Shaking Hands in Orbit: the Apollo-Soyuz Test Project

The space programmes of the USA and USSR began in a spirit of bitter Cold War rivalry but by the early 1970s internation tensions had eased a little into a d†étente and what had been unthinkable ten years earlier was possible. In 1975 the world saw the historic meeting in orbit between astronauts and cosmonauts. This was the Apollo-Soyuz Test Project.

The two crews pose together on the ground with a model of their docked craft. Left to right, they are Slayton, Stafford, Brand, Leonov and Kubasov. (image credit: NASA)

From the time of the earliest spaceflights, people had imagined scenarios where humans could be stranded in crippled spacecraft demanding the launch of an urgent rescue mission. Such a mercy flight could take any nation weeks to organise and the stricken crew could in such peril that this would be too late. The human instinct is to help those in danger regards of nationality, creed or other division, so perhaps some other nation, even one normally considered hostile, could send one of its vessels to assist.

This cutaway artist’s impression shows the Apollo and Soyuz connected by the Docking Module. Two astronauts are transferring to the Soyuz. (Image credit: NASA)

By 1969 US and Soviet experts had discussed this scenario and saw that would be far easier said than done. For a start, American and Soviet spacecraft had independently developed docking mechanisms to allow two vessels to join and people to move between them but the two nations used utterly incompatible systems. They used completely different radio frequencies and procedures to perform the docking manoeuver. Perhaps docking the spacecraft together in a rescue mission was not necessary, could the stricken crew don spacesuits and abandon ship, spacewalking to clamber abroad the rescue vessel? Sadly even this would be impossible, US and Soviet spacecraft used completely different atmospheric pressures and mixtures of gases, moving from one nationòÀÙs craft to another could be horrifyingly dangerous. If in, say 1970, the crew of a Soyuz had been unable to return home, an Apollo CSM could have been brought alongside their craft, but the Apollo crew could only be unlookers to the unfolding tragedy, unable to offer material assistance.

This seemed a grotesque prospect and it inspired meetings to plan how to make lifesaving in space a possibility. In 1972 the two superpowers signed an Agreement on Co-operation in the Exploration and Use of Space for Peaceful Purposes which called for the technology for a successful docking to be developed and tested by 1975 and so the Apollo-Soyuz Test Project was born.

Technicians and astronauts from the US and USSR would plan how to overcome their mutual differences and demonstrate their success by a rendezvous between their spacecraft. The other major aspect of ASTP was political, to enhance trust between the Americans and Soviets and prove to the world that the two superpowers could cooperate despite their radically different visions of the human future. For NASA the project was helpful in providing a bridge between the era of Moon landings and Skylab and the beginning of Space Shuttle flights (expected in about 1978).

Engineers from both countries made remarkable progress despite the enormous language and cultural barriers. There were two large technical challenges in docking an Apollo CSM and a Soyuz. How could two docking mechanisms of different sizes, with incompatible latches come together and make a rigid and safe pressurised seal? Then if docking was successful there was the problem of the craftsòÀÙ atmospheres. Apollo NASA astronauts breathed pure oxygen at about one third normal atmospheric pressure while in a Soyuz the cosmonauts used a mix of nitrogen (66-78%) and oxygen (19-32%) maintained at half to two thirds the atmospheric pressure on EarthòÀÙs surface. A cosmonaut acclimatised to this atmosphere who then transferred in the ApolloòÀÙs environment would experience the agonising and debilitating condition known to deep-sea divers as the òÀÜbendsòÀÝ (or more properly, decompression sickness) as bubbles of nitrogen formed in his body fluids.

