Crisis in Space – MiG Mad Marine, John Glenn and Friendship 7

Published on March 21, 2021
By Thomas Van Hare

On February 20, 1962, John Glenn, one of America’s most famous astronauts, climbed into the Mercury-Atlas 6 capsule “Friendship 7”.  His mission was to be the first American to orbit the Earth.  At the time, the United States was struggling to catch up with the Soviets in the “Space Race”. Both nations were aiming for the Moon.


President John F. Kennedy, Jr., at his Rice University speech committing America to land on the Moon.

Only nine months earlier, on May 25, 1961, President John F. Kennedy had committed America to exploring space:

“We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win.”




The Mercury 7 during training for their missions into space. Photo Credit: NASA

John Glenn, a Marine aviator, was one of the seven astronauts of the Mercury Program.  All were test pilots.  Many in NASA suspected that at least one or two of the Mercury 7 astronauts would die in the program.  Still, there was a sense that the mission was worth the risk.  Many of NASA’s earlier rocket tests had failed in spectacular, fiery explosions on the launch pad.  The odds were stacked against success, yet John Glenn was confident.

This was what he trained for.  He was confident that this was his moment in history.  His confidence wasn’t unfounded either.  Glenn was the only member of the Mercury 7 who was a member of the Marine Corps.


Two Grumman F9F-2B Panthers (BuNo. 123602 in the foreground) of Marine fighter squadron VMF-311 Tomcats being refueled at K-3, Pohang Airbase, during the Korean War. Credit:, Photo #: HD-SN-99-03071

A Marine in Combat Service

John Glenn had joined the Marines during World War II, soon after Pearl Harbor, and had flown the Vought F4U Corsair in the Pacific with Marine squadron VMO-155.  He flew 57 combat missions in the Marshall Islands and earned two Distinguished Flying Crosses among numerous other awards and decorations.


A Marine Corps Grumman F9F-2 Panther of Marine Fighter Squadron VMF-311 “Tomcats” at K-3, Pohang AFB, Korea, at engine start prior to a mission. . Photo Credit: US Navy National Museum of Naval Aviation, Photo No. 1996.253.7399.053

He was one of the minority who stayed in the military after 1945. For a time, he served as a flight instructor, but then when war broke out again, he was deployed with a combat squadron. He arrived in the middle of the Korean War in February 1953. Flying from K-3, Pohang Air Force Base, he threw his Grumman F9F Panther into combat.  He was assigned with VMF-331.


VMF-311 squadron insignia during the Korea War. Photo Credit:

Since the F9F Panther was vastly inferior to the Soviet-built MiG-15 fighter, his squadron was relegated to ground attack.  He flew dangerous, low level missions against intense flak. A true Marine, he never shied away from combat.  Twice he returned from missions with over 250 holes in his airplane. This earned him the respect of his fellow pilots but also the nickname of “Magnet Ass” because he seemed to attract enemy fire.


John Glenn in front of his F9F-2 Panther with VMF-311 at Pohang Airbase, 1953. Credit: John Glenn Archives, The Ohio State University

In June 1953, he was accepted into an exchange program with the US Air Force and assigned a second tour in Korea.  This time he was with the USAF’s 25th Fighter-Interceptor Squadron.  He flew an F-86 Sabre across “MiG Alley”, patrolling just south of the Yalu River. The other pilots in his squadron painted “MiG Mad Marine” on the side of his plane because of his “Gung Ho” attitude.  He liked the name, but added the names of his wife, Annie, and children, Lyn and Dave, to the side of his jet as well.


Then Maj. John Glenn, in “MiG Mad Marine”, his USAF F-86F Sabre, during the Korean War, c. August 1953, showing three stars painted under the cockpit, representing the three MiG-15s he had downed.  Credit: US Air Force

Once again, he was supremely confident.  Now that he was in an aircraft that could fight the MiG-15 on a more or less equal footing, he openly stated his desire to shoot down at least one MiG-15 before the end of his tour. The other pilots just smiled, expecting that few of them would get even one or two.  Still everyone had hopes, though the enemy picked its fights wisely and rarely took off to tangle with the F-86s.

