Tales of Immersion 1: How the Soviets Did Not Invent Neutral Buoyancy and Then Did Not Show the Chinese How to Use it to Fake a Spacewalk.

The past four months since my last blog entry have been filled with travel and work commitments. Some of these have fed my interest in the history of underwater neutral buoyancy to simulate weightlessness for spaceflight training and procedures development, usually for “extravehicular activity” (“EVA” in NASA-ese), also called “space walks.”  That is my "other" current recreational research interest, along with the biomedical aspects of the defunct Manned Orbiting Laboratory (MOL) program (see most of my recent posts).

ESA Neutral Buoyancy Facility, Cologne, Germany, July 2013.
(Photo and composite by author.)

In July, I attended the 19^th Humans in Space Symposium of the International Academy of Astronautics, in Cologne, Germany. This included a visit to the German space agency’s new biomedical research facility, “:envihab” (the creative spelling and punctuation are a branding and marketing tactic). Next door is the European Space Agency’s (ESA’s) European Astronaut Center, which houses ESA’s Neutral Buoyancy Facility, which I was able to see only through a security window.

2nd annual reunion of ERA divers, with spouses and admirers,
August 2013. Mattingly is in front row, near center, in white shorts.
(Photo by author.)

In mid-August, my wife and I flew into Baltimore and then drove east to Ocean Pines for the second annual reunion of the divers of Environmental Research Associates (ERA) at the home of its founder, neutral buoyancy pioneer Sam Mattingly. Sam also invited Michael Neufeld, a curator and historian from the Smithsonian Institution’s National Air and Space Museum, who is also interested in the history of ERA.

My recreational research into the history of neutral buoyancy for spaceflight purposes comprised two lectures to the JSC Spacesuit Knowledge Capture Series in August and September on ERA and the list of other early adopters who are less well-known in part because they were not successful in the Darwinian sense in competing with ERA.

All or parts of those lectures, including the list, will appear in my blog posts, starting with this one.

China Astronaut Training Center neutral buoyancy facility.
(Photo reproduced from China TV.)

I also gained some insights on the history of neutral buoyancy while at the 64th International Astronautical Congress (IAC) in Beijing, in September. I wasn't able to take any of the technical tours this time (as I did in 2007 on my only previous visit) so I didn't get to see the Chinese neutral buoyancy facility (which may or may not have been on the tours this year, but was not open for tours in 2007). That facility was probably in use back then, because Zhai Zhigang has been shown training in it before he performed the first Chinese EVA from Shenzhou 7 in September 2008 (1).

Space Hoax Claimed

An anti-regime website in Hong Kong insisted that the first and so far only Chinese spacewalk was faked underwater (2). Evidence cited includes so-called “bubbles,” which the “deniers” specifically deny are dust particles and left over bits of the spacecraft preparation process, commonly seen escaping from any spacecraft open to vacuum.

Chinese astronaut training for EVA underwater (left) and in spaceflight (right).
(Photos from China TV, composite by author.)

This claim of a Chinese hoax brings together three elements required for a hoax rebuttal: (1) the claim itself, (2) imagery from the purportedly actual event, and (3) imagery depicting the very hoax that is claimed, provided by the party being accused of perpetrating the hoax. A casual comparison of the very clear in-flight imagery provided by the Chinese (element 2) and of their own well-publicized underwater training (element 3) demonstrates the visual distinctiveness of the two elements, and thus the falseness of the hoax claim.

This hoax claim has been thoroughly debunked by serious skeptics with much greater credibility than I (3). But it is an echo of a similar claim four decades ago. In the 1960s, Lloyd Mallan, who was among the first “space deniers,” refused to credit any of the Soviet Union’s early successes in space. He said that the world's first spacewalk by cosmonaut Alexei Leonov and the rest of the Soviet space program were faked, finding it more credible that they were hoaxes (4). Specifically, he posited that footage of Leonov’s accomplishment was actually filmed on Earth underwater.

Russia's Space Hoax, Lloyd Mallan, 1966.

In 1975, Mallan's body of work was disputed by James Oberg, one of the foremost authorities on Soviet and Russian space history (5). However, Oberg agreed with one of Mallan's premises, that the Soviet photographic documentation of Leonov's excursion included footage made underwater, substituting neutral buoyancy for weightlessness: “Mallan is right when he says that most of the Leonov spacewalk movies are not genuine. They are shots underwater, shots from wire-suspension training sets, shots in simulations and practices. The Russians were often careless in describing the sources of these films. The spacewalk itself was real.”

