Home Science The Greatest Leap, part 1: How the Apollo fire propelled NASA to the Moon – Ars Technica

The Greatest Leap, part 1: How the Apollo fire propelled NASA to the Moon – Ars Technica

65 min read

Video shot by Joshua Ballinger, edited and produced by Jing Niu and David Minick. Click here for transcript.

Seated in Mission Control, Chris Kraft neared the end of a tedious Friday afternoon as he monitored a seemingly interminable ground test of the Apollo 1 spacecraft. It was January 1967, and communications between frustrated astronauts inside the capsule on its Florida launch pad and the test conductors in Houston sputtered periodically through his headset. His mind drifted.

Sudden shouts snapped him to attention. In frantic calls coming from the Apollo cockpit, fear had replaced frustration. Amid the cacophony, Kraft heard the Apollo program’s most capable astronaut, Gus Grissom, exclaim a single word.


Noise blared for a few more seconds—then stopped completely.

An awful silence pervaded mission control. Engineers—pale, rigid, and silent—contemplated the worst. Kraft wondered if three of his friends had just died on his watch.

At that moment, astronaut Walt Cunningham was flying into Houston. He had worked inside the Apollo 1 spacecraft the evening before, and he had planned to stay in Florida until Grissom and the rest of the prime crew had finished their tests. But as delays pushed the morning “plugs-out” test into late afternoon, Cunningham and his fellow astronauts bailed, jumping into their T-38 aircraft and returning home for the weekend.

Christopher Kraft, director of flight operations, at his flight operations director console in the Mission Control Center in 1968.

They knew something had gone wrong when they saw a grim-faced program manager waiting on the Houston runway as their aircraft taxied to a stop.

Norman Chaffee had left the space center in Houston earlier that evening, his day’s work done. An engineer helping to build the reaction control system thrusters used to orient the Apollo spacecraft, Chaffee was relaxing in an easy chair watching television when his telephone rang. Something had happened, a supervisor said, something bad with the prime crew. Chaffee had best prepare for some long days ahead.

That evening was clear and cold in Houston, as an almost-full Moon rose overhead. When the men and women of Apollo stopped for groceries on Friday evening after the fire, pulled in trash bins from the curb, or shivered and smoked a cigarette on the patio, they would have seen its brilliant light. And on that bitter night, it never seemed so far away.

All three astronauts had indeed died in the fire. In its aftermath, Kraft, Cunningham, and Chaffee were among thousands of Apollo program employees facing a harsh reality. Fewer than three years remained in the decade during which they were supposed to land on the Moon. And the spacecraft built to carry astronauts into deep space was now smoldering atop a rocket in Florida.

Outside of the aerospace industry, the story of Apollo 1, along with NASA’s rapid recovery through the historic Apollo 4 rocket launch and the Apollo 7 crewed mission, has largely been relegated to a historical footnote. It pales against the dazzle of six Moon landings. Yet without the fire, and the difficult decisions made in 1967 and 1968, NASA would never have met President Kennedy’s Moon mandate.

In fact, humans might never have reached the Moon at all.

“It really floored me”

A skinny kid with humble roots in rural Virginia, Chris Kraft had come to NASA in 1958 as one of its founding members, invited to join the Space Task Group after more than a decade as an engineer testing new aircraft. When the original spaceflight tasks were parceled out, it fell to him to figure out how to conduct space missions. This included drawing up flight plans, monitoring a spacecraft’s systems during flight, and communicating with astronauts.

No one in the Western world had done any of these things before, so Kraft set to work inventing the concept of mission control, basing the role’s rigorous procedures and iconic communication styles on how air traffic controllers operated. Soon, he attracted a cadre of talented young flight controllers.

In early May 1961, he was flight director when a slim Redstone rocket—really, a barely modified Cold War ICBM—flung a lone American away from the Florida Coast and into a parabola that arced 188 kilometers up before splashing down into the Atlantic Ocean. Alan Shepard’s entire flight in the tiny Mercury capsule had only taken 15 minutes, but at the end of it America had finally joined the space race.

The launch of the Mercury-Redstone rocket carrying Alan Shepard into space on May 5, 1961.
The launch of the Mercury-Redstone rocket carrying Alan Shepard into space on May 5, 1961.

Less than three weeks later, Kraft received a heads-up from a supervisor that he should watch President Kennedy’s speech to Congress later in the day. Kraft’s heart almost stopped when the president said, “This nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth.”

The Moon? Did he hear that right?

