There was an air of tension, anxiety, weariness.

Coming so soon after the Apollo-N tragedy, nobody in the Agency wanted to face up to another disaster, the first loss of a Saturn. Udet had heard the muttering. Who the hell can we blame for this one?

Dana was speaking, in his thin, frail voice. Udet drew a little more upright in his chair.

“At 6.6 seconds before launch, the Saturn’s kerosene-fueled F-1A main engines were ignited in sequence and run up to full thrust, while the entire structure was still bolted to the launchpad. The thrust of the main engines pushed the Saturn assembly upward, against the restraint exerted by the pin-down bolts anchoring it to the pad. When the Solid Rocket Boosters’ restraining bolts were explosively released the stack’s ‘stretch’ was suddenly relieved…”

On the screen behind Dana, clouds of smoke and steam billowed up around the base of the Saturn stack. Then the four Solid Rocket Boosters ignited, and yellow-white fire plumed from their engine bells. The camera shuddered, as testimony to the acoustic energy spewed out by the stack — but the film was without sound, and the brilliant launch sequence worked through in eerie silence.

The image froze. Billows of smoke stopped their evolutions, and became mounds of gray and white, solid-looking, like dirty ice cream.

Around Udet, rows of lined faces were illuminated by frozen rocket light.

An arrow pointed to a blurred patch of white near the base of the MS-IC; it was just below the “A” of the red-stenciled “USA” on the wide hull of the booster.

Dana said, “At 0.687 seconds into the flight, photographic data shows a strong puff of vapor spurting from the lower casing of the MS-IC, just above the engine fairing.” Dana glanced over his shoulder, wrinkling his nose. “As you can see here. The two pad cameras that would have recorded the precise location of the puff were inoperative. Computer graphic analysis of film from other cameras indicated the initial vapor came from that level of the MS-IC where the feed from the oxidizer tank exits the propellant tank.”

The MS-IC contained two huge cryogenic tanks. The oxygen tank was uppermost, and the fuel lower. Fat suction lines carried liquid oxygen through the kerosene tank for combustion in the five huge F-1A engines at the base of the stack. Dana was implying that there had been some kind of problem with that feed.

The film started again, in extreme slow motion; the smoke evolved around the Saturn with glacial slowness. White arrows continued to prod at the offending vapor patches at the base of the MS-IC.

“Six more distinctive puffs of vapor were recorded between 0.836 and 2.501 seconds. The multiple puffs in this sequence occurred at about four times per second, approximating the frequency of the structural load dynamics and resultant stack flexing…”

The wretched “stretch”!