Adapter in the Rough

Slightly edited and revised version of an article published in The Space Review, Monday, January 30, 2017.

Sometimes life is like a movie. Think of the scene when the hero finally finds the lost artifact, after years of searching, hope fading. In that moment, his years of study let him recognize it immediately, no matter how ravaged and incomplete it is. He points out features and fixtures, present or missing, and names them as his fellows approve and agree.

That doesn't happen often outside of the movies. It happened to me recently. Sort of.

My particular lost artifact was a piece of equipment from a long-cancelled space program. It was not lost as much as it was long neglected, hidden in plain sight in the wrong place as it gradually decayed.

Specifically, it is the adapter module of the Gemini-B vehicle designed to carry U.S. Air Force astronauts to and from their tours of duty aboard the Manned Orbiting Laboratory, or MOL, a series of single-use 1960’s-vintage manned spy satellites to keep an eye on America’s Cold War adversaries.

It was probably part of a Gemini-B spacecraft engineering mockup from 1968 (Figure 1), with some flight-worthy components and some simulated parts, but intended for ground evaluation instead of flight. The mockup was apparently designated the “ECV” which might have stood for “engineering configuration vehicle” but no one I have asked can confirm that.

Figure 1. Gemini-B ECV at McDonnell Douglas in St. Louis ca. 1968. Photo by McDonnell Douglas, courtesy Dr. Dwayne Day.

The adapter on Gemini-B and on its cousin, NASA’s Gemini (Figure 2), connected the crew re-entry capsule to the rest of the launch vehicle stack. Gemini’s designers at the McDonnell Aircraft Co. were anxious to minimize weight as much as possible, so they ingeniously used that otherwise wasted volume to accommodate life support equipment, maneuvering systems and experiments needed during flight but not during landing (1, 2). This kept the re-entry capsule’s weight to a minimum without sacrificing in-flight functionality.

Figure 2. Comparison of NASA Gemini and USAF Gemini-B for MOL, with sections labeled. Original Art by G. de Chiarra, modified by J. Charles.

The “B” version of the Gemini had MOL-unique modifications that distinguished it from NASA’s “A” version (which was never referred to as “Gemini-A” as far as I know.) Among the modifications was a pair of hatches in the aft end of the Gemini and its heat shield that led to a tunnel through the adapter connected to the pressurized module of the MOL. That module, the disingenuously-named “laboratory” in “manned orbiting laboratory,” was the business end of the MOL vehicle, containing the DORIAN KH-10 camera system with its 72-inch diameter mirror. MOL was to be built by the Douglas Aircraft Co. in Huntington Beach, California.

I had seen the Gemini-B ECV crew capsule, or re-entry module (Figure 3), on several visits to the National Museum of the U.S. Air Force at Wright-Patterson AFB near Dayton, Ohio, most recently at the October 2015 “MOL declassification event” staged by the National Reconnaissance Office. This was the NRO’s way of announcing the new public accessibility of 825 documents, 282 photographs and one short movie clip on MOL, all previously classified as “secret.” The museum’s Gemini-B was displayed until 2016 as an example of NASA’s Gemini, albeit without its adapter module, its rendezvous and recovery nose section and both of its hatches, and with “U.S. Air Force” and the star-and-bars roundel emblazoned on its flanks. That always seemed like a wasted opportunity to showcase the Gemini-B’s unique characteristics. Then again, maybe deception was appropriate for a top-secret spy satellite.

Figure 3. Gemini-B reentry module, possibly the same ECV as in Figure 1, now on display at the National Museum of the U.S. Air Force, Wright-Patterson AFB. Photo credit: Jim Cope, USAF.

When I say confidently that this display vehicle is the ECV, it is an act of faith based on deduction. The only known photographs of a vehicle in the Gemini-B configuration are of the ECV in about 1968 at the now-McDonnell Douglas plant in St. Louis, Missouri. No Gemini-B flight vehicles were ever constructed (4), so I assume that the vehicle now on display in Dayton is the ECV. Eventually I mentally connected the Gemini-B adapter module in the USSRC bone yard with the capsule in Dayton, although their physical and geographical separations gave me pause.  

By 1967, McDonnell-Douglas considered the Gemini-B/MOL system to be sufficiently flexible and capable for future space station programs as well as for the secret military missions for which it was originally designed. It was marketed aggressively to NASA for space station use, unsuccessfully. Undaunted, the company decided to compete head-to-head with North American Rockwell’s Apollo command-service module assemblage for space station support. Their concept was the Big Gemini (3), or Big G, which enlarged the carrying capacity of the basic Gemini-B reentry module to accommodate up to 10 more astronauts or their equivalent in cargo by extending its length by 60% (Figure 4). In particular, the removable hatch through the aft pressure bulkhead led not to a tunnel but into the additional crew compartment.

Big G never got beyond the mockup stage, but the Big G mockup in St. Louis must have initially used the existing Gemini-B engineering mockup as its basis, without its adapter section and with a modified rendezvous and recovery nose section. Instead of its adapter, it was attached to the extended crew module that made Big G big. However, a photograph of the Big G mockup from April 1969 shows the NASA Gemini, not the Gemini-B. The photo’s caption states clearly that the NASA Gemini is used in the mockup, and the paint job on the side of the capsule confirms it. Perhaps the Gemini-B mockup could not be used for the photo session because it had “U.S. Air Force” painted on its flank (see Figure 2) instead of NASA’s “United States,” poor strategy for marketing to NASA.

Figure 3. Big Gemini mockup at McDonnell Douglas in St. Louis, April 1969. At the core of the mockup is the “NASA Gemini,” possibly for marketing purposes, even though the concept required the Air Force MOL Gemini-B variant for it to be usable. Note Gemini-B adapter in background, separated from its Gemini-B re-entry module, which was probably used on this mockup for all work except for publicity photos. Photo by McDonnell Douglas, courtesy Dr. Dwayne Day.

Also of note: the Gemini-B adapter module was standing in the background of the Big G photograph, separated from its crew module, which was not in any of the photos.

When MOL was cancelled in 1969 and subsequent bids to market the Gemini-B and Big G spacecraft to NASA lost out to Space Shuttle concepts, McDonnell Douglas collected the MOL flight and ground hardware, including the ECV mockup, and either scrapped it or offered it to the Smithsonian Institution. By law, the Smithsonian is the official repository for important government space artifacts and keeps or distributes those it deems representative and important. Somehow, sometime, possibly in the early 1970s, this adapter unit was mixed in among other surplus items that seemed to represent Marshall, so it ended up on a pallet delivered to Huntsville. There it sat.

