Terranauts – From Flight Test to Mission Control

The International Space Station on September 29, 2021. Credit: NASA.

Today we kick-off the third season of the Terranauts podcast. It’s hard to believe two years and 40 episodes have already gone by.

In the seasons first episode Iain provides a short introduction of what to expect this year before plunging into the first topic.

This episode is the first in a series of episodes looking at how the advent of the International Space Station changed how we go to space. The series will culminate in a conversation with some Terranauts who have been working as ISS flight controllers for the past 20 years. They have seen and lived this transformation up close. But before we get to that conversation we need some context. So today we actually go back to the early days of aircraft flight testing to see where many of the techniques and much of the culture of spacecraft mission control came from.

Listen in.

Transcript of the From Flight Test to Mission Control Epidose

Hello, welcome to the third season of Terranauts.

I have done a lot of thinking about the show over the summer. When I first started the podcast two years ago, it was really to, I don’t know, scratch an itch that I had had for a while.

My idea was that while most people know about the space program, at least its big events, most of what they know is the story told from the perspective of the people who go to space. The astronauts and cosmonauts and taikonauts.

But, of course, those are only a small fraction of the people involved in going to space. The vast majority of people (including me) who are involved in getting Humanity and it’s inventions off the planet have never actually travelled there, at least not physically.

But I also know from having worked in this field for 30 years, that the stories of the people who work in space, but don’t go there, are interesting. At least they have always seemed so to me, and to the people that I have been telling those stories to for all that time.

So Terranauts was created so that I could have an excuse not only to tell those stories but to find more of those stories to tell.

In the first season, I spent most of my time looking for other Terranauts who had stories to tell, and in telling some of my own favourite stories. But toward the end of season 1, I started to get more interested in the history of the space program and I decided that telling the story of how we got to space from the perspective of the people who made it happen from the ground was also something that I wanted to do.

And so, in the second season I spent quite a few episodes tracing the history of the space program from the first Terranauts through to the first (western) space program – Project Mercury.

Along the way, I learned a lot. A lot of what I learned was not about the history of the space program – although a lot of it certainly was

No, I also learned a lot about the art of making a regular podcast, I learned a lot, I think, about how to tell the story I wanted to tell. And I learned a lot about how what I enjoyed about that experience.

And then at the end of last season, things really came together for me.

It actually started last winter when Mac Evans – a friend of the show – and one of my first interviews talked to me about an idea he had for a story we could tell on Terranauts. Mac had been in Mission Control during one of the seminal moments of space history – although it was a lesser known moment. He had also been witness to some high drama in mission control – although again, the story was almost unknown beyond the people who had been witness to it.

What is more, Mac had tapes! I keep coming back to this fact, I know. But, the fact of the matter is that it is actually an exceedingly rare thing to have an audio record of what goes on in Mission Control

Of course, we always have the recordings of what gets said between ground and space – those conversations, after all, happen on the public airwaves. But we have almost no recordings of the conversations going on behind the scenes – on the loops – as we would say in MCC.

This might not be obvious since the one exception to that rule, is Apollo 11, in which quite literally every word spoken into a microphone during that whole mission is a matter of public record

And it’s fascinating too, by the way, if you ever want to profitably waste a couple of hours – you should go look it up. I’ll post a link on the Terranauts Facebook Page.

Also, by the way, once we get to Apollo 11, I suspect that audio library is going to provide the fodder for some really interesting episodes.


The point was that Mac was providing the opportunity to peak behind the curtain and tell a really interesting story about what it is really like to work in space – even when you are literally stuck on the ground.

I took him up on the offer, and I was glad I did.

The two part episode that eventually became “The Flag is One” and it is my clear favourite of all of the episodes I have done. Based on some feedback from a few listeners it was a fan favourite as well.

Which has made me think, obviously, that I need to work at making more episodes like that. I need to find ways not just of telling the history of spaceflight from the Terranaut perspective, but also of talking to other Terranauts about their experiences as well.

