An International Docking System

[170] Before the winter meeting, both Caldwell Johnson and Vladimir Syromyatnikov had been thinking about what they would like to incorporate into a compatible docking system. Johnson had been urging that the group accept the double ring and cone docking concept he had described to the Soviets on his first trip to Moscow. In June, he had had an opportunity to chat with Soviet docking specialist Valentin Nikolayevich Bobkov during a free-wheeling round table conversation among the engineers. In addition to Johnson and Bobkov, George Hardy, Robert "Ed" Smylie, Edgar "Ed" Lineberry, Leroy Roberts, Ilya Vladimirovich Lavrov, and Igor Petrovich Shmyglevskiy took part in the shop talk. While Shmyglevskiy was the only one present who spoke both English and Russian, Bobkov could read and write English, so the eight men drew sketches, translated words verbally and on the drawing pad, and made hand gestures to understand one another.

During this conference, Bobkov had indicated that the Soviets also favored some version of the double ring and cone. Bobkov illustrated through rough sketches that the overall diameter of the docking system could not exceed 1.3 meters, because any larger system would require a change in the launch shroud. When Johnson raised the question of altering the shroud, the Soviets stressed the major impact that such a modification would have. In addition to having to design a new shroud, they would have to test out the launch aerodynamics of the altered hardware. The Americans had hoped to argue for a larger tunnel, but such a change appeared to be too great for their counterparts. The Soviets in turn understood the American's thoughts on an airlock module.19

After the June meetings in Houston, Johnson had put Bill Creasy and his mechanical designers to work on the preliminary design of a docking mechanism. By the time the NASA delegation left for Moscow, Creasy's crew had designed and built a 1-meter double ring and cone docking system that had four guide fingers and attenuators on both rings, so either half could be active or passive during docking. The Structures and Mechanics Laboratory at MSC made 16-millimeter movies demonstrating this system in action, which Johnson took to Moscow in November, along with a booklet describing the system and a model of the capture latches. He had gone prepared to sell his idea.20

Once he was in the U.S.S.R., Johnson discovered, however, that his job was that of an engineer, not a salesman. Since October 1970, Syromyatnikov had been working on a variation of NASA's ring and cone concept. Instead of the four guide fingers in the American proposal, Syromyatnikov suggested three, and in lieu of hydraulic shock-absorbers, he proposed....

....electromechanical attenuators. In essence, the Soviets had accepted the idea of using a set of intermeshing fingers to guide the two halves of the docking gear from the point of initial contact to capture. The concept of using shock absorbing attenuators on the active spacecraft's capture ring to buffer the impact of two spacecraft coming together was also acceptable. Both groups of engineers planned to retract the active half of the docking gear using an electrically powered winch to reel in a cable. Once retracted, structural or body latches would be engaged to lock the two ships together. Three basic issues had to be resolved - the number of guides, the type of attenuators, and the type of structural latches - before the design of a universal system could proceed.21

Johnson, Creasy, and the other engineers in the Spacecraft Design Division had wanted to use four guides because they believed that it provided the best geometry when using hydraulic attenuators. As Bill Creasy subsequently explained it, the most probable failure situation using hydraulic attenuators would be a leak that would cause one shock absorber to collapse on impact. A study of various combinations had led the MSC specialists to conclude that four guides and eight shock absorbers was the....

....optimum design. Creasy pointed out too that the most likely trouble with an electromechanical system would be a freeze-up or binding of one of the pairs of attenuators. Thus, the Soviets had sought to minimize the number of pairs in their system for the same reason that the Americans had preferred a larger number to limit the probability of something going wrong.* 22

As Johnson talked this out with Syromyatnikov, it became clear that they both wanted to stay with systems that would give them maximum confidence in the design. But they agreed that a compromise could be reached. Johnson reported on his discussions with Syromyatnikov:

