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Background

The Apollo 1 mission was scheduled to have been launched on February 21, 1967, with astronauts Virgil Grissom, Edward White, and Roger Chaffee onboard. This would have been the first manned Apollo mission; one in a series of missions designed to get an American to the moon by the end of the 70's.

However, on January 27, 1967, during a preflight test on the launch pad, tragedy struck. A fire swept through the Command Module (CM) which killed all three astronauts. What follows is an account of the events that occured before, during and after the fire.

Earlier that day

  • The astronauts entered the Apollo 204 spacecraft, which was attached to the Saturn rocket on launchpad 34 at 1:00 p.m.
  • Grissom's spacesuit oxygen loop had a "sour smell". The crew stopped to take a sample of the suit loop, and after discussion with Grissom decided to continue the test.
  • A high oxygen flow indication periodically triggered the master alarm. The matter was discussed with environmental control system personnel, who believed the high flow resulted from movement of the crew. The matter was not really resolved.
  • Faulty communications existed between Grissom and the control room for most of the test, even though the crew made adjustments. Later, the difficulty extended to include communications between the operations and checkout building and the blockhouse at complex 34. This failure in communications forced a hold of the countdown at 5:40 p.m.
  • At 6:31 the count was about to restart when ground instruments showed an unexplained rise in the oxygen flow into the spacesuits. One of the crew, presumably Grissom, had moved slightly.


 

The fire
Fire Cockpit
Fire in Cockpit


 

  • Four seconds later, an astronaut, probably Chaffee, announced almost casually over the intercom: "Fire, I smell fire." Two seconds later, Astronaut White's voice was more insistent: "Fire in the cockpit." The fire was visible in mission control via the video feed.
  • White began preperations to unlatch the hatch, the escape route fromt the module. This involved moving the headrest out of the way, operating the rachet-like equipment to open the latch, and removing the latch.
  • The command module ruptured. Flame and thick black clouds of smoke billowed out, filling the launch escape system atop of the spacecraft.
  • Some of the men on the launch pad evacuated while others tried to rescue the astronauts. They had dificulties getting close to the module because of the intense heat and dense smoke.
  • When the hatch was finally opened, it was determined that all three astronauts were dead. The primary cause of death was carbon monoxide posining, with thermal burns having contributing effects. Firemen arrived within three minutes of the hatch opening, doctors soon thereafter.

Afterwards

  • After removal of the bodies, NASA impounded everything at launch complex 34.
  • On 3 February, NASA Administrator Webb set up a review board to investigate the matter thoroughly.
  • Engineers at the Manned Spacecraft Center duplicated conditions of the Apollo 204 without the crewmen in the capsule.
  • The reconstructed events and the investigation on pad 34 showed that the fire started in or near one of the wire bundles to the left and just in front of Grissom's seat on the left side of the cabin — a spot visible to Chaffee. The fire was probably invisible for about five or six seconds until Chaffee sounded the alarm.
  • The exhaustive investigation of the fire and extensive reworking of the CMs postponed any manned launch until NASA officials cleared the CM for manned flight.
  • The next manned mission was launched on October 11th 1968. It included the following major improvements: onboard TV camera, S-band radio communications, a fire extinguisher, emergency oxygen masks, less combustible materials in the command module, better wiring, and a new system for minimizing volatility of the atmospheric conditions. It was successful.

Contributing Factors

As with most engineering disasters, the determination of the exact cause of the disaster was not easy. The Apollo 1 mission to this day still remains a mystery. The specific initiator of the fire has not yet been determined, and probably never will be. However, after investigation, a number of factors that signifacntly contributed to the disaster were determined. The fire began because of an electical short, it spread quickly because of the volatile atmospheric conditions and the presence of combustible materials inside the module. The hatch design and NASA's management of the Apollo program may have also been contributing factors.

  1. Electrical Components
    In the Apollo 204 spacecraft, many problems occurred with the electrical wiring. Teflon, has an excellent fire resistance and was therefore chosen as the covering for the wiring in the spacecraft. The specific type used for the craft was easily damaged or penetrated by abrasion. If this wiring experiences penetration by a metal structure (namely spacecraft components) a short is created at the point of conductor contact. Tests performed in highly pressurized atmosphere indicate that sparks blown from an arc can ignite combustible materials that are a short distance away from that arc. Taking this into consideration, it is quite feasible that the many arcs located by investigators on the spacecraft could have been the initiator of the fire.

