Reflections on Apollos 1 and 13

This weekend is a fateful one for space exploration.

Forty years ago today, the very first launch of the Apollo lunar mission ended before the spacecraft left the launch pad. A runaway fire took the lives of three astronauts as they prepared for a test of the Apollo-Saturn spacecraft.

Coincidentally, I screened the movie Apollo 13 for my physics students just last week, originally to focus on the zero-g scenes but later also to educate them. I was surprised to see so few students knew anything at all about the lunar missions of the 1960s and ’70s. So we watched the entire movie.No one died on Apollo 13, but they could have, had fate moved in a different direction. Although it is a tragic concept to appreciate, NASA learns from its mistakes.

Apollo 1 was not even planned as an actual launch on Jan. 27, 1967. The crew was supposed to practice a dry run of launch procedures to see if the Apollo Command Module could operate independently of ground connections. Pilots Gus Grissom, Roger Chaffee and Ed White were suited up, running through a well practiced check list.

Their suits — intended to protect them in an airless environment — were not fire proof. The atmosphere in the Command Module was pure oxygen, at normal sea level pressure. The hatch swung inward and was secured by 12 bolts. There was no escape rocket system atop the capsule. In retrospect, one wonders what NASA was thinking.

According to an official investigation, worn insulation on one of the thousands of meters of wire in the spacecraft allowed electricity to arc near a supply of ethylene glycol coolant. In pure oxygen, ethylene glycol (a kind of antifreeze) burns quite nicely. So does aluminum metal, as it turns out, and there was plenty of aluminum and other flammable materials in the Command Module. Within 17 seconds of reporting the fire to ground control, the astronauts were dead. The official cause of death was smoke inhalation — the heat destroyed their suits and air supply tubes.

In the months that followed the accident, NASA changed the atmosphere to a more Earth-like oxygen-nitrogen mix (requiring additional tanks of N2 gas) and lowered the cabin pressure. The suits and the cabin in general were made more fireproof. The hatch would now open outward, and included an emergency blowout device. The wiring was improved and faults corrected.

Those electrical improvements to the Apollo spacecraft probably helped save the lives of the Apollo 13 crew.

Unlike NASA’s other spaceflight accidents, which have all occurred at launch or on re-entry, Apollo 13 suffered a near-crippling explosion 320,000 km from Earth, as the spacecraft approached the Moon.

A routine procedure — stirring the tanks of liquified gas — resulted in an electrical fire near the oxygen tank. The heat caused the O2 pressure to increase, and the tank exploded, blowing off an access panel and rupturing electrical connections and O2 lines. The craft used O2 to power the electrical systems, so the crew soon found themselves with rapidly dwindling power and air in the Command Module.

The details of their survival are chronicled in the Ron Howard movie, and elsewhere, so I don’t need to review them here. One of their worries, though, was how the electrical systems would work once the Command Module was powered up for re-entry.

Under normal operations, the heat of the electrical equipment in the ship and the air circulation system would keep the humidity in Apollo under control. Apollo 13’s crew, however, had to shut off the heat and survive with minimal environmental systems running to conserve power. Jim Lovell, Fred Haise and Jack Swigert lived for four days in a cold, damp environment. Moisture from their bodies condensed on the cold equipment panels, so much that Swigert, for one, worried whether closing the breakers would cause the electrical systems on the Command Module to short out and fail, leading to the crew’s death.

Had NASA not improved the wiring and electrical connections following the Apollo 1 fire, those electrical failures may well have happened. After surviving the initial explosion, Lovell, Haise and Swigert would have died in space, by cold, suffocation, or fiery re-entry.

The loss of three lives on Jan 27, 1967, prevented the deaths of three more a little more than three years later.

Rest in Peace, Gus Grissom, Ed White and Roger Chaffee.

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