College of Liberal Arts | Spring 2021

Man + Machine: Research from the Neil A. Armstrong Papers

Neil Armstrong
(Photo from Neil A. Armstrong Collection, Courtesy of Purdue University Libraries, Karnes Archives and Special Collections)

To help commemorate the 150th anniversary of Purdue University and the 50th anniversary of the Apollo 11 moon landing, the Department of History, in partnership with Archives and Special Collections, have offered a yearly series of undergraduate archival research seminars (History 395) since 2014.

We feature excerpts from several student essays in this issue. Their work bridges the humanities and STEM education at Purdue, drawing from the students’ original historical research from the Neil A. Armstrong Papers, and from their own backgrounds in science, technology, engineering, and math. The Armstrong Papers are a comprehensive collection of more than 450 boxes of his personal and professional documents and items, catalogued in a 364-page guidebook. Two of the students also interviewed Purdue astronaut-alumnus, Jerry Ross, for their essays.

These works offer a glimpse into Armstrong’s exciting life experiences, from his time as an X-15 pilot to becoming the first person to step on the moon. For someone like myself interested in the medical and scientific aspects of Apollo 11, this collection reveals how nearly every aspect of a space mission is shaped by our understanding of the human mind and body in space.

School of Aeronautics and Astronautics student Sam Conkle’s “The Near Tragedy of Gemini 8: How Neil Armstrong’s First Space Mission was Almost His Last” shows how quick thinking and ingenuity were crucial in one life-or-death situation. Not only did Armstrong “save the Gemini 8 mission,” but he also did so by bypassing the well-crafted emergency procedures.

Computer science major Alex Crick studies the Apollo Guidance Computer in “Steering Saturn: It Took More Than a Calculator to Get Armstrong on the Moon,” once again illuminating the importance of composure in critical moments. Crick’s analysis shows the complex interactions and interdependencies between the astronaut and the computer in order to ensure a safe and successful mission.

Finally, Jaehyeok Kim, also from the School of Aeronautics and Astronautics, highlights the interplay between human and machine in “Neil Armstrong by the Numbers: Tracing the Small Steps to the Moon.” Here, Kim demonstrates Armstrong’s humanity, even with all of the astronaut training that emphasized logic, cool-headedness, and how to “think like a machine.”

Introduction: Caitlin Fendley is a Ph.D. candidate in the Department of History, focusing on the history of medicine and science. She has written a study of the Apollo 11 “Quarantine,” based on research in the Purdue and NASA Archives, and she is completing a dissertation on population growth, including the visions for space colonies after Apollo.


The Near Tragedy of Gemini 8: How Neil Armstrong’s First Space Mission Was Almost His Last

Sam Conkle, School of Aeronautics and Astronautics (Class of 2021)

What was the cause of the dangerous rolls that imperiled Gemini 8 as it docked with the Agena Target Vehicle? Agena’s previous problems made it a likely culprit.

Neil Armstrong worriedly instructed crewmate David Scott to turn off the Agena’s thrusters, believing they were the source of the problem. After multiple attempts at turning the thrusters on and off, they became more concerned. The roll would stop for a moment and then start back up again just as suddenly as it had stopped. Nothing was working, and the roll was slowly building.

To make matters worse, the crew was out of communications range with ground control, making it impossible to get a second opinion about the problem and any solution.

They were alone.

Armstrong and Scott made the decision to undock from the Agena, hoping to stop the spin. Yet this had the opposite effect, jolting the Gemini capsule into a violent, accelerated spin.

It was now clear that the Gemini capsule was at fault. Both pilots were in shock.

Over the past months, all eyes were on the Agena. If something had gone wrong, it was Agena’s fault more times than it was not. Armstrong and Scott had extensive training with every error that could occur with Agena, but neither astronaut, nor anyone at NASA, had ever dreamed a problem of this scale would plague the Gemini 8 capsule.

Thankfully, they had flown into communications range again.

“We have serious problems here. We’re – we’re tumbling end over end up here,” Scott radioed to ground control.

Ground had only just regained data and communication with Gemini and were struggling to come up with a solution to a problem about which they had only just learned, using up time the astronauts could not afford to lose.

As they backed away from the Agena, the Gemini capsule quickly gained rotational speed. Scott knew the “chances of recovering from such a high rate of spin in space were very remote.”

