Highways Into Space: A first-hand account of the beginnings of the human space program

by Glynn S. Lunney

  I considered the decision to transfer the CSM platform alignment to the LM as key to maintaining our future options and it was RETURN-HOME STEP #2 in our still evolving plan. We still had the choice to power it all down and reconsider later. At this point, keeping the LM alignment was a good trade for accurate, reliable control of future propulsion burns against a modest amount of LM power being used for a near term mid-course maneuver in a few hours to get back on free return. The free return mid-course would also verify that the alignment and the propulsion systems were in good shape. Also significant, the fact of being on a free return should be a psychological lift for the entire team. With respect to using the LM consumables, my judgment was that this team would find a way to stretch a nominal two plus days of mostly powered up LM consumables to a four-day, powered down survival mission. (But it still made us all nervous, some more than others.) And after the mid-course in the next two hours, we would have more accurate consumable forecasts available to decide whether to power down or stay up after that. This was a good example of the incremental development of the return-home plan. Take the bird-in-hand, especially when the tradeoff – in this case, the consumable cost – was reasonably low.

  58:54 GET (2 hours and 59 minutes since problem start)

  Jim Lovell then reported, “I still see a lot of particles and I cannot identify any constellations, at least in this attitude.” This strengthened my resolve to save the alignment reference in the LM until the propulsion maneuver and consumable picture became more clear. At about this time, we had more time to confer with the flight controllers studying the return to earth options. The LM coolant water was the critical item and the initial cooling water usage was high, about double what was normal for the electrical load, because it was cooling down the entire loop. The usage rate would soon slow down. But, the first estimates would have depleted the coolant water by 94:00 GET at current usage rates. This was obviously not good enough but the estimates had also been made for a very high power level in the LM, about thirty-five amps, for the remainder of the flight – both of these assumptions were much too conservative Merlin Merritt at the Telmu position pressed for a quick power down. I told him, “Merlin, I appreciate your concern, but I am still waiting for an overall plan from Control on the control system options.”

  It was time to focus the team’s attention on our primary goal of returning the crew safely. We had to develop a sound plan to accomplish that goal with LM power management as a supporting consideration. I selected what seemed to be the most promising option of those provided by the Trench. Then I asked for LM consumable forecasts, assuming a continued power up but at more nominal (lower) H2O usage rates. The power up would continue until a major propulsion burn at pericynthion (closest approach to the moon) plus two hours and then reduce the LM power to fifteen to eighteen amps for most of the trip home, allowing two mid-course opportunities. I asked for a range of variations in power levels around that timeline so we did not wait for “more perfect” answers. For now, the approach should be based on faster results including reasonable variations in order to enable the selection of the return home plan. We knew that the CO2 fix was needed, but definition of it was not urgent and the engineering team was on it.

  While that was being done, there was time to refine our near term maneuver options. We could do a mid-course correction quickly to establish free return and then still choose to power down or not. I decided to take the option of getting on free return as soon as practical. We then began to select a time for the mid-course that was adequate for the team to assure proper checklist procedures. We offered sixty-one hours GET and the crew wanted a little more time, settling on 61:30 GET.

  61:30 GET (5 hours and 35 minutes since problem start)

  The mid-course was performed and delivered a forty feet per second correction with the descent engine. Burn parameters were nominal and the tracking confirmed the maneuver. The accuracy of the burn also verified that we had a good alignment in the LM. This decision to go ahead with the mid-course to re-establish free return was RETURN-HOME STEP #3 – and an emotional lift for the crew and team. We were back on free return, but still a long way to go. LM current was decreased from about thirty-two amps to twenty-five amps in the period before the PC+2 burn.

  Through all this, Chris and Sig were present all the time and it was so easy to communicate with them. They followed all the traffic on the comm loops. Sometimes, we would sum up a situation and give them a how-I-am-thinking-about-this-subject before it came to decision time. Sometimes, the understanding was conveyed by a look or a thumbs up or down. I don’t really remember any questions that they had as we went along. I do remember a strong feeling of support. I always felt completely in sync with them, even with very little explanation communications.

