[ExI] AI fail

[Keith Henson]

An interesting AI logic fail

On Mon, Dec 2, 2024 at 6:54 PM Doug Space <dougspace007 at gmail.com> wrote:
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> Keith,
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> Here's ChatGPT's calcs:
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> To compare the energy in a SpaceX Starship launch to the energy released by the Hiroshima bomb, we can analyze the chemical energy in the rocket’s fuel versus the nuclear energy of the bomb.
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> 1. Energy in a SpaceX Starship Launch
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> Starship uses liquid methane (CH₄) and liquid oxygen (LOX) as propellants. A fully fueled Starship (Super Heavy booster + Starship upper stage) carries approximately 4,800 metric tons (4.8 million kg) of propellant.
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> • The energy release from methane combustion is approximately 55 MJ/kg.
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> • Total energy from the fuel:
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> 2. Energy in the Hiroshima Bomb
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> The Hiroshima bomb, Little Boy, released an estimated 63 TJ of energy (equivalent to 15 kilotons of TNT).
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> 3. Comparison
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> • Starship Launch Energy: ~264 TJ

ChatGPT obviously multiplied the whole 4800 tons of propellants x the
energy per kg for methane rather than just the methane
part.Interesting logic error and an example of why you need to check
the output of an AI.

I have used (because I saw it somewhere) a figure for LNG/LOX twice
that of TNT.  That's a reasonable number when you consider the
chemistry.  Digging around I found a NASA paper that mentioned the mix
being equal to C4.  C4 is 1.6 times as energetic as TNT.  That's ~7700
tons of TNT or about half the Hiroshima blast.

It isn't quite that bad though because a bulkhead failure and mixing
of both stages is unlikely.  The booster loads 700 tons of methane. Or
38.5 TJ.

Not as big as the Hiroshima bomb, but it is not something you want to
be close to if it detonated

> • Hiroshima Bomb Energy: ~63 TJ
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> A fully fueled Starship launch releases about 4.2 times more energy than the Hiroshima bomb. However, this energy is spread out over the duration of the rocket’s flight (several minutes), unlike the instantaneous release of energy in a nuclear explosion, which creates devastating shockwaves, heat, and radiation.
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> Key Takeaways
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> While Starship carries significantly more energy in its fuel than the Hiroshima bomb, the controlled combustion process and the purpose of the energy (to lift the rocket) make the comparison more about magnitude rather than effect. The bomb’s destructive energy is concentrated and instantaneous, while the rocket’s energy is spread over time for propulsion.
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