109 hours, 13 minutes the crew reported a Master Alarm and a battery light flickering. We had them turn up the, turn on the power amplifier and give us high bit-rate data so that we could look at the batteries here on the ground. After a look at them they telemetered the LM electrical systems engineer in Mission Control. He said that he was confident the problem was the same one that we'd seen yesterday, in which we probably have a sensor problem rather than a problem with the battery itself, and the sensor is triggering the alarm. The crew is advised to put the battery back on line and leave it there. The supercritical helium Burst-Disk ruptured at about 108 hours, 54 minutes, 40 seconds after reaching a pressure of 1,937 pounds per square inch. Lovell reported at the time seeing particles coming off, and also the pressure of the escaping gas, which was thought ahead of time to be a - was predicted to be a non-propulsive vent, turned out to be a very much a propulsive vent. Lovell said that the spacecraft stack which had been rotating about its longitudinal axis at a rate of about 3 revolutions per hour. This rotational rate was stopped by the vent and started up again in the opposite direction, and it is now rotating about one revolution every 2 minutes. One revolution a little less than every 2 minutes, as compared with a revolution every 18 or 19 minutes in the opposite direction prior to the vent. So, that was very much a propulsive vent. Hence, the remarks from Lovell, back to the drawing board on non-propulsive vent. The crew asked if there was any problem with the rotational rate they had as far as the structure of the vehicle and the temperatures on board. After a review of this situation in the SPAN engineering room, it was reported that there would be no problem, either with vehicle temperatures or structure, leaving this rotational rate as it is, and we advised the crew to let it continue to rotate at that rate, and the only problem might be in switching from one antenna to the other. Now, this of course, is function...

This is Mission Control. As we were saying, the only problem we, potential problem that we could see with the rapid rotation rate or the more rapid rotation rate of one revolution every 2 minutes might be that the crew would have to switch from one antenna to the next and it was felt that this might be troublesome, however, Lovell reported that it would be no problem and they would attempt to keep up with it. In the event that they miss an antenna switch we would lose data for perhaps 1 minute while the spacecraft rotated around in a position for the other antenna to be received on the ground. At the present time, Apollo 13 is 140,934 nautical miles from the Earth. Our velocity is up now to 4,700 feet per second. The very gradual velocity buildup we've been seeing since crossing the sphere of influence line, the imaginary line in which the Earth's gravitational force becomes the dominant gravity force acting on the spacecraft, and we begin to see at that point a gradual acceleration due to Earth's gravity.

This is Apollo Control at 110 hours, 2 minutes. That was Jim Lovell reporting that Fred Haise is sleeping at present time in a rather unusual position. Fred sleeping with his feet up into the docking tunnel, and his head is resting on the ascent engine cover which is on the floor of the LM. Relatively upside-down as you in a normal standing position in the LM. Jack Swigert sleeping on the floor of the LM.

This is Apollo Control at 110 hours, 8 minutes. We estimate that the amount of velocity change imparted to the combined stack of vehicles by the disk rupture and the super critical helium tank was about 2/10 of a foot per second. This amount of velocity, Delta V addition to the spacecraft, was able to stop the rotational rates in one direction and start them up in another. The rotational rate had been about 1 revolution every 18 - 19 minutes.

Jack Lousma just advised Jim Lovell that current estimates of water would indicate that he's got - the crew has sufficient water on the LM for 161 hours.