Two spacecraft drifted closer to one another far above planet Earth, as they prepared to dock. It was July 17th, 1975, and they were about to make history. For the first time, a United States Apollo and Soviet Union Soyuz spacecraft would dock with one another, an enormously symbolic mission that served as a small step towards international cooperation between the two superpowers.

The Apollo-Soyuz Test Project would become the first major collaborative experience between the two enemy countries. The mission was simple: fly two crews into orbit, and dock with one another, where the two crews would exchange gifts and collaborate on scientific experiments in orbit.

But this simple mission took several years to plan and coordinate, and involved the efforts of hundreds of people in diplomatic, scientific and engineering fields to accomplish.

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1975

USA Command Module Pilot, Vance D. Brand: Houston, Apollo.

USA Cap Com-Huston: Go ahead.

Vance: Okay, Dick; we’ve got Soyuz in the sextant.

Houston: Hey, super. Have you got a good view of him, Vance?

Vance: He’s Just a speck right now.

Houston: Okay. As you know, we’re really - we and the Moscow Control Center and a lot of other people listening are sure interested in how this rendezvous goes and how the ... gets closer, so Just keep us advised.

USA Commander, Thomas P. (Tom) Stafford: Okay.

Vance: Right now he’s hard to distinguish from the stars, except the stars are moving relative to the background and he is not.

Collaborative Roots

As Apollo 11 successfully splashed down in the Pacific Ocean, NASA administrator Thomas O. Paine flew along with President Richard M. Nixon, Secretary of State William P. Rogers and National Security Adviser Henry A. Kissinger aboard Air Force One. While on the flight, Paine spoke with his companions and spoke about “the desirability of greater substantive international cooperation in space projects, especially with the Soviet Union.” He was given the green light to pursue this.

Paine’s motivations were deep-seated. He had learned Russian in college, and had come to believe that exploration into space was a task that transcended nations: it had to be a collaborative enterprise. After being appointed Administrator for the space agency in 1968 following the retirement of James E. Webb, he began to push against the competitive narrative that NASA had used to ensure funding: with the goal of reaching the Moon successfully completed, it was time for a change. Paine began to write to his Soviet counterparts, looking for openings for collaboration.

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After some roadblocks, Paine found an ally in President of the Soviet Academy of Sciences, Mstislav Vsevolodovich Keldysh, who was receptive of Paine’s ideas. The pair continued to write, Following the success of Apollo 11, the pair had begun to establish a foundation upon which their two countries could work from.

It was a 1969 science fiction film that helped steer the conversation: Dr. Philip Handler, the President of the National Academy Of Sciences, had been involved with the talks, and happened to watch a film: Marooned.

The plot concerned a NASA mission in which a US spacecraft ran into problem. The three crew members on board were saved by a Soviet mission also in orbit. The plot stuck with Handler, who spoke with Soviet science officials about the potentials of collaboration.

Talk turned to the technological requirements of some sort of space mission: standardized docking equipment would be required for a mission with two different spacecraft. Following the Paine-Keldysh correspondence, negotiations continued, covering technical requirements for a mission. Engineers began work on a versatile docking module that could join together the two different spacecraft. There were other problems as well: Apollo spacecraft were designed to be piloted by its crew; the Soyuz vessels were far more automated.

On May 24th, 1972, the two countries signed an agreement to begin a test mission, one that would involve hardware left over from the cancellation of the Apollo program. The agreement laid out the plan, reinforcing each nation’s desire to work together, streamline scientific research, and continue the development of space law. The third article, however, was specific as to the how:

Article 3

The Parties have agreed to carry out projects for developing compatible rendezvous and docking systems of United States and Soviet manned spacecraft and stations in order to enhance the safety of manned flight in space and to provide the opportunity for conducting joint scientific experiments in the future.

It is planned that the first experimental flight to test these systems be conducted during 1975, envisaging the docking of a United States Apollo-type spacecraft and a Soviet Soyuz-type spacecraft with visits of astronauts in each other’s spacecraft. The implementation of these projects will be carried out on the basis of principles and procedures which will be developed in accordance with the summary of results of the meeting between representatives of the US National Aeronautics and Space Administration and the USSR Academy of Sciences on the question of developing compatible systems for rendezvous and docking of manned spacecraft and space stations of the USA and the USSR dated April 6, 1972.

The agreement, signed by President Richard Nixon and Soviet Premier Aleksei N. Kosygin, established the next major goals for space exploration: develop a means for US and USSR spacecraft to dock with one another for a mission that would take place three years in the future. This treaty is often mentioned as one of the events that ended the Space Race.