Nonetheless, he upheld the honor of the US Marine Corps and showed the US Air Force pilots which way was up. In the final three weeks before the armistice, over a span of just eleven days, the enemy finally launched to challenge the Americans.  Glenn downed a total of three MiG-15s in short order — one on July 12, another on July 19, and the third on July 22. The last was one of the final four kills taking place that day of the Korean War.


Glenn’s North American F-86F-30-NA Sabre (s/n 52-4584), c. August 1953, a rare color photograph. Credit: USAF

In all, he flew just 27 missions in the F-86F. He made the most of it, earning two more Distinguished Flying Crosses for his extraordinary heroism in the air.  He shrugged it off — he was just doing his duty as a Marine.  He had joined the rare few who had not only met the enemy in the air but had come away victorious.

After the end of the Korean War, Glenn became a test pilot.  From there, he was accepted as one of the first astronauts in NASA and assigned to Project Mercury. His flight into orbit, the third of the seven Mercury missions that were planned, was scrubbed three times due to technical problems in the launch countdown. Finally, he flew. The date was February 20, 1962.


Crushed capsule from Mercury-Redstone tests prior to the launch of the Mercury 7 astronauts — the quest to fly into space was dangerous indeed. Credit: NASA

3, 2, 1… Ignition!

The countdown to launch had multiple temporary holds, as was common on both previous Mercury missions.  Clock holds were instituted to check systems and troubleshoot potential problems and to ensure completely clear, blue skies.  Finally, everything lined up up.  The countdown was restarted and reached zero.  The rocket motor ignited.  Everyone breathed a sigh of relief when there was no catastrophic explosion.


Mercury Atlas-6 lifts off on Feb. 20, 1962, carrying astronaut John Glenn on America’s first orbital spaceflight. Photo Credit: NASA

With a constant upward push, the Atlas rocket flawlessly lifted Glenn’s Friendship 7 capsule skyward toward space.  As the rocket accelerated, it pitched downrange.  It was already far out over the open Atlantic.  Everything was going to plan.


NASA diagram showing phases of a Mercury launch and recovery. Credit: NASA

At the point where the two previous Mercury missions had turned earthward for splashdown, instead Glenn’s rockets continued firing.  With the extra rocket fuel on board, he was heading into orbit.

The Russians had achieved orbit on their very first mission.  Now, with Glenn’s flight, America was catching up.


Glenn prepares for the MA-6 mission, January 1962, some weeks before launch in the capsule procedures trainer. Credit: NASA

The rocket’s launch stage separated and the capsule arced higher into space.  It reached a maximum altitude (or apogee) of 162 miles and its orbital velocity was approximately 17,500 miles per hour.

For the moment, John Glenn held the speed record as the fastest American to have ever lived.  He was flying at a speed of 4.86 miles/second, or about 7.82 km/second.


Glenn enters the Friendship 7 capsule during the last part of the countdown on February 20, 1962. Credit: NASA

At first, everything seemed to be working perfectly.  Mission Control and Glenn were optimistic.  Glenn reported on the coast of Africa, fires along the edge of the desert, and other sights, as well as the clouds.  At around an hour into the flight, Glenn was over Australia.  People had turned their lights on and Glenn reported that he could see the outlines of their towns and cities from space — he thanked them for turning on their lights.

After over an hour and fifteen minutes in orbit, while broadcasting in the blind (out of communications with any ground stations over the Pacific), he reported seeing, “literally thousands of small, luminous particles, swirling around the capsule and going away from me at maybe three to five miles per hour.”  These were particles from the thruster exhaust that flying with the capsule in orbit, reflecting the first rays of the sun as it came over the horizon.

After that, John Glenn faced his first crisis in space.  And then another.


One of the rare photos of Glenn in space; he used binoculars to view the Earth through the window of the Mercury-Atlas (MA-6) Friendship 7 capsule. Credit: NASA

Meanwhile, back on Earth, the news media anchors were breathlessly reporting on Glenn’s progress.  They were blissfully unaware of the unfolding drama even as they celebrated Glenn’s spaceflight.  If Glenn could orbit the Earth and return successfully, then America would have caught up to the Soviet Union in the “Space Race”.