As the revolutions increased to almost one revolution a second, both Scott and Armstrong began to experience vertigo and blurred vision, and if they did not act soon, they would black out and perish.

Armstrong, running out of options, instructed Scott to try the hand controller that he was just using, making sure it was the hand controller that was problematic and not something he was doing. Knowing they could not wait for ground control to come up with a solution, Armstrong had no choice but to activate the re-entry control thrusters as a last-ditch effort to save their lives.

To the crew’s relief, the Gemini capsule finally slowed to a stop. The disaster had been handled and avoided, but only just.

If Armstrong had followed emergency procedure and possibly waited for a response from ground control, NASA might have lost two of its best astronauts.

The irony of the Gemini 8 mission is that it exhibited NASA at its worst, and at its best, in a moment personified by the piloting skills of Neil Armstrong.

He had saved the Gemini 8 mission in March 1966, just as he later saved the Apollo 11 mission in July 1969 with a dramatic landing on the lunar surface. He rescued NASA from a potential disaster and ensured its greatest triumph.

In each case, his piloting talents and calm demeanor were on full display, a rare combination of engineering know-how and superb flying ability, always invested in the greater goal of the mission.

One interesting detail about Gemini 8, and an apt commentary on Armstrong’s key role, was that he brought with him a token from a former trailblazer of flight: a watch belonging to Jimmie Mattern, one of the first persons to attempt an around-the-world flight in 1933.

Mattern never made it, as a fuel line in his plane froze once he entered the low temperatures above Siberia, and he crashed. The watch represented the drive of pilots to go where no one has gone before. But in the end, it also represented the common bond between two brave yet failed missions: Mattern’s and Armstrong’s.

Days after the astronauts landed, Mattern wrote a heartfelt letter, recently donated by Carol Armstrong to Purdue University Archives and Special Collections, congratulating Armstrong and Scott on their safe return home.

His poetic words captured just how the world felt about Armstrong through both his Gemini and Apollo years. Mattern said that Armstrong and Scott “did not fly alone,” but “a throng rode with you, the girls and boys, the fathers and mothers … all castes, all colors, all creeds of all Nations, as one, flew with you.”

It is fitting, then, that we all flew with Armstrong: the first man to step foot on the moon and the same man who prevented Gemini’s first near-disaster.


Steering Saturn: It Took More Than a Calculator to Get Armstrong on the Moon

Alex Crick, Department of Computer Science (Class of 2020)

In one of the many simulation runs for the Apollo 11 moon landing, when error codes were generated, Ground Control had to figure out to “go” or “no-go” –essentially to ignore and continue, or to abort and come back home immediately.

In the simulations, Ground Control operators looked at the 1202 code’s meaning in their notes and saw that it referenced an “Executive Overflow.” This error occurred when the Apollo Guidance Computer (AGC) was unable to compute the results that it needed in the time allotted to that specific program.

Operators eventually decided to call a no-go on this error code and the simulation ended. But program leader Gene Kranz discovered that the code was not a major problem if it did not occur frequently, as the computer was able to catch up and continue working as expected.

Armed with this knowledge during the actual lunar descent, Ground Control knew to keep going and told Neil Armstrong to ignore the code, produced because Buzz Aldrin had left the rendezvous radar on during descent in case the landing had to be aborted.

A small error in the AGC’s hardware caused the radar data to take more Central Processing Unit (CPU) time than expected, causing the code to appear. If that particular simulation had not been run, Apollo 11’s landing might not have taken place.

The AGC experienced another problem during Apollo 11’s descent, when Armstrong looked out the Lunar Module (LM) window and noticed that the landmarks he was supposed to be seeing were appearing at the wrong time. The AGC had miscalculated.

The site where the LM was heading turned out to be a boulder field. He decided to take manual control of the LM, slowing its descent to almost hovering, and flew across the surface looking for a better spot to land.

Once he found a small landing zone that was clear of debris, he landed the LM and the rest is history.

Something important happened during all of this. The need for an experienced pilot to have the instinct to take over the lunar lander’s descent created one of the first instances of a computer-augmented human performance.