So before we get started, I should say that anyone out there who is a Terranaut and has some stories to tell, I would really like to hear from you. You can drop me a message through the Terranauts facebook page or you can email me at Terranauts@sidekick65.com

But I also have good news, we are going to start Season 3 off with another series of episodes that culminate in talking to some terranauts about an important time in the history of human spaceflight.

Specifically I am going to have the great privilege of talking to some Terranauts who have been living history as it has been being made for the last 20 years. The guests I have lined up have been working as robotics flight controllers in the Mission Control centre of the International Space Station since, before it was actually a Space Station.

They have been witnesses to and participants in a true revolution in the way that Terranauts and Astronauts work together, and also in the way that countries around the world go to space together.

I am really excited about that conversation.

But before we get there – in typical Terranaut fashion – we need to go back a ways. Quite a ways in fact.

I remember listening to one of my favourite podcasts – Hardcore History in which the host – Dan Carlin once admitted that part of the reason that his episodes are so long and take so long to produce is that he is “addicted to context”.

I am beginning to see what he means.

So before we can jump into the revolution in Mission Control that happened at the turn of the millenium we are going to have go back and understand where Mission Control came from. Now we have talked about this a bit in the series on Project Mercury, but in that case we kind of jumped into the story in the middle.

No, to really understand where Mission Control came from we have to go back 50 years beyond that.

Because 1915 is the year in which the National Advisory Council on Aeronautics was formed by an act of the United States Congress.

NACA – as it was known – would, of course, become the predecessor and precursor to NASA – being effectively dissolved and recreated as NASA in 1958.

But more importantly, it would become an organisation that as much as any other, invented an refined the art of testing aircraft technology. Which, of course meant testing aircraft as they were in flight. Which means that the origins of what we call “Flight Control” really came from NACA.


The National Advisory Committee for Aeronautics (NACA) was formed on March 3, 1915, with a charter to “supervise and direct the scientific study of the problems of flight, with a view to their practical solution.”

The formation of NACA was really an American response to the fact that Europeans had taken over leadership in the field of aviation, despite the fact that the Wright brothers had been the first to successfully fly an powered aircraft.

NACA started out slowly but gradually through the period between the two world wars, it built a solid reputation for detailed and analysis and careful testing that allowed it to make important contributions to the emerging science and engineering of flight.

As much as anything NACA was a trailblazer in developing the methods by which aircraft engineering could actually be done.

One of the important challenges that aviation posed to engineers that was really quite different than almost any other field was that it was finding a way to follow the classic engineering (and scientific) approach of breaking a problem down into manageable pieces and solving the whole problem incrementally.

Such an approach simply could not work when the “system” under development was an aircraft. You pretty much had to solve the whole problem – of getting into the air and staying there – under control – in order to test any part of the problem.

As such, early aviation engineers could understand the problems that they needed to solve – how to maximize lift and speed while minimizing drag. They could even begin to develop theories about how to solve those problems. But they really didn’t have a way of testing their theories in any manageable way.

Which is where the wind tunnel came in.

Some of NACA’s most important early contributions were in demonstrating that wind tunnel facilities could be used to actually do Engineering on an aircraft.

A wind tunnel, if it isn’t obvious – is just a controlled environment in which wind is blown through – well – a tunnel. At the outlet of the tunnel, is a test cell in which or pieces of an aircraft, or a model of an aircraft – or even a whole aircraft if the tunnel is big enough – can be placed in the flowing air.

The rig is instrumented to allow measurements to be made regarding the flow of the air.

Various forces like drag and lift can be measured or calculated.

Small changes can be made and the results can be analysed.

With the advent of the wind tunnel, aircraft engineers were suddenly back on solid ground as it were. They were back to doing the solid systematic analytical work that is the basis for all good engineering development work.

The dividends were almost immediate.

Diligent work at NACA in the 1920’s and 30’s contributed significantly to the emerging field of aerodynamics.

Hard as it is for us to believe today, it was actually work at NACA that demonstrated that fixed landing gear – which were the norm in the early days of flight – actually contributed almost half of the drag experienced by a aircraft. This is why, there is such a sudden shift in the 1930’s toward aircraft with retractable landing gear.