I am, of course, no expert on cosmonaut training techniques or photographic trickery, but my casual review of the imagery does not support that hypothesis. Oberg's criticisms of the film's quality, editing and presentation may be true, but I don't believe water immersion was involved.

No Neutral Buoyancy for Leonov

Leonov EVA imagery as reproduced from Soviet -based sources on Internet.

If the hoax claim was correct, then any such footage would establish the earliest documented use of water immersion by any astronaut or cosmonaut for mission simulation purposes. But there is no strong evidence for an entity from the Soviet Union to be on my list of early practitioners of neutral buoyancy for weightlessness simulation. I covered the early Soviet use of neutral buoyancy in just two PowerPoint charts in my second lecture because the topic is not well documented in available source material. Their insistence on secrecy and ambiguity left an ambiguous record and provided opportunities for misunderstanding and even misrepresentation of their own legitimate efforts, as Mallan demonstrated.

In fact, there is no non-US entity among the first ten or more independent practitioners on my list. This does not mean there were none in existence—only that I have not yet found adequate evidence, possibly because my source material is dominated by English-language documents from the US.

Russian Spacesuits, Abramov and Skoog, 2003

Russian institutions, like their US counterparts, had long used water tanks (which the Russians called “hydrolaboratories”) for survival equipment testing and aircrew training, including space-suited activities. For example, Zvezda, the preeminent manufacturer of Soviet aerospace life support systems (6), had tested the Vostok SK-1 spacesuit with its integral flotation collar in a water tank in 1960, according to Isaak Abramov, a spacesuit designer at Zvezda, and Ingemar Skoog, a German spacesuit expert, writing in Russian Spacesuits (7), the definitive source for such information.  

Leonov, like his American contemporaries, prepared for the world’s first EVA (“ВЫХОД” in Russian, transliterated as “vykhod” and meaning “exit”—as seen on signs in Moscow subway stations) in 1965 using the established means. He practiced during brief weightlessness in parabolic airplane flights on the Tu-104—he wrote that he had done 200 parabolas (8) which probably required five to ten separate airplane flights—and in a vacuum chamber, but he did not mention any EVA training underwater (9). Abramov and Skoog explicitly stated that hydrolab testing had not been introduced at that time (10).

NASA’s decision to adopt neutral buoyancy using water immersion for astronaut training came in late 1966, a year and a half after Leonov’s flight, and after three of the five EVA missions in the Gemini program (and too late to help the fourth), and especially after significant internal NASA debate. The decision was a desperate response to the realization that only one flight remained in the Gemini program to demonstrate sufficient competence in EVA to undertake the ambitious plans of Apollo and follow-on programs, and that the other techniques used to date—parabolic flight, full-suspension and vacuum chambers—had not been adequate (11).

But there is no evidence that Zvezda or anyone else in the Soviet Union was using water immersion to simulate the weightlessness a suited cosmonaut would encounter in spaceflight before 1968.

According to Abramov and Skoog, by 1968 Zvezda had developed and was testing the Orlan space suit for the non-landing cosmonaut on planned two-man Soviet lunar missions. The Orlan and its wearer were to remain in lunar orbit while the other cosmonaut descended to the Moon’s surface wearing a slightly different suit called Krechet-94 (12). Underwater testing of a specially modified Orlan required weights to achieve neutral buoyancy, a hoist for water immersion and emersion, and a simplified life support backpack relying on pool-side pressurization, venting and cooling systems (13). Similar testing of the Krechet-94 would be a logical inference, but was notably absent in the descriptions by Abramov and Skoog.

Soviet Neutral Buoyancy in 1968?

In August 1968, at the United Nations Conference on Exploration and the Peaceful Uses of Outer Space in Vienna, Leonov presented a paper that emphasized the similarity between the experiences of Soviet astronauts and of crews of deep-sea exploratory craft. (The paper was originally written for Yuri Gagarin, who had died in a training jet crash in March.) Leonov said, cryptically, that “all actions taken in Soviet space vehicles were tried first in underwater craft” (14). Now there is a sentence with enough ambiguity to include a large range of possibilities! Did this mean that everything a cosmonaut could ever do while in space—outside the spacecraft and inside as well—were practiced in submerged, flooded mock-ups? Did “underwater craft” even mean spacecraft mock-ups, or did it include air-filled submarines and underwater habitats, and if so, what was their relevance? No additional details were provided. NASA’s adoption of neutral buoyancy was well-publicized by then, and Soviet pronouncements of the time were sometimes phrased ambiguously to suggest that they were using similar techniques if they appeared to be relevant.

