For the record, nor does Jerry Woodfill, the warning system engineer who was first alerted of the explosion.

For the record, hundreds of other experts who were also there and who are more qualified than Woodfill on the particular systems involved, disagree with him. There are plausible reasons for why Apollo 13 happened the way it is said to have happened.

Woodfill's web page is

http://www.ghg.net/woodfill/TRACT13.html

I urge you to read it carefully, because it's not necessarily what you think.

Woodfill's first point: The oxygen tank could have exploded at any time. Well, yes and no. Some of the conditions which caused the fire were present at launch -- even prior to launch. Other contributing factors such as the degree of tank depletion and stratification of contents took time to develop.

His point is that had the explosion occurred earlier, it would have been fatal because they didn't have enough consumables to get back. Had it occurred later, it would have been fatal because the LM would have been used for its intended purpose. Thus the time of the accident is somehow "convenient".

Codswollop.

The tank had to deplete to the point where it would stratify, then the bare wires could have arced. Prior stirs occurred before the tanks had fully stratified. That explains why it didn't occur earlier.

Once that condition had developed, we would expect the next instance of the initiating event -- the arc -- to cause the accident as soon as the conditions were right, not several stirs down the road. Tank stirs don't occur all that often. That explains why it didn't occur later.

But now Woodfill makes this great leap of faith and says that because this (and subsequent items) are so improbable and suspicious, Apollo 13 was meant to have a different outcome. It should have had a different outcome. Therefore the sequence of events in the mission was not due to chance, but according to some plan.

More on this down the page.

Woodfill's second point: The hatch would not close. His analysis is based on the unsupported assertion that the hatch was "perfectly designed". Nothing on a spacecraft is ever "perfectly" designed. We could argue that lots of things on a spacecraft ought to be "perfectly" designed, yet every mission has a discrepancy list. Apollo 14's docking mechanism was supposed to be "perfectly designed" too, yet it failed. Apollo 16's engine gimbal was a Criticality 1R component, yet it failed too. The notion that critical components should never fail (especially under exceptional conditions) is absurd.

Postulate a somewhat alarmed astronaut fumbling with a hatch in zero gravity, when the hole in which that hatch goes is fluctuating under mechanical stress pursuant to O2 venting and RCU corrections in degraded performance.

Says Swigert, "While Jim and I were trying to do this [i.e., dog the hatch], I misaligned it in the tunnel and we didn't get it in the first time." (Apollo 13 Technical Crew Debriefing, item 8.0)

In fact the problem was not that the hatch did not close, as Woodfill argues, but that the hatch was not being operated correctly, and understandably so. When it was dogged later in the flight, under less urgent circumstances, it worked perfectly.

Analogously, if you were being chased by a vicious dog and you fumbled with the key to your front door and couldn't properly align it because you were panicked, would you say that the key or the lock malfunctioned? Would you say this was a "suspicious" failure?

Point three: The power system simulation failed when the proposed LM-to-CM jump was simulated. But the jump actually succeeded.

Simple answer. The simulation is unfaithful. Lots of simulations fail when presented with extraordinary circumstances. Simulations can only represent what they are designed ahead of time to represent.

Point four: An unexplained drift in the CLSM stack which mysteriously went away.

An injured spacecraft vents. A spacecraft that vents, drifts.

Since spacecraft don't normally vent uncontrollably, they don't normally drift. Hence none of Apollo 13's guidance behavior can be considered normal. Therefore the cessation of venting and drifting can't be regarded as "mysterious".

If you're reading the web page, and the rest of Woodfill's site, you're probably getting the picture. The "unseen author" Woodfill credits with changing the "natural" flow of events for Apollo 13 is God. Woodfill found religion as a result of his involvement with Apollo 13, not an odd thing to have happen.

So my response sounds like I'm pitting science against religion and stomping all over this man's faith. Not in the least. If Woodfill wants to hypothesize that a little girl's prayer stopped Apollo 13 drifting, I certainly can't provide any counterevidence which disputes that.

No, we have to consider the evidence in the way I believe Squirm intended it. While he may or may not agree with Woodfill's conclusion regarding divine intervention, he likely agrees with the premises of Woodfill's argument, and instead applies them to the conclusion that Apollo 13 did not unfold as it "should" have and therefore may have been falsified.

Unfortunately, examining Woodfill's points from a purely scientific and engineering point of view, they don't necessarily present an implausible scenario. There are quite credible reasons for why these supposedly "improbable" things happened.

Improbability is a difficult thing to deal with in failure analysis. Part of my design engineering training is in failure analysis. I'm not one of the world's experts on it, but I do happen to know one of the world's experts on it: Charles Perrow.

The essence of system failure is precisely the combination of improbable events. You can say that an improbable chain of events led to the safe return of the astronauts. And I can turn right around and say that an improbable chain of events led to the accident in the first place. You can say that had one little thing been different, the astronauts would have been doomed. And you'd essentially be right. But I can turn around and say that if one little thing had been different, they wouldn't have been in danger in the first place.

So if you want to try to explain the improbable, you have to deal with all the improbables, not just the ones that fit your pet theory. Woodfill's hypothesis fails scientifically (even given the existence of God as an axiom) because while it suggests that God effected an "improbable" rescue, it fails to account for an equally or more improbable failure.

Okay, back to Perrow and Squirm.

We have contested the notion that the elements of the mission recovery were improbable.

The creation of a single downmoded spacecraft from the functional elements of two spacecraft actually resulted in a somewhat less complex system. Simpler systems have less chaotic function and are more deterministic and predictable. Perrow notes that the downmoding of the mission was supported by four complete expert teams working around the clock with intimate knowledge of the systems involved.

The downmoded spacecraft was optimized for one thing: crew survival. All the other objectives were rescinded. Therefore the improvisation of a new mission with a new spacecraft system concentrated only on a few critical systems.

The resulting engineering construct was loosely coupled and linear, two very desirable characteristics for a complex system. Although the complexity was increased by operational unknowns and the lack of redundancy, it was decreased overall by the omission of noncritical subsystems.

Although it seems counterintuitive, Apollo 13 after the accident was a lean, mean, survival machine.

Perrow goes on to note that redundancies reappeared as the downmoded mission progressed, decreasing overall system complexity.

Okay, so what does all this engineering-speke mean? A system which is loosely-coupled, linear, and simple is better understood and more tolerant of (subsequent) failure. That means mission controllers and astronauts can more easily grasp the meaning of new failures and have more slack in which to devise solutions.

The versatility of the Apollo spacecraft is legendary. The "spares in place" paradigm meant there were many ways to configure the spacecraft to accomplish any given task. The contingency planning is also legendary. We don't do much contingency planning anymore, but Apollo contingency plans were elaborate and exhaustive. Although the LM Lifeboat scenario was a bit dusty, the fact that it had been studied, simulated, and had procedures written for it is fortunate.

(cf. Perrow, Normal Accidents, pp. 271-281.)