Remembering the Apollo I disaster, 50 years later

Fifty years ago today, three American astronauts died in a sudden, uncontrollable cabin fire aboard the Apollo I space capsule. The deaths of Virgil “Gus” Grissom, Ed White, and Roger Chaffee could have spelled doom for the entire Apollo space program, particularly after a report surfaced showing NASA had been aware of problems and deficiencies in the work performed by North American Aviation, the contractor in-charge of building the Apollo 1 capsule. The loss of Apollo I’s crew ultimately didn’t lead to the cancellation of the space program, but it did drive significant changes to NASA’s testing methodologies and best practices, some of which endure to this day.

AS-204 was supposed to be the first manned flight test of the Apollo Command/Service Module (CSM). The goal was to keep the module in-orbit for as long as 14 days for a full evaluation of the spacecraft’s various capabilities. The Apollo I CSM was vastly more complex than any other spacecraft the US had previously built, and NASA’s chosen contractor made several decisions that directly led to the fire and loss of Apollo I’s crew. As Ars Technica notes, North American had used machines to bundle wires into the spacecraft, with a number of frayed wires and potential short-circuits. Spacecraft 012 (as it was then known) had shipped to Florida with more than 100 “significant” engineering issues. The astronauts themselves may have been wary of complaining too loudly about problems with the capsule, lest they be pulled off the flight. NASA has been described as being gripped with “Go Fever,” during this time — think “launch, baby, launch as opposed to “drill, baby, drill.”

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The Apollo I crew presented this photo to Joe Shea, Apollo Spacecraft Program Office Manager, on August 19, 1966. The caption reads “It isn’t that we don’t trust you, Joe, but this time we’ve decided to go over your head.”

NASA had been moving at a rapid clip. The first manned Mercury flight was in 1961, and while President Kennedy commissioned Apollo as a follow-up to Mercury, a new intermediate program was needed (Gemini). By 1967, NASA had built three distinct new spacecraft — Mercury, Gemini, and Apollo, with the Apollo I capsule under construction before the first manned Gemini flight.

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A size comparison of the three NASA spacecraft and their launch vehicles.

As Ars notes, in the fifty years since Apollo I, NASA has fielded just one new crewed spacecraft — the Space Shuttle. (To be fair, this says more about shifting Presidential priorities and a general lack of emphasis on the space program, post-Apollo, than it does about NASA.)

The Apollo I disaster

The launch simulation on January 27, 1967, was a “plugs-out” test designed to measure how the spacecraft would operate on simulated internal power, with no support from cables or umbilicals. Neither the spacecraft nor the rocket was fueled and all pyrotechnic systems were disabled.

In order to cut costs and trim mission weight, NASA had decided to utilize a pure-oxygen environment inside the Apollo I capsule. This wasn’t seen as a problem, since Gemini and Mercury had both used a similar system, and it saved weight compared with a more complex nitrogen-oxygen system. Grissom, Chafee, and White entered the spacecraft at 1 PM, expecting the test to take just a few hours. The internal cabin was pressurized to 16.7 psi, higher than the external pressure of 14.7 PSI. The Apollo I door hatch consisted of a removable inner hatch, a hinged outer hatch, and an outer hatch cover. Critically, the hatch could not be opened while the cabin was at a higher pressure than the outside environment, and it took 90 seconds to open in the best of circumstances.

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The original AS-204 hatch design couldn’t be opened when the cabin was pressurized.

At 6:31:04.7, Grissom (we think) exclaimed “Hey!” or “Fire!” A few seconds later, a partially indistinct voice shouts something along the lines of “We’ve got a bad fire, open her up,” followed by a cry of pain. There would be no further communication with the three astronauts. The fire drove the internal cabin pressure as high as 29 psi, well above its maximum rating. The module ruptured at 6:31:19, sending a curtain of flame across the module, from left to right. Thick black smoke and toxic fumes poured across the pad service structure. NASA didn’t have the proper equipment on-hand to deal with a problem of this magnitude, and the explosive rupture and thick smoke convinced some NASA techs convinced the entire command module was about to explode. It took rescue crews five minutes, 30 seconds to open the Apollo I module. Initial conditions inside the crew module were so thick with smoke, despite the lights still being on, that the NASA rescuers were unable to find the bodies of the crew.