Shepard had only just completed a suborbital flight, and Kraft and his fellow mission planners were still grappling with the mechanics of human spaceflight around the planet. Now his president was saying that NASA would put an astronaut on the Moon. In less than nine years.

“It really floored me,” Kraft said, reflecting on that moment. “I really thought it was beyond our scope. I must say, the team of people we had didn’t quite feel that way.

“I think they were excited as hell about it,” he added with a chuckle. “And so I became excited about it.”

President Kennedy’s 1961 speech in Congress.

Almost immediately, Kraft began thinking about all of the aerospace technology needed to reach the Moon. All of it would have to be invented and tested. And it wasn’t just a hardware problem; there were huge, basic questions to be answered. What was the surface of the Moon made of? How much radiation would astronauts be exposed to? How much power would they need?

He also began thinking about communicating with the crew. In 1961, state of the art communications consisted of landlines and teletypes. As Mercury capsules flew around Earth, controllers in Florida could communicate with remote monitoring sites in far-away places like Zanzibar—but only with a few words at a time, sent via teletype. This wouldn’t be nearly sufficient for the volume and speed of information expected on a lunar flight.

The Mercury program would see NASA address multiple challenges as it transitioned from short, suborbital flights to its capstone flight—when Gordon Cooper orbited the planet 22 times over the course of 34 hours. By then, the pioneering Mercury spacecraft had reached its limit; its batteries could not support longer flights. The vehicle also had little maneuverability in orbit beyond some attitude control and the firing of a retrorocket to bring it back to Earth. In the summer of 1961, even before NASA had flown its second Mercury mission, work therefore began on the Gemini spacecraft to address these issues.

NASA flew 10 Gemini missions between March 1965 and November 1966, or one flight every two months. Then and now, it was an astonishing cadence, considering that each mission was unique and built upon the achievements of previous flights. On one flight, the much more capable Gemini spacecraft might perform an endurance test of its new fuel cells, marking the first time a spacecraft flew without using batteries as its primary power source. On another, two vehicles might rendezvous in orbit. Then came a docking. Astronauts performed spacewalks. By the end of Gemini, NASA had demonstrated many of the basic technologies needed to reach the Moon.

Critically, the daring dash of Mercury and Gemini had covered only about five years since Kennedy’s speech. A few brief scares aside, the program had gone off almost flawlessly. By early 1965, with some of the early Gemini missions behind them, NASA had sprinted ahead of the vaunted Soviet space program. NASA had made it look easy—perhaps too easy.

Listing image by NASA / Aurich Lawson

“Go fever”

Preliminary design work on the Apollo spacecraft started almost immediately after President Kennedy’s speech, as engineers settled on a vehicle that could carry three crew into space for up to two weeks. By November 1961, NASA had given the contract to North American Aviation, a company with a fine reputation for building military aircraft, like the P-51 Mustang and the B-25 Mitchell bomber, but no experience with spacecraft.

Concerns soon emerged with the company’s construction of the Apollo Block I spacecraft. The initial version contained more than 600 switches, indicators, circuit breakers, and controls, along with 20 miles of wiring. Some of the work seemed haphazard, and machine bundling of the wires left them open to short circuits.

Despite these challenges, NASA’s successes in spaceflight increased its confidence in the ability to overcome any obstacle on the way to the Moon. For the first (but not the last) time, the space agency and its contractors succumbed to “go fever,” the urge to launch while the launching is good, downplaying or even ignoring safety indicators. Even the astronauts were imbued with such confidence.

Apollo 1 Commander Gus Grissom had already cheated death once during spaceflight. During America’s second human spaceflight, the hatch on his Mercury spacecraft blew too early after he had landed in the ocean. The vehicle began taking on water, and his flooded flight suit nearly pulled him under before a helicopter snatched him from the Atlantic. Later, Grissom flew the first Gemini mission. If not for the Apollo 1 fire, he would also have been in line to command the first mission to the Moon’s surface. Cool and calm, Grissom felt himself capable of tackling any problem that might arise.

Fellow astronaut Walt Cunningham came to NASA in 1963 as part of the third group of fliers chosen as the space agency enlarged its corps for the Apollo missions. A Marine Corps fighter pilot, Cunningham had flown 54 missions in Korea. “We were all interested in flying faster, higher, and farther,” Cunningham recalled recently. A little more than three years after arriving at NASA, Cunningham was named one of three back-up crew members for Apollo 1.

