Tag Archives: forgotten heroes

595. Apollo 10

Apollo 10 CSM, viewed from the LEM in lunar orbit.

Apollo 10 is a mission that, from the outside, looks unnecessary. It was anything but that. To appreciate it, you have to project yourself back into the state of ignorance that represented best knowledge in 1969.

I was also guilty of underrating it when I taught middle school science. I called it the most frustrating flight in the history of space flight, which was half true and half exaggeration. I also called the Command Module Pilots NASA’s soccer moms because they got to go to the game, but never got to play.

You have to know your audience, and middle school kids are looking for excitement, not “slow and steady wins the race”. And certainly not “they also serve who only stand and wait.”

In actual fact, without Apollo 10, the would have been no moon landings. There were two basic reasons for this. The LEM had only been tested in low earth orbit, not falling into a gravity well and then clawing its way out again. And we had an entirely inadequate understanding of the conditions on the ground at the proposed landing site. We especially needed to fine tune our understanding of lunar gravity for navigation purposes.

As the NASA history website puts it, “a test of the landing radar, visual observation of lunar lighting, stereoscopic strip photography, and execution of the phasing maneuver using the descent engine” were all performed on Apollo 10’s pass over the proposed landing site. If you want more data, check also here.


On May 18, 1969 Apollo 10 lifted off from Cape Canaveral on its way to the moon. Thomas Stafford was Commander, John Young was Command Module Pilot, and Gene Cernan was LEM Pilot. They entered orbit of the moon three days later. Stafford and Cernan undocked the LEM and began their descent fifty years ago today.

John Young was left alone in the Command Module, the first of seven men who would fly around the moon solo while their companions dropped toward the moon’s surface.

Stafford and Cernan fired the descent stage engine to slow the LEM. There followed a long unpowered descent, a rapid flyby of the proposed landing site, and a rise back up to the level of the CSM.

The reports at the time called it a dress rehearsal for Apollo 11, but it wasn’t that simple.

For comparison let’s look at a mission designed to land. At point A on the figure given here, the descent stage engine would fire briefly, changing from the black orbital path to the green one. At point B, a carefully calculated spot nearly half way around the moon, the descent engine would fire again. The descent from 60 miles to about 8 miles would have been in a flat curve, followed now by a very steep curve. The descent engine would continue to fire until the vehicle landed at point C. This is basically the exact reverse of a launch, as shown Monday.

Later, the ascent stage engine would fire, leaving the descent stage on the moon’s surface, and proceed along the second half of the green curve back up to the 60 mile level.

Apollo 10 (red orbit), on the other hand, passed over the prospective landing site and continued on.

This has always been called a dress rehearsal, so one would assume that the ascent stage would separate somewhere near the surface, fire its engines, and continue back up toward rendezvous separately from the descent stage. That’s what I thought for fifty years.

I was wrong. Imagine that. I probably learn more researching these posts than anyone does who reads them.

In fact, on Apollo 10 the descent stage fired again at point D (the red orbit represents Apollo 10), but it was merely a course correction, and the entire LEM continued up to the 60 mile level.

Apollo 11 would leave from the moon’s surface, starting at zero speed. Apollo 10 at its lowest point was at an altitude of 8 miles and a speed of 3554 miles per hour. Dress rehearsal was a considerable exaggeration. It wasn’t that reports were inaccurate; things were just more complicated than the summaries suggested.

It’s a little like science fiction novels. A two line blurb on the back of a 180 page paperback may not actually lie, but it can certainly give a false impression.

At point A on the trip back up for both missions another burn was necessary to get back onto the black curve. However, the CSM had gone its own way; it wasn’t waiting there for the LEM. The final rendezvous for the LEM and the CSM, which were at different places on roughly the same orbit, would be up to the pilot of the ascent stage, and would take an additional three hours.

At this point on all the moon landing missions, the ascent stage would be by itself. For Apollo 10, the ascent stage still needed to separate from the descent stage before performing the orbital insertion burn using its own engine.

That was the plan, but things didn’t entirely go well. Just before the separation, the LEM began acting up, corrected itself, then seconds later started a rapid roll. It was later determined that this was due to erroneous computer input. Stafford and Cernan quickly separated and regained control, but it was another of those close calls which could easily have led to a deadly outcome.