Despite the media’s ignorance, however, the NASA engineers and Flight Control team knew that the situation had turned dire.  The problems were so severe that some thought that John Glenn might not make it.  One way or another, they knew, John Glenn was destined to make history, either as the first American to die in space or as the first to successfully orbit the Earth.  Nobody knew which it would be.


Mercury capsule design, showing: 1. Retropack. 2. Heat shield. 3. Crew compartment. 4. Recovery compartment. 5. Antenna section. 6. Launch escape system. Credit: NASA Photo with modifications by Soeren F. M.

NASA’s Key Goals for Friendship 7

The most critical goal of John Glenn’s planned spaceflight was to fly multiple orbits around the earth.  At launch, he was cleared for “at least seven orbits”.  Every minute of his flight had been planned and filled with experiments.  Throughout the flight, he was busy reporting on the status of systems, down to circuit breaker settings, and doing the various communications checks, physiological checks, and other scheduled activities.  As well, he was to work out problems with spacecraft control and test a number of human factors regarding how the body responded to the weightlessness of space.


Showing control along the yaw, pitch, and roll axis.

NASA’s engineers had theorized no man could control a spacecraft in the empty vacuum of space.  The tiny rocket thrusters mounted around the capsule’s small nose were imprecise and, even if they worked perfectly, they felt that an astronaut should be unable to avoid over-correcting in the weightlessness of space.  Without the aerodynamic effects from airflow around the capsule, they surmised that only an autopilot could effectively control the spacecraft.

Their logic was sound.  In an airplane, when a pilot lets go of the controls, it tends to stabilize and return to level flight.  The airflow over its wings and tail tends to return the plane to forward flight, much as the feathers on the back of an arrow keep it flying straight once it leaves the bow.  In space, however, there is no airflow.


This NASA illustration demonstrates how small the Mercury capsule actually was.

Since space is a vacuum, the theory went that once the spacecraft started to roll or pitch up, there would be nothing the astronaut could do manually to stop it.  In fact, it was expected that the astronaut would actually worsen the situation by over-correcting on the controls, inducing what is known as PIO — Pilot Induced Oscillation.  The spacecraft would then tumble faster, end over end as g-forces gradually increased until the astronaut was unconscious.

The engineers were confident that only a sophisticated autopilot could make it impossible to control flight attitude through the vacuum of space.  Nonetheless, an experiment was necessary to prove the theory.  Space was an unknown.  Everything had to be tested.  Everything had to be learned.


Artist Cecelia Bibby, employed by NASA contractor Chrysler Aerospace, paints Glenn’s “Friendship 7” logo onto his capsule. Credit: NASA

To prepare for the expected excessive g-loads, John Glenn had trained for months in a simulator — the Project Mercury Altitude Wind Tunnel Gimbaling Rig at MASTIF (the Multiple Axis Space Test Inertia Facility).  He had been subjected to extreme G-loads and rapid spinning in all directions at once.  He had built up an almost unrivaled physical capacity to withstand the accelerations and remain conscious.


The spinning rig for training at MASTIF. Credit: NASA

He had handled up to 16Gs of acceleration in the training program and had managed instantaneous changes from plus 9G to minus 9G, a span of 18Gs of acceleration.

John Glenn’s test pilot experience included work on the development of advanced flight control systems.  He was the best astronaut suited for the experiment.  If anyone could survive the expected oscillations, high g-loads, and spinning that were expected, it would be him.


The NASA gimbal training system, located at MASTIF, would rotate the astronaut up to 30 times per minute simultaneously in roll, pitch, and yaw, allowing the astronaut to practice returning the capsule to level flight by hand control. Glenn perfected his technique on this device during training. Credit: NASA

Still, it was only a theory.  Nobody knew whether a spacecraft was humanly controllable, even in Russia.  Past Soviet flights had treated cosmonauts as little more than human meat packed into a spherical capsule.  That capsule was then thrown up into space by a powerful rocket and, once in orbit, it tumbled lazily along completely out of control.  Only at the end did an autopilot stabilize the Soviet capsules for reentry into the atmosphere.

The problem was that to do any real work in space meant that manned flight control was essential.  The plan to land on Moon required it — how could a capsule land on the Lunar surface if it was impossible to control which way was up relative to the Lunar surface?  The engineers expected that they would have to build much more sophisticated, fully automatic autopilots capable of computerized flight control.  Only the tiniest micro-blasts of the control thrusters could be employed.