We knew where the adapter was in 2006 because Tom Hancock, a space historian in Huntsville, Alabama, had posted photographs of it on the Internet in his “US Space News” blog (now retired). He occasionally visited it in the outdoor storage area, or “bone yard,” of the U.S. Space and Rocket Center in Huntsville. The USSRC, originally the Alabama Space and Rocket Center, is the visitor center for NASA’s Marshall Space Flight Center, and it is full of mockups, prototypes and spares of spacecraft and their systems from the Apollo, Skylab and Shuttle programs for which Marshall was responsible.

This bone yard is like most outdoor storage areas for museums, schools, factories and my grandmother’s farm. Pieces of machinery and other items with no planned use but possible future value sit in the open air, usually grown up in weeds and inhabited by wildlife.

The NRO event is also where I first met Mike Jenne, an author whose breakout work is an alternate history trilogy (Blue Gemini, Blue Darker Than Black and Pale Blue, Yucca Publishing, New York, NY) about clandestine Cold War space missions aboard modified Gemini spacecraft. It is carefully researched as well as well-written, and I quickly appreciated Mike’s grasp of the subject matter.

So, it was that, on June 29, 2016, eight months after the NRO event, I emailed Mike to see if he would be interested in a MOL-related challenge: reuniting the capsule in Dayton with the adapter in Huntsville, so they could be displayed in Dayton, together for the first time in decades. He accepted the challenge.

A few days later, on July 3, Mike drove north from his home near Birmingham to Huntsville to reconnoiter the bone yard. He is retired Special Forces, so he prepared for this mission by looking at overhead imagery of the bone yard from Bing and Google Earth. Based on his research for the trilogy, no one could have been better prepared for this quest. Actually, it was multiple quests: others in his network of space history buffs had suggested their own favorite space artifacts as targets, so he had a shopping list.

After his visit, Mike emailed that he hadn't been able to find the adapter. The closest he came was a fiberglass cylinder over near the Titan II ICBM display model, but with none of the expected internal features, especially the crew transfer tunnel, and larger than the 10-foot diameter of the Titan rocket which was to be MOL’s launcher. That was discouraging, but I began to accept that it was gone, scrapped or otherwise disposed of, or dissolved unrecognizably into the weeds and dirt.

However, Mike is more persistent than me. A couple of days later, on July 5, as he searched through the overhead photos again, he spotted an inconspicuous cylindrical item that he had seen but dismissed during the visit. I sent him Hancock’s pictures from 2006 and told him the adapter is a tapered cylinder 10 feet across at its wide end, 7 feet at its narrow end, and 5 feet high. When I confirmed it was probably gray, unlike the white Gemini adapter he had been looking for (oops, did I not mention that difference before?), he was convinced this was the missing item.

The adapter is barely recognizable in the low-resolution Google Earth image from October 29, 2015 (Figure 5), sitting sixteen feet southeast of a storage building at the western end of the USSRC complex: look for it at 34 degrees, 42 minutes, 35.38 seconds north, 86 degrees, 39 minutes, 32.49 seconds west.

Figure 5. Google Earth view of USSRC bone yard dated Oct. 29, 2015, showing location of Gemini-B adapter module. Screen capture by J. Charles from Google Earth.

Coincidentally, Hancock reposted some of his 2006 images on the Space Modeling page on Facebook on that same day (5), reinvigorating public interest in the item.

Mike returned to the bone yard on July 17, two weeks after his first visit, and went straight to the artifact. It was as if I were there, too, because he sent me pictures from every angle as he inspected it (Figures 6 and 7). It was surprisingly recognizable after having been exposed to the elements for at least a decade and probably much longer.

Figure 6. Current location and condition of Gemini-B adapter module at USSRC bone yard. Photo by Mike Jenne, July 17, 2016.

Figure 7. Detail of Gemini-B adapter module showing crew transfer tunnel (top) and retrorocket assembly (bottom) with five of the six original simulated retro rockets still in place.  Photo by Mike Jenne, July 17, 2016.

How much longer is not clear. Available imagery does not show where it was when Hancock photographed it in 2006, but something that resembles it was sixty feet further to the south, across an access road, from 2007 to 2013.

And there the story might have ended, except for a whim. My wife and I have been discussing a post-retirement plan to buy a recreational vehicle and use it to see the country affordably. We decided to “practice” retirement this year on a week-long road trip in a rented RV. Driving from Houston to Huntsville would provide the needed distance and scenery, so I asked Mike if he was up for another trip to the bone yard. He was, and recruited two friends in Huntsville to meet us there. One of them was Tom Hancock, who had taken the very photos that had inspired our search. We were escorted by Ed Stewart, Director of Exhibits and Curation.

That is how, on the sweltering sunny morning of August 24, I found myself in the USSRC bone yard with four other space history buffs approaching the adapter. It wasn't a profound or moving experience but it was gratifying to see it for myself and to imagine it as it once was. I immediately recognized the vestiges of the simulated retrorockets, the crew transfer tunnel, and the empty fixtures for the oxygen and water tanks. We searched for data plates on every piece and established that most of it had been built by October 1967—49 years ago.  With the USSRC curator, we immediately started scheming how to rescue it from the elements, refurbish it and put it on display somewhere. All those steps would require funding as well as a destination, although the curator said he would try to move it indoors in the mean time. The USSRC never had any connection to MOL—aside from this adapter’s unexpected and unrequested delivery—so the problem also included shipping it somewhere else that did have a connection.

The obvious “somewhere else” is the National Museum of the U.S. Air Force at Wright-Patterson Air Force Base in Dayton, Ohio. The museum’s Gemini-B crew capsule was, I believe, originally paired with the adapter module now at USSRC as the complete ECV of 1968. Thus, it makes sense that they should be reunited and displayed there among the museum’s unique collection of unmanned reconnaissance satellites.

However, here is where the realities of museum operations complicate matters. First, the adapter is officially the property of USSRC, and they would have to transfer it. This part sounds easy, because the USSRC curator said he would support such a decision. Second, as John Luchin, Registrar of the Collection Management Division, explained, the NMUSAF establishes its restoration and exhibit projects and budget years in advance, so even if they acquired the adapter, it could sit in storage for years.

Storing it indoors at the Air Force museum in Dayton seems preferable to leaving it outdoors at the NASA museum in Huntsville, and not just because of the ravages of nature. There is apparently also larceny involved. One of the six simulated retrorockets is missing, and Hancock recalls an earlier visit to the artifact when all six were present. On the day that Mike took pictures of it at USSRC, a security guard told him that the USSRC had experienced problems with people raiding the bone yard for scrap metal, particularly aluminum. If anyone suspected the market for these and other rare historical artifacts—perhaps a collector wanting something to go with his purloined simulated retrorocket—then four men and a pickup truck could bring our story to an untimely end.

