For almost two decades, the United States and Russia have collaborated in the grandest scientific, engineering, and human endeavor ever undertaken in human history: the construction of the International Space Station. Since the days of Shuttle-Mir, these two former superpowers—which once viewed each other with mistrust through the lens of differing political ideologies—have forged an enduring partnership. It has not been an easy journey and down-to-Earth politics has often strained relations, but it seems likely to continue. Yet, as described in last week’s history article, the seeds of this partnership were first sown way before Shuttle-Mir and the ISS … back in the early 1970s, when America and the then-Soviet Union emerged for the briefest of times from the “deep cold” of the Cold War and staged a manned space mission together. It was known as the “Apollo-Soyuz Test Project” (ASTP).
By 21 July 1975, after a successful docking in orbit and two days of joint operations between Apollo astronauts Tom Stafford, Vance Brand, and Deke Slayton, and Soyuz cosmonauts Alexei Leonov—the world’s first spacewalker—and Valeri Kubasov, the end of the mission was in sight. On that day, Leonov and Kubasov made their final maneuver: a 4.5-minute “burn” of their retrorocket to begin a ballistic descent through the atmosphere to land back on Soviet soil. Within half an hour, recovery pilots could hear the cosmonauts chattering on the radio and a helicopter-borne television crew showed the descent module, hanging beneath its single parachute as it floated down toward a 1:50 p.m. local time touchdown. The landing occurred in central Kazakhstan, and shortly thereafter both cosmonauts extricated themselves from the vehicle and waved at photographers.
Since it had long been evident that ASTP would be the final American manned mission for some years, NASA opted to take advantage of the Apollo spacecraft’s consumables and keep it in orbit for a full nine days of research work, returning to Earth on 24 July. It would be the last time that astronauts would perform such tasks for the better part of a full decade. Earth observations were aided by Apollo’s low orbit, and Stafford made reference to this effect in a Houston press conference on 9 August. “Deke made a comment that it looked like the thunderstorms came a quarter of the way up in altitude to our altitude, but, for example, on a clear day over El Paso International Airport, where we usually land going to the west coast, right there were the runways, the taxiways, and the hangars. It was a clear day and you could see them, just visually, with your eyes.” Another point, he added, was the earlier higher orbital latitude, which permitted them to see much broader swathes of Earth … and a realisation that “so much of this world … is just desert and mountains.”
Major work on 23 July included Doppler tracking and geodynamics experiments, which employed the Applications Technology Satellite (ATS)-6 in a geostationary orbit above the equator to assess techniques for monitoring terrestrial plate tectonics and mass anomalies. ATS-6, which was launched in May of the previous year, had already seen significant service during ASTP as a communications relay, providing voice links between the spacecraft and Mission Control for up to 55 percent of the time. Its use marked the first occasion on a manned flight in which such a satellite had been employed for voice communications. The docking module, jettisoned in these latter stages of the mission, provided valuable data in support of the Doppler experiment and would eventually re-enter the atmosphere to destruction in August 1975.
As they packed up the last of their equipment on splashdown day, 24 July, Capcom Bob Crippen—who would incidentally fly the United States’ next human space mission, the maiden shuttle flight in April 1981—told them that the weather conditions in the primary recovery zone were good. The de-orbit burn was executed at 3:37:47 p.m. CDT, and six minutes later Apollo’s service module was jettisoned, leaving the cone-shaped command module alone for a fiery plunge back to Earth.
During re-entry, Brand assumed the left-hand seat, with Stafford in the middle and Slayton on the right side. The computer used a series of tiny reaction control thrusters to control re-entry and aim for the recovery point. One of Stafford’s tasks was to deactivate these thrusters, whose propellants included a particularly noxious chemical, called nitrogen tetroxide, at an altitude of around 15 miles. After descending another six miles or so, the drogue chute and finally the main canopy were supposed to automatically deploy, followed by the opening of a vent valve to admit fresh air into the cabin. The command module would then splash gently into the Pacific Ocean, a few hundred miles northwest of Hawaii. It did not work out that way … and almost led to the death of the entire crew.
