THE SIX CIRCUITS OF SIGMA

Throughout training, Schirra and the other Mercury astronauts would allow only O’Hara to draw blood samples, fearing that the physicians – highly educated, but lacking practical skills – would collapse a vein. She came to their quarters every morning during training, was among the last to see them off before a flight and, as a devout Catholic, “counted beads when we went on missions’’. One day in September 1962, Schirra and his backup, Gordo Cooper, decided to give O’Hara their daily urine sample… with a difference. They filled a huge bottle with warm water, added iodine to colour it and laundry soap to make it foamy, then dumped it onto O’Hara’s desk. The two astronauts, for good measure, tagged the bottle with the time of delivery in Greenwich Mean Time and added a handful of lollipops, then disappeared to await their nurse’s arrival. O’Hara took one horrified look at Schirra’s enormous specimen bottle and burst into tears of laughter. Schirra would later dedicate a photograph of O’Hara, clutching the bottle, with the inscription: “Gotcha!”

By this time, both he and Cooper had been preparing for Sigma 7 for almost two months. After NASA managers decided to proceed with a six-orbit mission, their names had been announced on 27 July and last-minute adjustments to the flight plan were being made as late as September. Unlike the test flight of Friendship 7 and the exclusively scientific nature of Aurora 7, the mission internally dubbed ‘Mercury – Atlas 8’ would be devoted to engineering objectives, with Schirra expected to focus on the management and operation of his spacecraft’s systems, including the hydrogen peroxide attitude-control fuel and electrical power. In fact, the only ‘scientific’ experiments on the agenda would be an attempt to observe a ground- based xenon floodlight at Durban in South Africa, which would blaze with 140 million candlepower, and a one-million-candlepower quartet of flares at Woomera, which had eluded Carpenter. A few terrestrial and weather photography tasks were timelined and eight ablation panels were fused onto Sigma 7’s hull to evaluate passive thermal effects on a variety of materials.

Technical planning for such a lengthy mission had begun in February, when it was recognised that oxygen supplies, reaction-control system reserves and power considerations had to be taken into account. A three-orbit Mercury mission, with all systems operating, consumed about 7,080 watt-hours of battery power from an available 13,500 watt-hours, but a six-circuit plan was predicted to leave a reserve supply of only 6.7 per cent. Engineers insisted that at least a ten-per cent post­landing reserve should be available as a safety factor and made recommendations as to how to achieve this: either that some unneeded systems be turned off during a substantial portion of the flight or that telemetry-transmission and radar-beacon operations be transferred to ground command. This, it was felt, could raise the reserve power levels as high as 15 per cent and provide a healthy safety margin. Oxygen posed another problem: some 1.9 kg was expected to be consumed during a six-orbit flight, leaving an insufficient remainder for emergencies. Unwilling to relax safety rules, a vigorous effort was implemented to reduce cabin-leakage rates to 600 cm3 per minute, two-thirds of the previous value, and a higher capacity of lithium hydroxide would be carried to remove carbon dioxide from the cabin atmosphere throughout the longer mission. (Eventually, the cabin oxygen-leakage rate was reduced to just 460 cm3 per minute.)

Even as these efforts were ongoing, NASA and McDonnell engineers had their sights set on a much longer Mercury mission, up to a day in duration and completing as many as 18 orbits. However, this would very much depend on the ability of Sigma 7 and Schirra to validate the changes and verify that an astronaut could indeed tolerate the weightless environment over long periods. The Mercury Project Office also suggested alternating a combination of automatic and manual modes to provide safer fuel reserves at the end of a flight; then, in the case of a malfunction in one of the modes, Schirra would be assured of an adequate supply in the other. Recovery procedures also needed adjustment, for Sigma 7’s flight path during its fourth, fifth, sixth and (conceivably) seventh orbits predicted a splashdown point in the northern Pacific Ocean, some 440 km north-east of Midway Island.

Mission rules dictated that a contingency recovery capability must be in place within 18 hours after splashdown; a capability easily met for flights lasting up to six orbits, but requiring additional recovery forces for seven orbits. Consequently, Sigma 7 would be restricted to six circuits of the globe. Two Mercury capsules – Spacecraft No. 16 and No. 19 – had been delivered to Cape Canaveral in January and March 1962, respectively, with the first of these selected for the mission. By April, work needed to validate the capsule for its lengthy sojourn was well underway: temperature surveys of its critical points were complete, its environmental system passed altitude-chamber tests and its reaction-control system was put successfully through its paces. However, niggling glitches with emergency oxygen rate valves, water coolant and a higher-than-allowable oxygen leakage rate conspired to delay Sigma 7 past August to at least 18 September and, ultimately, into the first week of October.

