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Why is Venus hell and Earth an Eden?

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Re: Why is Venus hell and Earth an Eden?

#191

Post by meindnoch »

brazzy wrote: post #150
gorgoiler wrote: post #121

Earlier quoted context omitted.

I once heard a similar point and it has fascinated me ever since: an alien observing human culture would be appalled at how dangerous our lives are. Everything around us is bathed in warm oxygen, just waiting to catch fire! Our homes, our clothes, our fields, our possessions, … our hair . Ready oxidation brings vitality to Earth but it’s also ridiculously dangerous.

It's very unlikely the aliens would not have something very similar going on in their own biosphere. Life needs energy to operate, after all.

They need a sufficiently dense energy source, sure. But it may not involve their atmosphere at all. Their plants could store solar energy in self-contained chemical batteries, and the aliens could be using those batteries to power their bodies. Instead of having to constantly breathe, they would instead need a daily battery swap.

Re: Why is Venus hell and Earth an Eden?

#192

Post by stavros »

eloisant wrote: post #181
JumpCrisscross wrote: post #147

Earlier quoted context omitted.

> such a way that your inflatable balloon city comes to a gentle stop, 30 miles up, and just floats there? Literally how floating works. > Worse still, when people need to leave and return to Earth, how do you launch a rocket from the balloon city and return to orbit? By launching your rocket from the ballon city and returning to orbit. (I'm struggling to see the novel problem.) > Where are materials manufactured for…

I'm sure we can figure out stuff, but I guess my point is, why would we do that at all? How fucked up Earth needs to be than living on a floating oil platform above Venus is better? The point is already hard to make for the Moon or Mars.

It's less about the earth being uninhabitable and more about redundancy of species.

Re: Why is Venus hell and Earth an Eden?

#193

Post by dredmorbius »

meindnoch wrote: post #187
dredmorbius wrote: post #177

Earlier quoted context omitted.

And the concentration into BIFs, banded iron formations, was all but certainly the result of biological activity. Our present technology based on iron and steel owes itself to early life on Earth, from 1.6 to as much as 4 billion years ago. As with petroleum and coal-bed formation, a process unlikely to repeat in Earth's future. Iron ores are abundant, but still a finite resource. https://en.wikipedia.org/wiki/Banded…

>Iron ores are abundant, but still a finite resource. The iron doesn't go anywhere (ok, except for the iron making up our space probes). It is infinitely recyclable.

It doesn't concentrate itself, at scale.

That's what ores are. Ores are useful because they are concentrated, the result of some ore-formation or ore genesis process.

The "not going anywhere", after it's been dispersed throughout the lithosphere, is precisely the problem.

https://en.wikipedia.org/wiki/Ore_genesis>

Re: Why is Venus hell and Earth an Eden?

#194

Post by stavros »

sleepy_keita wrote: post #120
yazantapuz wrote: post #116

Earlier quoted context omitted.

If i remember right, according to one of Asimov's Foundation sequels, the Earth was unique due to its high level natural radioactivity, which allowed it to develop an ecosystem more vibrant than any other planet in the galaxy.

Was just rereading - it was the radioactivity and the large natural satellite that was unique in his universe. Tides are interesting because once you have life in the oceans, it's a kind of forcing function to adapt to land conditions

Why are tides a forcing function? Marine life has been perfectly content just not going near a beach.

Re: Why is Venus hell and Earth an Eden?

#195

Post by JumpCrisscross »

bryanrasmussen wrote: post #186
JumpCrisscross wrote: post #147

Earlier quoted context omitted.

> such a way that your inflatable balloon city comes to a gentle stop, 30 miles up, and just floats there? Literally how floating works. > Worse still, when people need to leave and return to Earth, how do you launch a rocket from the balloon city and return to orbit? By launching your rocket from the ballon city and returning to orbit. (I'm struggling to see the novel problem.) > Where are materials manufactured for…

>By launching your rocket from the ballon city and returning to orbit. (I'm struggling to see the novel problem.) I believe they are having trouble envisioning how you would launch rockets from a balloon city without disturbing the equilibrium of the balloon city because it is assumed that rockets thrusting down with great force would damage the balloon city in a way it would not easily recuperate from. I also find t…

> how you would launch rockets from a balloon city without disturbing the equilibrium of the balloon city because it is assumed that rocks thrusting down with great force would damage the balloon city in a way it would not easily recuperate from

It's a floating platform. Same as the ones SpaceX lands its rockets on. Same as a gunboat firing projectiles.

Will a launching rocket impart force to the platform? Yes. But unless the platform is super weirdly balanced, or the rocket absurdly oversized for the platform, it will stabilise after rocking a bit. (You'd have to design the platform to be stable in winds, anyway.)

And if you do have an absurdly oversided rocket, you don't launch it from your platform. You float it off to the side on a dedicated launch "boat" and have it ditch its floaty as an ultra-early first stage.

Re: Why is Venus hell and Earth an Eden?

#196

Post by ckastner »

bryanrasmussen wrote: post #186
JumpCrisscross wrote: post #147

Earlier quoted context omitted.