The crew rendezvoused and docked with the CSM, then returned to Earth. The ascent stage engine was fired again and went into solar orbit. The necessary data had been obtained for the moon landing in July.


At present, I plan for this to be my last full Apollo mission post. Everybody will cover the anniversary of Apollo 11. Everybody has already watched the movie Apollo 13, and I covered the other landings in 187. The Rest of the Landings. Of course, I reserve the right to change my mind.


589.5 Tequila and Lederhosen

Cinco de Mayo caught me by surprise this year. It is an important holiday in California, and was particularly important to about half the kids I taught before I retired.

You will note that I did not say Mexican-American kids. Even before the advent of Trump, a surprisingly large number of (whatever) students didn’t like that name. Some wore a T-shirt that said:

Not Mexican-American
Not Hispanic
Not Chicano

I’ve already had my say on the subject of Cinco de Mayo. I invite you to check out these two older posts to see what that was.

One post had the full title: Juan Angus Georg Angelo O’Malley celebrates St. Patrick’s Day by drinking tequila and while wearing lederhosen under his kilt.

The other was titled: Who said you were Mexican?

586. Slogging Toward Space

One of the things I have to offer is a viewpoint that reaches back half way through the twentieth century. That can be a problem, actually. I don’t want to talk about the good old days. Fortunately, I never thought the good old days were all that good. They were, however, both exciting and hard.

It has become almost cliché to point out how little computing power the Apollo 11 computer had, but there are a thousand other instruments which we take for granted now, which were also not available during the early space program. I used a few of them myself, early on.

Some of these instruments became fossilized into early science fiction, as in Slip-stick Libby, one of Heinlein’s regular characters. Slip-stick was a slang term for a slide rule, an instrument of sliding scales which was used in computation. It was only good for estimating to about three significant figures. I learned to use one in high school in 1966. Early Texas Instrument portable calculators made them obsolete a few years later, although you will still see them in use at Mission Control when things began to go bad in the movie Apollo 13.

Another nearly obsolete instrument from the Apollo era is the theodolite. I learned to use one in the same class. We took it out to the back lot of the school for some practical examples of the uses of trigonometry. We didn’t call it a theodolite, however. We called it a transit, which is somewhat less accurate. Real surveyors called it a gun.

A transit measures elevations and angles. You level the instrument on its tripod and align it to true north, then you look through a telescopic sight, with crosshairs, at a distant target, usually a rod with red and white inch markings.

(We’re talking sixties here — everything in America was in inches, feet, and miles.)

This instrument was used in surveying everything from house foundations to radar installations before lasers replaced them. It gave you direction. It didn’t give you distance. For that you walked, dragging a measuring device called a chain.

The dictionary will tell you that a chain is a unit of length equal to 66 feet, subdivided into 100 links. It may not tell you that a chain (of length) was represented by a heavy, physical, steel chain that the rod man dragged behind him — for thousands of miles during a career.

Today, laser radar does it all.

An alidade or plane table worked like a transit except that it was attached to a narrow steel plate which moved freely on a plywood table. It was used for mapping. You would slide the alidade around on the table, over a sheet of paper, take your sightings, and use the edge of its base as a ruler. It allowed you to  draw a map as you went. I used one of them two years after high school at an archaeological site in Bay City, Michigan.

To fully understand what a tremendous undertaking the space program was, you should remember that a line of radio/radar stations was built all around the world to track spacecraft in orbit. At the same time, the same Russian missiles which scared American into the space race had to be watched for. A line of radar installations (the DEW — distant early warning — line) was built across Canada for that purpose.

The building of these two sets of installations was an immense undertaking. Even before the first foundation was laid, the positioning of these instruments had to be determined to the highest possible tolerances. This was done by survey engineers working with transits and doing their calculations by hand, with rod men dragging chains. A slide rule might provide estimates, but after that it was paper, pencil, and mathematical tables — which had themselves been calculated by hand.

The word calculator first meant a person who calculated such tables. By hand.

These engineers didn’t all come from Harvard, or other prestige colleges. There were thousands of them, possibly tens of thousands, and they came from every college in America. Bear that in mind as we contemplate the present college entry cheating scandals.

Speaking of which — prestige colleges my &#^$%!  Math is math, whether you learn it at USC or Palomar Junior College.