  Once the free return mid-course burn was performed, an attempt was made to setup passive thermal control (PTC) to control the thermal balance of the spacecraft with the usual difficulty made worse by the fact that we were doing this with the LM control system for the first time versus the CSM as on past missions. The PTC was designed to cycle cold (away from the sun) and hot environments (facing the sun) uniformly around the CSM/LM stack to avoid extreme temperatures anywhere. The technique is to stand the stack perpendicular to the earth/sun plane and spin it slowly, about one revolution every couple of hours, to spread the heating and cooling throughout the vehicle in a uniform way. It is a delicate maneuver in that the vehicle tends to wobble off like a top slowing down and not spin on the same axis for very long.

  63:05 GET (7 hours and 10 minutes since problem start)

  After more trajectory and consumable discussions, I was confident enough to confirm the most reasonable return option in terms of propulsion, configuration and landing time and location. MCC passed a preliminary advisory for a PC+2 hour LM descent maneuver of about eight hundred ninety feet per ssecond designed to land at the mid-Pacific recovery site at 142:40 GET, twelve hours better than the present free return landing time. These advisories were regularly sent so that the crew always had the best return-home info, in case of communication loss. This was RETURN-HOME STEP #4 (preliminary) and basically the same plan we confirmed as the final plan to the crew about seven hours later.

  63:20 GET (7 hours and 25 minutes since problem start)

  We were able to soon reconfirm that the earlier advisory message sent to the crew would have adequate consumables. The time margin for the two most limiting consumables would be twenty hours of electrical power and the water margin would be 12 hours. This all assumed a continued power up through the PC 2 time of 79:30 GET, and then powering down to a life support and communications mode using about fifteen point five amps and with two power-up mid-course opportunities. We had a workable plan and expected that it would continue to improve as we had more chance to refine it.

  At about this time, we got back to the CO2 removal concern, which was not immediately urgent. Span reported that they were already working with the Crew Systems Division on how to use the CSM canisters in the LM and planning to test the configuration. They expected a solution in a couple of shifts. And I knew from past experience that they would succeed. They were very good at improvising. Not to worry about that one.

  63:50 GET (7 hours and 55 minutes after the start of problem)

  The attempt to set up the rolling PTC was given up because of the difficulty in setting up a stable, slowly rolling spacecraft. With a crew man awake at all times, the simpler PTC attitude hold for an hour and then roll ninety degrees to a new attitude for another hour was selected. The Guidance team began looking ahead to later darkness opportunities while in the shadow of the moon to permit guidance system alignment checks or a new earth/sun technique for checking the present alignment. This Guidance initiative was typical of a fairly steady stream of configuration choices and future possibilities to consider and plan for. All shifts had some level of traffic like this as the mission progressed.

  Span was also considering the pros and cons of jett
isoning the SM in order to burn most of the descent fuel and achieve a one-day landing earlier time of 118:00 GET time. The two concerns for this option were the cold environment to which the head shield and the CM RCS would be exposed and the fairly small amount of descent fuel which would be left. None of us liked the idea of jettisoning the SM and dealing with the uncertainty of the cold environment. Unless we could get a lot more confidence, that option would not be exercised. Still, there was not a real urgency to decide that issue at this time and they continued with the analysis of that configuration.

  67:00 GET (11 hours and 5 minutes since problem start)

  Near the end of the Black team shift, the consumable projections were solid and MCC was comfortable with the plan. Four open issues were: SM jettison, CO2 removal, recharge of the CSM entry batteries and the entry procedures. Gerry and the Gold team were coming on duty and were well up to speed because they were following in MCC for hours before their on-duty call.

