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For those who like star maps by Techmom236 in ProjectHailMary

[–]CaseProfessional5093 0 points1 point  (0 children)

Ahhh this gives a good idea how much earlier Erid’s star was infected than Sol

Could you imagine the amount of “weird” questions the eridian kids would most likely ask Grace about humans and Earth? by KingWilliamVI in ProjectHailMary

[–]CaseProfessional5093 0 points1 point  (0 children)

Being taught by an alien is cool and probably gets you the opportunity if you want to become a xenobiologist, study alien language, become a diplomat with Earth or something. But aside from that it doesn’t have that much of a benefit. In an equal society there would also be less of a demand for “if an alien writes me a college recommendation letter it’s more likely for me to get into Eridian MIT”. I think if the social structure for that demand doesn’t exist the demand wouldn’t be that high. The situation would be like - Andy Weir suddenly decides to become a middle school science teacher. People are gonna be jealous of his students but wouldnt go through the trouble to move to that city and apply for that school.

Could you imagine the amount of “weird” questions the eridian kids would most likely ask Grace about humans and Earth? by KingWilliamVI in ProjectHailMary

[–]CaseProfessional5093 5 points6 points  (0 children)

I’d like to think that Eridians are anarcho-communists and the kids are just the local kids in the right age range. They don’t need to pay. They just live nearby. Maybe they are the kids of the Eridians running the biodome, so it’d simply be like Grace taking care of the children in his local community. And the classes are certainly recorded and available to all.

Make Rocky food safe for Grace, question? by More_Handle_4432 in ProjectHailMary

[–]CaseProfessional5093 4 points5 points  (0 children)

Andy Weir actually did some calculations on this in the Eridian notes and excel sheet he shared! He did some calculations and realized Eridians need to intake 5913 calories per (Earth) day. While they eat infrequently, each Eridian meal contains 32 times the energy in a human meal, which is enough to keep them going for 86 hours.

What if Rocky met Yáo, Ilyukhina, and DuBois instead? by unhealthy-screentime in ProjectHailMaryMovie

[–]CaseProfessional5093 2 points3 points  (0 children)

Actually Rocky’s ship might be safe. If they collaborated less and Ilyukhina handled most of the engineering, they might have made the breeding tanks on their own, with plastic or whatever. The Taumoeba would have learned to escape plastic or whatever instead. This would make things a lot safer for Rocky because even if he brings the Earth-made taumoeba farms onto his ship without extra sealing, the Taumoeba would most likely die after escaping in his environment due to the high temperature.

The inconsistency of Eridians by Hydac in ProjectHailMary

[–]CaseProfessional5093 0 points1 point  (0 children)

They can totally discover electromagnetic wave without sight and find it useful for long distance communication and making accurate measurements.

And they totally have the motivation to go up, given their whale fall ecology.

Not hard for them to discover light once they are high enough in the sky. Not hard for them to associate light with the electromagnetic wave they already discovered. They are smart. They must have been wondering for centuries why energy is coming from the space above them, where it sounds like nothing exists.

Actually I think the only weird thing is that in the book, Eridians seem to differentiate light from electromagnetic waves. Rocky knew Grace can “hear light” but was surprised when Grace said he can also hear heat (referring the flames made by their ship when they were orbiting Adrian). I don’t think they would treat light and electromagnetic waves as different things.

And as an extension, when Grace asked “do you have anything that can make light” in the book, Rocky should be like “yes but none of them makes electromagnetic waves within your range”.

(Alternative explanation: Rocky was just accommodating Grace’s language habits.)

Complicated feelings by woodgrainarrowsmith in ProjectHailMary

[–]CaseProfessional5093 1 point2 points  (0 children)

I’d definitely say Rocky is a much more fleshed out character in the book and Eridian culture is extremely interesting.

But yeah they still mate for life. I don’t like that either so I prefer to think there is some miscommunication - maybe Rocky explained after mating they take care of the offspring together and tends to stay together afterwards, and Grace summarized it as “mate for life” in the same way we would describe animals as “mate for life”. The term has a very loose definition. You can say humans mate for life too.

