Power the batteries

The fuel cells were not the only source of power in the spacecraft. A collection of batteries were included and, despite their weight, there were good reasons for their inclusion. The fuel cells had a limited range of output power. They could not deliver more than 1.4 kilowatts at any one time, yet their power output had to be maintained above 400 watts at all times. The demands from the spacecraft were much more variable, especially when the SPS engine was operating. It had sizeable motors that gimballed its nozzle from side to side during a burn, and these made heavy drains on the spacecraft's electrical system. Batteries were a way of smoothing out the load on the fuel cells by supplying extra power during the peaks in demand. At other times, their need to be recharged provided a load for the fuel cells. At the end of the mission, after the fuel cells had departed along with the rest of the service module, the batteries were all that remained to power the command module as it streaked through the atmosphere during re-entry. They were therefore essential!

The CM carried a total of five silver oxide-zinc batteries mounted in the lower equipment bay below the navigation instruments. Two of them were never recharged after launch. Their only use was to provide energy for the various pyrotechnic devices around the spacecraft. These devices separated the launch escape tower, the S-IVB and, at the end of its mission, jettisoned the lunar module. At re-entry, they separated the CM and the SM, jettisoned the upper heatshield from around the spacecraft's apex and deployed the parachutes.

A further three batteries provided supplementary power during busy periods, and became the main power supply through re-entry, splashdown and post-landing operations. It was these that were recharged at times when the load on the fuel cells was low. All five batteries were installed in separate pressure cases and, in case they were to emit gases through failure or improper operation, these could be vented to space to ensure that it did not enter the cabin.

In general, the batteries gave very little trouble. Only once, during the Apollo 7 Earth-orbital flight, were problems encountered when Walt Cunningham discovered that the batteries were recharging more slowly than expected. Then when the CM

separated from the SM for re-entry, the voltage delivered by the batteries fell low enough to make the caution and warning lights "glow yellow the rest of the way", as Cunningham put it. "This was a slightly traumatic experience at this point because we hadn't expected anything like it," he added. However, the spacecraft's systems operated satisfactorily with the slightly low operating voltage.

THE PERSONAL BIT

When humans are cooped up in a spacecraft for a week or two, they have a potential waste and hygiene problem that has to be dealt with just as much as guidance, propulsion or power. In the Apollo era, individual astronauts who were not on a specific flight assignment were regularly sent to do the public relations rounds on NASA's behalf, showing the American taxpayer how their money was being spent. Mike Collins, the CMP for Apollo 11, reported that the all-time favourite question asked of the astronauts by the public was, "How do you go to the bathroom in space?" He answered the question in his autobiography by detailing the 20 steps a crewman had to accomplish to urinate during the Gemini 7 flight by Borman and Lovell.

On Apollo, a crewman had multiple methods of urinating depending on whether he was suited or not and whether he preferred to simultaneously dump the urine into space. If he was suited, urine would be collected by a device worn under the suit which filled until the crewman had an opportunity to dump its contents overboard; a valve in the suit enabled the bag to be drained while suited. However, wearing a suit was not the norm over the span of a mission. Instead, the crew spent most of the coasting period wearing at least their constant-wear garment, and perhaps some coveralls. Urination then required the use of a rollover tube and a short hose that led to a bag. The contents of this bag could be dumped later, or be dumped even as the crewman was filling it, with a bypass valve protecting him from the direct vacuum of space. The exterior of the command module sported two nozzles through which either waste water or urine could be dumped. These were heated to prevent ice forming and blocking the orifices. When the liquid was dumped into space, it sprayed into a gleaming cascade of ice crystals that sparkled in the sunshine. At a press conference, Wally Schirra dubbed this starry display, the "Constellation Urion'', a play on Orion.

Whereas urine could be expelled from the spacecraft, faeces had to be kept on board and returned to Earth for analysis. Defecation was carried out into a bag whose adhesive flange allowed the crewman to attach it to his buttocks. Having finished his motion, the bag was removed and a germicidal sachet added. Once the bag was sealed, the sachet was ruptured and mixed with the contents by kneading.

Water and urine dump nozzles below the roll thrusters on Apollo 10's CM.