Aurora 7’s fuel-thirsty mission also prompted engineers to slightly redesign the spacecraft’s attitude-control thrusters. Despite Scott Carpenter’s reservations, the heavy periscope – which he felt was useless on Earth’s night side – would be retained. The post-flight inspection team had reported that Aurora 7’s landing error had been caused by a faulty yaw attitude, mainly because the astronaut had used the trapezoidal window as his primary means of reference. However, it was speculated that the periscope might have assisted in correcting the attitude and reducing Carpenter’s overshoot. As a result, Schirra would test both periscope and window as a spacecraft-attitude reference point on Earth’s day and night sides. He would then check his visual judgement to gauge his attitude and compare his own abilities against those of the periscope and the spacecraft’s instruments. Retaining the periscope, though, proved unfortunate for the Goddard Space Flight Center’s Albert Boggess, who had hoped to fly his ultraviolet airglow spectrograph in its place.

Additional fuel-saving techniques, at Carpenter’s prompting, included integrating the control-mode selector switch with the control system, thus ‘sealing-off’ the high thrusters until they were needed for fast-reaction manoeuvres. A radiation dosimeter was also installed in Sigma 7’s hatch, the astronaut was provided with a hand-held unit and several more instruments were affixed to his pressure suit, thanks to the effects of the Atomic Energy Commission’s Operation Dominic high-atmosphere nuclear test in July 1962. This test, conducted high above the Pacific Ocean, had created a new zone of radiation which was already thought to have affected the solar batteries of several satellites, including the Ariel 1 physics mission. Admittedly, by the end of August, the radiation hazard seemed negligible, but the doubts of Project Mercury managers remained.

Schirra’s Atlas rocket, too, had experienced its own fair share of problems. Originally scheduled to be delivered to Cape Canaveral in July, it failed its initial composite test at Convair’s San Diego facility and arrived the following month. Next, the Air Force revealed that its military Atlas programme had suffered four recent turbopump failures and advised NASA that the rocket assigned to Sigma 7 would be put through a flight-readiness static test-firing. This postponed the launch by another week, but, even before the test was made, a fuel leak was found in a seam weld, effectively pushing the mission back from 24 September to 3 October. Still, Schirra’s Atlas promised to be the safest so far: its engines would utilise hypergolic fluids instead of pyrotechnics, thus eliminating a two-second ‘hold-down’ at ignition, which saved fuel and provided for smoother initial combustion. Additionally, baffled injectors prevented combustion instability.

Five relay stations aboard a quintet of Air Force C-130s, based in Florida, Puerto Rico and on Midway Island, would augment the tracking network by covering areas previously out of communications range. Nineteen ships stood by in the Atlantic and nine in the Pacific, while no less than 134 aircraft covered the primary and secondary splashdown areas. In total, around 17,000 personnel would support the Sigma 7 recovery effort.

Early on 3 October, Schirra was awakened in the quarters of Hangar S by Air Force flight surgeon Howie Minners, after which he showered, dressed and ate the traditional pre-launch breakfast of steak and eggs with Bob Gilruth, Walt Williams and the newly-appointed Co-ordinator of Astronaut Activities, Deke Slayton. Another item also took pride of place on the breakfast menu. The previous evening, Schirra and Slayton had gone fishing – Cape Canaveral being renowned for its excellent surf fishing, especially in the spring and autumn – and had hooked several bluefish. They were ‘‘in the five-pound range,’’ wrote Schirra, ‘‘but they fought free by severing our leaders with their razor-sharp teeth. I managed to land one by slinging it on the beach and pouncing on it before it could wriggle back to the surf”. The bluefish, it seemed, was not the only individual with a shock in store. The two astronauts were aware of a military Thor-Delta rocket on a nearby launch pad, but they did not know how close it was to launch!

‘‘It wasn’t until we heard a roar that we realised the Thor-Delta was lifting-off,’’ wrote Schirra. ‘‘We were looking right up the tailpipe of its monster engine and we knew right away that we were in the danger zone. Had there been an abort, it would have been a bad day for Mercury, with the chief astronaut and the pilot of MA-8 incinerated like the legendary rattlesnakes.” Fortunately, he added, the bluefish for breakfast the next morning was delicious. Another pleasant surprise at the breakfast table, literally hot off the press, was a copy of the New York Times. It had been flown from New York to Florida that very morning, at no small expense, and Schirra was so impressed that he kept it.

