In the aftermath of the fatal Apollo 1 launchpad fire in January 1967 — among the most egregious examples of sacrificing safety and reliability to schedule — NASA learned the hard lessons of the avoidable tragedy, pulled up its socks and built some of the most reliable machines ever devised by engineers.

Among them was the one component of the American lunar landing that lacked redundancy, a design imperative for manned spaceflight: the ascent engine that would lift moon walkers off the lunar surface to rendezvous with the orbiting mother ship, the Apollo command module.

Virtually every component of the Apollo Saturn V and spacecraft had redundant systems, often multiple redundancy. Space is deadly, the engineers and astronauts were always looking for ways to reduce the inevitable risks. Backup systems were an obvious choice.

But the lunar module’s ascent engine could not be hot-fire tested before installation. The primary reason was its nasty but reliable propellants: nitrogen tetroxide and a mixture of hydrazine and unsymmetrical dimethylhyradrazine. Those storable propellants would ignite on contact, providing reliability along with some major engine wear and tear.

Apollo 17 Lunar Module

The Apollo 17 lunar module ascent stage and crew module after the sixth successful surface ignition of the its single engine, seen underneath the hatch. The engine had to fire, there was no backup. Hence, it was powered by ignite-on-contact propellants referred to by Soviet rocket designer Sergei Korolev as the “devil’s venom.” (Source: NASA)

In the words of Timothy Harmon, project engineer at NASA contractor Rocketdyne, there was no backup engine to get astronauts off the lunar surface. “There was no second chance, therefore this engine had to operate.”

The ascent engine designers at Rocketdyne faced problems similar to other Apollo propulsion systems, namely combustion instability and the added problem of thrust chamber erosion from those noxious propellants. The same schedule pressures that contributed to the Apollo 1 fire — landing a crew on the moon and returning them safely by the end of the decade — also drove lunar lander development.

But the Rocketdyne engineers had the advantage of hindsight: They and all the other 400,000 Apollo technicians woke up each morning with the realization that the lives of astronauts — guys they worked with on the factory floor and hung out with in bars after work — hinged on getting every technical detail right.

And then you ran another test to be doubly sure.

By 1967, “The ascent propulsion system had become the pacing Apollo program item,” Harmon noted in a paper delivered at a 1992 aerospace engineering conference. In other words, the LM and its balky ascent engine were holding up the entire American moon-landing effort.

Undoubtedly applying the hard lessons of the Apollo 1 fire that recommitted the space agency to crew safety and system reliability, the Rocketdyne engineers undertook a crash, seven-month effort to design, develop and qualify a propellant injection system that solved the combustion instability problem. The injection designers incorporated Y-shaped baffles and special acoustics to dampen the resonance that could shatter a combustion chamber like a vibrating wine glass.

The fixes worked, the lunar module engines were tested in Earth orbit in March 1969. Four months later, the LM ascent engine lifted Neil Armstrong and Buzz Aldrin up and away from Tranquility Base and into the welcoming embrace of Apollo 11 command module pilot Michael Collins, who later admitted the failure of the LM ascent engine was his “secret terror.”

The pressure-fed ascent engine that provided 3,500 pounds of vacuum thrust and a restart capability “had a perfect flight record,” Harmon proudly noted. It lifted six lunar-landing crews off the surface and on their way home. The Apollo astronauts variously described the ride as “very smooth” and akin to riding a very fast elevator.

Those 400,000 engineers and technicians who labored for a decade to reach the moon learned bitter lessons along the way, culminating in the deaths of the crew of Apollo 1. Among the causes was “Go Fever,” a group-think mentality that blinded otherwise brilliant aerospace engineers from seeing problems right in front of their noses.

Project Apollo rose from the ashes of a disaster, and great space-faring machines were built that took 24 humans to the moon.

Will Boeing, Toyota and the others currently paying a steep price for their haste in pursuit of market dominance learn from their mistakes and restore their good name?