I want to introduce you to a survey engineer you have never heard of. He is a distant in-law, a fine man I only met once. I ran across a decades old newspaper clipping of his obituary the other day, and it triggered this post.

I’m appending a copy of that clipping, minus family matters, to give you an idea of how the space race, and the missile defense of America, looked from the mud below. The gentleman’s name was William Mussetter.


Mr. Mussetter graduated from Willmington College in 1917 and also attended Haverford College in Haverford, Pa. He retired after working 40 years in government service as an astronomical geodetic engineer. He served with the US Coast and Geodetic Survey, Army Map Services, InterAmerican Geodetic Survey United States Department of Foreign Services where he worked in many different countries.

Mr. Mussetter was a veteran of World War I, serving as a second lieutenant. In World War II he served as a captain and taught artillery.

At the end of the World War II, Mussetter received a call from Washington, D. C. He was assigned to head a survey group to be based in Panama and to work in south America, principally on the west coast of Chile, Peru, Ecuador, Columbia to Venezuela. This project lasted four years.

The Mussetters came home to Wilmington and he worked with the Ohio State University doing contract research for the U.S. Air Force. There was a need to connect the continents of the world, locating them with respect to each other, then to lay out guided missile courses from Cape Canaveral to the Bahamas. [This means during the early testing of IRBMs and ICBMs, before they began to be used to launch space vehicles. The same tracks were used through Mercury, Gemini, and Apollo. See 578. That Odd Spiral.]

In 1953, he transferred to the U.S. Army Corps of Engineers to define the Earth’s parameters, its diameters, flatness at the Poles and other data. [We are talking about building the DEW line here.]

He worked with a survey team measuring the arc of the Meridian at 30 degrees East Longitude from the Mediterranean Sea at Egypt to South Africa, down through Egypt, the Sudan, Uganda, Belgian Congo, Tanganyika, and into North Rhodesia; 4800 miles. [Many of these names no longer exist.] He also did some survey work for the Aswan Dam on the Nile River.

In 1964 he was sent to Antarctica, to Byrd Station, and the South Pole.

He had retired in 1964, but during the last four months of 1964, he worked in Peru, S. A. on a contract for a hydro-electric project; and in 1966 he was sent back to Afghanistan for three months, to inspect the work that was begun in 1961, and complete the Tri-lateration of Afghanistan.


All this without a computer. Imagine that.

577. The First Space Walk (2)

The space suit worn by Alexei Leonov on the first human space walk. On display at the Smithsonian National Air and Space Museum. Author: Nijuuf

This is the rest of Tuesday’s post. If you haven’t read it yet, take the time to do so, or this won’t make much sense.

Alexey Leonov had extreme difficulty reentering the airlock. His space suit had over inflated; the boots and gloves had slipped beyond his toes and fingertips, and his suit had increased in girth. He had to vent part of his rapidly depleting oxygen in order to bring his suit down in size, and even then he entered the airlock head first, instead of feet first as planned. Once inside the airlock, he had extreme difficulty contorting his body to close the outer door. All this time, his body was heating up dangerously; surrounded by vacuum, there was nothing to carry away the heat his body was generating.

Once air pressure had been restored in the airlock, Belyayev opened the inner door and Leonov was safe. For the moment. As he said in an article for Smithsonian’s Air and Space magazine in 2005, “the difficulties I experienced reentering the spacecraft were just the start of a series of dire emergencies that almost cost us our lives.”

The mission had achieved it’s goal and it was time to return, but just before the scheduled time for firing retro rockets the cosmonauts discovered that their automatic guidance system was malfunctioning. It took time to prepare for manual entry, so they had to wait one orbit, which would make them miss their return point by a thousand miles. (To find out why it would be a thousand miles, see the post coming on March 25.) Most of that orbit they were out of radio communications. (The Americans had built a string of radio relay stations around the world to maintain constant communication with their astronauts, but the Soviets had not.)

When communications were restored, ground control asked them where they had landed.

Their orbital path was set; the moment of firing their retro rockets would determine where on that orbit they would land. They chose a target just past the Urals. Using the clumsy and difficult manual backup equipment, they achieved the correct attitude and fired the retro rockets in the conical rear portion of the craft called the orbital module. The orbital and landing modules were supposed to separate ten seconds after retrofire. They didn’t.