But this was no small task, because of the different docking mechanisms and the vastly different procedures and technical requirements between the two agencies.

1975

Houston: Incidentally, Tom, during that last transmission, there was a - there was a big squeal and ...

USA Docking Module Pilot, Donald K. (Deke) Slayton: Soyuz, Apollo. (How do you read me?)*

USSR Flight Engineer, Valeriy Kubasov: Very well. Hello, everybody.

Speaker in Docking Module: (Hello, Valeriy. How are you?)

Slayton: (Good day, Valeriy.)

Kubasov: How are you? (Good day.)

Slayton: (Excellent.)

Slayton: (I’m very happy. Good morning.)

USSR Commander, Alexey Leonov: Apollo, Soyuz. How do you read me?

Slayton: (Alexey, I hear you excellently. How do you read me?)

Leonov: I read you loud and clear.

Slayton: (Good.)

*Translated from Russian.

Crew Selection

With the signing of the agreement in 1972, planning for the mission began. There was much work to be done if the mission was to fly in the summer of 1975. There were other problems, as noted by M. Pete Frank, chairman of Working Group 1 during an early planning meeting:

Don’t seem to be able to complete anything quickly.

Spent a lot of time on correcting or modifying unimportant trivia.

Translations cannot be trusted. . . .

Russian language takes about twice as long to say as does English.

Much time was spent trying to understand jargon. . . .

And with all these stumbling blocks, there was a lot of ground to cover. The timing of each launch, the altitude of the mission, the relative spacecraft air pressures, and the transfer of orbital trajectory data were among the minutiae that was discussed during these early planning stages, demonstrating the complicated nature of this mission. Putting one spacecraft in orbit was already a major event: launching two radically different ones at once was another thing entirely. Despite the differences, by the end of 1972, the hardware configuration of the mission had largely been worked out.

On January 30th, 1973, NASA announced the crew assignments for the Apollo-Soyuz Test Project. Brigadier General Thomas Stafford, a veteran of Geminis 6 and 9 and Apollo 10 would command the Apollo spacecraft. Astronaut Vance Brand would be the Command Module Pilot, while Donald “Deke” Slayton, the only Mercury astronaut who had yet to go into space, would be the Docking Module Pilot. In May, the Soviet Union announced its crew members: Alexei Arkhipovich Leonov would command the Soyuz spacecraft, while Valeriy Nikolayevich Kubasov would be the backup technical scientist.

Later in the year, the astronauts, Cosmonauts and backup crews began to meet and familiarize themselves with the equipment that they would be working with. The American astronauts also began to learn Russian, while the Cosmonauts began to learn English.

By 1974, the actual procedures of the mission were being hammered out, with the astronauts and cosmonauts learning how to dock the two spacecraft to one another, as well as other portions of the launch.

1975

Stafford: Starting braking, Dick.

Houston: Roger.

Stafford: Less than 20 feet per second.

Houston: Apollo, Houston. I got two messages for you: Moscow is GO for docking; Houston is GO for docking; it’s up to you guys. Have fun.

Stafford: All right, it sounds good. (Half a mile, Alexey.)

Leonov: Roger. 800 meters. What is this? 21. What is the range rate?

Stafford: (Very good, 80 seconds.)

Stafford: You can see his antennas from out here, Dick.

Brand: Yeah.

Houston: Roger.

Brand: (I see a green ship.)

USSR: Thank you, Vance. Thank you, Vance.

Launch

By 1975, the mission was ready. On July 15th, Leonov and Kubasov blasted off in their Soyuz from Baikonur Cosmodrome in Kazakhstan at 8:20am EDT. Foreign journalists were barred from the launch site, but for the first time ever, the launch of the Soyuz was filmed and broadcast live.

Seven and a half hours later, Brand, Safford and Slayton took off from Kennedy Space Center in Florida at 3:50 pm EDT. The mission was underway.

Once in orbit, the Apollo command module separated, turned and docked with the docking module, the first step in joining the two spacecraft together. At an altitude of 173 miles above the Earth, they began to get into position to meet up with their Soviet counterparts. Over the course of July 16th, the two spacecraft began a dance in orbit in order to match altitudes and speeds.

With the spacecraft in orbit, the two missions converged on one another at an orbit of 299 miles above the earth. At 8:00am, Brand reported spotting the Soyuz spacecraft, and as they approached, the two crews made radio contact, speaking in the language of their counterparts. As the two approached, Leonov radioed Apollo: “Tom, please don’t forget about your engine.”

At 12:12pm on July 17th, Apollo and Soyuz came together in a hard dock.