The drive to the launch pad was uneventful, with the exception that the astronaut fell asleep, to be awakened – for the second time that morning – by Howie Minners. Several months later, Gordo Cooper would actually doze off whilst atop the Atlas rocket, waiting out a hold in the countdown. It was testament, Schirra explained, “to our training, and it shows the confidence we had in the people who supported us, both from NASA and the contractors. We could ask questions of technicians at the pad or construction guys and we’d get straight answers. We could call the executives, like Mr Mac of McDonnell, and they too would level with us. That’s one reason we completed Mercury with seven healthy astronauts’’.

By 4:40 am, Schirra, assisted by Cooper and Pad 14 leader Guenter Wendt, was aboard Sigma 7. The countdown proceeded with exceptional smoothness, the only minor problem being a radar malfunction at the Canary Islands tracking station, and the United States’ third orbital mission set off at 7:15:11 am. In his post-flight debriefing aboard the destroyer Kearsarge, Schirra would describe the ascent as “disappointingly short’’, with all of his training to handle emergencies rewarded by a perfectly nominal climb into orbit. “I still believe that the amount of practice we had prior to [orbital] insertion is important,’’ he debriefed, “in that you must be prepared for reaction to an emergency, rather than thinking one out.’’

Sigma 7’s rise was not, however, entirely nominal. Ten seconds after liftoff, it became clear that the clockwise roll rate of the Atlas was greater than planned, giving flight controllers cause for concern. “My course was being plotted against an overlay grid called a ‘harp’, since it’s shaped like the musical instrument,” Schirra recalled in his autobiography. ‘‘Green lines in the middle of the grid designate the ‘safe’ zone and on the outer limits the lines go from yellow to red. I was headed into the yellow area. If I had reached the red, there was a likelihood that the Atlas would impact on land, possibly in a populated area.’’ Such a dire eventuality would have forced the Cape’s range safety officer to abort the mission, ejecting Sigma 7 and destroying the rocket. Indeed, the primary and secondary sensors within the Atlas had registered a ‘rifling’ roll only 20 per cent short of an abort condition…

Thirty seconds into the climb, Schirra reported that the Atlas was ‘‘getting noisy’’, after which he briefly lost contact with the control centre. ‘‘You had your transmitter keyed,’’ Capcom Deke Slayton told him two minutes after launch, when communications were restored. ‘‘That’s why we couldn’t read.’’ The remainder of the ascent proceeded normally and, at 7:18 am, Slayton radioed Schirra with the cryptic, but loaded, question: ‘‘Are you a turtle today?’’

The roots of the strange question were explained by Schirra on his website, www. wallyschirra. com. He tells the tale of a good and noble man, sickened by the vulgar minds of those around him and gradually driven to despair over whether he will meet someone of his own intellect. At length, he retreated, turtle-like, into a protective shell and found his only respite in the consumption of alcohol (“for purely medicinal purposes, of course”). Over time, he sought out other like-minded individuals to join his ‘Ancient and Honourable Order of Turtles’ drinking fraternity. However, he needed money and gambled his most prized possession – a donkey, which he had raised from birth – on a horse running at long odds at the local track. Fortunately, he won the bet and kept his donkey. To commemorate his triumph, all future members of the fraternity, when asked ‘‘Are you a turtle?’’ were expected to reply, without blinking or hesitating, ‘‘You bet your sweet ass I am!’’ Failure to do so would consign the victim to buy drinks for everyone close enough to have overheard the question.

Unfortunately for Schirra, the question had been asked over a ‘hot-mike’ and, if he did not answer correctly, the number of people ‘within earshot’ demanding alcoholic beverages could have run into hundreds! On the other hand, even though ‘ass’ in this context referred innocently to the donkey, responding correctly to Slayton’s question over the open mike could have led to misunderstanding, embarrassment and a reprimand from NASA. Schirra was in a quandary. Then, he told Slayton ‘‘Going to VOX record only’’ and announced the correct response, privately, into Sigma 7’s on-board voice recorder. Schirra would not need to buy drinks, but Slayton had scored his own launch-day ‘gotcha’ and put his friend briefly in the hot seat.