The two cosmonauts knew immediately that something was terribly wrong. Instead of the steady press of force against their backs as they decelerated, they found themselves whipped about by confused forces that exceeded ten gravities. A communication cable between the two modules had failed to release, and now both modules were whipping about each other, tethered by the cable.

Finally, about 60 miles up, the cable burned through and the cosmonauts were freed. The drogue chute deployed, and then the main. All was peaceful and in order – briefly. Then it became dark as they dropped below cloud cover, the final rocket fired to slow them to landing speed, and they touched down in six feet of snow.

They were 1200 miles beyond their intended landing point.

They blew the explosive bolts to release the hatch. It didn’t open. They had landed in the middle of a forest and the hatch was held shut by a tree. By yanking violently they dislodged it and it fell away, lost in the snow.

They made their way out of the spacecraft and waded through snow to a small clearing. Those back at headquarters had not heard their landing signal, but a passing cargo plane had. It circled, and was soon joined by other planes and helicopters, but none of them could land in the rough taiga. Pilots threw a bottle of cognac; it broke. They threw warm clothing which got caught in the trees, but at least two pairs of wolfskin boots made it to the ground.

The light was failing. The cosmonauts returned to their craft for shelter. Leonov was walking in calf deep sweat still trapped in his space suit from his space walk. Both cosmonauts stripped, removed the liners from their space suits and wrung them dry, then put the on again along with the wolf skin boots. They abandoned the useless space suits and crawled into the landing module for the night, well aware that the taiga was filled with bears and wolves, and that this was mating season, when they were most aggressive.

The hatch was out of reach. The lights failed, but the circulation fan ran all night, adding to their misery. The temperature dropped to 22 below zero.

A rescue party arrived on skis the next morning; they chopped trees to build a small log cabin and a big fire. The cosmonauts spent a second night, then skied out to where a second, larger party had chopped down enough trees for a helicopter to land.

I guess they made ‘em tough in those days. I suspect they still do.

576. The First Space Walk (1)

I posted this in 2016, under the title Spacecraft Threatened by Bears. The title was snarky but accurate. Back then I had few followers, so it seems time to post the amazing story again.

My admiration for the people of the early American space program is boundless, but the Russians were no slouches either. They were the first to perform many feats, including the first space walk, during the flight of Voskhod 2 on March 18-19, fifty-four years ago.

I had the great good fortune of living through the early days of manned space flight. I was nine years old when the Russians orbited the first satellite, and the early manned flights came when I was in high school. I watched every American launch with fascination and envy, but the Russian launches were shrouded in secrecy. I knew only the bare minimum that all Americans knew. I’m not sure the president knew much more.

During those early days, nothing was routine. Every mission was dangerous. They still are, of course, but not so much as then. American failures were there for all the world to see, while the Soviets kept their’s secret.

After the breakup of the Soviet Union, information about the early Russian space program became generally available, but by then few people cared. I did, and I sought out the stories.


Oceans are big targets and landing in water cushions the fall. That is why Americans always splashed down. The Soviets were unwilling to land their craft anywhere outside of the USSR for reasons of security. Their hard landings had an effect of the design of their spacecraft.

The first six manned Soviet spaceflights were aboard Vostok craft, which came down on land — hard. Vostok astronauts wore space suits throughout their flights and landed by personal parachute separate from the capsule. Before the second generation Soyuz spacecraft came on line, the Soviets launched two additional manned missions on modified Vostoks called Voskhod.

On Voskhod, an additional rocket was added to the spherical descent module to fire at the last minute. This softened the landing enough so the cosmonauts could remain within the descent module all the way to the ground. Since ejection seats were no longer used, the weight saving allowed Voskhod 1 to carry three astronauts.

Voskhod 1 cosmonauts flew without space suits, as did early Soyuz missions. Voskhod 2 cosmonauts Belyayev and Leonov wore space suits because they were scheduled for the first space walk.

American space walks first took place during the Gemini program (see post 87). That craft had two hatches but no airlock; both astronauts were in vacuum during the entire spacewalk.