The Johnsville Centrifuge, on which Glenn did his g-load training. Credit: Johnsville Centrifuge & Science Museum

NASA’s plan to test the theory was both simple and brilliant.  Upon reaching orbit, John Glenn would allow the autopilot to stabilize the capsule.  Then he would switch off a single axis of control, while leaving the other two on autopilot.  This way, he could fly that axis manually while the autopilot managed the other two.  For instance, he would leave the autopilot engaged in both yaw (left or right) and roll (spiraling along the axis of flight) and switch off the pitch control (nose up and down) to test whether he could control that.

Once the capsule began to pitch around and into an end over end spin, getting completely out of control, then the idea was that Glenn would simply flick the autopilot back.  The autopilot would then rescue the situation and return his capsule almost instantly to level flight. He did the first check, hand-flying the spacecraft in yaw only even as he crossed the coast of Africa.  He fired the thrusters, established a rotation to the right of about one degree per secret, stopped that when he was about thirty degrees displaced, and then returned to his normal orbital attitude.


Map showing Glenn’s orbital flight path and communication listening posts for the flight. Credit: NASA

Glenn was try each axis of control separately:  roll, pitch, and yaw.  If all three experiments went well, then he was to attempt full manual control without any autopilot assistance whatsoever.  After that, he would switch the autopilot back on, allowing the autopilot to rescue the situation once again, and after a few more orbits, the capsule would fire its retropack rockets to begin its fiery reentry back into the Earth’s atmosphere.  Naturally, the autopilot would fly the spacecraft through reentry because a single tumble of the spacecraft during that time would result in catastrophe.

A heat shield was installed on the bottom of the capsule to protect John Glenn from burning up as Friendship 7 reentered the atmosphere.  Once he was slowed enough, the capsule was to deploy its parachutes, and splash down in the ocean.


Heat shield of Friendship 7 after recovery, showing the effects of extensive friction during reentry. Credit: NASA

Crisis in Space

At 1 hour and thirty-three minutes into the flight, just as he was nearing the coastline of Mexico and California by the Baja Peninsula, Glenn reported that the autopilot system was not working properly in yaw.  Glenn reported calmly to Mission Control, “This is Friendship 7, the yaw drifted out of limits about twenty degrees to the right.  I’m bringing it back in manually at the present time, over.”  Before he could resume the next phase of his flight control tests, he was suffering some kind of malfunction.

After a few checks, they realized that the automatic flight system couldn’t hold the spacecraft stable.  A yaw attitude control jet had clogged, however, and yaw corrections caused a loss of control in both pitch and yaw.  When he reengaged the autopilot, the capsule drifted right about 20 degrees, then the autopilot would kick the thrusters on at “high thrust” to return it to the correct attitude.  Then it would begin to drift again to the right at a rate of one degree per second

If the autopilot was left on, it would be potentially a greater threat to Glenn than he might be to himself if he flew it manually.  He elected to turn the autopilot off and fly the capsule by hand through the “fly-by-wire” system.


Flight Control Stick in Glenn’s capsule. Credit: NASA Illustration

To save the spacecraft from pointlessly yawing right, then back quickly left, then back right again in endless cycles, and to avoid any risk of starting an autopilot-induced tumble, Glenn switched the autopilot off.  He reported, “This is Friendship 7, controlling manually on fly-by-wire, having no trouble controlling.  Very smooth and easy, controls very nicely.”

He had no choice but to take over direct flight control by hand.  At least the manual-electrical fly-by-wire system was working correctly.  Everyone was calm — above all, Glenn himself, who made it seem like a walk in the park.  He was seemingly immune to the potential risks.  Yet everyone was masking a deep concern over the risk that Glenn actually faced in that moment.

For now, Glenn seemed to be managing it, but they were essentially just letting things drift along with Glenn making minor attitude adjustments as he felt were needed.  Soon he was reporting that he could see Florida on the horizon.