1975

Stafford: (Less than 5 meters distance.)

Houston: Deke, Houston. Deke, Houston. Can you close down the f-stop some?

Stafford: (3 meters.)

Stafford: (1 meter,)

Stafford: (Contact.)

Leonov: We have capture.

Stafford: (We also have capture. We have succeeded. Everything is excellent.)

Mission

The two ships had docked perfectly, and the crews prepared to open the two hatches. The Apollo crew entered the docking module and regulated their pressure of their spacecraft to match Soviet ship.

At 2:17 pm on July 17th, 299 miles above the city of Metz, France, the respective crews opened the hatches, and drifted together: their mission has succeeded. The two commanders, Stafford and Leonov, shook hands in orbit.

The two crews exchanged gifts, which included each nation’s flag, plaques, medallions and other items. President Gerald Ford called the spacecraft with the following message:

All of us here in Washington, in the United States send to you our very warmest congratulations for your successful rendezvous and for your docking, and we wish you the very best for a successful completion of the remainder of your mission.

Your flight is a momentous event and a very great achievement, not only for the five of you but also for the thousands of American and Soviet scientists and technicians who have worked together for 3 years to ensure the success of this very historic and very successful experiment in international cooperation.

It has taken us many years to open this door to useful cooperation in space between our two countries, and I am confident that the day is not far off when space missions made possible by this first joint effort will be more or less commonplace.

The American crew shared a meal onboard Soyuz with their counterparts, and after several hours of ceremonial activities, they retreated to their respective spacecraft and closed the hatches to rest.

On July 18th, the two crews met up once again, where they would spend the day working on experiments in orbit. Brand went over to the Soyuz, where he and Kubasov filmed several experiments concerning microgravity, while later in the day, the astronauts answered questions for members of the press. They returned to experiments later in the afternoon, taking pictures of the Earth, and the two crews later assembled a joint plaque to commemorate the occasion. At 3:49 in the afternoon, the crews shook hands once again, and closed their hatches for the last time.

On the morning of the 19th, the two ships undocked for another experiment, with the Apollo spacecraft positioning itself to eclipse the sun, allowing the Soviet crew to take photographs of the sun’s corona. After that, the Apollo spacecraft conducted an ultraviolet absorption experiment, which involved pointing a laser at the Soyuz and several special reflectors to measure levels of atomic nitrogen and oxygen at that altitude.

Their experiments complete, the two ships docked once more to test some equipment, and after the test, the two spacecraft split apart once and for all, and moved out of one another’s way. They each spent July 20th conducting other experiments, and on July 21st, with the Soyuz reentering the atmosphere first, landing in Kazakhstan.

The Apollo crew remained in orbit for another two days, conducting a battery of tests and experiments. On July 23rd, they jettisoned the docking module, and on July 24th, they tipped back into the atmosphere, splashing down in the Pacific ocean at 4:18.

Their reentry wasn’t without problems: while landing, the cabin filled with nitrogen tetroxide from the thrusters when a cover failed to eject. After NASA retrieved them, the three astronauts had to be hospitalized.

The cooperative mission came to an successful and historic end, six years to the day of the end of the Apollo 11 splashdown. Just over half a decade after going to the moon, the United States and the Soviet Union had accomplished something everyone had thought impossible. It was also the final mission for the Apollo spacecraft, and the last time Americans would go to space for over five years.

Lasting Influence

It’s hard to understate the importance of the Apollo-Soyuz Test Project. It was a major, symbolic mission in the midst of the Cold War. While the two countries were still hostile to one another, it was a vivid demonstration that we could put political differences aside in the interests of greater pursuits, such as the exploration of space.

ASTP was a also critical first step in the advance of space travel for all of humanity because of its collaborative nature. Over the past 40 years, exploration and travel to space has become a collaborative enterprise, utilizing the collective resources of many nations. The mission gave each space agency a better understanding of one another’s systems, which helped engineers with future projects, such as the Mir and International Space Stations, each of which required compatibility with one another’s systems.

Without the ASTP, major programs such as the International Space Station, the Halley Armada, the International Cometary Explorer, and even the Dawn Spacecraft probably wouldn’t exist in their present form.

In an age of declining government support for space travel, international cooperation is all the more important, so that grand projects such as the ISS to succeed. And these projects are essential for us to keep learning about our planet, the universe around us, and ultimately, ourselves. In some ways, the ASTP was a grander, albeit less dramatic, mission than the Apollo landings: it taught us that together, we can continue to voyage beyond our atmosphere.

Image credits: NASA, Toytoy at English Wikipedia