At least such a collector would recognize the significance of the MOL program. Even if we considered it a failure because it was cancelled before its first flight, MOL was a massive undertaking in which thousands of workers labored and billions of taxpayer dollars were expended. The Air Force press release announcing its cancellation said that “about $1.3 billion had been spent to date” on MOL, equivalent to $9.4 billion in 2015.

Despite that mind-boggling investment, there are few MOL artifacts remaining. In addition to the intact mockup crew capsule at the NMUSAF, the less-intact mockup adapter module at the USSRC, there are six 72-inch diameter mirrors used in the Multi-Mirror Telescope, Mt. Hopkins, Arizona, 1979-1999, at least five blue Hamilton-Standard spacesuits, three buildings at the Douglas, then McDonnell Douglas, now Boeing plant in California, a re-purposed launch pad in California now used for commercial launches, a building at the Air Force’s mission control center, also in California, a flown heat shield test capsule in Florida, and an alligator clip-lined aluminum sheet at the NMUSAF labeled a “prototype food dispenser for the Manned Orbiting Laboratory, one of the very few full-scale objects to survive the MOL project…”  The scarcity of physical artifacts associated with the MOL program would seem to be adequate motivation to properly preserve this piece of history.

It is clear that any progress will require coordination and collaboration at high levels. The first step might be to identify who those high-level decision-makers are so they can specify the steps required at USSRC and NMUSAF to effect the transfer: who has approval authority, what has to be approved, in what order, for which options (restore, refurbish, display as is or other option) and most importantly what it would cost. Presumably items are shared among museums all the time, so how has it been done before? If it isn't on their multi-year plan, what would it take to get it into that plan?

Whatever fate the future holds for the adapter, I think it was appropriate and not at all ironic that we pinpointed this artifact—a vestige of a high altitude photographic spy program—by examining high altitude photographs of the target area. That’s the kind of closure that you usually only get in the movies.


John Charles is a senior space life sciences manager for NASA in Houston with a life-long interest in spaceflight and particularly in MOL. Suggestions on ways to reunite the wayward adapter with its crew capsule are welcome in the comments and at



(1) Grimwood, James M., and Hacker, Barton C., with Vorzimmer, Peter J, Project Gemini, Technology and Operations, A Chronology, NASA Special Publication-4002, Washington, D.C.: NASA, 1968, (accessed Dec. 24, 2016). See entries for July 7 and July 27-28, 1961, in PART I (A), Concept and Design, April 1959 through December 1961.

(2) Kolcum, Edward H., “Manned Space Flight Program Expanded; McDonnell to build 12 two-man capsules and modify four Mercury spacecraft for flights of 18 orbits,” Aviation Week & Space Technology, Dec. 18, 1961, pp. 26-7, (accessed Jan. 1, 2017; subscription required).

(3) Petty, Chris B, “Space Trucks! Big G and the TKS,” The High Frontier (blog), Dec. 14, 2015, (accessed Dec. 25, 2016); Day, Dwayne, “The Big G,” The Space Review, Dec. 7, 2015, (accessed Dec. 25, 2016).

(4) “Program Schedule Status, 10 June 1969,” (accessed Jan. 9, 2017), pp. 22 of 41, item IV.

(5) Hancock, Thomas, Facebook post, July 5, 2016, (accessed Dec. 26, 2016).



The First Time Anyone Shaved in Space

(With apologies to Roberta Flack, 1969)

I recently spent an entertaining hour and a half at a “wet shave meet-up” speaking about NASA space biomedical research in general and shaving in space in particular.

That sentence begs at least two separate explanations.

First, a wet shave meet-up is not a variation on Sir Arthur Conan Doyle’s “The Red-Headed League.” I didn't know it but wet-shave meet-ups are a national phenomenon where aficionados, enthusiasts and artisans can buy, sell and discuss blades, brushes, sharpeners, etc. It sounds a little crazy but there is actually a community of wet shaving aficionados who enjoy shaving with a razor and related tools as opposed to an electric razor. “Wet Shave Meet Ups” is a resource page (1) put together by Doug Smythe and Matthew Broderick to keep the community informed. Individual meet ups are organized by people in the community when and where the spirit moves them.  The “mother ship” of meet ups was held April 23 in Pasadena, California: “Big Shave West” (see it at “The Heart of Shaving: Big Shave West 2”) (2).  It had about 250 men and women in attendance, including manufacturers, YouTube “celebrities” and just-plain-fans from all parts of the globe.

I didn’t go to Pasadena, California, or even Pasadena, Texas. The Space City Meet where I spoke was organized by Adam Lindberg, artisan soapmaker for Stubble Trouble in Houston, a local meet-up at Rosewater, a new bar here in Clear Lake, Texas, co-owned by Pasha Morshedi, a colleague at NASA, and coincidentally where Adam is a bartender. There were about 30 wet shaving fans in attendance from as far away as Boston, along with manufacturers of small batch shaving products. It was organized by Gail Wells, the US brand manager for Edwin Jagger, an English company (3). She asked me to speak about shaving and grooming in space, and anything else of interest to the group.

This talk was arranged through the Johnson Space Center Speakers Bureau (4) so I had planned to give my usual 60-plus slide presentation on NASA’s Human Research Program and our work on resolving the risks to astronauts on future deep-space exploration missions, with a few interstitial slides on the history of shaving in spaceflight. Technical problems spared the attendees my full presentation, but luckily the shaving part could be retrieved. Being a NASA scientist, I use PowerPoint for all my presentations. The figures in this article are most of the charts I used at the meet up. Their text reveals the maturation of my approach to this topic.

Second, and contrary to my wife’s expressed disbelief, there is actually at least 30 minutes’ worth of presentation material on the topic of shaving in spaceflight.  

I was substituting for Neal Pellis who wasn’t available, but leaped at the excuse to explore this little appreciated aspect of everyday life in human spaceflight.

When I said “yes,” I already knew a few facts (remember: I'm a space geek): the first in-flight shaving was done on Apollo 10; Frank Borman requested an electric razor be waiting for him on the recovery helicopter after Apollo 8; some of the Skylab astronauts grew bushy beards while in orbit. But I had about three weeks to do some more research, so the first thing I did was contact some astronauts I know and ask them about wet shaving in flight. They responded almost apologetically that they used the electric shaver but without the vacuum attachment that featured in early designs. Instead, they just shaved near the inlet of the air conditioning system and let the spacecraft’s filters catch their whiskers.

If you are old like me, you remember the bearded faces of pioneering astronauts, beaming but exhausted, on the aircraft carrier after splashdown. In particular, the men on NASA’s second, third and fourth Gemini missions in 1965 extended our experience base of manned spaceflight stepwise to four, then eight and finally 14 days (figures 1), demonstrating that astronauts could come through the planned duration of the upcoming Apollo lunar landing missions with no debilitating physical effects. (The longest of seven previous American flights was 34 hours and the average was just under eight and a half hours.) Their beards confirmed what we already understood: that they had returned from the frontier, at no small risk to their lives and health, and had pushed back the boundary of the unknown just a little bit farther in man’s conquest of space, and in particular, America’s race to beat the Soviet Union to the moon.

