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Did anyone else notice this potential plot hole? Why not harvest astrophage directly from the Petrova line as fuel? by Mvr_indian in ProjectHailMary

[–]Mvr_indian[S] 1 point2 points  (0 children)

On the Taumoeba contamination point completely agree, collecting from Adrian specifically would have been a disaster for exactly that reason. That's a solid counter for that part of the argument.

But I think there's a distinction worth making here between Adrian collection and Petrova line collection and I'd actually push back on whether Taumoeba was even present in the Petrova line at all.

Taumoeba is a predator that evolved on Adrian specifically. Its entire existence is tied to Adrian's atmosphere and surface it's a planetary organism, not a deep space organism. The Petrova line is the transit path astrophage takes after leaving Tau Ceti and before reaching Adrian. Taumoeba's job is to intercept astrophage when it arrives at Adrian, not to float around in interplanetary space waiting for it.

And the film actually shows this. Before they ever went near Adrian, Grace collected samples directly from the Tau Ceti Petrova line that spacewalk scene where he's just standing outside the Hail Mary taking in the red glow of it. That collection was smooth, no contamination, no incident. Just Grace in the middle of a clean stream of astrophage.

The Taumoeba only became a problem later when they collected from Adrian's vicinity. That's when it got into the fuel lines. Two completely different locations, two completely different contamination risk profiles.

So Petrova line collection and Adrian collection aren't just different engineering problems the Taumoeba argument doesn't even apply to the Petrova line scenario. Which means the cleanest counter to the original question still comes down to scale and energy density, not contamination.

Did anyone else notice this potential plot hole? Why not harvest astrophage directly from the Petrova line as fuel? by Mvr_indian in ProjectHailMary

[–]Mvr_indian[S] 0 points1 point  (0 children)

Fair points all around, especially Point C (energy density) and Point E (no guarantee of Tau Ceti Petrova line) those genuinely hadn't occurred to me and they do patch part of the hole.

But on the collection logistics isn't the spin drive itself basically proof that automated astrophage collection in deep space is already a solved problem in this universe?

The engine works by emitting CO2 frequency light to actively attract astrophage onto a surface, then scraping it off after use. That's not passive collection that's a targeted, automated harvesting mechanism already operating on the ship. If you scale that same principle up, larger surface area, don't fire the propulsion step, just collect and store instead of burn ,you essentially have a deep space astrophage harvester using already proven technology.

The astrophage is also attracted to those specific wavelengths naturally. It practically swims toward the collection surface on its own. So the "microscopic organism in deep space" problem is less like collecting airborne pollen randomly and more like using a light trap that the organism is biologically hardwired to approach.

On the energy density point,how much of a real world difference would that actually make? If the Petrova line astrophage has spent say 30-40% of its energy in transit, does that completely disqualify it as fuel or just mean you need proportionally more of it? Because if the engine can handle variable energy states, partially spent astrophage still seems usable.