Since there was no conflict in principle, nor was there envisioned to be a conflict in subsequent engineering detail between interfacing features of the proposed US and proposed Soviet docking mechanisms, and since the US had no significant engineering or hardware equity in its proposed design, and since the USSR had considerable equity in its proposed design, the Soviet design was selected as a baseline for the next phase of study.23

By the end of the November-December meeting, the two Group 3 teams had signed a set of minutes outlining the basic concept for a universal [173] androgynous docking system. The formal statement read, "The design concept includes a ring equipped with guides and capture latches that were located on movable rods which serve as attenuators and retracting actuators, and a docking ring on which are located peripheral mating capture latches with a docking seal." Basic information on shapes and dimensions of the guides were also included in the minutes. They were to be solid and not rodlike; as first proposed by the Soviets, and three in number. As long as the requirement for absorbing docking forces was met, each side was free to execute the actual attenuator design as it best saw fit. The Soviets planned to use an electromechanical approach designed for the Soyuz docking probe, and the Americans proposed to stick with hydraulic shock absorbers similar to those used on the Apollo probe. This proposal also called for developing docking gear that could be used in either an active or passive mode; when one ship's system was active, the other would be passive.

Looking into the detailed design of the mechanism, the two sides had further agreed that the capture latches would follow the design developed at MSC and the structural latches and ring would follow the Soviet pattern. These paired sets of hooks had been successfully used on both Soyuz and Salyut. In addition, Group 3 concurred on details regarding the alignment pins, spring thrusters (to assist in the separation of the spacecraft at undocking), and electrical connector locations. To evaluate the docking system concept and to ensure the establishment of compatibility at an early point in the development, the men planned to build a two-fifths-scale test model, the exact details of which would be decided at the next joint meeting.24

Upon his return to Houston, Caldwell Johnson prepared a memorandum to document some of the informal understandings reached in Moscow. He indicated that this reflected "upon the manner in which the two countries will conduct and coordinate the next phase of the engineering studies of those systems. . . . The understandings . . . were reached more often than not outside of formal meetings, and so are not likely otherwise to be reported." For example, in the area of hatch diameter, he noted that "it became apparent from the beginning . . . that a hatch diameter greater than about 800 mm could not be incorporated into the Salyut spacecraft without great difficulty," but MSC had "long since reconciled itself" to a test hatch diameter of less than 1 meter. Johnson went on to comment that "the capture ring assembly had variously been called ring and cone, double ring and cone, and ring and fingers. It was agreed henceforth to call the capture ring 'ring' and the fingers 'guides.'" Thus it went - negotiation, understanding, compromise, and accommodation.25

The docking talks in Moscow had convinced Johnson that frequent face [174] to face communications were necessary. He believed that an acceleration of the design process was also in order if they were to settle on a single design by June 1972. It would not be possible to develop a design through correspondence or meetings every six, three, or even two months. He saw two possible alternatives:

Accelerate the iterative process by very frequent and informal, face-to-face negotiation between the key designers - each having authority to make technical decisions on the spot; or, assign design responsibility for each interfacing element of the mechanism to one country or the other. Of the two alternatives, only the first is practicable, since apportionment of responsibility would likely take just as long as the design process.26

While tentative arrangements had been discussed for telephone and Teletype exchanges, Johnson thought that limited progress had already been made when it came to "the exchange of [a] vast amount of technical detail data such as drawings, diagrams, performance analyses, etc., that are necessary for each side to understand the nature of the interfacing system." The concerns expressed in Johnson's memo reflected the thoughts that other members of the American delegation had as they returned home. A joint mission with the Soviets was clearly feasible from a technical standpoint, but the key to such a complex project would be creating the proper management format. That task would fall on Glynn Lunney's shoulders.