    Electric power distribution malfunctions in the Apollo 204 module were also related to the Environment Coolant System leakage. RS-89 was the coolant the leaked, which is a mixture of 62.5 percent ethylene glycol, 35.7 percent H20, and 1.8 percent stabilizer and corrosion inhibitor. This mixture is not highly combustable, however leakage and spillage of this fliud does present a threat. The water in this fluid evaporates much faster than the ethylene glycol. This results in a salt formation that does not evaporate and which is highly combustable. Furthermore, the residue from RS-89 is electrically conductive, therefore contact with uninsulated wire would result in current exposure to the internal atmosphere. It was proved in laboratory tests that this coolant provides an mechanism to ignite a fire.

  2. Spacecraft Atmosphere
    The high pressure and concentration levels of oxygen gas largely contributed to the dispersion of the fire. During the initail stages of the fire oxygen levels were reported to be at saturated levels which may have prompted the spread of the fire. The initial flow rate increase was probably due to crew movement which normally results in increased leakage to the cabin.

  3. Combustible Materials
    The fire moved rapidly from the point of ignition, traveling along the Raschel net debris traps which were installed in the Command Module (CM) to prevent items from dropping into equipment areas during tests. These nets were made mainly of nylon, and were thus highly combustible. Since these nets ran along large sections of the CM they generated firebrands which scattered, igniting more materials. NASA was aware of this undesirable property, but not anticipating a fire in the test runs, allowed them to be used on the ground but not during space flight.

  4. Hatch Design
    The main exit from the Command Module was through inner and outer hatches. The hatch design for the Apollo 1 spacecraft was not a cause of the disaster, but it had a large impact on the outcome. With this particular design three hatches were installed. The outermost hatch (the Boost Protective Cover (BPC)) covers the Command module during launch. The inner hatch or ablative hatch becomes the outer hatch when the BPC is jettisoned after launch. The inner hatch closes off the Command Module and is the first to be opened by the crew in the case of the emergency.

    In the case of the AS 204 testing, the outer BPC was not fully latched because of wiring that was temporarily in place for the tests. The problems maily arose with the inner hatch. As indicated by reports, one of the astronauts attempted to open the inner hatch but was unsucessful. The inner Command Module became highly pressurized as the fire heated up the module, causing the gases to expand. To release the inner hatch it was necessary to open it into the cabin, a task that would have been impossible in the higher cabin pressures. The release valve to allow pressure to be normalized, was not large enough to have any effect in the event of a fire. The crew had also been having problems evacuating in the 90 second benchmark time due to the complicated, multi-step nature of the hatch design.

  5. NASA's Mis-management
    It was determined by the review board that the organizations responsible for the planning, conduct and safety of the test had failed to identify the situation as hazardous. It was also determined that deficiencies in design, manufacture, installation, rework and quality control existed in the electrical, Environmental Control, and the communication systems. These problems werewstrongly influenced by governmental pressure to minimize cost and time and a lack of communication between NASA and it's contractors.

Recommendations

Space exploration is a considered a highly dangerous job field and because of this safety is considered very important. The Apollo 1 disaster was the first major disaster that NASA encountered. It was reviewed in detail by a board of authorities who investigated the problems that caused it. From the investigation the review board came up with recommendations that would prevent future disasters. The following are some of the main recommendations that were put forth by the review board.

  1. Oxygen or any other material that is combustible should be restricted and controlled
    - That the location and amount of combustible materials should be strictly controlled, both on missions and simulations.
    - That combustible materials used should be replaced wherever possible with non-flammable materials.
    - That atmospheric conditions of %100 oxygen are not permissible on tests.
    -
    Full-scale flammable mockups should be used to test spacecraft in future.
  2. Spacecraft should be designed with saftey as a primary consideration
    -
    Electrical wiring and insulation should be appropriate for the application.
    - In future the time to escape be decreased through other escape routes and a hatch that can easily open under extreme pressure difference.
    -
    When the fire broke out in the module, bits and pieces of the conversation between the module and command were heard. At times it left command guessing as to what the astronaut was saying. The review board recommended that a better communication system be set up.
  3. Emergency personnel should be availible
    -
    It was recommended that all personnel should have proper training and should practice for emergency procedures.
    - The emergency equipment be reviewed for adequacy in dealing with this incident, and that the launch facilities should be modified to facilitate emergency egress situations.
    - Inspectors should continually monitor the safety of all test operations and assure that emergency procedures are in place to handle these types of situations.