Pushing barriers was part of an astronaut’s job. This often happened in the sleek T-38 aircraft assigned for astronauts to fly from Houston to Kennedy Space Center in Florida or to Los Angeles, where North American was building the Apollo spacecraft. “It was like the last great flying club,” Cunningham recalled. “We ended up doing things with the T-38s, pushing them to levels anyone flying today will tell you, ‘Can’t do that.’”

For instance, Cunningham flew his T-38 nonstop from Los Angeles to Ellington Field in Houston, a journey of nearly 1,400 miles that normally required a refueling stop in El Paso. A nonstop flight typically was attempted only during the winter, when the jet stream moved south. Under the right conditions, a T-38 could save fuel by cruising to a high altitude and catching a strong tailwind. To succeed, a pilot had to average 60 knots of tailwind, Cunningham recalled—and had to hit that average by Albuquerque or El Paso. Otherwise, the plane would run out of fuel before reaching Houston. 

Astronaut Walter M. Schirra standing beside a T-38 in 1963.
Astronaut Walter M. Schirra standing beside a T-38 in 1963.

One time, with Wally Schirra flying, Cunningham passed El Paso but still had not hit the requisite average. Schirra took the plane up to 47,000 feet, where the duo found a roaring 160-knot tailwind. Even so, after passing San Antonio, Schirra shut one engine down and pulled the other one back to idle. At a few thousand feet above the Houston runway, he started up the second engine and circled down.

“All the way down, I had my hands on both eject handles,” Cunningham recalled. “It was very close. But in those days, we never even really thought a whole lot about it. We never talked a whole lot about it. That represents the difference in attitude we had. Not that I would recommend it, or even say it’s healthy for people. But it’s part of what made that program what it is now remembered for.”

The fire

The “plugs-out” test on January 27, 1967, was a standard step in the run-up to the first crewed launch of an Apollo spacecraft. Essentially, the test simulated the launch of both the rocket and its spacecraft, during which both vehicles switched to internal power. Although this was a serious test, no one expected the catastrophe that unfolded inside the capsule. Everyone assumed the real danger would come later, in space.

The definitive cause of the Apollo 1 fire, which killed Grissom, Roger Chaffee, and Ed White, has never been found. An incident review board pointed toward a “most probable cause,” in which cabling bundled beneath a door leading to the environmental control unit frayed during repeated openings and closings. It seems likely that when Grissom opened this door, electricity arced between exposed areas of wire. That was a problem because, in flight, the spacecraft would follow the same design as Gemini and Mercury—filling its internal volume with pure oxygen. This design choice saved considerable weight over a more complex two-gas system, but it also meant there were “many types and classes of combustible material” in the craft, the review board report stated.

A fire broke out, and conditions deteriorated rapidly inside the pressurized spacecraft. Only eight seconds passed between the time when a significant voltage transient was recorded and when someone, probably Grissom, shouted “Fire!” Two seconds later, someone, likely Chaffee, said: “I’ve [or ‘We’ve’] got a fire in the cockpit.” Seven seconds later came a final transmission, which has been variously interpreted as “We’ve got a bad fire—let’s get out… We’re burning up!” or “I’m reporting a bad fire… I’m getting out. Oh, AAH!” This was followed by a scream. The radio went silent.

The interior of the Apollo 1 capsule after the fire.
The interior of the Apollo 1 capsule after the fire.

Following all of the investigations, Apollo’s program office manager, Joe Shea, took much of the blame. He had led development of the Apollo spacecraft and was a burgeoning celebrity due to his extensive efforts to get the Apollo command module’s development on track. Indeed, Shea’s acclaim in the press had begun to rival even that of German rocket builder Wernher von Braun. Time magazine planned to feature Shea on its cover after the Apollo 1 launch.

Shea knew that NASA had taken delivery of a flawed spacecraft from North American, having reviewed all the reports of fixes that needed to be made. Moreover, Shea was sympathetic to problems raised by Grissom and the other astronauts. To gain first-hand understanding of the problems plaguing the Apollo 1 spacecraft, Shea had asked technicians at Cape Canaveral on January 26 to rig a fourth communications loop inside the spacecraft so that he could join the crew during the plugs-out test. But such a system couldn’t be wired in time, so Shea flew back to Houston on Friday afternoon. He arrived at his office just about when the fire began.

Shea could never forgive himself for the accident; he had failed to recognize the danger of the plugs-out test in a pure oxygen environment. In the weeks and months after the fire, he worked himself to exhaustion. For Apollo to survive, he would have to go. Shea was offered a transfer to headquarters in DC by NASA Administrator George Mueller, though the deputy administrator position that had sounded so good on paper turned out to be nothing more than a bureaucratic version of purgatory. Shea spent his days reading in his office or wandering around the nation’s capital. Soon, he would be gone from NASA, forever knowing that he could have been sitting in that capsule alongside Grissom, White, and Chaffee.