After a day of shopping for gifts in Moscow, the NASA delegation had left the Soviet capital on 7 December via England, where they briefly visited the Royal Aircraft Establishment at Farnborough. This pleasant diversion, according to Lunney, took "many of us back to the NACA days." In Houston, the Working Group members soon found that they had their work cut out for them. On 16 December, Lunney distributed a memo outlining tasks to be done and clarifying who was responsible for each. Lunney anticipated convening special joint sessions for the Group 2 members involved in radio tracking discussions and for the Group 3 members concerned with the docking mechanism. "In considering our experience so far in these discussion," Lunney commented, "we have found it absolutely essential to have well-prepared documents for each meeting in order to efficiently conduct and steer the discussions and resultant agreement documents." He believed most of the documents that had to be ready in the near future were relatively "straightforward" and easy to prepare, but they must schedule the work carefully and pursue it in a businesslike manner.27 (See box below.) While Lunney and his colleagues began to work their specific tasks, the Office of Manned Space Flight (OMSF) staff in Washington was looking more deeply into the costs of an international flight.

[175] Schedule for Next Six Months*   Mid-February (two months) Long-term Exchange papers on: Connection of liquid cooled garments LOG's to other ship Quantitative characteristics and possible solutions for pre-breathing Apollo/Salyut Exchange papers on launch window constraints and solutions to daylight Apollo launch U.S. provide agendas for "Special Subject Meetings" in March Finalize Working Group 2 documents agreed to in December meeting March 1 meeting Special meetings in Houston on: Docking mechanism Radio tracking system Mid-March (three months) Apollo/Salyut U.S.S.R. comments on U.S. proposal for communication between control centers U.S. proposal of organization plan Exchange outlines for project documentation U.S.S.R. provide Salyut life support system data Mid-April (four months) Apollo/Salyut Each country exchange "Statement of Position" Each country exchange "Project Technical Proposal Document" May to June (five to six months) Next full-scale meeting *Informal planning schedule distributed by G. S. Lunney, Dec. 1970, after trip to Moscow.

* At an earlier meeting, V. Zhivoglotov had told R. D. White that the Soviets were opposed to a system using eight attenuators because the electrical device they had planned to employ to dissipate the docking energies could not be used with eight attenuators but it could be used with the six shock absorbers.

19. Johnson to Gilruth, memo, "Miscellaneous Engineering Information Pertinent to CSM/Salyut Docking," 30 June 1971.

20. NASA, MSC, "A Docking Mechanism for Apollo/Salyut-Type Spacecraft," 17 Nov. 1971; interview, William K. Creasy-Ezell, 7 July 1975; and Johnson to Lunney , memo, "Documents and Visual Aids for Moscow Meeting," 16 Nov. 1971.

21. Johnson to Lunney, memo, "IRDM Docking Mechanism, Concept Verification Study, January through May 1972," 16 Dec. 1971; [V. S. Syromyatnikov], "Printsipalnaya konstruktivniaya skhema stukovochnogo ustroistva periferiinogo androginnogo tipa" [Design concept of a docking mechanism of the peripherial and androgynous type], 2 Dec. 1971; and R. W. Kubicki to W. W. Petynia and Johnson, memo, "International Docking System Design Review," 26 Oct. 1971, which presents an in-house systems engineering view of the hydraulic attenuators.

22. Interview, Creasy-Ezell, 7 July 1975.

23. Johnson to Lunney, memo, "IRDM Docking Mechanism, Concept Verification Study, January through May 1972," 16 Dec. 1971.

24. "Appendix C, Working Group No. 3, Minutes of Meetings on Assuring the Compatibility of the Docking Systems and Tunnel," 29 Nov.-6 Dec. 1971.

25. Johnson to Lunney, memo, "IRDM Docking Mechanism, Concept Verification Study," 16 Dec. 1971.

26. Ibid.

27. Lunney to distribution, memo, "Schedule of Work as a Result of the Third Meeting on International Compatibility of Rendezvous and Docking," 16 Dec. 1971. Lunney had taken drafts of the Summary of Results and Working Group minutes with him to Moscow in November. See also Dale D. Myers to Lunney and Frutkin, memo, "Sample Summary of Results," 22 Nov. 1971.