However, this wasn't enough because the bag contained air at cabin pressure and, on the final three missions a spacewalk out of the command module's hatch was planned. Therefore the faecal bag was placed in an outer bag with double seals to ensure that the contents would, hopefully, remain there, even when the cabin was exposed to vacuum. However, the Apollo 16 crew had their doubts.

"Our concern was that with cabin depressurisation, the bag would blow up,'' said Ken Mattingly during their debriefing.

John Young agreed. "Boy, would that have been a mess!"

This crew had placed their double-sealed faecal bags into a large black bag to keep them contained, but Mattingly wanted to get as much air out of the bag as possible. "I vented the bag to make sure that the big bag didn't burst. That had nothing to do with the little bags. As far as I know, none of them burst. I didn't open the bag to find out either!''

"Fortunately, you can't really get an airtight seal on those faecal bags,'' said Charlie Duke. "That probably saved us. I'm sure they went down. We filled up that black bag.''

The truth was that this crew for one, at least, did not like carrying their solid waste around with them in the command module. At least the LM crew had to lighten their ship by jettisoning their waste, including any faeces. Mattingly continued, "I guess the rationale for using the supplementary bag first was a holdover from the desire to be able to throw it away, which we weren't allowed to do for other reasons, but I really think that's what you should do.''

"You should have been in the LM when we got rid of it,'' said Young.

"I just don't think you ought to carry that stuff around, if you can avoid it. I think it's a health problem if you ever get some of that stuff loose in there.''

In fact, Apollo 16 was given some preliminary research to do in support of the upcoming Skylab programme. Duke was first to try one of these experiments. "The first time I had to go was right after waking up on the first day. Ken broke out one of those Skylab bags, and I tried that the first time. I thought it worked pretty good. Once you performed the task, the clean up was still as horrendous as ever.''

While on his own in lunar orbit, Mattingly got the task of dealing with human bodily functions down to a fine art. When his crewmates returned, he told them all about it. "Man, one of the feats of my existence the other day was, in 42 minutes, I strapped on a bag, went out of both ends, and ate lunch,'' he laughed, "by doing it all at one time.''

"Fantastic," said Duke. "That's a record!''

"I had this bag on the front end, a plastic bag on my rear, and a juice bag in my mouth,'' laughed Mattingly. "That's the only chance I had all day; with one backside pass.''

Mattingly's mirth continued. "I used to want to be the first man to Mars. This has convinced me that, if we got to go on Apollo, I ain't interested.''

The bags used on Apollo were the same as used on the Gemini spacecraft. Their design included a moulded finger tube. The theory was that the crewman could use it to help dislodge any faeces adhering to their skin. Young and his crew did not like it. "I still don't see any use for that finger in the bag,'' he said during their debriefing.

"That was one thing I was going to add," said Duke. "You want to get that finger out of there."

"Get the finger out of there to keep the faeces from hanging up," affirmed Young, "which it does every time the finger's in the way. All that's going to do is give you a bigger cleanup problem than you already got.''

Mattingly agreed: "I tried doing it the way they suggested - pulling the finger thing out first and then use it afterwards. All that does is smear. Absolutely no advantage to it. It looks to me like you could simplify the bag and remove one more potential weak spot in it by just deleting that whole [finger] thing.''

Frankly, doing a 'number two' on Apollo was no joke. According to Duke, "Our technique was to abandon the [lower equipment bay] to whoever had to go, get naked, and go. That was about a 30- to 45-minute task.''

Apollo 11's Buzz Aldrin had come to a similar conclusion after his flight. ''It certainly is messy and it's distasteful for everybody involved to do it in that particular fashion.''

On the later, longer flights, the crews were finding that towards the end, they were becoming more prone to bowel problems. Apollo 17's Jack Schmitt pointed out the dangers. ''The best thing you can do is to work out some prevention of loose stools rather than trying to handle them. Loose stools is one of the major hygiene, sanitary and operational problems that you can have on a flight. I can't emphasize that more. If it happened on a daily basis, you would eventually cut the efficiency of the crew member as much as 30 per cent. I think it's important to try to understand why Apollo 17 was different than Apollo 16 in the delay of the problem of loose stools till about the eleventh or twelfth day.''

Faecal bags were stored in a container on the right-hand side of the cabin. In case of leakage or burst bags, there was a vent with which any odorous air could be expelled overboard.

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