To exit his Voskhod in space, Leonov used an inflatable airlock (see drawing above), leaving Belyayev in the craft and unable to aid him. I had known this for several years but just in the last few days found out why. Russian electronics within Vostok and Voskhod were air cooled. American electronics were not. This meant that if a Voskhod were opened to space, the electronics would overheat.

On Voskhod 2, Leonov crawled into the airlock, sealed the inner door and opened the outer one. Belyayev remained in the pressurized descent module.

For ten minutes, Leonov remained within the airlock but exposed to the vacuum of space, then he slipped free and floated on a tether for another ten minutes. He was called back in to terminate his space walk, and his difficulties began.

(Or perhaps they had already begun. Some sources state that he “experienced a disorienting euphoria” during the space walk and other sources state that he suffered bends like symptoms after the space walk was over; I haven’t been able to confirm these statements.)

This post concludes on Thursday.

574. Learning Spaceflight

I learned how to fly in space before spaceflight existed, from science fiction writers who, in turn, learned it from pioneers like Robert Goddard, Willy Ley, Herman Oberth, and Wernher von Braun. Or Tsiolkovsky in Russia. The pioneers’ tool was mathematics. They speculated, then looked at those speculations through the unblinking eye of calculations. They taught everyone how to fly in space long before NASA existed. Later some of them worked for NASA.

When I was researching for a post on Apollo Eight, I encountered reference to the barbecue roll. I had known about that maneuver from science fiction, long before Apollo Eight.

The barbecue roll is needed because vehicle in deep space is surrounded by vacuum with sunlight impinging on one side and sub-polar cold on the other. In low Earth orbit, that condition only lasts 45 minutes of every 90 minute orbit followed by pure cold in the Earth’s shadow. Apollo Eight was the first manned vehicle to endure that temperature imbalance on a long term basis — roughly five days. That’s a lot of stress.

The solution, used on Apollo Eight, then Apollo’s Ten through Seventeen, was to spin the craft about it’s long axis. It was called the barbecue roll, as in a rotisserie. You can hear that phrase used in the movie Apollo 13, and it will probably appear on the movie First Man when it comes out in October.

Anyone who had read any science fiction knows about spinning ships to provide artificial gravity. That’s not what we are talking about. The barbecue roll was quite slow, the distance from center of craft to skin was small, and any pseudo-gravity produced was probably imperceptible. The entire purpose of the roll was to equalize heat distribution by exposing all parts of the skin to heat, then cold, in sequence.

Long before there were real spacecraft, I had read about this maneuver in early science fiction, probably multiple times. It made me want to know who thought it up, which scientist first wrote about it, and how many decades before it was needed was it speculated into existence.

It struck me as a prime example of the kind of thing the pioneers did while they were writing the rules of the game, long before the game was ever played.

I looked for answers and struck out. I spent far too many hours reading the same few references on the internet, usually repeated without credit, or reading technical articles. The papers scientists and engineers write are long on facts, but short on history.

Somewhere, somewhen, somebody was dreaming about his imagined spacecraft out in a long orbit between the planets, and figured out how to equalize temperature. It might have happened several times independently. I would love to have been there, in the dormitory lounge of some engineering department, or in a meeting of enthusiasts at some model rocket club, or in the bedroom of some kid like Asimov in America or Clarke in Great Britain or some kid whose name I can’t even guess in Russia. What fun to be there when some nerd (before the word existed) slapped his head and said, “Hey, listen to this!”

Of course that moment in inaccessible, but somewhere, sometime, somebody wrote down his speculations in a paper that only enthusiasts would ever read. That is what I could have reasonably hoped to find. If you have any clues where I could continue the search, please reply to this post.

What I finally did find was one partial reference in Heinlein’s The Rolling Stones, quoted here:

The weather outside the orbit of Mars is a steady ‘clear but cold’; no longer would they need reflecting foil against the Sun’s rays. Instead one side of the ship was painted with carbon black and the capacity of the air-heating system was increased by two coils.

I clearly remember, from several sources, the notion of painting part of a vehicle black to better absorb solar energy as ships moved out further from the sun. One nagging memory has a ship painted with white and black stripes and spun. Heinlein did not spin his ship; he distributed heat to the cold side via refrigerant coils. In that particular novel, Heinlein had to maintain a non-spinning ship for plot reasons. In science fiction, physics start the ball rolling but plot determines where that ball ends up.