In their respective accounts of what happened, neither Brand nor Stafford could be entirely sure of who did what—or who did not do what—but certainly the re-entry phase was considerably more dynamic than anticipated and an irritating squealing noise in their headsets momentarily distracted them. For whatever reason, Stafford did not throw the switch to deactivate the reaction control jets. “The noise made it impossible for us to hear each other or Houston,” he wrote in his autobiography, We Have Capture. “In order to be heard in the cockpit, we had to shout. Either the noise kept Vance and Deke from hearing me or I was too distracted to give the command.”
Nine miles above the Pacific, as intended, the drogue chute deployed and the vent valve opened, but the reaction control jets were still spurting and the valve admitted not fresh air … but a potentially lethal dose of nitrogen tetroxide. “The vent valve was located right below the … thrusters,” Stafford wrote, “and it sucked some of the nitrogen tetroxide into the cabin.” As soon as he saw the yellowish-brown mist and sniffed its pungent, acrid odour, he knew instantly what it was. So did Brand and Slayton. Moreover, all three instinctively knew what it could do to them.
Nitrogen tetroxide is one of the most deadly chemicals used in manned spaceflight; highly toxic and extremely corrosive, if inhaled at concentrations of just 400 parts per million, it can kill. In the same vein, it is one of the most important chemicals ever used in the field of spacegoing rocketry: it is hypergolic with various forms of hydrazine, meaning that it can burn on contact, without a separate ignition source. As Stafford saw this noxious stuff steadily filling the cabin, he immediately flipped a pair of switches to shut off the propellant gate valves and cut the fuel supply … but since some residue remained in the lines, it gave little relief. As the fumes set to work irritating eyes and burning faces, noses, mouths, and throats, Stafford, Brand, and Slayton began hacking and choking uncontrollably.
The main parachute canopies deployed as scheduled and the command module struck the Pacific at 4:18:24 p.m. CDT—“a real bone-cruncher,” Stafford remembered, “nearly 10 positive Gs”—and promptly flipped into the “Stable 2” position, with its nose submerged and the crew hanging from their harnesses. Brand was seated closest to the vent valve and quickly passed out, his hands clenched. Slayton, too, was feeling nauseous, and it was Stafford who loosened himself and grabbed three sets of oxygen masks. “For some reason, I was more tolerant,” he explained later. “I knew that I had a toxic hypoxia … and I started to grunt-breathe to make sure I got pressure in my lungs to keep my head clear.” He secured a mask over the unconscious Brand’s face and held it there until he revived, thrashing his arms about for several seconds. At length, with all three astronauts breathing on masks, they were able to inflate airbags on the apex to right the command module into a “Stable 1” position in the water and Stafford fully opened the vent valve. With a sudden influx of fresh air, the remaining nitrogen tetroxide fumes quickly disappeared.
They were by no means out of the woods yet. “Then it was my turn to screw up,” Slayton wrote in his autobiography, Deke, co-authored with Michael Cassutt. “We were in the water a few minutes, still hacking, when they dropped the frogmen. One of them appeared in the window and like a dumb shit I gave him the thumbs-up sign! Everything’s okay. Well, of course, it wasn’t … but everybody outside thought it was, so there was no special effort to get us out of the command module.”
Splashdown came a few miles from the recovery ship, USS New Orleans, and within minutes Stafford, Brand, and Slayton were aboard a helicopter, still coughing, but not thinking too much about what they had just endured. Only when they were seated at a press conference on the ship’s deck—and, ironically, whilst speaking to President Gerald Ford on the telephone—did they inadvertently drop out that the mission had gone well, except for the final few minutes. As soon as chief flight surgeon Arnauld Nicogossian learned about the nitrogen tetroxide, he stopped the conference and whisked all three men down into the New Orleans’ medical bay.
Cortisone was pumped into them to reduce lung inflammation and, in Slayton’s words, it was a good thing: they had felt fine during the helicopter ride, but within three-quarters of an hour, they suddenly began showing the symptoms of full-blown pneumonia! “The next day,” Stafford recalled, “we saw X-rays and our lungs, where they were completely clear before and right after landing, the next day they were all white.” It was, said Nicogossian, a classic case of infiltration: an accumulation of abnormal substances in the body. The astronauts were hospitalized at the Tripler Army Medical Center in Honolulu for two weeks, during which time it was found that they had inhaled 300 parts per million of the toxic gas.
Had Stafford not reacted as he did and applied the face masks, all three would certainly have been dead in a matter of minutes.
The final part of this article will appear tomorrow.