Shea would never forget a meeting on August 19, 1966, when NASA accepted the Apollo 1 spacecraft from North American. The Apollo 1 crew members were in attendance during the six-hour meeting during which Shea led a discussion of major and minor problems with the spacecraft, which would be transferred from California to Florida for checkout procedures.

Charles Murray and Catherine Bly Cox’s Apollo: Race to the Moon recounts that Grissom asked for the floor toward the end of the meeting and took out two photos of the Apollo 1 crew seated behind a table, heads bowed as if in prayer. Grissom gave a signed copy of one photo to Stormy Storms, general manager of North American’s space division, and another copy to Shea.

“Joe [Shea] advised us to practice our backup procedures religiously, so here we are practicing,” Grissom said, according to the book. Shea’s photograph carried an inscription: “It’s not that we don’t trust you, Joe, but this time we’ve decided to go over your head.”

Shea kept the photograph displayed in the entrance of his home for the rest of his life.


Norm Chaffee, the engineer, had known the crew. Not intimately, perhaps, but well enough that when he’d bump into Roger Chaffee at the grocery store, perhaps picking through vegetables, they’d joke about sharing a last name without being related.

“These guys were not the heroes the rest of the world saw,” Chaffee said. “To us, they became just regular folks.”

For Chaffee and the other engineers who had worked on the Apollo spacecraft, the Apollo 1 fire came as a shock. They’d always understood the risks. Chaffee worked on the reaction control thrusters that the Apollo capsule would use to maneuver in space, and many things could go wrong with those. But like a lot of other spaceflight hazards, those risks wouldn’t manifest themselves until after launch.

Following the successes of Mercury and Gemini, the Apollo engineers began to feel some of the invincibility the crew felt. “I think we, as young guys, most of us considered ourselves able to leap tall buildings in a bound, and we were bulletproof, and we were going to get it right, and that kind of stuff,” Chaffee said.

Faced with the reality of three dead astronauts, it fell to Chaffee and thousands of other engineers to figure out what had gone wrong and how to overcome it. In Houston, where the power and propulsion division had a test stand that could handle fire and toxic materials, Chaffee and his fellow engineers worked to discover exactly how much of the spacecraft’s interior was flammable and under what conditions.

To better understand the accident’s cause, and to prevent it in future vehicles, they outfitted a boilerplate Apollo 1 capsule with original plastics and wire insulation. Then they began setting fires. Painstakingly, Chaffee’s team documented temperatures and pressures, then filmed how the fire spread. They studied the toxicity of materials as they burned. Not only did they want to know what had started the fire, but they wanted to find other flammable materials they had missed. They now knew that if they missed something, more of their friends would die. “As simple as that,” Chaffee said.

The Apollo capsule program manager, George M. Low, left, and rocket designer Wernher von Braun.
The Apollo capsule program manager, George M. Low, left, and rocket designer Wernher von Braun.

As engineers and technicians worked through the flaws with the Apollo 1 spacecraft and carefully identified solutions, NASA’s managers reorganized themselves. Probably the most important change came with the replacement of Shea by engineer George Low, a former refugee from Austria whose Jewish family had fled Nazi Germany in 1938. Under Low’s steady leadership and ability to foster cooperation, the program got back on track.

By the time of the fire, a mere 35 months remained in the decade. The highest any human had flown was 850 miles, yet the moon was 240,000 miles away. NASA didn’t yet have a rocket to get there, its spacecraft had just caught fire, and the work-in-progress lunar lander had not yet been tested in space.

Apollo 4

Before the fire, NASA had planned to fly an Apollo 2 mission that would test the Lunar Module in low-Earth orbit, then launch a crew aboard the Saturn V rocket for the first time with Apollo 3. Because of the need to radically remake the Apollo capsule, however, NASA canceled those missions. The next mission after the fire, therefore, would come to focus on the big Moon rocket.

The world had never seen a spaceship quite like the Saturn V rocket take flight. While the Apollo spacecraft had issues, the rocket was by no means proven, either; it stood a staggering 111 meters tall, the height of a 36-story building. Fully fueled, it weighed 2,800 tons. Its thrust at launch, as the rocket trembled and shook and slowly climbed away from Earth, was equivalent to the power output of 85 Hoover Dams. A fully fueled Saturn V rocket had the explosive power of nearly two kilotons of TNT, or a small nuclear bomb.

