Apollo 13

written on November 12, 2026, read 2006

I love the film “Apollo 13”. It’s one of those films I like to watch when I’m in the mood for a film, but not for a new one. I think I could recite parts of it by heart. After all, the film is now 31 years old, as I recently realised with a start.

At some point during all those years, I also bought the book that Jim Lovell wrote together with Jeffrey Kluger about the events. It’s the book the film is based on. You can tell in many places, because passages from the book turn up almost word for word in the film.

My copy is titled “Apollo 13”, so it’s an edition that came out after the film. Originally, the book was called “Lost Moon”.

The book is really interesting to read because it offers considerably more detail in many places. For example, you might think the lunar module’s power consumption had to be cut so drastically because otherwise the batteries would have been “sucked dry” before re-entry. But on page 167, the book puts the situation in a different light: power consumption generates heat. That heat is removed from the spacecraft by evaporating water. But the lunar module didn’t have enough water to permanently remove the heat of a fully powered-up module – it was only enough for 17 amps. Otherwise, the module would have run out of cooling water for the electronics. In the end, they reduced the power draw to 12 amps, the figure that’s also mentioned in the film.

Elsewhere, the discrepancy is bigger. In the film, they say the power-up procedure must not draw more than 20 amps. On page 299, however, the book says the re-entry batteries are “20 amp-hours” short.

That’s quite a difference: the former would mean that the systems must not draw more than a certain current during power-up. The latter, that the batteries are missing a certain amount of charge – so they can’t deliver the required current for long enough to get the capsule safely back to Earth.

But I can well imagine why they changed it: an ammeter with a swinging needle is simply far more dramatic than a calculation in amp-hours.

On the other hand, in the book the limited battery capacity leads to a moment when they suddenly realise they’ve switched on one device too many – and the power it used is gone for good. That makes for a highly charged situation of its own.¹

That doesn’t make the film any worse for me. It simply doesn’t have 350 pages to tell the story, just under two and a half hours.

Besides, “Apollo 13” is also a bit of a film about Gene Kranz. In any case, I think that alongside the film, you should read both this book and Gene Kranz’s book “Failure Is Not an Option”, which also tells part of the story of this mission’s problems – from the flight director’s point of view.

The books and the film tell the story from different perspectives, and you certainly have to grant the film a certain amount of poetic licence. But I think that together they give a pretty good picture of what was achieved back then to bring the three astronauts back to Earth.