Saturday, March 31, 2012

Hoodies in Outer Space: Functional and Fashionable

Recently, the hooded sweatshirt, or “hoodie”, has been elevated from ubiquitous casual wear to political statement in the aftermath of a tragedy. An earlier and very different tragedy led to the widespread adoption of hooded space suits. By the end of 2011, hooded soft-helmet space suits had been used 284 times, by 23% of all space flyers, and those numbers will increase for the foreseeable future.   

In 1973, the resumption of Soyuz launches after an interruption of 15 months was marked by the first Soviet space suits since 1965. In 1971, the three Soyuz 11 cosmonauts died before re-entry when their capsule accidentally depressurized a hundred miles above Earth.  Starting with Soyuz 12, cosmonauts would wear protective suits during launch and landing, as a second line of defense against cabin pressure loss.

As a young space geek, fascinated by the “look” of space technology as well as by its functionality, I immediately noticed that the new Russian suits lacked the most identifiable features of previous space suits: hard helmets and neck rings. Instead, pliable fabric hoods with built-in transparent faceplates clamped shut at the front of the neck to ensure air tightness, and could be folded back behind the head when not needed. These Sokol-K “rescue suits” were manufactured by the Zvezda design bureau in Moscow, makers of all Soviet and Russian space suits before and since then. (“Sokol” is Russian for “falcon”). The Sokol-K was as compact and light-weight as possible, but its associated life support equipment displaced one person, so only two cosmonauts flew where three previously rode in the already cramped Soyuz reentry capsule.

As a young patriotic space geek who grew up in the 1960s and 1970s, an era of rampant Russophobia, I naturally assumed that the soft-helmet Russian suits were “inspired” by the soft-helmet suits worn by American astronauts on a single space mission, eight years earlier.

Frank Borman and James Lovell wore light-weight G5C-model suits made by The David Clark Co. for their record-setting 14-day Gemini 7 mission in 1965. (The “C” in “G5C” stood for Clark.)  Astronauts on the preceding four-day and eight-day Gemini missions blamed much of their post-flight fatigue on the confinement and discomfort of their heavy G4C-model suits. These were reinforced for extravehicular activity (EVA, or space walks), and weighed 14.4 kg, including a 2.8-kg helmet with multiple visors. The G5C had only two layers and weighed 7.4 kg, including a 2.2-kg aviator’s helmet. It could be removed for comfort, and Borman and Lovell were the first people to doff, and later don, space suits in-flight.

The Americans approached suit-less spaceflight tentatively. NASA had long recognized that space suits were a compromise between functionality and comfort, and that functionality outweighed comfort.  In 1963, the B.F. Goodrich Company had developed the G2G-model suit for Gemini flights (the final “G” in “G2G” stood for Goodrich) which featured a removable hard helmet, sleeves and legs, leaving only the torso of the suit to be worn continuously.  But problems with this suit kept it from being accepted for flight.

Before the G5C was adopted, the astronauts training for both Gemini 7 and its eight-day predecessor, Gemini 5, wanted to fly their missions in more traditional pilot garb: standard coverall-style flight suits and aviators’ helmets with oxygen masks.   Gemini 5 commander Gordon Cooper and Elliot See, the backup co-pilot, demonstrated that concept inside their spacecraft during vacuum chamber testing. The fourteen-day Gemini crew had been the backups for the four-day crew, and saw first-hand their post-flight fatigue. In anticipation, Borman and Lovell’s official crew portrait showed them in their preferred space flight ensemble: light blue flight suits—complete with white scarves!—and aviators’ helmets with dark sun visors and oxygen masks. 

But NASA and the spacecraft manufacturer were more concerned about crew safety if the capsule lost air pressure in space, and about thermal and humidity control in the spacecraft.  So, both crews’ requests were disapproved.  In an ironic twist, the eight-day Gemini crew not only didn't fly suit-less, but—because EVA was originally planned for their mission—they had to wear their G4C suits the entire flight!  

Under continued lobbying by the astronauts, NASA Headquarters agreed that the Gemini 7 crew not use existing pressure suits during the 14-day mission.  The new, light-weight G5C full pressure suits were developed and certified just in time for their flight.

After Gemini 7, the last five Gemini flights lasted no more than four days, and all used the G4C suits because they all had EVA planned.  The next opportunity for American  astronauts to fly suit-less would be aboard Apollo, when even standard space suits could be removed in the comparatively spacious cabin, so the astronauts could spend most of their flights in casual comfort.  NASA considered the G5C for use for launch and landing on Earth-orbital Apollo missions, but its peripheral vision was too limited.  NASA revisited the hooded soft suit in 1968 for Apollo, and again in the 1970s for Space Shuttle, but they were not pursued.