No rocket like this had flown before. Earlier in the same decade, von Braun and other scientists had struggled to launch a booster with a single engine in each stage. Often, a rocket would blow up on its first and second tests, and maybe for the third test, the upper stage would fail.

Now NASA had assembled a rocket with 11 engines, many of them flying for the first time. The rocket’s first stage was powered by five of the most powerful rocket engines in existence; each F-1 had a sea-level thrust of 1.5 million pounds, but the F-1 had never flown before. The second stage housed five Rocketdyne J-2 engines, which had only flown for the first time in 1966. The third stage had a single J-2 engine.

Early morning view of Pad A, Launch Complex 39, Kennedy Space Center, showing Apollo 4 before its launch.
Early morning view of Pad A, Launch Complex 39, Kennedy Space Center, showing Apollo 4 before its launch.

NASA engineers had begun testing pieces of the titanic Saturn V rocket at Cape Canaveral several months before the Apollo 1 fire, and work continued on the booster even as the fire investigation proceeded. The entire rocket rolled out from the Vertical Assembly Building for the first time in August 1967, and, by September 27, engineers were ready to start the “countdown demonstration test.”

Rockets are mountains of fuel and gases in tanks, with regulators to manage the flow of these propellants through pipelines. New computers and software had been installed for the Saturn V rocket to manage all of this; none worked correctly. Every component had to be tweaked, which was the purpose of the countdown test. For the first Saturn V rocket, this test proved an ordeal, stretching out over 17 long days. But eventually it ended, and the booster was cleared for its maiden test flight.

To the amazement of almost everyone, the rocket launched more or less on time on its launch date of November 9. For those who had watched smaller boosters zip off the pad, the Saturn V climbed agonizingly slowly as its 7.5 million pounds of thrust gradually overcame its 6 million pounds of mass.

Among those watching in 1967 was Michael Collins, eventual command module pilot for the Apollo 11 lunar landing.

“One wonder to me was that no Saturn V rocket ever blew up,” he recalled much later. “When you have gigantic machines churning away at extraordinarily high temperatures and pressures, it’s a real tribute to the engineering of von Braun’s people.”

Apollo 7

So NASA had a rocket. But did it have a spacecraft? The months kept ticking away. NASA would not attempt its next crewed launch until October 1968. By then, all margin in the Moon schedule had washed away. Less than 15 months remained until NASA’s end-of-the-decade deadline. There could be no more accidents.

Since the fire, NASA had ordered more than 1,000 changes to the Apollo spacecraft. Only if this mission were successful could NASA engineers clear the Apollo spacecraft to go beyond low-Earth orbit and fly out to the Moon. Along the way, the leadership of George Low had been tested, and the refugee from Austria had responded.

“It was a hell of a job by George Low,” Kraft said. Low had changed people, thinking, and culture in a short period of time, and he had rescued a spacecraft that was seriously flawed.

“I don’t think we would have ever had the opportunity to do that if the fire hadn’t happened,” Kraft added. “If we had just kept going, and the fire hadn’t happened, I think we would have been making mistake after mistake after mistake, and I think we would have killed a lot more people in flight.”

The Apollo 7 mission launched without incident. The commander, Wally Schirra, came down with a bad cold shortly afterward, however, and became testy with flight controllers. (Cunningham said that because Schirra had a cold, the mission’s two other astronauts had to have “colds,” too. Schirra’s actions prejudiced any chance Cunningham or his crewmate Don Eisele ever had to fly again.)

The crew’s recalcitrance aside, the Apollo spacecraft performed beautifully. On its 11-day mission in low-Earth orbit to shake out any flaws with the vehicle, Apollo 7 proved to be the longest, most ambitious, and most successful first test flight of any new flying machine.

Walt Cunningham is photographed during the Apollo 7 mission.
Walt Cunningham is photographed during the Apollo 7 mission.

“We knew the first mission was very important,” Cunningham recalled. “We were not there for the fun of it. We were not there just for the notoriety of it. We were there to help an objective along that, as we look back on it today, was probably the greatest accomplishment of the 20th century.”

The work paid off. After the fire, NASA had endured 21 months of soul-searching, late nights, and grueling effort. Now, very rapidly, those dues would be repaid. In less than two months, three humans would take perhaps the greatest risk ever in human spaceflight, leaving the cradle of Earth and entering the gravity well of another world.

In the end, the tragedy of the Apollo 1 fire did make NASA stronger. Strong enough, in fact, to change history forever.

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