This seems like a pretty obvious choice in hindsight, but at the time it was a genuine debate between the extra drag of fixed gear and the extra weight and complexity of retractable gear that was only resolved with engineering test data such as that provided by NACA.

It helped to develop a culture at NACA that was devoted the disciplined application of the modern methods of engineering that persist today.

First analyse a problem and develop analytical models to understand how it should behave

Then test those predictions using incrementally more complex models in controlled settings.

Finally assemble the final article and confirm those findings in increasingly complex tests in the real world.

Chance are if you have ever developed a new instrument, system or even piece of software code – you have followed something approximating this method.

In 1930 in aviation it was not the method that was the issue. It was how to apply it and the engineers and scientists at NACA were at the forefront of setting the standard.

And that mean that as well as spending a lot of time in wind tunnel testing, they also had to spend a lot of time figuring out how to confirm the results of that testing in the “real world”

And that meant doing tests using real aircraft.

And of course the challenge there was that real aircraft were not just flying laboratories they also had to be functioning aircraft that took off, flew and landed


No matter what changes engineers wanted to make in order to test their theories.

As well, aircraft exhibit a distressing tendency not to stay in one place for very long – and the early ones really had no facilities for taking experimenters along for the ride so that they could continue to make measurements

All of this mean that a whole new discipline, that of The Flight Test had to be developed.

It also spawned a whole new profession – that of the Test pilot.

Combining the mindset of the engineer with the skills and training of a pilot, test pilots needed to be able, not only to fly very precisely so as to make data collection predictable and repeatable, but they also had to be expert observers assimilating not only data from their instruments but also the cataloging their observations and sensations as they flew at the edges of the performance envelope of their aircraft.

So this new discipline of flight testing was going to demand the collaboration of the engineers on the ground who knew what data they wanted to collect and pilots in the aircraft who would have to fly the aircraft precisely in order to collect that data.

It was during the 1930’s in establishments like NACA that this new discipline of flight testing was developed and honed.

One group at NACA that grew to depend particularly heavily on flight testing was the Operational Research group at the Lewis Research Centre

This group was formed to look at problems related to the operation of aircraft, as opposed to problems related to their design. One of the problems that became a particular focus for the group was that of icing. Icing is what happens when an aircraft flies through a cloud where the atmospheric conditions are such that the water droplets in the cloud are super-cooled such that when the hit the metail surface of the aircraft they freeze immediately.

This can be a dangerous and even fatal issue for an aircraft. The build up of ice adds a huge amount of weight and can effectively destroy the aerodynamic properties of the surfaces it adheres to.

Modern passengers can testify to how serious a problem icing can be everytime they wait on the tarmac to be “de-iced” prior to taking off during the winter at northern airports.

During WWII, icing was becoming a serious problem as US and allied aircraft were increasingly being called upon to fly into icing conditions in order to fulfill their missions over Germany and even over Japan in certain conditions. So NACA was asked to work on understanding and solving the icing problem.

One of the things that researchers discovered fairly quickly is that icing is an effect that is quite difficult to reproduce in a controlled setting – like a wind tunnel.

Their early attempts to build an icing wind-tunnel so that they could study the problem “in the lab” were pretty much abject failures. They simply couldn’t replicate real world effects in their wind tunnel – even with a sophisticated refrigeration system provided by the Carrier company who specialised in industrial grade refrigeration.

Instead, the researchers had to rely purely on flight testing in order to collect the data they needed. This meant deliberately sending aircraft into icing clouds and conducting specific test profiles in order to understand how the aircraft interacted with the cloud – and the physics of how the ice formed.

Then, they had to take this carefully (and courageously) collected data back to the lab and come up with a model that agreed with the data. Finally, with that in hand, they were eventually able to design and build an icing wind tunnel that acted like a real icing cloud.

It was an impressive engineering achievement because it basically meant inventing a whole new engineering discipline that depended on doing experiments in the real world, learning from them, and creating new ways of modelling processes that could not be observed in the lab, learning from those models, and being able to predict what would happen when the conditions were changed or effected.