The Soviets had dispensed with space suits almost entirely starting with the first Voskhod flight in 1964, when fitting three men into a re-purposed one-man Vostok capsule meant providing the minimum necessary life support equipment. Except for two missions with spacewalks, all Voskhod and Soyuz crews from 1964 to 1971 wore only “training suits” (what we would call “track suits”) from launch to landing. When the Soyuz 11 tragedy proved the necessity of a pressure suit as backup to the spacecraft life support system, they considered modifications of several existing light-weight high altitude suits, and selected the Sokol aviation suit. But to fit into the existing crew couch, they eliminated its hard helmet and re-used a concept they developed as early as 1953: a large soft hood helmet with a clear visor, clamped to the torso of the suit with two hinged semi-frames (think of almost any lady’s purse).  Interestingly, the aviation suit's soft helmet reverted to a hard helmet starting in 1956 because, when opened and swung behind the head, it interfered with the airplane seat’s headrest—not a problem on Soyuz, when the cosmonauts can float out of their seats in weightlessness.

Going even further back, one of the first hooded pressure suits was a British suit from the 1950s, which resembled the G5C but was found inadequate.   And, of course, U.S. Air Force partial pressure suits from the 1950s had a soft hood covered and sealed by a hard, impact-resistant shell.

The Sokol-K evolved through the unflown –KR, -KM and –KV variants to the Sokol-KV2, introduced in 1980 and still in use today. Another variant, named the Strizh (“swift”, like the bird) rescue suit, was developed for the Buran space shuttle program and used in the Tu-160 "Blackjack" high altitude supersonic bomber.  Chinese astronauts on the Shenzhou spacecraft wear rescue suits that appear identical to the Sokol-KV2 and are probably produced in China under license from Zvezda.

In my youth, I assumed that the soft-helmet space suit must have been a recent American invention. But as it happens, such soft-suits were not new, nor were they of American origin.  I even briefly wondered if David Clark had “borrowed” the idea from the Russians, since Soviet propaganda had been showing the soft-helmet suits for years. In the end, it was probably just another example of parallel evolution: smart designers of all nationalities can come up with solutions to their problems, and similar problems lead to similar solutions.

Interestingly, after dispensing with pressure suits for several years, both the Soviet and U.S. space programs resumed using such suits during launch and landing after space flight fatalities caused them to reconsider the wisdom of flying without such protection.  The Soviets had a graphic demonstration of their value on Soyuz 11.  The Americans adopted them in a convoluted response to the “what-if” question about crew survival of an in-flight emergency less abruptly fatal than occurred on Challenger. But neither party recognized the other’s decision as relevant to its own circumstances: each had to experience a tragedy, suffer the consequences and then learn from it.

I began working on this essay on Nov. 3, 1994, and finished it up on March 31, 2012. Edits for corrections on April 1, 2012.


--, “Hoodie” at (last accessed March 31, 2012).
--, “Sokol space suit” at (last accessed March 31, 2012).
--, “Soyuz 11” at (last accessed March 31, 2012).
--, “Strizh” at (last accessed March 31, 2012).
Abramov, I.P., and A.I. Skoog, Russian Spacesuits (Chichester, U.K.: Springer-Praxis, 2003).
Alekseyev, S.M., and S.P. Umanskiy, "High Altitude and Space Suits" (translation from Russian original, 1973), NASA Technical Translation TT F-15165 (Washington, D.C.: NASA, Jan. 1974), at (last accessed April 1, 2012).
Borman, F., and R.J. Serling, Countdown (New York: Silver Arrow Books, William Morrow, 1988).
Brooks, C.G., and I.D. Ertel, The Apollo Spacecraft, A Chronology, NASA SP-4009, vol. III (Washington, D.C.: NASA, 1976).
Crickmore, Paul F., Lockheed SR-71, The Secret Missions Exposed (London: Osprey Aerospace, 1993)
Ertel, I.D., and R.W. Newkirk, The Apollo Spacecraft, A Chronology, NASA Sp-4009, vol. IV (Washington, D.C.: NASA, 1978).
Grimwood, J.M., and B.C. Hacker, with P.J. Vorzimmer, Project Gemini: A Chronology, SP-4002 (Washington, D.C: NASA, 1969).
Gruenfelder, Michael, "'Bears' & 'Blackjacks', The strategic bombers of Divisia Engel's", Air Fan International Vol. 2, No. 2, March 1997, pp. 24-30.
Hacker, B.C., and J.M. Grimwood, On the Shoulders of Titans: A History of Project Gemini, NASA SP-4203 (Washington, D.C.: NASA, 1977).
Kozloski, L.D., U.S. Space Gear: Outfitting the Astronaut.  (Washington, D.C.: Smithsonian Institution Press, 1994).
Mallan, L., Suiting Up for Space, The Evolution of the Space Suit (New York: John Day Co., 1971).
Morse, M.L., and J.K. Bays, The Apollo Spacecraft, A Chronology, NASA SP-4009, vol. II (Washington, D.C.: NASA, 1973).
Newkirk, D., Almanac of Soviet Manned Space Flight (Houston, Tx.:Gulf Publishing, 1991).
Slayton, D.K., and M. Cassutt, Deke! U.S. Manned Space From Mercury To The Space Shuttle (New York: Forge, 1994).