Figure 1. Unshaven astronauts after early Gemini spaceflights. (Credits: NASA.)

The first astronauts were all males, all white and all military or former military qualified jet pilots (civilians without military experience and pilot qualifications were not selected as NASA astronauts until 1965), and they personified America’s image of the clean-cut hero. Intentional facial hair was not in vogue among such men in the early 1960s, and a few years later, shaggy beards would be a defining feature of the exact opposite of these men: “hippies.”

The early astronauts didn’t shave in space because they couldn’t, not because they didn’t want to. It wasn’t considered a priority in a program that was just trying to prove that man and machine could function long enough to get to the moon and back. By 1964, however, electric shavers were in development for future longer flights (figure 2A, right picture) that included a cumbersome vacuum hose to collect the cut whiskers (5) so they would not be a health hazard or contaminate the electronics (figure 2B), but they were not yet ready to fly (6).  Wet shaving was unthinkable: free-floating water droplets were considered anathema by engineers who remembered the problems caused to spacecraft electronics by Gordon Cooper’s body moisture during his 34-hour Mercury flight just two years earlier.

Figure 2. Early and later attempts at mechanical razors for shaving in space. (Credits: Historic Images and unknown manufacturer; Cunningham Collection.)

Figure 2B. A simulated space station mission in the 1960s established the justification of both the electric shaver and the vacuum attachment. (Credit: NASA in "Living in Space, NF-27, April 1969.)

There was no lack of desire to shave. Setting aside matters of comfort and hygiene, some astronauts also were sensitive about appearances. Jim McDivitt on the four-day Gemini 4 and Jim Lovell on the 14-day Gemini 7 had grown unmistakable beards. Frank Borman, also on Gemini 7, hinted at his uneasiness in comparison when he wrote in his biography that “Lovell had a full beard and I looked like a skid row bum recovering from a week-long binge.” (6) When Borman he flew with Lovell again, this time on Apollo 8, he made sure there was an electric razor waiting for him in the recovery helicopter (7)--which apparently only he used (figure 3).

Figure 4. Borman was able to shave aboard the helicopter after Apollo 8 but not after Gemini 7 (Credits: NASA.)

The breakthrough came in May 1969 aboard Apollo 10, the last mission before the lunar landing. First John Young, then Tom Stafford and Gene Cernan, homeward bound and taking advantage of the hot water available on the Apollo command module (9) advised Mission Control they were performing scientific experiment “Sierra-Hotel-Alfa-Victor-Echo” (figure 4). This transparent code-name was their light-hearted effort to let friends and family but not the press know that, thanks to brushless shaving cream and a safety razor, they would emerge from their spacecraft clean shaven after their eight-day mission. But the difference was noticeable in their last color TV broadcast before splashdown, so the secret was out.

According to Chris Spain’s website, “Space Flown Artifacts" (10)

Despite the original concerns it was found that using brushless shaving cream and safety razors there was actually no problem with loose whiskers. The process of shaving was still far from easy - most crews reported that the razors quickly became clogged with used shaving cream and whiskers and were almost impossible to clean out in the absence of running water.

The brushless shaving creams used by the astronauts were regular commercial products and the crews were apparently free to choose the brand they wanted to carry with them on a particular flight.

Figure 4. SHAVE experiment on Apollo 10. (Credits: NASA.)

(I wish I had found Chris’s article before my presentation to the wet shave meet up—wonder if I can get a do-over?)

Once it was established as an option, wet shaving even allowed Mike Collins on Apollo 11 to express himself creatively (figure 5).

Figure 5. Michael Collins before, during and after Apollo 11. (Credits: NASA.)

The preflight press information kits for the pre-shaving Apollos 7, 8 and 9 and the post-shaving Apollos 10, 11, 12, 13, 14 and 16 (10) shows they all list the personal hygiene items carried on each spacecraft: toothbrushes and toothpaste, tissues, solid waste collection bags and urine collection devices. However, none of them lists any devices for either wet or dry shaving, not even on those missions where shaving was known to occur. The relevant text was obviously copied from one press kit to the next, but it is hard to understand why such intimate activities as tooth-brushing, urination and defecation were acknowledged publicly but shaving was not.

A better place to check is the Apollo stowage lists, but Mr. Spain noted,

The Apollo Stowage Lists make no mention of the shaving equipment carried by the crews, but we do know that Apollo 11 Command Module Pilot Mike Collins used Old Spice brushless shaving cream on that flight as it is now part of the Smithsonian collection [along with his Gillette Techmatic safety razor (figure 6)]. We also know that a tube of K-34 Gillette brushless shave cream was used by the crew of Apollo 12, as this was given by them to Support Crew member Paul Weitz as a memento after the flight. On Apollo 13 we know that they used a shaving cream by Mennen, as this is mentioned in the technical debriefing.

Figure 6. Razor and brushless shaving cream used by Mike Collins on Apollo 11. (Credit: Smithsonian Institution.)

However, a wind-up mechanical razor was available by the time Apollo 14 flew in early 1971. It was even featured in a well-acted in-flight skit in which Alan Shepard shaved with it (12) then appeared to order his reluctant crewmate Ed Mitchell to do likewise (figure 7). (I made figure 7 from YouTube via a screen capture but cannot now find the video again.)  Their razor looked very much like the unflown prototype intended for the Skylab space station in 1973 (see figure 2A, left side) except with a black body.

Mr. Spain observed that:

[a]lthough safety razors were found to work reasonably well in a weightless environment the evaluation of mechanical razors for use in space continued. These efforts led to the adoption of a wind-up mechanical design made from acrylic which was used for the first time on Apollo 14 with reasonable success.

On Apollo 16 Ken Mattingly used a mechanical razor and found it worked well if used frequently. If used on two day old stubble however, he reported that it felt like the whiskers were being pulled out rather than cut. His crewmates apparently used Wilkinson safety razors when they had to shave, but found the same problem with clogging blades as earlier crews.

Figure 7. Ed Mitchell tried but failed to resist an order from Al Shepard to shave during Apollo 14. After the flight, Mitchell grew a beard which h kept for the rest of his life. (Credit: NASA.)

Thus, with both a wet and a dry option available, the difference was like night and day. All previous crews were scruffy if not shaggy, and all subsequent crews looked more “kempt” (figure 9)…except for Apollo 13, who did not shave before splashdown, lacking both the warm water and the inclination to do so while they struggled with their crippled spacecraft.