Glenn used a photometer to view the sun during orbital sunset. Credit: NASA

For a half hour, the problem was calmly assessed as the mission progressed.  At one point, Glenn liked the fact that the yaw malfunction had turned him around 180 degrees to face forward, but then he returned the capsule to the planned orbital orientation.  Then he added, “This is Friendship 7, I’m going to depart from flight plan for a moment and try and work this out a little better here, we are drifting in yaw. I am cutting automatic yaw off. And, and will control manually in yaw temporarily. Over.”

After a short while, he reported that it appeared that the problem had reversed; he had control on the right at one point, but now on the left.  None of the issues that he was facing made sense.  Spacecraft control was the one item that was critical to the safety of the flight.  If things were starting to go wrong, would the problem worsen?  Would he lose all control and tumble?

What if the engineers were right and no human could manually control a spacecraft in space?  He was already over Africa and in contact with the ground communications at Zanzibar.

Glenn took the stick and lightly moved it to return the capsule to level flight.  Instead of experimenting with one axis of control at a time, he was flying it all at once — roll, pitch, and yaw together — intermittently relying on the capsule’s ASCS (Automatic Stabilization and Control System).  He reported that he was having no trouble holding the capsule steady at all.  At two hours and twenty minutes into the flight, while over the Indian Ocean, Glenn reported, “I have some problems here with ASCS. My attitudes are not matching what I see out the window. I’ve been paying pretty close attention to that.”

The engineers worried that things seemed to be worsening.  Would the capsule start to tumble out of control?

As for John Glenn, he never doubted for a moment that he could control the spacecraft himself.  He managed it perfectly.  With deft movements of the control stick, he found that he could easily bring the spacecraft back to level flight.  He experimented with bigger inputs into the controls.  It was just the same experience as when he had previously tested numerous prototype aircraft during his test pilot career.  With each maneuver, data on how the capsule performed in the vacuum of space was recorded.  Glenn found that he could easily manage it all.  He flew “Friendship 7” flawlessly.

Glenn had proved that the engineers’ theory about uncontrollability was incorrect.  All it required was the practiced hand of a reasonably good test pilot — or at least a pilot from the US Marine Corps.

The score was Marines – 1, Engineers – 0, but everyone knew that the games were beginning.


Glenn in his silver Mercury pressure suit in preparation for launch. Credit: NASA

The Other Goals

Glenn’s mission was also the first in NASA’s history to bring food into space.  Glenn had tubes of freeze dried food pastes and powders.  There were packets of mushroom soup, orange-grapefruit juice, cocoa beverage, pineapple juice, chicken with gravy, pears, strawberries, as well as beef and vegetables.  All were pureed or powdered.  This was to be an astronaut’s fare.

The flight surgeons and engineers worried that in the weightlessness of space, it might be impossible to swallow food.  If so, they might have to feed and hydrate astronauts a lot before flights, if once in orbit, they would not be able to eat or drink at all.  This might make reaching the Moon almost impossible, though there was discussion of intravenous feeding and hydration.


Samples of food from the Mercury program. Credit: NASA

Indeed, when Glenn opened his processed food paste tubes, he found that he had no problem sucking them down.  He swallowed the contents easily.  Glenn did report after the flight, however, that the food was only barely palatable.  Who had dreamed up toothpaste tubes of pureed chicken anyway?  It wasn’t a chef, after all, but the engineers themselves.

The score was Marines – 2, Engineers – 0.

Another concern the engineers had and needed to test was whether extended flight without gravity would cause an astronaut’s eyes to lose their shape.  The medical staff had theorized that without gravity, the human eye would rapidly become blurred and out of focus.  If they knew what changes to expect, however, they could develop a set of “space glasses”, corrective lenses to bring the astronaut’s vision back to 20-20.  To get their data, they had pinned a small eye chart to the instrument panel.


The eye chart that Glenn used, affixed to the instrument panel of Friendship 7.

Every 30 minutes through his mission, John Glenn was directed to read the eye chart and report on the increasing degradation of his vision.  Based on the data he collected, the engineers would then create different sets of lenses for the different phases of flight in the next Mercury mission.  Dutifully, Glenn followed their guidance, but found that he could see as well from the beginning to the end.  There was no eyeball misshaping at all.

The score had increased to Marines – 3, Engineers – 0.