Sunday, March 18, 2012

The Orderly Mind of Deke Slayton: Why Delta 7?

Donald "Deke" Slayton seems to have possessed an orderly mind, because he opted for straightforward, simple, even unimaginative approaches to his tasks.  In future blogs, I hope to give examples, but for now, let's look at the first one Slayton provided in his spaceflight career.

Before he became the legendary first Director of Flight Crew Operations at the new Manned Spacecraft Center near Houston, Slayton was one of the original Mercury astronauts. In late 1961, Slayton was assigned to pilot the fourth manned Mercury mission in spacecraft number 18, which (as he revealed years later) he planned to name "Delta 7."  He would explain that it was inspired by the engineering term “delta” (written as the Greek letter D or d) representing a change in a number, such as a change in velocity, or Dv (pronounced “delta-vee”) (1).  In any attempt to reach orbit, especially so early in the space race, delta vee was a very important parameter: insufficient velocity means mission failure. So Slayton's explanation has the sound of a deliberate decision.

Slayton would have kept the pattern established by Virgil "Gus" Grissom, the pilot of Liberty Bell 7, the second Mercury flight, who appended "7" to his spacecraft’s name to honor the whole astronaut team (7).  Alan Shepard, the pilot of Freedom 7, the first Mercury capsule to carry a pilot, had simply incorporated the serial number of his spacecraft, #7 (8) and his booster rocket, also #7--an omen apparently too powerful to ignore; Grissom’s capsule was #11, but he opted for the poetic symbolism of Shepard’s “7” in his call-sign.  Slayton’s spacecraft was to be the unpoetic #18.

But that explanation of the designation is based on a specific interpretation of “delta” and sounds too simple, even for a no-nonsense man like Slayton.  In general, a delta represents any appreciable increment in a variable (2), no matter how small (just as a "quantum" step is the smallest possible change in electron orbital energy, not the largest step possible, as popular culture would have it). Slayton's intended mission was a three-orbit flight very similar to John Glenn's planned first orbital flight aboard Friendship 7, so the “delta” would have been very small indeed (3). In this sense, to designate one's spacecraft “Delta” is to invite an unflattering comparison. 

It may be that Slayton had something else in mind when he chose the designation.  He was not given to philosophy (4), even compared to some of his colleagues. His immediate predecessors had named their spacecraft after the lofty concepts of Freedom, Liberty and Friendship, particularly relevant in the Cold War between the forces of freedom, liberty and friendship on the side of America, and dictatorship of the Soviet Union. 

Delta is not only the fourth letter in the Greek alphabet but was also the fourth letter in the military phonetic alphabet of Slayton's experience (5). As a military man, Slayton was entirely familiar with the practice of designating a series of sequential items as "alpha, bravo, charlie, delta," and so on.  At the time he was assigned to his Mercury mission, the astronauts were thinking in terms of the first Mercury flight, the second flight, the third flight and so on; the distinction between suborbital and orbital was secondary to them (6). Slayton thus may have been more attuned to the fact that he had been assigned the fourth Mercury flight, rather than the second orbital attempt; thus, the “delta” mission.