Figure 9. Astronauts after splashdown on Apollo 7, 8 and 9 before inflight shaving became possible and with Apollos 10-17 after on-board shaving became possible. (Credits: NASA.)

In fact, according to Chris Spain, Apollo 10 was not the first to carry wet-shaving equipment, only the first to use it:

[t]he first long duration Gemini spaceflights [Gemini 4, 5 and 7] brought the issue of shaving in space to the fore. The main concern was to ensure that loose whiskers would not end up floating into critical flight instrumentation, but early experiments with electric shavers fitted with simple vacuum attachments were a failure.

On Gemini [presumably after Gemini 7] through Apollo, the crews were issued with Gillette Techmatic safety razors but they apparently went unused until the flight of Apollo 10.

Unfortunately, this is hard to square with Borman’s request for an electric shaver in the helicopter: why didn’t he just shave in flight instead? Presumably, any razor and cream that flew on Gemini was manifested only after its longest-duration mission, Borman and Lovell’s Gemini 7, or Borman would have shaved during that flight as well. Unless, that is, he didn’t relish cold-water shaving: Gemini did not provide hot water.

At the risk of contradicting Chris Spain (whose web article did not give a source for the presence of inflight shaving paraphernalia prior to Apollo 10), it only makes sense to me that the Apollo 10 astronauts were the first to shave in spaceflight because they were the first to be equipped to shave in spaceflight.  Apollos 7, 8 and 9 also had hot water, plus lots of relatively idle hours toward the ends of those missions. Admittedly, it would have been more tedious to shave a week-old beard under those conditions, but not impossible.

Wet shaving has continued to be a part of subsequent missions, programs and eras (figure 9), as demonstrated by Joe Engle on STS-2 in 1981 and Mike Mullane on STS 41-D in 1984. I don’t know how the post-Apollo practitioners solved the problem of clogged razors, however, in the absence of freely-running water.

Figure 9. Joe Engle (STS-2) and Mike Mullane (STS 41-D) wet-shaving in the Space Shuttle era. (Credits: NASA.)

Interestingly, the inability or even reluctance to shave was not just a feature of American spaceflights: no Russian cosmonauts shaved in space until 1974, five years after the Americans. My colleagues Anna Kussmaul and Yuri Smirnov of the Institute of Biomedical Problems of the Russian Academy of Sciences in Moscow told me about the history of shaving on their flights.

In 1966 the Russians were preparing a series of Voskhod missions to exceed the Americans’ recent accomplishments in Gemini, including the planned 18-day flight of Voskhod 3 to break the 14-day record of Borman and Lovell on Gemini 7 (13). (The longest previous Russian mission was five days, and the average of the eight was just over two days.) One record the Russians apparently did not intend to establish was the first shave in space: Voskhod 3 cosmonaut Boris Volynov asked his boss, Gen. Nikolai Kamanin, for permission not to shave in flight, so Kamanin ordered that no shavers be flown (14). (This was about two months before planned launch, but sometimes things get overlooked until too late.) Voskhod 3 and its follow-ons were cancelled a few months later and Volynov didn’t fly until an early next-generation Soyuz mission in 1969.

In 1970 the Soyuz 9 crew flew for 18 days, taking back the endurance record. In 1971 the Soyuz 11 crew lived and worked aboard the first space station, Salyut, for 24 days--and apparently did not shave (figure 10A). But their appearance may have impressed space managers because that same year the Ufa factory received an order to create the first electric shaver for spaceflight (15). Three missions later, the Soyuz 14 crew tested the Agidel-K electric shaver (figure 10B), with vacuum attachment (not shown), during their two-week stay on Salyut 3. The first confirmatory photo I could find shows the Soyuz 18 crew clean-shaven after their 63-day flight aboard Salyut 4 in 1975 (figure 10C).

I still don't know when the Russians adopted wet shaving in flight, but they do it today.

Figure 10A. Soviet cosmonauts on Salyut/Soyuz 11 before and during spaceflight in 1971. (Credit: TASS.)

Figure 10B. The Agidel-3 commercial version of the Agidel-K (for "cosmic") electric shaver used in spaceflight. (Credit: Ufa.)

Figure 10C. Obviously clean-shaven Soviet cosmonauts Pyotr Klimuk (left) and Vitaly Sevastyanov (right) shortly after their 63-day spaceflight on Salyut 4/Soyuz 18 in 1975. (Credit: TASS.)

As Chris Spain noted,

Despite the difficulties, which led many astronauts to let their beards grow for at least part of the missions, most reported that it felt very refreshing when they did manage to shave.

In the American space program, starting in 1965, new cadres of astronauts were selected who were not military pilots. The scientist astronauts of 1965 and 1967 including university professors with more relaxed and contemporary tastes in facial hair.

The first to launch and land with facial hair was Owen Garriott, whose mustache only got longer during his 59 days in orbit during the Skylab 2 mission in 1973 (figure 11). Many subsequent astronauts have sported mustaches throughout their spaceflight careers.

Figure 11. Owen Garriott and the first mustache to go into spaceflight. (Credits: NASA.)

The very next crew all launched clean-shaven, but during their 84-day Skylab 3 flight, Gerry Carr and Bill Pogue both grew substantial beards (figure 12), confident that they would not be mistaken for hippies.

Figure 12. Skylab 3 astronauts before and after 84-day spaceflight. (Credits: NASA.)

The first man to launch with a full beard was Paul Scully-Power, an Australian-born payload specialist (e.g., visiting astronaut). He and six crewmates spent eight days orbiting Earth aboard the Space Shuttle Challenger during the STS 41-G mission in October 1984. His experience is notable because he was under some pressure to shave before flight to ensure the face seal of his helmet would function correctly during an emergency. Instead, he demonstrated that it sealed adequately despite his beard (figure 13). Two more fully-bearded men have followed Scully-Power's example: payload specialist Loren Acton on STS 51-F/Spacelab-2 in 1985 and Reinhard Furrer, a German payload specialist on STS 51-A/Spacelab-D1 also in 1985). (American astronaut Ron McNair had a beard when he was selected as a NASA astronaut in 1978, but by the time he flew on STS 41-B in 1984, he was clean-shaven.) The problematic style of helmet was superseded after the first 25 Shuttle flights, and subsequent helmets were indifferent to beards, but I can recall no other fully bearded men who have flown in space since then.

Figure 13. Paul Scully-Power and crewmates on STS 41-G in 1984. (Credits: NASA.)

Today, both wet- and dry-shaving continue to find adherents aboard the International Space Station (figure 14), as demonstrated in 2000 by Yuri Gidzenko and Sergei Krikalev on the first ISS crew and Yuri Usachev on the second crew.

Figure 14: Russian cosmonauts Yuri Gidzenko and Sergei Krikalev (left) on the first ISS expedition and Yuri Usachev (right on the second ISS expedition. (Credits: NASA.)