Four months later, in December 1968, an American aerospace trade journal, Aviation Week and Space Technology, reported:

“the Soviets have conducted extensive zero-gravity crew exercises with a Soyuz descent capsule [sic], simulating weightlessness in water tanks [plural, sic]. Cosmonauts with self contained underwater breathing equipment practiced entry and exit through a compression chamber [sic]. They also mounted external equipment carried from the capsule and simulated rescue maneuvers for crew members in trouble outside the spacecraft. The exercises are viewed as preparation for forthcoming EVAs.” (15)

This might have been what Leonov had been referring to, and it corresponds in time with preparations for the extravehicular transfer of Yevgeni Khrunov and Alexei Yeliseyev from Soyuz 5 to Soyuz 4 in January 1969 (16), and maybe even for their previously planned transfer from Soyuz 2 to Soyuz 1 in April 1967 (17). The Aviation Week article also demonstrated western unfamiliarity with both the design of the Soyuz vehicle and the mission profile, understandable due to Soviet secrecy. Western journalists were only just becoming familiar with the recently-revealed configuration of Soyuz as a two-part vehicle, and with the fact that such extra-vehicular transfers were only possible between the docked habitation modules and not the adjoining descent capsules (18). Only the Soyuz habitation module was decompressed independently in the role of a “compression chamber” (19).

But this simple inference is challenged by an authoritative source. While at the IAC in Beijing in September, I met and chatted briefly with Boris Kryuchkov, head of the science directorate of the Gagarin Cosmonaut Training Center (GCTC) near Moscow, about cosmonaut neutral buoyancy work in Russia before 1980. Kryuchkov stated, as translated by Igor Sokhin, his deputy, that neutral buoyancy was not used in training of Leonov, Khrunov and Yeliseyev (20).

After my conversation with Kryuchkov and Sokhin, I reviewed my own notes, and found that long-time British space sleuth Rex Hall had told me much the same thing by email in 2008 (21). Hall noted that the Cosmonaut Training Center had had a swimming pool since the mid-1960s, and he maintained that some training for Voskhod and early Soyuz spacewalks occurred there. He said there was no evidence of submerged mock-ups being used, which suggests that any water immersion training done then was very limited.

First Cosmonaut Neutral Buoyancy Experience

Sevastyanov (left) and Schweickart
in American Apollo spacesuits
at NASA Neutral Buoyancy Simulator.
(Best available photo from Internet.)

Ironically, the first documented evidence of neutral buoyancy involving a Soviet cosmonaut comes from the depths of an American water immersion tank. In October 1970, when Cold War relations between the US and the USSR were in a thaw, cosmonauts Andrian Nikolayev and Vitaly Sevastyanov visited several NASA facilities during a goodwill tour. They had set a new endurance record of 18 days in orbit in June, but their mission had no requirement for EVA training. NASA astronaut Russell Schweickart, in training as a backup crewmember for the Skylab space station missions, had recently met Sevastyanov, and when their tour came to the Marshall Space Flight Center, invited him into the Neutral Buoyancy Simulator (NBS) wearing a US EVA suit (22). On October 21, Schweickart and Sevastyanov simulated changing film canisters in the Skylab solar telescope. Schweickart inferred from Sevastyanov’s behavior and comments that this was his first experience in such a neutral-buoyancy setting, although that does not necessarily mean other cosmonauts had not done something similar.

Neutral Buoyancy Simulator, Building 4705,
NASA Marshall Space Flight Center (left);
Hydrolaboratory, Gagarin Cosmonaut Training Center right).

Perhaps coincidentally, the long-awaited “hydrolaboratory” planned for GCTC at Star City, outside of Moscow, was approved in December 1970 as part of the 1970-1975 “Five-year Plan,” at the request of Gen. Nikolai Kamanin, head of cosmonaut training (23).  By November 17, Kamanin was planning it (24), and when completed, in January 1980, the cylindrical water tank had the same dimensions as the NBS tank: 23 meters in diameter, 12 meters in depth and 5 million liters in volume (25). These were the dimensions Kamanin had specified almost a decade earlier, less than four weeks after Sevastyanov’s dive in the NBS.