Schirra’s membership of the Turtles would arise again during his Apollo 7 mission in October 1968, with the exception that this time he would gain his revenge on Slayton, by asking him – through the capcom – if he was a turtle. Even President Kennedy, also a Turtle, was asked at a press conference about his membership of the order, to which he responded that he would buy the questioner a drink later. Aside from the time-honoured tale of its formation, it can supposedly trace its origins back to the Second World War, when pilots used it as a means of amusement whilst relaxing between combat missions. ‘‘It was not meant to be serious,’’ founder Hugh McGowan once told his son, ‘‘it had no constitution or by-laws and was a relief from the horrors and dangers we saw every day on our missions.’’ To attain membership, candidates had to answer correctly at least four out of 25 questions; each of which, although suggestive of an obscene answer, was actually quite innocent. Examples included: What does a woman do sitting down, that a dog does on three legs and a man does standing up? (Shake hands), What is a four-letter word, ending with ‘k’, that means ‘intercourse’? (Talk), What is long, hard and filled with seamen? (A submarine) and so on.

Schirra’s hot seat rapidly turned into a weightless one, when, a little more than five minutes into the flight, the Atlas’ sustainer shut down and Sigma 7 cleanly separated from the rocket. ‘‘I have SECO,’’ the astronaut announced as sustainer cutoff occurred, then continued ‘‘Cap sep and in aux damp and it’s very pleasant. Going to fly-by-wire.’’ By now at an altitude of some 280 km and an orbital speed of 28,250 km/h – higher than any other Mercury astronaut – Schirra set to work evaluating his spacecraft’s systems. ‘‘With my eyes fixed on the control panel, studiously ignoring the view,’’ he wrote later, ‘‘I began a slow – four degrees per second – cartwheel. Once in the correct orbital position, I checked my fuel. I had used less than half a pound of hydrogen peroxide. The thruster jets worked perfectly. They responded crisply to my touch and shut off without any residual motion. I was able to make tiny, single-pulse spurts, the micromouse farts, to assume an exact position.” During this time, Schirra oriented his capsule to gain a better view of the sustainer as it tumbled away. He would conclude in his autobiography that his efforts demonstrated that rendezvous in space was possible. On his next mission, in barely three years’ time, he would achieve just that.

The manual system, however, seemed somewhat “sloppy”, with a tendency to ‘overshoot’, and Schirra switched next to the third control mode: the autopilot, which he referred to as ‘‘chimp mode’’. At around this time, his pressure suit began overheating. The suit had been one of Schirra’s areas of responsibility during training and he would comment later on the seriousness of the situation; in fact, Flight Director Chris Kraft even considered terminating the mission after just one orbit. Before launch, Schirra had developed his own technique should overheating occur: he would inject cool water very slowly into the system, advance the temperature knob by half a mark at a time and then wait for ten minutes. He did not want to rush the water, lest the heat exchanger freeze. It worked. By the end of his first orbit, the temperature had dropped to 32°C, which Schirra considered ‘‘hot but not unbearable”. Flight surgeon Chuck Berry advised Kraft to press on with a second orbit and the happy news was relayed to Schirra by Capcom Scott Carpenter, based in Guaymas in Mexico.

Schirra was pleased, not only with the prospect of a full-length mission, but with the realisation that the problem was ‘‘solved through no great amount of ingenuity, but the point was it was solved by a human’’. The necessity of flying people into space, in his mind, had been vindicated. After the mission, Schirra would receive a plaque, signed by Frank Samonski of the spacecraft’s environmental control system team and emblazoned with the legend that they had ‘sweated more than you did during the first orbit of MA-8’. Attached to the plaque was the valve used by Schirra to control the water flow to his suit.

Later, as Sigma 7 began its third orbit, Schirra entered a period of drifting flight, during which time he undertook a psychomotor experiment: closing his eyes and touching certain dials on the control panel. ‘‘I missed only three out of nine,’’ he wrote later, ‘‘concluding that my sense of direction and distance had not been impaired by weightlessness.” Repowering Sigma 7 over the Indian Ocean, Schirra switched back to fly-by-wire and successfully fixed his attitude using the Moon in the window as a reference point. Aware that flight controllers had been closely monitoring his fuel consumption, he expressed a hearty ‘‘Hallelujah!’’ when Capcom Gus Grissom, situated at Kauai in Hawaii, radioed approval to fly a full six orbits.