Shaving is now a standard part of routine hygiene for astronauts and cosmonauts, a normal activity of daily living, as it will be as long as men fly in space, the foundation having been laid in this area, as in so many others, by their predecessors decades earlier.


(1) Wet Shave Meet Ups resource page, (accessed Aug. 14, 2016).

(2) "The Heart of Shaving: Big Shave West 2," (accessed Aug. 14, 2016).

(3) Edwin Jagger,

(4) To request me or other NASA employees a a speaker at your next event, please contact the NASA Johnson Space Center Speakers Bureau,

(5) “Living in Space,” NASA Facts, NF-27 (Revised 4/69).

(6) Borman, F., with R.J. Serling, Countdown, William Morrow and Co., New York, 1988, p. 219. Borman reported a value of $5,000 for the unsuccessful development effort, or $38,000 in 2016 (, which would probably have paid for only a very small developmental effort and no flight-qualified hardware.

(7) Borman, p. 149.

(8) Borman, p. 219.

(9) SM2A-03-Block II-(1) Apollo Operations Handbook, 15 April 1969, Systems Data, Sec. 2, Subsection 2.7, Environmental Control System (ECS), 2.7.1 Introduction, p. 2.7-5, (accessed Aug. 7, 2016).

(10) Spain, C., “Space Flown Artifacts,”, 2009 (accessed Aug. 6, 2016).

(11) Godwin, R., ed., The NASA Mission Reports series, Apogee Books, Toronto, 2000-2002.

(12) Framepool, Apollo 14 / NASA / Crew / Space Capsule / 1971, (accessed August 12, 2016).

(13) Siddiqi, A., Challenge to Apollo (SP-2000-4408), NASA, Washington, D.C., 2008, p. 522, (accessed Aug. 19, 2016).

(14) Kamanin, N., Hidden Space (Russian: Skritiy kosmos), diary entry for March 21, 1966, (accessed August 16, 2016).

(15) Space reliability, (accessed Aug. 16, 2016).



A Jones for MOL #12: The Retroactivity of MOL (The Conclusion)

Note: this post may not make much sense unless you have already read Part 1 (1).  Even then, I make no promises…

In Part 1, we considered the use of the overpowered Gemini retrorockets and the even more overpowered Gemini-B retrorockets for de-orbiting those spacecraft. Despite the obvious nature of their designations, it appears the retrorockets were sized for launch escape purposes, but were conveniently available for de-orbiting when the spacecraft made it safely to orbit. De-orbiting by use of the Gemini retros resulted in a faster return from orbit than the theoretical minimum capability provided by the Orbital Attitude and Maneuvering System thrusters would have provided, with the added advantage of depleting the explosive solid fuel rockets instead of letting them burn and explode during re-entry. 

The discussion and calculations in Part 1 assumed that the de-orbiting thrust was delivered exactly into the direction of travel, in what is the most efficient application of that thrust. However, in practice, the Gemini retro maneuver involved an element of pitch. If Gemini-B had ever flown it might also have involved an element of yaw.

First, note that NASA oriented its Gemini spacecraft slightly nose-down (“pitch down”) during retrofire, apparently to help the command pilot maintain the proper attitude by keeping the Earth’s horizon at the top edge of his forward-looking window.  I have calculated that the nose-down pitch angle for manned Gemini in four cases was about 21 degrees. This angle allowed the pilots to confirm visually that their retro attitude was correct: in those early years of the space age it was not unheard of for spacecraft to have significant errors in the direction they were pointed for retrofire. The nose-down pitch presumably allowed them to confirm that the flow of the earth’s surface past the Gemini’s nose was the same on the left and right sides, and thus that they were correctly oriented “blunt-end forward” (yes, that is what they called it; it even had an acronym: “BEF”) so the retrothrust slowed them down and they fell out of orbit. 

Nose-down pitch of 21 degrees at retrofire would deliver less effective thrust directly opposite the orbital motion, thus extending the travel time in the de-orbit arc. However, the downward component of the thrust would have “pushed” the orbit lower, making it more elliptical and shortening the time and distance traveled to entry interface. A purely downward push would have produced a new low point, or perigee, about ¼ of the way around the Earth, and a new high point, or apogee, about half an orbit after that. 

My math skills only allow me to calculate simple orbit changes from thrusting directly forward or backward. I might be able to struggle through the calculations for a purely upward or downward maneuver. But the combination of the two is beyond me. Luckily, I was able to enlist Ryan Whitley of NASA JSC to mathematically model an inclusive set of Gemini and Gemini-B de-orbit cases. Along the way he helped me understand my own questions better.

I will present the results from the case of a circular orbit at 344 kilometers (186 nautical miles, 214 statute miles), but we also modeled elliptical orbits of 344 by 148 km. (186 x 80 n.mi., 214 x 92 st. mi.) and 256 by 144 km. (138 x 78 n. mi., 159 x 90 st. mi.). The circular orbit provides the most challenging scenario; the elliptical orbits represent likely reconnaissance orbits early and late in the 30-day mission whose intentionally-low perigees are already very close to the threshold for atmospheric entry.

The Gemini de-orbit maneuvers combining retrograde thrust and nose-down pitch produced a terminal orbit designed to intersect the atmosphere—and thus initiate re-entry—at its low point about ¼ of the way around the globe. This orbit had a slightly flattened angle of entry into the atmosphere and slightly increased the entry velocity compared to the nose-horizontal case (see Table 1).

Table 1. Effects of Nose-down Pitch and Yaw on Gemini Descent Orbit Characteristics

Second, there is a simple solution to the problem (if it really is a problem) of Gemini-B having 50% more retrorocket thrust than Gemini: waste the excess thrust. 

By trigonometry, aiming the Gemini-B sideways (this is called “yaw”) by 48 degrees—that is, just over halfway between parallel to its direction of travel and perpendicular to its direction of travel—before its six retrograde rockets fired would still have produced the same orbital deceleration as Gemini would have achieved by firing its four retro rockets directly backwards. Achieving the same atmosphere re-entry velocity and flight path angle (the angle of intersection with the atmosphere) as Gemini had would keep re-entry thermal loads within the qualification limits validated during testing. Those limits were validated by Gemini spacecraft #2 in two separate suborbital flights, first for NASA’s Gemini program in January 1965 and then for the Air Force’s Gemini-B development program in November 1966.