> such a way that your inflatable balloon city comes to a gentle stop, 30 miles up, and just floats there? Literally how floating works. > Worse still, when people need to leave and return to Earth, how do you launch a rocket from the balloon city and return to orbit? By launching your rocket from the ballon city and returning to orbit. (I'm struggling to see the novel problem.) > Where are materials manufactured for…

>By launching your rocket from the ballon city and returning to orbit. (I'm struggling to see the novel problem.) I believe they are having trouble envisioning how you would launch rockets from a balloon city without disturbing the equilibrium of the balloon city because it is assumed that rockets thrusting down with great force would damage the balloon city in a way it would not easily recuperate from. I also find t…

There is precedent: SpaceShipOne was successfully launched from an airplane [1].

The great force downward is (mostly) irrelevant if there is nothing below. Just hang the rocket between two towers over a void, with the atmosphere below.

[1]: https://en.wikipedia.org/wiki/SpaceShipOne#Launch_aircraft

Re: Why is Venus hell and Earth an Eden?

#197

Post by meindnoch »

dredmorbius wrote: post #193
meindnoch wrote: post #187

Earlier quoted context omitted.

>Iron ores are abundant, but still a finite resource. The iron doesn't go anywhere (ok, except for the iron making up our space probes). It is infinitely recyclable.

It doesn't concentrate itself, at scale. That's what ores are. Ores are useful because they are concentrated , the result of some ore-formation or ore genesis process. The "not going anywhere", after it's been dispersed throughout the lithosphere, is precisely the problem . https://en.wikipedia.org/wiki/Ore_genesis >

But scrap metal is still purer than any ore.

Re: Why is Venus hell and Earth an Eden?

#198

Post by [deleted] »

rkagerer wrote: post #124

Venus is arguably the worst place in the solar system From another perspective, its atmosphere is "one of the most Earth-like in the solar system", and scientists long ago postulated the idea of establishing floating cloud cities. Big balloons filled with nitrogen and oxygen would naturally settle at the right altitude, 30 miles above the surface, where gravity, ambient pressure, and radiation aren't far off that of…

[deleted]

Re: Why is Venus hell and Earth an Eden?

#199

Post by JumpCrisscross »

dredmorbius wrote: post #190
JumpCrisscross wrote: post #156

Earlier quoted context omitted.

> I think Newton’s third law may cause trouble No more than for a floating platform on the ocean. (Or frankly any sea or airborne firing platform.) If your launch mass is a significant fraction of station mass, and you can't counterweight, you could float it off to the side and then have the baloon detach when its engines fire. But none of this is in even the top thousand problems that come with colonising Venus.

Floating on a liquid surface is markedly different from floating within a fluid (liquid or gaseous). To float on a liquid, one merely needs to maintain a lower average density within the vessel than the surrounding liquid. Assuming a largely hollow vessel (as with a ship or barge), it's possible to add or remove considerable payload without losing stable flotation characteristics as the draft of the vessel automatica…

> To float in a fluid, one must maintain precise neutral buoyancy, which is an entirely different animal

You're right, I was oversimplifying. An aerial or submerged launch platform, then.

> the tendency is for a vessel to contract as it sinks and expand as it rises, leading to a runaway buoyancy shift (increasingly negative with depth, increasingly positive with height)

This is inherent to the cloud city design. Rockets would be a subclass of buoyancy risks, eclipsed entirely by atmospherics.

> Rocket launch from an inhabited floating atmospheric platform would require accumulation of large stores of fuel (the Tsiolkovsky rocket equation also works against you), as well as presenting various risks associated with enormous barely-contained explosions

This is a fair criticism. It's also solved by having offboard propellant storage and launch platforms.

> risks are immense, and hand-waving them away is disingenuous to the extreme

Didn't mean to suggest it isn't risky. Just that the risks from the rocket launch component are dwarfed by many, many others, and to the extent there are risks here, they are ones we've already solved on Earth in analogous contexts. (Maintaining buoyancy isn't remotely the main problem with launching rockets from high-altitude blimps.)

Re: Why is Venus hell and Earth an Eden?

#200

Post by JumpCrisscross »

stavros wrote: post #194
sleepy_keita wrote: post #120

Earlier quoted context omitted.

Was just rereading - it was the radioactivity and the large natural satellite that was unique in his universe. Tides are interesting because once you have life in the oceans, it's a kind of forcing function to adapt to land conditions

Why are tides a forcing function? Marine life has been perfectly content just not going near a beach.

> Why are tides a forcing function?

"Nucleotide formation and polymerization are both more favored thermodynamically when subunit and nucleotide concentrations increase and the water concentration decreases (i.e., at low water activity)" [1].

Tide pools provide a regularly-cycling low-water and high-water environment. (And you get thermocycling, nutrient refreshment, and a path to the oceans, too.)

They're not a forcing function, generally, because we don't know how life formed. But I believe they're close to one in a RNA-first or metabolism-first origin-of-life universe.

[1] https://www.nature.com/articles/s41467-018-07389-2

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