This, at least to me, sounds an awful lot like the skills that would be needed by the first Terranauts as they set out on their journey to create the discipline of “space flight operations”.

And, in fact, a significant proportion of the new flight operations directorate of the Space Task Group – that eventually became Project Mercury came from the icing team at Lewis.

Of course the other NACA program which donated several key alumni to the flight operations directorate and the space task group more generally was the X-1 program.

This was the US program to break the sound barrier and whose test pilot, famously, was Chuck Yeager.

The X-1 was not the first manmade object to break the sound barrier – famously, the most famous previous example being, of course the V-2 during the second world war. But the X-1 was the first piloted air vehicle to do it – in a controlled and survivable way.

Aircraft had been flirting with the sound barrier throughout the latter years of the second world war. A number of late war piston engined fighters were capable of reaching high subsonic speeds if they dove steeply at high altitudes.

The P-38 lightning was actually quite notorious for it’s very poor handling qualities at high subsonic speeds due a phenomenon known as “compressibility” where the air flowing over the control surfaces changes it’s fundamental properties as the speed of sound is approached – leading to ineffective or even unexpected control responses. In fact, more than one P-38 pilot was killed in the process of finding out that they had inadvertantly entered a region of flight where the airflow over their control surfaces had reached transonic speeds.

So, the X-1 program truly was a step beyond human experience to that point. Before Chuck Yeager no human being had travelled faster than the speed of sound. At least none that had lived to tell the tale.

Walt Williams who led the X-1 flight test program once said that there was

“a very lonely feeling as we began to run out of data.” (From Orders of Magnitude A History of the NACA and NASA, 1915-1990 – Chapter 3, Going Supersonic (1945-1958)

In the region of high transonic speeds. Of course, despite crossing a barrier that no one had corssed before, the X-1 program would go on to be a huge success and to make Chuck Yeager a household name.

Walt Williams would put those experiences leading the X-1 program to good use when he moved to Florida to head up NASAs flight operations at Cape Canaveral and as the associate administrator of Project Mercury.

So it is not much wonder, then that the initial approach to the Mercury program was firmly rooted in a flight test mindset.

In fact the directorate responsible for planning, organising and staffing Mercury control was called the “flight operations directorate” and the control center was called “Mercury Control”. The concept of the space “mission” was still in the future.

The most obvious proof of the mindset of the early Mercury program is, of course, provided by the selection of the initial “mercury 7” astronauts.

There was never any doubt in the minds of the management of the Space Task Group that the first astronauts were going to be, universally, military test pilots.

In fact, only top-rated military test pilots were approached to apply for the new jobs before being competitively selected down to the final 7.

As we have talked about before, this heritage of flight testing really informed the entire Mercury program from it’s organisation, to its planned activities, and of course in the design of the Mercury capsule itself.

Project Mercury was conceived, designed and, in the early days, implemented as a flight test program to determine if a Human being could be launched into space and kept there for at least 3 orbits before returning them to the planet – safely.

So, when the team began filing into the new purpose-built Mercury Control Centre in Cape Canaveral, they were pretty much one and all, steeped in the discipline of high speed flight testing. Not all of them came from NACA – as we have talked about before Gene Kranz, like many others came from other military aerospace programs. Many of them had military backgrounds. Almost all of them had some background in flight research and flight testing.

And this approach, by and large, stood Project in good stead in the early days of project Mercury. The first two orbital flights, in particular, were very similar to high speed flight test campaigns like the X series planes. The latest of which, the X-15 was capable of reaching the very edges of space itself.

The flights were only a few minutes long, the distance travelled downrange was only a few hundred miles. The speeds obtained were not all that much higher than those experienced by the X-15. The only operational parameters that really exceeded any flight test program to date was the altitude achieved and the lack of gravity experienced by the pilot.

But with John Glenn’s flight, the flight control team truly entered a new regime.

Now, suddenly they were not just running a short flight to test some new designs or to determine some flight parameters.