When Armstrong took over the landing controls from the AGC, he was just acting as another source of inputs to the computer. No matter what he did, he still was not bypassing the computer and its programs. It was impossible to land the craft while at the same time conducting the many simultaneous and complex AGC calculations, like those relating to the balance of the craft and its orientation to the lunar surface.

So, while he took over the AGC to guide it to a new landing site, he was still at the mercy of the computer doing everything else correctly. Without the AGC, landing on the moon would have been an impossible task.

Both Armstrong and the AGC made it work.


Neil Armstrong by the Numbers: Tracing the Small Steps to the Moon

Jaehyeok Kim, School of Aeronautics and Astronautics (Class of 2020)

Neil Armstrong’s humanity stands out during his landing of the Lunar Module (LM), piloted in tandem with the Apollo Guidance Computer. He was part of the machine, but always human.

At the start, his heart rate never went below 100 beats per minute, the average for a normal human. But it did rise dramatically as he, Buzz Aldrin, and the LM descended to the surface, forming an inverse relationship between his human body and the engine’s thrust.

Armstrong’s heartbeat spiked up to 120 bpm at 2,000 feet and soon rose to 145 bpm at 1,000 feet. These sudden jumps in his heart rate matched exactly when the computer error codes occurred. Despite all his training and experience, his body still reacted. His heart rate returned to its original state when the Mission Control Center (MCC) ordered Armstrong to ignore the error codes and continue the descent.

His heartbeat continued to rise with a new alarm, about 11 minutes into the descent (102:42 in mission time), with the Low Fuel Quantity alarm.

Despite the intense situation, Armstrong remained outwardly calm. As Armstrong biographer James R. Hansen explained, the indicators were a “distraction that only endangered the landing slightly by prompting him to turn his eyes away from his landmarks.”

He might have been worried, but only about the distraction, not about any impending failure. “We were getting good velocities and good altitudes; the principal source of my confidence at that point was the navigation was working fine,” he said.

After the “Low Fuel” alarm triggered, the LM passed 160 feet above the lunar surface. With 5% of fuel left or 20 seconds before depletion at the current descent rate, Armstrong had to decide to both save his life and the mission.

“We were very aware of the fuel situation,” Armstrong said. “We heard Charlie [Duke, the capsule communicator] make the bingo call and we had the quantity light go on in the cockpit, but we were past both of those. I knew we were pretty low by this time. But below 100 feet was not a time you would want to abort.”

With the desire to succeed in the mission and his skill combined, Armstrong landed safely.

Armstrong’s heartbeat reached its peak at 150 bpm about 12 minutes after the descent (102:45 in mission time). This was exactly when he took control of the vehicle to find a new landing site.

Surprisingly enough, at this point his heartbeat stayed constant. With confidence, Armstrong controlled the LM and brought it down to the surface.

The heart rate only began to decrease a full minute after the landing was complete, and finally stabilized after the MCC announced “go” for stay.

Until this order was given, he stayed sharp and ready, always focused on the task. “We were not concerned with safety, specifically, in these preparations. We were concerned with mission success, with the accomplishment of what we set out to do,” Armstrong said.

How did he do it, and what did the higher heart rate mean? Armstrong’s experience as an X-15 pilot offered a clue. Dr. James Roman’s medical tests in 1965 – focused on his physiological readings of special tests of pilots during their flights in high-performance aircraft – found that their heart rates reached 170 bpm or even higher.

His conclusion was stunning: The higher rates were more a function of how they took on responsibility and control rather than nervousness or worry. They occurred when the pilots took command of their vehicles, despite their calm and confident appearance.

Armstrong’s higher heart rate was evidence of this phenomenon. It increased with the error codes and fuel-consumption issues when the LM was under the control of the guidance computer. But it maintained or decreased dramatically when he took control of the vehicle – at the decisive moment – when he was in command of the vehicle and responsible for the mission.

These experiences taught Armstrong to “think like a machine” – to practice processing direct orders from MCC without hesitation and error.

In a recent talk at Purdue, Space Shuttle astronaut Jerry Ross highlighted Armstrong’s “comfortable familiarity” with his piloting skills. “Armstrong was a natural at becoming part of the machine,” Ross said. He could “make a plane dance.”

Thus, we ought not to forget the human equation in the human-machine complex of the Apollo systems. Machines made the missions a success, but so did the piloting training and experiences of veterans like Armstrong: astronauts with heart.