We’ll look closer at The Rolling Stones as a textbook for spaceflight within the solar system on Monday.

572. Apollo 9: Spacesuits

Left photo, the first American spacewalk using an umbilicus. Middle photo, the inner layer of a moon rated suit. Right photo, same suit with outer layer, visor, and backpack.

If you have not been following these Apollo posts, here is a quick summary: when three astronauts died on the launch pad, their scheduled flight was renamed Apollo 1. The flight which completed their mission, after much delay, was called Apollo 7 following the original sequence. Apollo’s “2 through 6” never existed.

The next flight, originally Apollo 8, was to be a repeat of 7, but was changed to be the first launch of the complete Apollo package, Control Module, Support Module, and Lunar Module. However, delays in building the LM (or LEM as it was called in the early days) meant that flight could not happen by the scheduled date. The Apollo 8 which actually flew was a different Saturn, different CSM without an LM and different crew. They <flew around the moon>.

The first flight with all parts of the Apollo was pushed back, renumbered to Apollo 9, and flew fifty years ago yesterday, March 3, 1969. A full picture of the shuffling of missions and crews would take more words that even the geekiest reader could tolerate.


Apollo 9 was the second manned flight atop a Saturn V, and the first to have both CSM and LM on board. Jim McDivitt was in command. David Scott was the CM pilot and Rusty Schweickart was the LM pilot. Don’t confuse him with Jack Swigert of Apollo 13.

There were two main objectives for the ten day mission. First was to test the ability of the astronauts to dock the CSM to the LM, to undock and fly the LM separately, both as a complete unit and the ascent stage alone, and to dock the ascent stage to the CSM once again. The second objective was to test out the first American space suit which was not tethered to its mother vehicle.

We will concentrate on the space suit today and look at the testing of the LM on Friday. That will be posted at 3 PM, PDT, fifty years to the minute from the first separation of the LM from its CSM.


The space suits worn by both Americans and Russians had not allowed true freedom. Cooling, power, and life support gasses were never contained in the suits, but were sent to the suits by umbilical connections. As long as the crew was inside the vehicle, this posed no problem. The suits were deflated and for long periods of each mission, helmets and gloves were removed. During launch and return, the suits were again made air tight but were not inflated. There was no need. If the cabin had been breached during those maneuvers, the suits would have continued to provide life support.

I never seen it admitted, but clearly both NASA and the Russians were flirting with disaster through all those early flights. Let me explain.

When the first spacewalks (EVAs, extra vehicular activities) were made by Alexey Leonov and then Ed White, the space suits proved to massively restrict mobility. Leonov could barely get back into his vehicle because his suit had puffed up so much. Ed White only got back into Gemini IV with great difficulty and with the help of fellow astronaut Jim McDivitt.

You can imagine what would have happened on any early fight if there had been a hull breach during a reentry, and the pilot’s spacesuit had suddenly become stiff and unmanageable when every second was critical.

Small glitches kill pilots, as everyone in aeronautics knows.

Five missions after White’s EVA, Eugene Cernan nearly died during a spacewalk because his suit was so unmanageable. See  posts 295 and 296. It took three more EVAs on three missions by three additional astronauts until before spacewalks were brought under control.

All of these EVA’s, Russian and American, used umbilicals to provide life support and to tether astronauts to their vehicles. That was not going to work on the moon.

The development of a suit suitable for moonwalks took seven years. Pressurization, oxygen, and cooling were taken care of by an inner layer that rarely made it into photos. See the middle picture above. The outer layer was a laminate designed to resist abrasion, radiant heat, and micrometeorites. The backpack took the place of the umbilicus and provided power and oxygen.

Backpacks were first tested on Apollo 9 by McDivitt and Schweickart. David Scott performed a standup EVA — that is, he stood up in the open hatch of the CM — but he received life support through an umbilicus. This was the pattern for Apollos 9 through 17. The moon bound astronauts used backpacks, the CM pilot did not.

If the LM tested on Apollo 9 had worked, but the backpack hadn’t, Apollo 11 could still have landed on the moon, but Armstrong could not have left the Eagle to make “once small step . . .”

But it did work. The EVA was cut short by Schweickart’s space sickness, but the backpack worked fine.

more on Apollo 9 Friday