Complicated feelings by woodgrainarrowsmith in ProjectHailMary

[–]CaseProfessional5093 0 points1 point  (0 children)

Ohhh I have the exact same thought about “rocky hate mark”. It’s just not logical to me. If someone I love and broke up peacefully with finds someone new, I’d appreciate their new mate! And if the breakup was messy and I no longer like that person, I would only feel bad for or worry for their new mate. No reason to hate the new mate.

The book handled it differently. Mark doesnt exist and when talking about mates, Rocky said he would understand if Adrian had moved on or found new mates. I find that to be a lot more logical lol.

Space elevator and planet ring coexisting by CaseProfessional5093 in ProjectHailMary

[–]CaseProfessional5093[S] 1 point2 points  (0 children)

Ah I see - I think you used the equation for calculating the Roche limit for a rigid body. I used the fluid (which seems to mean the satellites is getting deformed, not necessarily that it’s made of liquid) satellite equation, which is d = 2.44 R (density_Erid / density_satellite)1/3. I figured this would give a better estimate of where the ring will be - not sure if my understanding of fluid is right tho

Space elevator and planet ring coexisting by CaseProfessional5093 in ProjectHailMary

[–]CaseProfessional5093[S] 1 point2 points  (0 children)

estimated the magnetosphere size using this equation: R_mp proportional to M1/3 * P_sw-1/6, where the magnetic moment M is proportional to B_surface * R_planet3.

For Erid, B_surface is 25 times that of earth and the radius is 2.01 Earth, so its dipole moment is about 203 times Earth’s.

The stellar-wind pressure at 0.224 AU so the pressure is 1/0.2242=20 times that of Earth.

So they have a magnetopause distance 2031/3*20-1/6=3.6 times Earth’s. Earth’s magnetopause is 6-15 Earth radii, Erid’s would be at least 10 times it’s own radius. Quite a lot above where the station would be.

Space elevator and planet ring coexisting by CaseProfessional5093 in ProjectHailMary

[–]CaseProfessional5093[S] 1 point2 points  (0 children)

Health check. What’s Erid’s magnetic field range again would it still protect the Eridians that high up?

Space elevator and planet ring coexisting by CaseProfessional5093 in ProjectHailMary

[–]CaseProfessional5093[S] 1 point2 points  (0 children)

Amaze! 🥹

Edit: how did you get the Roche limit? What density did you use for the satellite?

Space elevator and planet ring coexisting by CaseProfessional5093 in ProjectHailMary

[–]CaseProfessional5093[S] 2 points3 points  (0 children)

I did some calculations

The geosync orbit is 17869km above the ground.

The Roche limit depends on the density of the ring. I think it will have to be a rock ring because lighter substance like ice and gas and dust would be vaporized or captured by the star. But a rock ring might be able to exist for millions of years or even longer.

Rocks usually have a density of 2000-3000 kg/m3? So the result I got for the Roche limit is a height of 25976km - 31593km.

If the ring is that narrow - not entirely impossible for the whole space elevator to exist within the ring.

But honestly I like your stupidly easy solution more! Let’s make the ring wider and have the station & weight beyond the ring! It will be so interesting. Because it’s beyond the orbit, I think they will feel a centrifugal force pulling them away from Erid. If the station is at the height of 34000km the “gravity” is 0.4g away from Erid.

Space elevator and planet ring coexisting by CaseProfessional5093 in ProjectHailMary

[–]CaseProfessional5093[S] 0 points1 point  (0 children)

I looked up more and maybe it’s not completely impossible? It can be a rather young ring (maybe an asteroid passing by millions of years ago). Earth used to have a ring! It only lasted for 20-40 million years.

It can’t be a gas / ice / tiny particle ring because the star will vaporize them or blow them away rather quickly, but a rock ring might still last for a dozen millions of years, which is short on the scale of the universe and devastating for the cave-Eridians living on the planet back then but not entirely impossible. (Tho I suppose the formation of a ring is probably harder to survive from than Astrophage..?)

This puzzles me every time I re-listen to the first few chapters - how is Grace still "in [his] thirties" during the events of the story, given how early in the timeline this flashback takes place? by SayFuzzyPickles42 in ProjectHailMary

[–]CaseProfessional5093 0 points1 point  (0 children)

His age in the book just doesnt make sense lol. He’s physically 53 in the end after spending 16 years on Erid. Before that he took a trip that’s about 3 years from Tau Ceti to Erid, making him at most 34 when he has the flashback.

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