There is no reason the Gemini-B/MOL flights would not have continued the practice of nose-down pitch established during NASA’s ten manned Gemini missions, to provide the same assurance. Assuming deorbiting was to take place on the southbound leg (called the descending node) of a polar orbit, Ryan’s model showed that aiming the Gemini-B’s 50% excess retrograde thrust to one side or the other with a yaw of 132 degrees (which is 48 degrees less than the usual 180 degrees of yaw, that is, aiming directly backwards to the direction of flight) while maintaining Gemini’s 21-degree nose-down pitch would have produced a re-entry essentially identical to a typical Gemini re-entry except that its landing point would be moved 84 kilometers (53 statute miles) either to the east or the west of its polar orbital track (Table a). In both cases, the capsule would have intersected the upper atmosphere at the official re-entry altitude of 400,000 feet (122 kilometers, 76 miles) at an angle of no more than 1.3 degrees and a velocity of 7,872 meters per second (see Table 2). 

Table 2. Effects of Nose-down Pitch and Yaw on Gemini and Gemini-B Descent Orbit Characteristics

All that would seem to be required is to tell the recovery forces which way the Gemini-B would be aiming so they could position themselves appropriately to the east or west of the polar orbit ground track. 

But wait—there’s more. The effect on Gemini-B would have been even further complicated by the geometry of the retrorockets’ mounting in the adapter module. They would all have been mounted at or below the module’s left-right centerline (see Figure 1) because the top half of the module would have accommodated the transfer tunnel from the Gemini-B cabin back to the MOL. Remember that plug hatch in the heat shield I mentioned in Part 1? It would have opened up into the transfer tunnel to allow the pilots to transit in shirtsleeves from their capsule to their habitat for their month-long mission without ever passing through the vacuum of outer space (2).  The NASA Gemini retrorocket arrangement could not have been used because, among other reasons, one arm of its cross-shaped braces would have interfered with that tunnel.

Figure 1. Retrograde rockets in NASA Gemini (4 retrorockets) and Air Force Gemini-B (6 retrorockets) illustrating the central symmetrical arrangement in Gemini and the asymmetrical off-center arrangement in Gemini-B. Note that the Gemini retrorockets are viewed from the top while those of the Gemini-B are viewed from the bottom. (If this figure looks familiar, it was previously Figure 3 in Part 1.)

I estimated that this arrangement of the Gemini-B retrorockets would have required the command pilot to aim about 25 degrees nose down, compared to 21 degrees for Gemini, to keep the direction of the thrust through the spacecraft’s center of mass in the same relative direction as on Gemini (see Figure 2). Early in the Space Age, there had already been considerable nervousness about making sure the retro thrust was delivered in the correct direction, compounded by the fact that the Gemini-B may have also required a unique decision about whether to aim left or right of the ground track. If I were a MOL planner, I might well have decided that the 21-degree nose-down pitch was already well-established by Gemini and that the small loss (9% by trigonometry) in retro thrust due to the 4-degree offset would not have had a significant effect on the velocity change delivered by the six retro rockets.

Figure 2. Thrust vectors of Gemini-B retrorockets (approximated graphically).

I don’t know if the 48-degree yaw or the 25-degree nose-down pitch were ever established as standard procedure for Gemini-B; maintaining the standard Gemini yaw of 180 degrees and 21-degree nose-down pitch during Gemini-B retrofire would have produced a flight path angle still within acceptable limits and only a slightly higher entry velocity, so the 48-degree yaw may not even have been evaluated. Maybe there is one among the 825 MOL documents (3) declassified in October 2015 that confirms or refutes my hypothesis, but I have not found it yet. 

This has been a circuitous disquisition on some arcane aspects of an almost invisible aspect of a cancelled space program from five decades ago; it certainly justifies the “crypto” and “trivio” parts of this blog’s name, as well as the “astro.” However, these are the details that lure me to this type of in-depth analysis. If you have read this, I thank you for your patience and congratulate you on knowing something that practically nobody else in the world knows, or even knows they don’t know. 

My thanks to Ryan Whitley of NASA Johnson Space Center for doing the calculations, and to Roger Balettie, Jorge Frank, Jonathan McDowell and Jim Oberg for their patience and good humor in educating me about orbital mechanics.


  1. “A Jones for MOL #11: Retroactivity of MOL (Part 1),” (accessed July 23, 2016).
  2. “A Jones for MOL #3: Down the hatches,” (accessed Oct. 4, 2015) and “A Jones for MOL #7: Hatches? We Don’t Need No Stinking Hatches!” (accessed Oct. 4, 2015).
  3. National Reconnaissance Office, Declassified Records, Index, Declassified Manned Orbiting Laboratory (MOL) Records, (accessed July 23, 2016).

A snapshot of MOL in 1968

The National Reconnaissance Office (NRO) declassified and released 825 documents spanning the history of the Manned Orbiting Laboratory (MOL) program for a public gathering of MOL pilots, managers, historians, and fans at the National Museum of the US Air Force in October 2015. One of the most informative is number 521 in the NRO list, the MOL Flight Test and Operations Plan, dated May 8, 1968. Its 523 pages give a detailed overview of the MOL flight program, including management organizational structure, flight objectives, and ground support. It is a snapshot of planning for MOL three years before the scheduled date of the first launch, and describes a maturing—but not yet mature—program. 

Click here to read the article published on-line in The Space Review, January 11, 2016.

A Jones for MOL #11: The Retroactivity of MOL (Part 1)

I am not trained in orbital mechanics, also called “astrodynamics,” as practiced by Rich Purnell in the movie The Martian. But I feel some kinship with him because, except for his youthful good looks, his grasp of extreme mathematics and his access to the “NASA Supercomputer,” he and I are a lot alike. He used orbital mechanics to solve a life-or-death problem on a Mars mission gone wrong twenty years in our future. I used orbital mechanics to decipher an obscure feature of a military space program cancelled almost fifty years ago.

If the U.S. Air Force’s secret Manned Orbiting Laboratory (MOL) had flown into low Earth orbit in the 1970s, its astrospy[1] pilots would have ridden in the Gemini-B variant of NASA’s retired Gemini spacecraft during launch and landing (Figure 1). Gemini-B looked outwardly very similar to its predecessor (see Figure 2), but it was stripped down for its supporting role during month-long reconnaissance missions. It would have gotten its on-board electricity from batteries instead of hydrogen-oxygen fuel cells, giving it an independent lifetime of only 14 hours, shorter than all but two Gemini missions. Gemini-B would have been launched already bolted to the MOL, so it wouldn’t have needed rendezvous radar or a full set of maneuvering thrusters. Fuel cells and maneuvering thrusters would have been on the MOL, the central component of the mission.

 Figure 1. Stylized view of Gemini-B/MOL in low Earth orbit. Note the absence of any maneuvering thrusters, antennae or reconnaissance telescope aperture, but the gratuitous addition of a red nose on the Gemini-B. (Credit: McDonnell-Douglas, 1967)

One area in which Gemini-B was not stripped down was its retrograde rocket complement. It was to carry six of the same Star-13E rocket motors[2] as Gemini (see Figure 3). But the MOL mission called for orbits as low as or lower than those of Gemini, which had only used four retrograde rockets: de-orbiting from a lower orbit should not have required more retrograde rockets. Why did Gemini-B need six?