It is always interesting to reconstruct the chain of causality in such events. Schweickart recalled meeting Sevastyanov when they co-chaired a technical session at an IAF (International Astronautical Federation) meeting (26). The only IAF meeting between Sevastyanov’s June 1970 Soyuz flight—when his identity as a cosmonaut would have become public—and his October 1970 visit to the US was at the 21^st IAC (of which IAF is a constituent organization) in Constance, Germany, October 4-10, 1970 (27). Thus, the sequence of events leading to the construction of the GCTC Hydrolaboratory, which opened in January 1980 and is still in use today, is due at least in part to a brief meeting at a scientific conference just 10 days before the NBS event took place.

At this year’s IAC, Kryuchkov and Sokhin told me that the first neutral buoyancy EVA training in the Soviet Union was in preparation for Salyut 3 (28) in 1974 and Salyut 5 (29) in 1976, even before the Hydrolaboratory was built (30). I was struck by the fact that they did not say just “Salyut”—Sokhin specifically said “Salyut 3 and Salyut 5.”

Now this was interesting. Salyuts 3 (31) and 5 (32) were both the military version of the Salyut space station, whose full Russian name is best just abbreviated to “OPS,” which were intended to evaluate the usefulness of manned orbital reconnaissance—the Soviet analog of the MOL (about which I have blogged previously). These Salyuts had an airlock for EVA (33), and their cosmonaut crews were presumably trained for EVA (although no EVAs were executed during those missions).

Once again, Abramov and Skoog provided the answer (34). The OPS had a requirement for extravehicular transfer from the crew transport vehicle (not originally intended to be the Soyuz) to the space station, apparently in case the internal pressurized tunnel was unpassable. In November 1969, a modification of the Orlan suit was selected for this purpose, and its development continued until the OPS program was terminated in the late 1970s. In parallel, a variant of the same suit was selected for the civilian version of the Salyut space station designated “DOS,” giving the suit the identifier “Orlan-D.” (Abramov and Skoog didn't say whether the OPS version of Orlan would have been designated “Orlan-O.”) This suit was being tested at “neutral buoyancy facilities” [plural, sic] in 1977.

Kryuchkov and Sokhin confirmed that cosmonaut neutral buoyancy training occurred in the swimming pool at Star City, and that this training included space suits (they agreed when I asked “skafandr?” using something close to the Russian word). Assuming this referred to what I am now calling the “Orlan-O” suits, we may place the 1974 underwater training for Salyut 3 on a continuum from the 1968 Orlan testing to the 1977 Orlan-D training, all before the opening of the GCTC Hydrolaboratory in 1980. [Edit by JBC: apparently I was too presumptuous--Abramov and Skoog reported (Appendix 3, p. 336)  that Orlan-D was to be used in both the OPS and DOS--so, no "Orlan-O."]

Obviously, neutral buoyancy training does not require a dedicated facility. After all, the first US astronaut underwater mission-specific training took place in a boys’ school swimming pool (35).

Romanenko and Grechko training for Salyut 6 EVA
in cosmonaut center swimming pool, 1977
(photo from Hall, Shayler and Vis).

Hall, along with David Shayler and Bert Vis, also published a history of the GCTC and Russia’s cosmonauts, including a brief description of pre-Hydrolaboratory underwater training (36) for Salyut 6 in 1977. They included two photographs of the cosmonauts, Yuri Romanenko and Georgi Grechko, in spacesuits, with scuba divers and a Salyut 6 mock-up underwater in what appears to be a shallow swimming pool with straight, flat walls, unlike the curved cylindrical walls of the Hydrolaboratory. They executed a 20-minute EVA (37) in December 1977.

Subsequent long-duration crews of Salyut 6 also performed single, brief EVAs, in July 1978 (38) and June 1979 (39), the latter being an unplanned EVA to jettison a temporary radio-astronomy antenna. All were trained in what space historian Dennis Newkirk referred to as the “hydrobasin” at Star City, as apparently were the two 2-man crews of Salyut 3 (1974), the three 2-man crews of Salyut 4 (1975) and the three 2-man crews of Salyut 5 (1976).