One of a series of photographs by an automatic sequence motion picture camera during his flight. Credit: NASA

Yet another theory the engineers had was that in the weightlessness of space, after a short time, the fluids in the inner ear would start to freely move around.  Without gravity, the astronauts would suffer from increasingly debilitating nausea, vertigo, and motion sickness.  As a result, Glenn was directed to report regularly on any signs of motion sickness.  Once again, however, the engineers were wrong.  Glenn experienced no problems at all.

The score had risen to Marines – 4, Engineers – 0.


Glenn and his capsule, “Friendship 7”. Credit: NASA

The Most Deadly Crisis

A warning light at Mission Control then came on.  Ominously, it indicated that a clamp that held the capsule’s heat shield in place had prematurely released.  This was the most serious malfunction of all.  The heat shield was detachable by design, but only after reentry.  Only then would the heat shield be discarded to fall away.  This would make the capsule lighter for its final descent by parachute to splashdown.  As a result, the clamp had been designed to hold the heat shield in place until it was time to discard it — a switch would then be triggered and it would fall off and into the ocean below.


Photo of North Africa taken by John Glenn from the “Friendship 7”. Credit: NASA


Photo of North Africa from space, taken by John Glenn in the “Friendship 7”. Credit: NASA

If the clamp had malfunctioned and opened early, that meant that the heat shield was no longer attached.  Therefore, as soon as the capsule started reentry, it would fall away from the buffeting of atmospheric pressures during the descent.  Left unprotected from the extreme heat that would result from the descent, Glenn would burn up in his capsule.  It would happen in mere seconds.  The engineers pondered the issue.  If the heat shield was detached, there was nothing they could do to reattach it.

It was either that the heat shield was unclamped or the warning light switch connected to the clamp was faulty.  There was no way to know.


Credit: NASA

The only option was to attempt reentry and see if he survived.  There were no back up systems.  There were no redundant clamps.  There were no fail safe procedures.  There wasn’t even a way to test if only the warning light switch had failed.  The engineers had never considered such a failure to be even remotely possible.

The score might have just become Marines – 4, Engineers – MINUS 1.  And probably Glenn was going to die.

Reentry was unavoidable.  It couldn’t even be reasonably delayed to give more time to troubleshoot the problem.  The capsule was coming down, no matter what.  Leaving Glenn in orbit longer was impossible too.  The oxygen systems weren’t designed for longer times in space.  The batteries that ran the electrical controls didn’t have enough excess power to stay in orbit longer and yet still power the systems needed to reenter the atmosphere.  Every milligram of extra weight had been shaved from the capsule — the result was that the capsule had been optimized for exactly six or seven orbits.


Credit: NASA

There’s an old saying, “Aviation has a perfect record — we’ve never left one up there.”

The best option was to fire the retrorockets and bring him down early.  With the flight control system failure earlier, they had already decided to cut the mission duration in half anyway.  There’s another old saying in aviation, “Expect accidents to come in threes.”  If the clamp had failed — and they didn’t know why — what else would fail next?  The situation could potentially worsen.  Glenn would come down early — it was decided.

This raised yet another question:  how would they tell him that in their best judgment, most likely the heat shield had slipped and that he was about to be burned to death?


Photo of Florida taken by John Glenn. Credit: NASA
Photograph of Florida from space, taken by John Glenn. Credit: NASA

Avoidance is the Best Strategy

The engineers were concerned that if they told Glenn of his predicament, he might panic.  If that happened, they wondered if they could depend on him to manage the situation to the end.  Yes, he was a test pilot and had “nerves of steel”, but the situation was really dire.  In yet another meeting, the engineers decided to not say anything to Glenn.

Still, they needed information from him — maybe the warning light in the capsule wasn’t illuminated?  However, they knew that Glenn would get suspicious if they asked their questions directly, so they decided on a plan, hoping that Glenn wouldn’t notice.


Honeysuckle Creek Tracking Station in eastern Australia, which tracked and communicated with Glenn as he made his orbits. Credit: Graham Watts

The Flight Director called the different ground stations around the world that supported communications through each orbit with a request.  They were instructed to inquire as he passed overhead from one ground station’s communications arc into the next.  Did Glenn see any warning lights illuminated in his cockpit?  They were told to ask it casually.