Later analysis showed the senior pilot, Ed White, had likely attempted to open the hatch but had been unable to do so. The fire burned incredibly hot — an image of the space suits recovered from the incident can be seen here. Fair warning — it isn’t pretty.

Apollo_1's_Command_Module_-_GPN-2003-00057

The command module, post-fire.

The fire is believed to have begun in the lower forward portion of the left equipment bay, and may have been initially slowed by a lack of combustible material and the aluminum skin of the spacecraft itself, which would have acted as a heat sink. Debris traps across the top of cabin, made from woven nylon, proved exquisitely flammable, and as the nylon burned through, it scattered throughout the cabin, spreading further. The NASA report states that by 6:31:12 “A wall of flames extended along the left wall of the module, preventing the command pilot, occupying the left couch, from reaching the valve that would vent the command module to the outside atmosphere.”

The stages of this particular fire were incredibly fast. Stage I lasted 15 seconds after Grissom’s cry. Stage II began at 6:31:19 and ended six seconds later, with the module engulfed in flame. With the cabin’s internal oxygen depleted, heavy smoke formed and huge amounts of soot were deposited on all control surfaces and the remains of the astronauts themselves. By 6:31:30, the atmosphere inside the capsule is believed to have been lethal. Total time elapsed: 26 seconds.

Aftermath

The Apollo program’s manned mission development was put on a 20-month hiatus while the incident was investigated. Significant changes to the Apollo program were made as a result — changes that dramatically improved the safety and reliability of the Apollo CSM, and that many have credited with helping NASA reach the moon at all. Rules were changed to allow engineers and astronauts to take suggestions back to North American Aviation, and North American was required to allow detailed inspections. The new, Block II CSM was substantially redesigned and a new quick-release hatch mechanism was implemented.

Three days after the accident, Flight Director Gene Kranz gave a speech to Mission Control which has since become legend.

Spaceflight will never tolerate carelessness, incapacity, and neglect. Somewhere, somehow, we screwed up. It could have been in design, build, or test. Whatever it was, we should have caught it. We were too gung ho about the schedule and we locked out all of the problems we saw each day in our work. Every element of the program was in trouble and so were we. The simulators were not working, Mission Control was behind in virtually every area, and the flight and test procedures changed daily. Nothing we did had any shelf life. Not one of us stood up and said, “Dammit, stop!” I don’t know what Thompson’s committee will find as the cause, but I know what I find. We are the cause! We were not ready! We did not do our job. We were rolling the dice, hoping that things would come together by launch day, when in our hearts we knew it would take a miracle. We were pushing the schedule and betting that the Cape would slip before we did.

From this day forward, Flight Control will be known by two words: “Tough” and “Competent.” Tough means we are forever accountable for what we do or what we fail to do. We will never again compromise our responsibilities. Every time we walk into Mission Control we will know what we stand for. Competent means we will never take anything for granted. We will never be found short in our knowledge and in our skills. Mission Control will be perfect. When you leave this meeting today you will go to your office and the first thing you will do there is to write “Tough and Competent” on your blackboards. It will never be erased. Each day when you enter the room these words will remind you of the price paid by Grissom, White, and Chaffee. These words are the price of admission to the ranks of Mission Control.

Today, NASA unveiled a new exhibit dedicated to the crew of the Apollo I. Titled Ad Astra Per Aspera — A rough road leads to the stars — it includes the three hatches of Apollo I, now on display for the first time ever.

Feature image by Collectspace

Source : https://www.extremetech.com/extreme/243548-remembering-apollo-disaster-50-years-later

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