Summary and Conclusion

In summary, it is probable that the earliest Soviet cosmonaut training for EVA in 1964-1965, like the earliest American astronaut training, did not included neutral buoyancy, even though both programs immersed space-suited astronauts and test subjects in water for survival training and other human engineering purposes. By 1964, efforts are known to have been made in the US—but not Russia—to mimic aspects of weightlessness using water immersion, including human engineering and spaceflight-related operational assessments, and they were expanded to include astronaut preflight training starting in 1966. There are conflicting reports of Soviet crew training using neutral buoyancy in 1968, and the first documented instance of a cosmonaut donning a spacesuit and interacting with a spacecraft mock-up underwater occurred in the US in 1970. By the mid-1970s, neutral buoyancy training for cosmonauts had become established, even though in-flight EVAs were still rare and brief. After the Hydrolaboratory opened at Star City in 1980, both preflight neutral buoyancy training and in-flight EVA took on major significance in the Soviet space station programs.  

In addition, the claim that underwater film footage was used to fake the world’s first EVA appears to require a technology that did not exist at that date.

The details of its adoption in the Soviet Union, including the facilities and their dates of use, may be as revealing as are the details of its adoption in the US, but they are still to be discovered.

[Edited Oct. 22, 2013, to fix typos and enhance clarity.]