The vital ASTP Docking Module. This was built by Rockwell International who also was responsible for the Apollo CSM and Shuttle Orbiter. In the 1990s Rockwell was absorbed into Boeing. (Image credit: NASA)

The solution to both problems was to develop a specialised piece of hardware called the Docking Module (DM) which was manufactured by Rockwell International. Carried into space stowed under the Apollo CSM (just like a Lunar Module) on the same Saturn 1B rocket, the Apollo would dock with a compatible port on one end of the tubular DM, on the other end of the DM was a Soyuz-compatible port. Essentially the DM was an adaptor between the two spacecraft. Once the two ships were successfully joined, the DM would service as an acclimatisation chamber. Transferring between spaceships would not be quick and easy. To move from the Apollo to the Soyuz, astronauts would go into the DM and close the hatch behind them. The atmosphere in the DM would gradually increase in pressure and be enriched with nitrogen. When the pressures in the DM and Soyuz were equal, the hatch into the Soviet craft would be opened and the Apollo crew could meet their fellow space travellers face to face. This procedure was reversed for moving from the Soyuz to the Apollo.

The plan for the mission (Image credit: NASA)

The mission began on 15 July 1975 with the launch of Soyuz 17 which was the first Soviet launch to be televised live. On board the craft was its commander, veteran cosmonaut Alexei Leonov (b1934), the first man to make a spacewalk, and his flight engineer Valery Kubasov (1935-2014), a veteran of the Soyuz 6 mission. Both men had been intended to spend time on the Salyut 1 space station during the Soyuz 11 mission but had been grounded for medical reasons and taken off the flight. This inconvenience had saved their lives, their replacements on Soyuz 11 perished in a dreadful accident. As Soyuz 17 was being prepared for its mission,ˆà a complete backup Soyuz and launch vehicle were readied should Kubasov and Leonov fail to reach orbit. Happily this was not needed.

The Soyuz 19 spacecraft seen from the Apollo. These vehicles are normally dark greyish green all over. This was considered to make the Soyuz too dark to see against the blackness of space for NASA’s docking procedure. The white areas and several flashing beacon lights were added to Soyuz 19 especially for the ASTP to increase its visibility. (Image credit: NASA)

Seven and half hours later the Apollo (which, contrary to myth, was not designated Apollo 18) blasted off. This was both the last flight of an Apollo spacecraft and the final flight of a Saturn series rocket. The American crew was commanded by Thomas Stafford (b1930) who had orbited the Moon on Apollo 10. The Command Module Pilot was Vance Brand (b1931) who was making his first space flight but went on to command three Shuttle missions. The third Apollo crew member was the DM Pilot Donald òÀÜDekeòÀÝ Slayton (1924-93) , one of the original òÀÜMercury SevenòÀÝ astronauts. Slayton had been picked as an astronaut in 1959 but to his intense disappointment had been grounded for medical reasons throughout the Mercury, Gemini and Moon landing missions. By 1972 the heart murmur that had caused his grounding had cleared up and he was cleared to fly but this would be his only space flight. At the age of 51, he was at the time the oldest person to go into space.ˆà Also on board the Apollo was a very confused mosquito which had somehow been sealed in the Command Module (alas the insect stowaway failed to survive more than a few hours; perhaps the reduced pressure/pure oxygen atmosphere of the CSM was eventually fatal to it).

The ASTP crews (and their backups) had learned each othersòÀÙ languages and trained and socialised together in Moscow and Houston. All former fighter pilots, they had got on well together (especially surprising when you consider that their early military careers had been spent practising how to kill each other). The crews agreed to speak in the other’s language and to listen in their own.

The crew of the Soyuz had this view of the approaching Apollo with its attached DM (Image via NASA)

Thanks to its much larger propellant reserves the Apollo was the active participant in the initial docking manoeuver. The docking took place over Metz, France on 17 July 1975 and was pretty flawless. It was covered live on TV around the world (I remember the BBC coverage used Aaron CopelandòÀÙs Fanfare for the Common Man as opening music; ever since I have thought of this piece as òÀÜspace musicòÀÝ). The only technical issue with the docking procedure was the failure of the TV camera on the Soyuz, so only the Soyuz filmed from the Apollo could be seen on screen.