  A number of flight controllers and I went to a press conference at about 9 a.m. CST for the regular change of shift briefing. At the press conference, the decision on the exact return plan was left open because we had a management briefing to discuss it scheduled after the press conference. I have never been to a press conference when the press, many of whom we knew well and by first names, was so supportive. They all cared as much for the safety of the astronauts as any of us doing the briefing.

  69:30 GET (13 hours and 35 minutes since problem start)

  A meeting was held with all of the executive management from NASA HQ, all the major NASA and contractor executives at JSC and representatives from other centers and the DOD recovery manager. Gerry and I attended and I recapped the events of the night before with the stipulation that we did not know the exact root cause of the original problem. But I did recount all the downstream effects and what the team did to cope with them. This got us to our present posture, still about ten hours to go before the PC+2 burn. Continuing with the RETURN HOME options, they encompassed the total range of possibilities. All speed up burns were scheduled right after the most efficient time (i.e. behind the moon) plus two hours to be well around the moon and in sight of our Earthbound communication coverage. The options were:

  No speed up maneuver, landing in Indian Ocean at 155 GET.

  Descent burn of 850 fps, landing in primary mid-Pacific at 143 GET.

  Descent burn of 2000 fps, landing in South Atlantic at 133 GET.

  Descent burn of 4800 fps, landing in mid-Pacific at 118 GET. Requires SM jettison.

  SPS burn of 4800 fps, landing in mid-Pacific at 118 GET.

  The recovery capabilities were much stronger in the planned mid-Pacific with a carrier and helicopters.

  Option #1 was the longest return time to a difficult area with only aircraft support. Recommendation – NO.

  Option #2 was conservative on fuel, leaving a large reserve for mid-courses, Best recovery posture, solid plan for consumables. RECOMMENDED.

  Option #3 left LM descent prop nearly depleted, not much margin for mid-courses, South Atlantic recovery posture is only aircraft, no surface ship coverage. Saves ten hours over option #2. Not enough gain versus downsides – NO.

  Option #4 improves return time by a day, twenty-four hours. But the SM jettison introduces new failure potential – NO.

  Option # 5 improves return also but requires a power up and likely depletion of the CSM entry batteries, which may or may not be rechargeable. Also requires using the SPS engine where the problem started – NO.

  Our recommendation was Option #2. Deke Slayton had a question about one of the faster return options. I answered. Gerry and I were still bracing for a prolonged discussion. The senior NASA official was Dr. Thomas Paine, the NASA administrator. He did not know us, but George Low, his deputy, did. After the one question from Deke, Dr. Paine took over and thanked me for the discussion and the clarity of the situation report and then he said, “I only have one question –-- What can we do to help you men?” WOW – Gerry and I looked at each other and I replied that we believe that we have all the needed support in place, but, “Thank you for the offer. We will certainly ask if we identify something needed.”

  The meeting was over. The Administrator was satisfied and offered his full support. It was only later that I had time to reflect on that simple exchange and what it displayed about how NASA operated in those days. I can only assume that George Low “sold” the MCC team to his boss, probably on the airplane ride to Houston. It was an empowering conclusion to what could have been a much tougher meeting. I have thought about it often in later years and marvel at the delegation of trust that Dr. Paine bestowed on our team. Quite a man – Quite a leader. The return plan was settled.

  About 70 hours GET (14 hours since problem start)

  The RETURN-HOME STEP #4 (final) plan was confirmed with the same plan that we preliminarily sent to the crew at 63:05 GET (7:10 since problem start). We still had the CO2 fix, the battery charging and entry procedures to solve. Plus a raft of non-standard operations and procedures for the spacecraft, crew and mission still needed near continuous attention. The team was in full-court press mode. Outside the MCC floor, the engineering talents of every involved organization and company were fully engaged, from the prime contractors – North American Rockwell and Grumman – to the flight software at MIT, the space suit builders and to the laboratories and simulators across the country. Most of the crews assigned to upcoming flights, plus Ken Mattingly, were verifying procedures, duplicating the planned propulsion burns and the entry scenarios in the simulators and trainers. Another recovery ship was being added for the mid-Pacific landing site. And when people showed up and were un-busy, they could always get coffee for others. This was “whatever-it-takes-time.” Outside the team, we gradually became aware of the outpouring of concern, support and prayers from fellow humans across the globe. And it seemed to grow in intensity and scale all the way through landing and recovery.