Sunrise from space, the curvature of the Earth apparent, taken by John Glenn in the “Friendship 7”. Credit: NASA

After the second time the question was asked, however, Glenn became suspicious.  After the third, he knew something was up.  He scanned the panel but could find nothing amiss.  The warning light they were inquiring about wasn’t illuminated, but he didn’t know what they wanted so he couldn’t report on that.

For a pilot who had spent over a thousand hours in the Mercury capsule’s “procedures trainer” rehearsing all kinds of malfunctions and failures, Glenn considered what might have gone wrong.  Mentally, he went through each checklist.  He considered the likelihood that they had detected a problem with the heat shield.  His worst fears were confirmed when the engineers notified him that he was to attempt reentry with the capsule’s rocket retropack still attached.


The retropack with its lightweight straps holding it into place, photo from a replica of the capsule at The Museum of Flight in Seattle, WA. Credit: Ciar

Keeping the retropack in place during reentry was a smart idea.  Normally, after it had fired to slow the spacecraft to bring out of orbit and into reentry, it would be jettisoned to reduce weight.  With the retropack gone, the heat shield presented a smooth, aerodynamically stable face into the friction of the atmosphere during reentry.  If the retropack was left in place, it’s straps might hold the heat shield in place long enough to get the capsule back down to slower speeds before Glenn burned up inside.  However, no aerodynamic tests had been run to determine how the retropack might affect the capsule’s flight attitude.

The worst case scenario was that it might cause the capsule to tumble.  If it tumbled, the heat shield would no longer keep the capsule from burning up anyway.  Furthermore, now Glenn would have to fly it through reentry, since the autopilot couldn’t be used.  The very thing that the engineers had thought impossible — that Glenn could never control the spacecraft manually — was now the one thing that they were counting on for him to save himself.  He was told what he already knew, that he would leave the heat shield in place and fly the capsule manually through reentry.

The score was precariously holding at Marines – 4, Engineers – MINUS 2.  Or maybe MINUS 3 — nobody was sure anymore.


Shadowgraph from NASA depicting shockwave patterns from the manned capsule design — this design, dating from 1957, was essentially used in the Mercury program. Credit: NASA

Reentry and Rejoicing

After the third orbit, the retropack was fired.  Friendship 7 was on the way home.  Throughout the fiery descent, the spacecraft would be out of radio contact — what was called “blackout”.  If it burned up, when communications should have been reestablished, which should have been after about four minutes of blackout, all they would hear was silence.  If the capsule made it through, they expected that John Glenn would radio Mission Control with the good news.  It was possible too that he would be badly burned but somehow still alive to splashdown, but would a damaged capsule sink?


“Friendship 7” floating in the Atlantic Ocean along side USS Noa during the recovery phase. Credit: NASA

As the Friendship 7 capsule reentered the atmosphere, John Glenn flew it carefully.  He left part of the autopilot engaged and flew the other axis manually, so as to save fuel.  For three and a half minutes during the reentry, he alternated between his attitude instruments and the small side window of his capsule as flames and sparks flew past.  He could see the bright glow of the heat shield doing its work.  The first of the straps holding the retropack’s staps broke away and flew past his window within only about five seconds of reentry.  The heat shield seemed to be holding.

Less than fifteen seconds into the reentry, all of the straps were gone.  The retropack broke away and flew past his window.  For a few seconds, he waited to feel for any rapidly intensifying heat.  The heat shield held.  It was nothing more than a sensor failure after all.  The clamp had never released.


Glenn’s capsule is recovered by USS Noa and hoisted onto deck. Credit: US Navy


After three and a half minutes, the capsule had reached lower altitudes and slower speeds.  Glenn radioed Mission Control — he was out of blackout.  Then his parachute blossomed above.  “Friendship 7” slowed its decent and hit the water — splashdown!  He had returned to Earth.  As he floated, bobbing up and down in the waves inside the capsule, he stared out the window at the open Atlantic.  For the first time in the flight, Glenn relaxed as he waited for the arrival of the ship that the Navy had sent to the splashdown location — USS Noa (DD-841).  Glenn would remain in the capsule until it was hoisted onto the deck of the destroyer.