Unfortunately, Slayton was grounded from spaceflight just four months after being designated the fourth Mercury pilot by his recurring atrial fibrillation, an irregular heart rhythm that was considered too potentially debilitating for space flight. Scott Carpenter was designated to fly the mission instead, and Delta 7 became Aurora 7. Walter Schirra, Slayton's backup pilot and close friend, flew the fifth manned Mercury capsule, which he named Sigma 7. Like delta, sigma is also a letter of the Greek alphabet which has acquired a mathematical and engineering meaning: a summation. Schirra explained that his 9-hour, 6-orbit flight was to build upon its predecessors and be a summation of their efforts. He might also have said  that his 6 orbits were the mathematical sum of Glenn's and Carpenter's 3 orbits--and if Slayton had flown instead of Carpenter, then Schirra's "sigma" would have represented more of a change from what went before than Slayton's "delta". (Okay, it's a bit of a stretch, but you see what I mean.)

How like Slayton simply to choose the name Delta for the fourth American manned space flight, as if to say that it wasn't the name that was important, it was the mission.  If he did a good job, then the history books would immortalize any name he chose.  Perhaps it was lucky he wasn't selected for the fifth flight: the next letter in the military alphabet was "echo." Communist propagandists might have appreciated the opportunity to deride to the Mercury flights, with their all-too apparent limitations, as faint echoes of the dramatic Vostok missions flown by the Soviet Union.

(My first draft of this blog was in 2002, and now maybe I have made my last edits on March 20, 2012.)

(1) Slayton, Donald K., with Michael Cassutt, Deke! (New York: Forge, 1994), p. 105, p. 110.
(2) The Collins English Dictionary © HarperCollins Publishers, referenced online at, on Sep. 14, 2002.
(3) Scott Carpenter’s “duplication” of Glenn’s mission proved to be significantly different in some important respects; see Carpenter, Scott, and Kris Stoever, For Spacious Skies (New York: Harcourt, Inc., 2002), pp. 238-240.
(4) Trafford, Abigail, “Apollos and Oranges,” Second Opinion, Washington Post Health, July 19, 1994, p. 6.
(5) This is based on the Korean War version of the military phonetic alphabet, the last of three stages of its evolution, as listed in the “Saving Private Ryan Online Encyclopedia”,last updated Apr. 2, 2002, accessed on Aug. 8, 2002.
(6) Schirra, Walter M., and Richard N. Billings, Schirra's Space (Boston: Quinlan Press, 1988), p. 72.
(7) Grissom, Virgil "Gus", Gemini! (New York: The Macmillan Co., 1968), p. 93.
(8) Slayton, pp. 97.

My very first blog post!

Welcome to my first posting in my first blog! I will populate this blog with short, succinct essays, ramblings and other offerings about little known aspects of space exploration by humans. They will include questions I have always wondered about, and--if available--answers, so you won't have to wonder.

A life-long space nerd, I am lucky enough to work in the best possible field (space life sciences) in the best possible location to indulge myself: NASA's Johnson Space Center, near Houston, Texas. Even after three decades here, every meeting I go to, every lunch in the cafeteria, every walk across the center puts me in the offices, conference rooms and footsteps of the heroes of spaceflight: the astronauts, engineers, physicians, scientists and technicians who gave America and the world some of the proudest moments in human history--and some of the most crushing sadness.

After deciding to start this blog, I made a list of questions and topics that seemed like a fun set with which to begin (in no particular order, and with no promise of completion):
  • NASA's first efforts to land astronauts back on land instead of splashing down at sea (the Rogallo inflatable wing vs. the parasail-and-solid landing rockets of "El Kabong")
  • Was there a last-ditch capability to de-orbit a Gemini or Apollo capsule even if the usual means (retrorockets, SPS) were unavailable? (An alternate ending to the space movie Marooned, maybe...)
  • The history of astronaut cabin fires and other toxic events in spacecraft and simulators.
  • Use of lower body negative pressure to mimic the effects of gravity on the cardiovascular systems of weightless astronauts. (An excuse to delve into other biomedical aspects of spaceflight--so be forewarned.)
  • Space nomenclature and jargon, and what it says about its users (examples: "microgravity", "crew", "Mercury 9" and "Delta 7").
  • Hatches in heat shields: a good idea or not?
  • Tunnels in the sky: moving through long narrow tubes in spacecraft and aircraft.
  • Space people I have known, known about, wish I'd known and been inspired by.
  • My current personal favorite: the early history of underwater weightlessness simulation.
Part of my motivation is to celebrate the trivia of the space age: the endless list of questions no-one thinks about because everyone already "knows" the right answers--even if they really don't. The trivia fleshes out the bare bones of spaceflight, and shows us that this supposedly impersonal, technocratic science-factual undertaking is a truly human adventure, with drama to match anything in science fiction.