  As the time for the PC+2 maneuver approached, Gene and his White team went through a review of the mission rules for the burn and the attendant variations. The burn went just fine, the power down started to about twelve amps, equivalent to three one-hundred-watt light bulbs. Apollo XIII was on the way home. After this shift, Gene took the entry team offline and continued the work of detailing the CSM and LM plans for the end of mission phase.

  CO2 Fix

  90:09

  GET (34 hours and 14minutes after the start of the problem)

  Joe Kerwin, the Capcom who followed it the whole time, began to read up the procedure for using the CSM LIOH canisters to scrub the CO2 out of the LM cabin. Once implemented, the CO2 readings dropped from seven-and-a-half mm Hg to zero point seven mm in short order. The RETURN-HOME STEP #5 worked fine, full credit to the Crew Systems Division guys. A later seven feet per second mid-course correction was performed at 105:18 GET. The LM consumable status at 107 GET continued to improve to the point that the required consumables would have been supportable by the LM Ascent stage only consummables, augmented by the PLSS (backpack) O2 and H2O as supplements.

  The MCC pipeline was regularly delivering a number of new and non-standard checklists for required activities. There were some very effective leaders of specific areas and probably hundreds of operations and engineering personnel evaluating all options and astronaut crews testing each procedure in the simulators.

  Soon after the explosion and the CSM was powered down, Gene had gathered up most of his team offline in one of the staff support rooms and started to assess the situation. Very quickly, John Aaron announced that we did not have enough CM battery power onboard. Gene then put John in charge of approving all power usage for the entry phase. John took the challenge and did not go back to front room console duty until time for the entry phase. John was always effective at laying out a concept and power profile as a starting point and then engaging a wider group of experts to buy-in and refine the concept into a workable timeline. In this case, a back room expert name
d Jim Kelly was the key critical help to John in getting the solution ready for wider participation. A well-analyzed timeline was a prerequisite for the detailing of a checklist of “circuit breakers and switches.” In the hours before PC+2, the LM team did not want to commit any power to the CSM. Nevertheless, John still saw his work as having two options – one without a LM recharge of the CSM batteries and one with the recharge.

  As a result of PC+2,the return trip was shortened by twelve hours and the team had the opportunity to see the LM power down to twelve amps. The support for a recharge improved. The team first had to devise an entirely new procedure for charging the CSM batteries. Jim Kelly (CSM) took the lead for this critical invention, with support from Bill Peters of the LM team, while John Aaron continued with the entry plan.

  The spacecraft design for normal power transfer was from the CSM to the LM. The new procedure (from the LM to the CSM) had to be ready by the time when there was sufficient confidence in the LM power situation to charge the CSM batteries. Also, the solution was complicated by having to power up a Main DC bus and a Main AC bus plus its associated inverter in the CSM and live within the current limits of a seven-and-a-half amp circuit breaker on the charging line. It also required careful closeout once done. And it required Jack Swigert to configure the CSM switches and circuit breakers by flashlight and in the cold. This critical checklist was prepared almost entirely by Jim Kelly (CSM) and Bill Peters (LM). All done successfully.

  From about 112 GET to 129 GET, LM power was used to bring the half depleted battery A to full charge and, finally, to top off the other two entry batteries. This was a small fifteen percent increase, but which proved very helpful in providing John’s team with just enough power to ease some of the earlier difficulties in fitting the desired power-up steps to the power available and it resulted in a less time-compressed timeline. In retrospect, the LM power was managed conservatively and that was understandable. The LM cabin had been cold, cramped and with difficult sleeping conditions. Even so, the crew never complained and performed heroically.