“The first visible indication of main engine thrust reduction was detected on image-enhanced film at 58.788 seconds into the flight. It is visible in this frame, as a dimming of the plume from the right-hand F-1A bell — just here.

“One film frame later from the same camera, the reduction is visible without image enhancement.” The engine bell had grown dark, and its four brothers were also clearly ailing. “At about the same time telemetry showed a differential between the pressures in the main engine chambers. The right-most booster chamber pressure was lowest, confirming the growing reduction in the flow of propellant.

“At 62 seconds into the flight, the control system was responding to counter the forces caused by the differential thrusts from the main engines…”

The film ran on, slowly; the main engines flickered or died, but the Solid Rocket Boosters still blazed with fire. The stresses on the stack were enormous as the SRBs tried to compensate for the loss of the main engines.

No change in the attitude of the complete stack was visible to the naked eye. Udet knew, however, that at this point his doomed Saturn was already fighting for its life.

Dana cleared his throat, and pushed his glasses against his face; his gestures were small, precise, almost apologetic. “Analysis has shown that the primary cause of the malfunction evident at this point in the flight was the feeder valves set in the underside of the MS-IC’s oxygen tank, which carry oxidizer into the feeders to the main engines. Tests have indicated that under certain circumstances, the valve design could go into a ‘flutter’ regime and effectively shut off the supply of oxidizer, resulting in a total failure of all F-1A engines. As was observed here. The frequency of the possible flutter has been shown to be close to the frequency of the launch ‘stretch’ and to oscillations caused by instabilities in the burning of the Solid Rocket Boosters…”

Udet massaged the bridge of his nose, trying to control the irritation that flared within him. We know this. My team at Marshall, and the contractors independently, determined this root cause of the fault within an hour of the malfunction. The Saturn had already been vibrating, from the “stretch,” at three or four cycles a second just after launch. Then one of the Solid Rocket Boosters had started vibrating lengthwise, at about the same frequency. Such oscillations had been observed before. But the coincidence of frequency was unfortunate, for that frequency, as it turned out, had been just right to set up standing waves in the valve system carrying liquid oxygen into the main engines…

We know all this, and we are already working to correct the problem. Have you no more wisdom to add than this, Dr. Dana?

But Dana was continuing; he was describing how some preliminary tests, carried out during the MS-IC’s design stage, had indicated the possibility of a resonant flutter — although no change in the stage’s design had resulted — and he even referred to the problems encountered with the Apollo-N flight, when similar resonance problems had caused that stack to pogo.

That link with the fatal Apollo-N mishap showed Udet clearly which way the report was shaping.

It was ludicrous, of course; anyone who understood anything of the complexity of a ship like a Saturn — with its millions of moving parts — would recognize the impossibility of adjusting the design to counter every possible problem that could be conjured up. There was never the time, or the resources; the realistic way was to balance the risks, and exercise judgment as to what is acceptable, and what must be changed. Why, if one waited for the perfect rocket, one would never fly at all!

Udet felt enormously tired. He was sixty-eight years old. And sometimes — especially since the death of von Braun — he wondered whether the battle was still worth the effort, whether he still had the strength for the endless struggle to convince the Americans to accept the great rockets he was building for them.

Udet had donned something of the mantle of von Braun, since Wernher’s retirement a decade earlier. He had even inherited Wernher’s office, there on the tenth floor of Marshall’s headquarters building. But Udet had no pretensions; he knew that he was no substitute for Wernher. The Americans had adored von Braun: they responded to him, Udet thought ungraciously, as they did to evangelists, and the salesmen of cars. And, it seemed, questions about the Germans’ past — possible complicity in “war crimes” during the Peenemьnde period — were irrelevant for Wernher.

Well, Wernher was dead. And it was different for Udet. He knew that, try as he might, he could not help but project an aloofness, an aura of the disdainful Prussian aristocrat. The Americans did not trust Udet; and they appeared to find it much easier to believe ill of him than ever they had of von Braun.

And meanwhile, he had been forced to watch as Gregory Dana had risen in status and power within the organization. His fatherhood of the lost hero James, and the fact that his once-vilified mission mode had been chosen as the basis for the new Mars program, had raised Dana’s status almost to national celebrity.

And Dana continued to pronounce his damning testimony on Udet’s life-work, his tone dry, level, like a soulless prosecutor.

Udet’s dark, dwarfish twin.

“Beginning at about 78 seconds, a series of events occurred extremely rapidly that terminated the flight. Telemetered data indicate a wide variety of flight system actions that support the visual evidence of the photos, as the Saturn struggled against the forces that were destroying it.

“At 78.9 seconds the lower strut linking Solid Rocket Booster Number Four and the MS-IC was severed or pulled away. This failure was evidently caused by the abnormal stresses placed on the structure by the failure of the main engines. SRB Four rotated around its upper attachment strut. This rotation is indicated by divergent yaw and pitch rates between the Solid Rocket Boosters.

“At 79.14 seconds a circumferential white vapor pattern was observed blooming from the side of the MS-IC. This was the beginning of the structural failure of the MS-IC’s propellant tank, which culminated in the separation of the aft dome of the tank. This released massive amounts of RP-1 from the tank and created a sudden forward thrust of about 2.8 million pounds, pushing the propellant tank upward through the motor casing toward the S-II. At about the same time the rotating SRB Four impacted the lower part of the MS-IC’s liquid oxygen tank. This structure failed at 78.137 seconds, as evidenced by the white vapors appearing in this area…”

The images on the screen continued to unroll, frame by frame, their pace matching Dana’s dry, analytical delivery. The pictures were blurred and shrouded by the haze of distance, and a fog of escaping vapor, but it was just possible to see how the Solid Rocket Booster was swiveling around, and its conical tip was puncturing the flank of the central first stage.

Then brilliance erupted, within the space of one frame, engulfing the image.

“Within milliseconds there was a massive, almost explosive, burning of the propellant streaming from the bottom of the failed tank. At this point in its trajectory, while traveling at Mach 1.92 at an altitude of 46,000 feet, the Saturn was totally enveloped in the explosive burn. The Apollo spacecraft’s reaction control system also ruptured, and a hypergolic burn of its propellants occurred; the reddish brown colors of this burn are visible on the edge of the main fireball. As you see here. The second stage also ruptured at this point, adding one million pounds of propellant and oxidizer to the fireball. The stack, under severe dynamic loads, had by now disintegrated into several large sections, which emerged from the fireball; separate sections which can be identified from film include the instrumentation module, trailing a mass of umbilical lines, and the first stage’s main engine section with the engines still trailing vapor…”