References

1. “Shenzhou 7,” http://en.wikipedia.org/wiki/Shenzhou_7 (retrieved 8 Oct. 2013).
2. Haishan, Zhang, and Shi Yu, “Chinese Space Walk Filmed in Water, Say Chinese Bloggers,” October 7, 2008, last Updated: October 9, 2008, http://www.theepochtimes.com/n2/china-news/chinese-space-spacewallk-china-bloggers-5326.html; Yu, Shi, “Confirmed Discrepancies in CCTV’s Live Broadcast of Shenzhou VII Launch,” http://www.theepochtimes.com/n2/china-news/shenzhou-vii-fake-spacewalk-5809.html (both retrieved 8 Oct. 2013).
3. Plait, Phil, “Did the Chinese fake their space walk?” October 8, 2008, http://blogs.discovermagazine.com/badastronomy/2008/10/08/did-the-chinese-fake-their-space-walk/#.UlSVnlCsiM4;  O’Neill, Ian, “Bubbles, Reflections and Space Walks… Did China Really Fake It?” October 8, 2008, http://astroengine.com/2008/10/08/bubbles-reflections-and-space-walks-did-china-really-fake-it/; O’Neill, Ian, “China Really Didn’t Fake It (Part Deux),” Feb. 27, 2009, http://astroengine.com/2009/02/27/china-really-didnt-fake-it-part-deux/ (all retrieved 8 Oct. 2013).
4. Mallan, Lloyd, Russia's space hoax: Documented Proof that the Soviet Space Program has been Faked, Science & Mechanics Pub. Co, 1966, http://www.amazon.com/Russias-space-hoax-Documented-mechanics/dp/B0007ELCD8 (retrieved 8 Oct. 2013).
5. Oberg, James, Space World, 1975, at http://www.jamesoberg.com/phantoms.html (retrieved 7 Sep. 2013).
6. Research, Development & Production Enterprise "Zvezda,” http://www.zvezda-npp.ru/engl/ (retrieved 19 Oct. 2013).
7. Abramov, Isaak P., and Skoog, A. Ingemar, Russian Spacesuits, Springer-Praxis, Chichester, UK, 2003, Chap. 3, pp. 43.
8. Scott, David, and Alexei Leonov, with Christine Toomey, Two Sides of the Moon, Thomas Dunne Books, St. Martin’s Press, New York, 2004, p. 98.
9. Kryuchkov, Boris I., and Igor G. Sokhin, personal conversation, Sep. 25, 2013, 64^th International Astronautical Congress, Beijing; Wade, Mark, “[FPSPACE] Soviet underwater EVA training preceding Star City Hydrolab?” http://www.friends-partners.org/pipermail/fpspace/2008-March/024472.html (retrieved 9 Oct. 2013).
10. Abramov and Skoog, Chap. 4, pp. 78-79.
11. Mattingly, G. Samuel, with John B. Charles, “A Personal History of Underwater Neutral Buoyancy Simulation,” Monday, February 4, 2013, http://www.thespacereview.com/article/2231/1 (retrieved 11 Oct. 2013).
12. Abramov and Skoog, Chap. 6, pp. 117-20.
13. Abramov and Skoog, Chap. 6, pp. 116-7.
14. Hamilton, Thomas J., “Soviet Astronaut Asks Renaming of a Lunar Sea; At a U.N. Parley He Proposes 'Ocean of Gagarin' to Honor the First Man in Space,” New York Times, Fri., Aug. 16, 1968 ($$),Page 42, 711 words; ASTRONAUTICS AND AERONAUTICS, 1968 (NASA SP-4010), Chronology on Science, Technology, and Policy. http://history.nasa.gov/AAchronologies/1968.pdf (retrieved 2 Sept. 2013). Note that this is the complete final sentence of Hamilton’s article—no further details are available.  This sentence is not included in any other newspaper coverage of the event that I have found.
15. Industry Observer, Aviation Week & Space Technology, December 16, 1968, p. 11.
16. “Soyuz 5,” http://en.wikipedia.org/wiki/Soyuz_5 (retrieved 8 Oct. 2013).
17. “Soyuz 1”, http://en.wikipedia.org/wiki/Soyuz_1 (retrieved 19 Oct. 2013).
18. Winston, Donald C, "Soyuz series aims for orbital platform", Aviation Week & Space Technology, Nov.18, 1968, pp. 121-123.
19. “Soyuz (spacecraft),” http://en.wikipedia.org/wiki/Soyuz_(spacecraft) (retrieved 8 Oct. 2013).
20. Kryuchkov and Sokhin, Sep. 25, 2013.
21. Hall, Rex, “[FPSPACE] Soviet underwater EVA training preceding Star City Hydrolab?” http://www.friends-partners.org/pipermail/.BC.ac6F85/2008-February/024433.html (retrieved 9 Oct. 2013).
22. Schweickart, Russell L., interviewed by Rebecca Wright, Houston, Texas, 8 March 2000, Oral History 2 Transcript,http://www.jsc.nasa.gov/history/oral_histories/SchweickartRL/RLS_3-8-00.pdf (retrieved 8 Oct. 2013).
23. “Nikolai Kamanin,” http://en.wikipedia.org/wiki/Nikolai_Kamanin (retrieved 9 Oct. 2013).
24. Wade, March 2008.
25. Luna, Bernadette, W. Curtis Lomax and Douglas D. Smith, “Space Simulation in the Neutral Buoyancy Test Facility,” SAE 932554 Sep. 1993; McHale, Suzy, “Kosmonavtika, Hydrolab training,” undated but no earlier than 2004, http://suzymchale.com/kosmonavtka/trainhydro.html (retrieved 19 June 2007).
26. Schweickart, 8 March 2000. http://www.jsc.nasa.gov/history/oral_histories/SchweickartRL/RLS_3-8-00.pdf (retrieved 8 Oct. 2013).
27. Dates of previous IAF meetings, per the IAF website, http://www.iafastro.com/index.php/events/past-iacs (retrieved 11 Oct. 2013). Date of 21^st IAC meeting, per http://www.worldcat.org/title/international-astronautical-congress-21-abstracts-4-10-oct-1970-konstanz-federal-republic-of-germany/oclc/310714997 (retrieved 11 Oct. 2013).
28. Zak, Anatoly, Russian Space Web, http://www.russianspaceweb.com/almaz_ops2.html (retrieved 1 Oct. 2013).
29. Zak, Anatoly, Russian Space Web, http://www.russianspaceweb.com/almaz_ops3.html (retrieved 1 Oct. 2013).
30. Kryuchkov and Sokhin, Sep. 25, 2013.
31. “Salyut 3,” http://en.wikipedia.org/wiki/Salyut_3 (retrieved 19 Oct. 2013).
32. “Salyut 5,” http://en.wikipedia.org/wiki/Salyut_5 (retrieved 19 Oct. 2013).
33. Portree, David S.F., Mir Hardware Heritage (JSC 26770), NASA Johnson Space Center, Houston, TX, Oct. 1994, pp. 66-8, 71-2.
34. Abramov and Skoog, Chap. 8, pp. 147-51.
35. Mattingly with Charles, February 4, 2013.
36. Hall, Rex D., David J. Shayler and Bert Vis, Russia’s Cosmonauts – Inside the Yuri Gagarin Training Center, Praxis Publishing Ltd, Chichester, UK, 2005, p. 57-62.
37. Newkirk, Dennis, Almanac of Soviet Manned Space Flight, Gulf Publishing Co., Houston, TX, 1990, pp. 173-4.
38. Newkirk, p. 189.
39. Newkirk, pp. 204-5.