Now they were running mission. A mission that lasted for a few hours – but more importantly, a mission where there pilot and their test vehicle were literally on the other side of the planet from them.

The changes in their role in this new “paradigm” were subtle but they were profound.

The most obvious first difference was that the control team was now spread out over the entire planet, the subtle effect of this change was that knowledge and expertise had to be distributed across a much wider team than was typically necessary for normal flight control operations where usually systems expertise could be concentrated in a single individual – now the knowledge needed to be spread across the entire team.

The second obvious impact was the length of the flight and the amount of interaction required with the test pilot or crew. In a typical flight test environment the flights might last a few hours, but the period of testing was actually usually quite short. Most of the flight was routine, requiring a bit of monitoring from the ground but not much detailed interaction or problem-solving.

In the new environment there was no such thing as a routine moment. The flight control team and the astronaut on orbit were in full-on test mode for the entire flight – and rather than testing a few isolated systems or maneuvers, everything, the capsule, the astronaut and, in fact all of their plans and procedures were under test the entire time.

In fact, the team was to discover, time and again, any time they relaxed and started to feel like they were jsut “clicking off the miles” some small anomaly would appear which, if left uninvestigated could eventually become a mission and life threatening emergency.

Because that was the really essential difference between mission control and flight control. For the new Terranauts, they were not just performing and engineering test. They were flying a mission, that no matter what else happened, had to get home safely.

In a flight test environment, if things started to go horribly wrong, the final back up plan could almost always be to get everything stable and find a place to land – or failing that eject safely and live to test another day even if the aircraft was lost. Which is not to say that the flight test environment was not dangerous, because pilots did lose their lives during testing. But, there was always an option of terminating the flight early to avoid imminent tragedy.

This was definitely not true once orbital flight began. Once the spacecraft and the astronaut were given the go for orbital insertion the only way to end the mission without tragedy was to end it successfully. Failure really was not an option any more.

And this led to teh really fundamental change in culture that marked space mission control as different from a flight test environment. Which was the focus on planning for failure and contingency. More and more as mission controllers prepared for life on orbit they found themselves spending time in simulation rather than in flight.

It is no exaggeration to say that even early in the Mercury program flight controllers were spending much more time on console in sims than they were during missions.

And the purpose of these sims was not simply to train individual flight controllers – or astronauts – in how to deal with contingencies. It was to train the whole team to work together, because the other fact that was becoming obvious was that a spacecraft, even more than an aircraft was an integrated system, failures in one system or changes in one procedure could rapidly cascade into issues in systems that might, at first, appear entirely unrelated.

The classic instance of this effect was during the last Mercury flight when the sensor responsible for sensing the onset of gravity failed, but in so doing it took the entire re-entry autopilot system off line because that systme would not engage if it thought the spacecraft had already left orbit.

The net effect of all of this was that flight test engineering and flight control gradually morphed in a brand-new discipline – spacecraft mission control. Along with it came a new culture and new traditions.

By the end of the Mercury program the culture of mission control had been firmly established and the first generation of mission controllers was training, or already had trained the next generation.

That is very much the point in the story of mission control that we had already reached in our earlier episodes on the history of Project Mercury. But I wanted to review it here with a particular emphasis on the culture of Mission Control, because in our next episode we are going to take a look the job of being a flight controller and the culture of Mission Control continued to develop through the years of the Apollo program and beyond into the space shuttle era. And how that well-established culture collided with the new reality on the proposed International Space Station.

And, as I promised, after that we are going to spend some time talking to some Terranauts who were actually there as the space station was being planned built and operated and finding out what THAT was like.

Thanks for listening and we’ll take to you again soon.

About Marc Boucher

Boucher is an entrepreneur, writer, editor & publisher. He is the founder of SpaceQ Media Inc. and CEO and co-founder of SpaceRef Interactive LLC. Boucher has 20+ years working in various roles in the space industry and a total of 30 years as a technology entrepreneur including creating Maple Square, Canada's first internet directory and search engine.

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