After another hour of drifting, during which he focused his attention on Earth observations and photography, Schirra told Capcom Al Shepard, based on a tracking ship in the Pacific Ocean, that his pressure suit temperature had dropped to a more comfortable 20°C and his fuel in both the manual and automatic tanks stood at around 80 per cent; good news, it seemed. On the fifth orbit, busily working through his pre-retrofire checks, Schirra was infuriated to hear a voice interrupt from Quito in Ecuador. ‘‘We had what we called a ‘mini-track’ there,’’ he wrote, ‘‘a miniature tracking station, and it wasn’t supposed to come on the air except in an emergency.” The speaker asked the astronaut if he had any words for the people of South America. Schirra, irritated, wished them “Buenos dias, you all’’ After splashdown he would receive a handful of telegrams, complaining of his brusqueness. “But there was one,’’ he wrote, “I treasured from a US diplomat in Ecuador. He said in effect that Schirra had proved his devotion to the people of Latin America by wishing them a good day.’’ By addressing them as ‘you all’, the diplomat continued, Schirra was simply noting that he would soon become a resident of Texas. . .

Scientific experiments on the mission, thankfully, had been trimmed down, lessons having been learned from the grossly overloaded work schedule on Scott Carpenter’s flight. Indeed, more time was granted to Schirra to complete each of his tasks. One of the earliest, a little under an hour after launch, was another attempt to see the million-candlepower flares from Woomera in Australia. Initially, Schirra thought that he had seen them – only to discover that he had actually witnessed enormous lightning flashes – and, when notified that the flare firings were imminent, was hampered by heavy cloud cover. A similar test over Durban in South Africa was ruined by rain showers. The astronaut also had the opportunity to examine the fireflies observed by Carpenter and John Glenn, reporting them to be far too small to photograph and moving, in clouds, at a slower velocity than Sigma 7 itself.

Another experiment was conducted on both Schirra and his capsule. Since the Operation Dominic detonation in July 1962, concern had remained over radiation intensities in low-Earth orbit and the astronaut was outfitted with five thermo­luminescent dosimeters over his eyes, on his chest and on his interior thigh. Sigma 7 was instrumented with two nuclear emulsion packs, on either side of the control panel, to monitor its internal proton dosage. No major issues were raised, with upward of 65 per cent of the electrons from the artificial ‘belt’ of radiation created by the Dominic test having energies less than 1.3 MeV. This, it was noted, was insufficient even to penetrate the capsule’s hatch cover, its least-protected region. Post-flight analysis concluded that the radiation had a negligible impact on both Schirra and his spacecraft.

Preparations for re-entry commenced over Africa, when Schirra transitioned to fly-by-wire control to orient Sigma 7 using celestial reference points, then switched to the autopilot to ensure that it operated satisfactorily in this mode. ‘‘The flight plan called for me to position the spacecraft using manual controls,’’ he wrote in his autobiography, ‘‘then switch to automatic for retrofire, because the power of the big thrusters offsets the unbalancing force of the retrorockets. The retrorockets exert their force through the centre of the spacecraft, so they don’t kick it off course.’’ Manual control during retrofire and throughout re-entry had always remained a reserve option for the astronauts. Indeed, on Gordo Cooper’s Mercury mission in May 1963, he would experience a failure of his electronics systems, forcing him to initiate and guide retrofire entirely by hand.

In Schirra’s case, however, the retrorockets of his ‘‘sweet little bird’’ fired perfectly and in sequence under automatic conditions at 4:07 pm. Shortly thereafter, he switched the capsule to fly-by-wire, although Sigma 7 was ‘‘steady as a rock’’, with

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so much fuel remaining in its automatic and manual supplies that he had to ‘dump’ it during re-entry. Minor adjustments were needed to damp out wobbles after the jettisoning of the retrorocket package, but the descent proved to be as ‘textbook’ as the mission itself. Schirra manually deployed the drogue and main chutes, his elation evident in his words to Capcom Gus Grissom, and splashed down just 7.2 km from the Kearsarge at 4:28:22 pm. Within minutes, wrote Schirra, ‘‘a whaleboat was alongside and the underwater team had the flotation collar in place’’. Stepping aboard the Kearsarge, he noted that it was barely ten hours – and six full orbits – since his launch from Cape Canaveral. Another surprise awaited him in the admiral’s quarters: an oversized urine-collection device, sent specially by Dee O’Hara. Almost identical to the one he and Cooper had dumped on her desk a few weeks earlier, it concluded the perfect mission with the perfect Gotcha.