Slayton and Leonov share a moment in orbit. The Apollo crew were the first NASA crew (and only Apollo astronauts) to wear the so-called “Worm” logo on their unappealingly-coloured seventies jumpsuits. The then futuristic emblem was introduced in 1975 to replace theˆà blue”Meatball”ˆà roundel, but was retired in 1992 when the former emblem was re-instated.ˆà (Image credit: NASA)

Three hours after the craft joined, the Soyuz hatch opened and there was laughter and handshaking as Stafford and Slayton joined Leonov and Kubasov in the Soviet craftòÀÙs Orbital Module (the missionòÀÙs procedure ordered that neither spacecraft be left unattended so Brand stayed in the ApolloòÀÙs Command Module). The meeting was followed by conversations between the men and Soviet Premier Leonid Brezhnev and US President Gerald Ford and a ceremonial exchange of flags and medals. The whole event was televised live and was described by BBC space reporter Reginald Turnhill as òÀÜa slightly confused affairòÀÝ: the crews seemed awkward and nervous, Stafford forgot briefly to speak Russian and held a camera upside down, there was annoying squeal on the communications circuit and the flag exchanges had to be rushed as the crews ran out of time.

Once the cameras were off the astronauts and cosmonauts shared a meal and began a programme of five joint experiments mainly to investigate the industrial potential of processing materials in microgravity but there was also a life science experiment to observe fish embryos developing beyond Earth. In the next few days there were more TV broadcasts and press conferences, Kubasov visited the Apollo crew and the crews exchanged food and practiced undocking and redocking their craft. Leonov, an artist, sketched portraits of his American comrades while they were together.

Alexei Leonov displays one of his drawings of Stafford during the ASTP mission. (Image credit: NASA)

After 44 hours together, the space travellers said goodbye, and the two ships separated As the Apollo maneuvered away it created an òÀÜartificial solar eclipseòÀÝ and the crew of the Soyuz photographed the solar corona. The Apollo crew tried a tricky experiment to measure traces of EarthòÀÙs atmosphere by bouncing a UV beam off the Soyuz. Both vessels remained in orbit for a few days for further independent research. The Soyuz crew landed without mishap on 21 July but on 25 July 1975 as they returned home the American crew endured one of the most serious accidents of the Apollo project.

As the crew prepared for re-entry a single line was missed from a checklist and so a valve was left open. As a result of this seemingly minor omission, during the descent toxic nitrogen tetroxide propellant from the craft’s reaction control thrusters was released into the Command Module. The crew were in very great danger; Brand and Stafford managed to don oxygen masks in time but Slayton lost consciousness under the influence of the noxious vapour. After splashdown, the crew was hospitalised for 14 days for treatment for chemical-induced pneumonia and edema. Apart from Apollo 13, this probably counts as the nearest an Apollo crew ever came to dying during a mission.ˆà Due to the unforeseen difficulties in getting the Shuttle ready, this would turn out to be the last US crewed mission for almost six years.

These US Navy divers look surprisingly casual as they secure the Apollo Command Module. (Image credit: NASA)

Despite this almost fatal finale, the ASTP was a technical and diplomatic triumph, but it did not immediately lead to a new era of co-operation in space between the USA and USSR. To be honest the project was a dead end as the technology and protocols developed during it were specific to the Apollo and Soyuz vehicles andˆà there were to be no further Apollo flights (Soyuz are still in use to this day). There was a vague hope for follow-up missions, the idea of perhaps a Shuttle visiting a Salyut was floated but nothing came of it.

Within five years, D†étente was just a memory and the Cold War was as icy as it had ever been.ˆà In fact space was once again regarded as a Cold War battlefield. Future orbital encounters between the Superpowers were envisaged as sly espionage operations or even murderous dogfights. It would be twenty years before there was another docking of international spacecraft when the Shuttle Atlantis docked with Mir in June 1995 (using a docking adapter descended from the DM), ushering the co-operative era which has brought us routine flights to the International Space Station.

(Article by Colin Johnston, Science Education Director)

REFERENCES AND FURTHER READING

Turnhill, Reginald, The Observer’s Book of Manned Spaceflight (3rd edition), Frederick Warne, 1978

Gatland, Kenneth et al, The Illustrated Encyclopedia of Space Technology, Salamander, 1981

Edward Clinton Ezell and Linda Neuman Ezell, The Partnership: A History of the Apollo-Soyuz Test Project, NASA, 1978 (link)

The First Time NASA Docked with a Soviet Spacecraft in Orbit (link)