An image showing the recovery of the astronauts after the mission — this of Alan B. Shepard Jr., who was rescued by a US Marine Corps helicopter after his mission. Credit: NASA

He waited longer than was expected because the engineers had made yet one more mistake.  They had miscalculated the capsule reentry weight.  They hadn’t subtracted the weight from the extra burn times of the control thrusters that Glenn had used in his more extensive flight control experiments.  The result was that the splashdown location was 41 miles west and 19 miles south of the originally planned point.  He was almost 800 miles southeast of Cape Kennedy, not far from Grand Turk Island.  After three orbits, John Glenn’s flight time from launch to splashdown was 4 hours, 55 minutes, 23 seconds.


Smiling, calm, and cool, Glenn relaxes aboard USS Noa (DD-841) after being recovered from the Atlantic near Grand Turk Island. USS Noa picked him up 21 minutes after impact. Credit: NASA

After recovery, he was brought on board the US Navy Destroyer USS Noa.  The capsule was hoisted onto the deck.  Glenn examined it carefully.  It seemed flawless.  Despite the problems he had encountered, the mission had been the most successful in Project Mercury to date.  It had been a ride to last a lifetime.


President John F. Kennedy, astronaut John Glenn and General Leighton I. Davis ride together during a parade in Cocoa Beach, Florida, after his historic flight. Credit: NASA

The final score for the mission was Marines – 5, Engineers – MINUS 2. John Glenn had come through it all and he did it with a smile.

After his successful mission during Project Mercury, John Glenn applied to take another flight into space.  He was denied.  Unbeknownst to him, President Kennedy had quietly instructed NASA to keep him on the ground.  He didn’t want to risk losing an American hero in space.  Finally, decades later on October 29, 1998, John Glenn did get his wish when he flew back into space on the Space Shuttle Discovery.


On STS-95, Space Shuttle Discovery, John Glenn flew as a payload specialist. Credit: Made Public Domain by NBC

In that flight, NASA had an unprecedented opportunity to learn yet more about human factors in space by comparing his body records from 1962 against his experiences in 1998. Naturally, being a Marine veteran, Glenn had kept in good shape.  He was mission ready.  At age 77, he was the oldest astronaut to have ever flown into space.  That record is still unchallenged.


John Glenn poses in the cockpit of his “MiG Mad Marine” F-86 Sabre while assigned to the 25th Interceptor Squadron during the Korean War, probably c. July 15, 1953. Credit: John Glenn Archives, Ohio State University

The Last Word

John Glenn seemed always to be smiling and never showed any fear, no matter what crisis he faced.  Whether it was in the cockpit of “MiG Mad Marine” or flying into orbit on the Space Shuttle in 1998, he seemed to love every moment of it.

When summing up the greatest risk of his Mercury 7 mission, he remarked:  “I was sitting on top of two million parts, all built by the lowest bidder on a government contract.”  He smiled and took it all in stride.

A Marine to the end, he would add, “Semper Fi!”


John Glenn shows his children, Lyn and David, how he shot down a MiG-15 jet during the Korean War, late 1953. Credit: John Glenn Archives, Ohio State University


One More Thing

Gordon Cooper was the only other Mercury 7 astronaut who had to hand fly the capsule through reentry.  His challenge was even greater than Glenn’s because his capsule’s attitude instrumentation system had suffered a catastrophic short circuit.  The autopilot had no attitude and orientation data — nor did Cooper.  There was no way to precisely align the capsule with the horizon for the firing of the retropack.  If he was few degrees too steep, he would be too fast and burn up in the atmosphere.  If he was a few degrees too shallow, he would “skip” off the atmosphere and into space with no hope of return.  He had only one chance to get it right and he had to do it by hand — it was the most challenging “instrument out” approach to landing in aerospace history.

All Cooper had was a grease pencil and the capsule’s small window, which gave him some outside reference points.  He drew a line across the glass at the angle he needed the spacecraft to fly relative to the horizon during the retropack burn.  He drew dots to mark the positions of key stars as reference points to keep the capsule properly oriented upright during the descent.  He would fly it by eye and hand alone.  In the end, he got it right — he landed the capsule just a few miles from the aircraft carrier that was stationed to pick him up after splashdown.  His skill on the controls was good that he landed closer to the target than the best autopilot landing in the entire program.



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