Figure 3. Retrograde rockets in NASA Gemini (4 rockets) and Air Force Gemini-B (6 rockets). (Credit: McDonnell-Douglas.)

Not being an engineer or astrodynamicist like Rich Purnell, I inquired among known experts. They didn’t know either, but they made some reasonable guesses.

Was it because Gemini-B was carrying more mass than Gemini at deorbit? I estimate that Gemini-B was to be only 10% heavier than Gemini,* certainly not requiring 50% more retrograde rocket thrust for de-orbit.

Was it some sort of military requirement to "get 'em down ASAP," or to simulate a lunar re-entry profile, or a need for a shorter orbital arc from retrofire to re-entry to minimize any guidance (“aiming”) errors during the de-orbit maneuver. The first two seem unlikely, but the shorter arc was mentioned by a few experts as being a factor in NASA Gemini re-entries. Using an even shorter arc on Gemini-B might have stressed its heat shield with more thermal loading than Gemini experienced. But a re-entry test validated the modified heat shield with a plug hatch cut into it[3]under similar conditions as for the original Gemini heat shield.[4] Clearly the re-entry conditions for Gemini-B were planned to be the same as for Gemini.

Was it somehow driven by the geographical limitations of available equatorial ground stations tracking the re-entry trajectory of a polar orbiting spacecraft? This suggestion seems to assume that the entire de-orbit, re-entry and landing sequence could be accomplished within view of a single tracking station, which were scattered around the Earth within about 30 degrees of the equator.[5] Such an extremely abrupt de-orbiting seems unlikely, unsafe and unnecessary; more likely, a tracking ship or aircraft could be stationed in the high northern or southern latitudes far outside the existing U.S. network, which sounds like a good idea in any case.

The only justification I have ever seen for carrying six retrograde rockets is that they were primarily for off-the-pad launch aborts of the Titan III-M launcher with its two highly-explosive side-mounted seven-segment solid boosters (see Figure 4). If an abort was required before liftoff or up to 31 seconds later, salvo-firing all six retrograde rockets simultaneously would rocket the Gemini-B to a safe distance from the exploding booster, allowing the pilots to eject and land under their personal parachutes.[6] In any abort from 31 seconds to separation of the solid rocket boosters, the pilots would not eject but would stay in their Gemini-B capsule through re-entry and splashdown. The NASA Gemini also had a salvo-fire option of its four retrograde rockets, but only for launch aborts above 70 thousand feet.[7] Lower altitude aborts would have used only the ejection seats because the Titan rocket without the solid rocket boosters represented less explosive potential.

Figure 4. Gemini-B/Titan-IIIM abort modes. Note “salvo fire” of all six retrograde rockets near point B during the period when the solid rocket boosters are in operation, compared with one-at-a-time “ripple fire” near point C for an abort late in the launch phase. (Credit: McDonnell-Douglas.)

In fact, I have concluded that Gemini did not even need its four retrograde rockets to de-orbit at all, and Gemini-B certainly did not need six. The first two piloted Gemini missions demonstrated a fail-safe de-orbit option in case their retrograde rockets failed to fire.[8] On its final orbit, Gemini 3 fired its Orbital Attitude and Maneuvering System (OAMS) thrusters, already known to be functioning correctly from maneuvers on earlier orbits, for two minutes while passing near Hawaii, setting up an orbit with a low point of 54 miles, well below the 76-mile altitude used as the “top” of the atmosphere.[9] Then the retrograde rockets were fired as planned near Los Angeles, bringing the spacecraft to its intended landing site about 70 miles east of Grand Turk Island in the Atlantic Ocean. If the rockets had not fired, the spacecraft would still have landed about 1,000 miles west of Ascension Island in the central Atlantic (see Figure 5).

Figure 5. Possible re-entry trajectories.

Of course, the Gemini retrograde rockets worked on-time every time on every mission, and the fail-safe option was discarded after Gemini 4, permitting the full maneuvering fuel supply to be applied to rendezvous maneuvers. For example, Gemini 10 de-orbited near Canton Island in the Pacific Ocean[10] (due south of Hawaii), began re-entry over Mexico south of Texas and splashed down in the western Atlantic Ocean.[11]

The fail-safe maneuver provided only slightly more than the theoretical minimum velocity change required, which would have produced an arc of 180 degrees and 12,400 miles (20,000 km)—halfway around the Earth—in what is called a Hohmann orbit (see Table 1.) Thus, both Gemini 3 and Gemini 10 started their descents from approximately the same longitude, but Gemini 3 followed a shallower trajectory until it fired its four retrograde rockets to end up splashing down approximately where Gemini 10 did.

Table 1. Approximate travel in orbit from de-orbit maneuver to atmospheric entry for the Gemini 3 standard and fail safe cases compared with Gemini 10 (typical de-orbit) and theoretical minimum de-orbit maneuver.

The highest circular orbit from which the four retrograde rockets could de-orbit a standard Gemini (using a Hohmann orbit with a perigee of 400,000 feet, which is 122 kilometers or 76 miles) was much higher than any Gemini ever flew unless it was docked to an Agena-D rocket stage (see Table 2). This demonstrates that the four retrograde rockets were overkill for de-orbiting purposes.

Table 2. Maximum-altitude circular Gemini orbit consistent with de-orbit using four retrograde rockets, compared with highest typical Gemini mission orbits.

Gemini-B/MOL would have been in an even lower orbit than Gemini to improve its high-resolution Earth photography, and constant atmospheric drag would have been slowing the vehicle enough to de-orbit it in hours or days. This would surely have required frequent orbital boosts from the on-board maneuvering engines in the MOL’s Attitude Control and Translation System (ACTS). Mock-ups and images of MOL from late in its design phase show the largest ACTS thrusters were those pointed to the rear (“+x” in spacecraft parlance) (Figure 6) to speed up the MOL. There didn’t seem to be any thrusters at all pointed forward; maybe the designers didn’t foresee any need to slow MOL down more than atmospheric drag would already achieve.

Figure 6. Full-scale mockup of MOL with Attitude Control and Translation System (ACTS) quad shown in detail. The Gemini-B spacecraft was to be mounted atop this module, indicating the "forward" direction. Note absence of any forward-directed thruster nozzles, and thus an absence of deceleration capability.

Based on the same type of analysis as for the NASA Gemini orbits, the six retrograde rockets on Gemini-B would have permitted de-orbiting from a circular orbit over twice as high as the final orbit we assumed for the MOL missions and forty percent higher than the initial orbit we assumed (see Table 3).