Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Why is Venus hell and Earth an Eden?

quantamagazine.org

Post reply on HN
Print view View original

261–270 of 358 posts

Re: Why is Venus hell and Earth an Eden?

#261

Post by dredmorbius »

potato3732842 wrote: post #249
dredmorbius wrote: post #240

Earlier quoted context omitted.

The dock/barge case is addressed here: https://news.ycombinator.com/item?id=45330638 > An aerostat doesn't float on a liquid at stable equilibrium through draft displacement, it is suspended in a fluid, with the problems noted previously. Docks and barges (along with general watercraft) may be constructed arbitrarily robustly from strong and resilient materials. Aerostats somewhat less so.

>The dock/barge case is addressed here: https://news.ycombinator.com/item?id=45330638 > Addressed naively and wrongly hence the ongoing discussion >An aerostat doesn't float on a liquid at stable equilibrium through draft displacement, it is suspended in a fluid, with the problems noted previously. If you let a baloon go will it reach space? No, because the atmosphere is not constant density. Balloon type objects hav…

The analogy isn't letting go of a balloon, it's of dumping a large mass of payload (rocket + fuel) from an aerostat quickly.

The aerostat will rise. It will float higher in the atmosphere, with decreased pressure around it. It will expand. It will then rise still further.

And there's no ready supply of solid or liquid ballast (as would be available on a near-ground cargo drop) to compensate for the lost mass.

This is untenable for any manned / habitable module, and you'd all but certainly want any of same well outside the danger zone of a rocket malfunction.

One likely consequence is that any launch aerostats would be at best highly unstable in their altitude and station-keeping characteristics. It's quite possible that a disposable, single-use design might be required. Given that materials would likely have to be shipped from Earth, or possibly from near-Venus asteroids via space-mining, this considerably increases cost and complexity of any such missions.

Aerostats, as lighter-than-air craft, have vastly more-tightly constrained mass budgets than any water-based floating structures. Ignoring and/or waving that away is obtuse in the extreme. Particularly given the additional concerns and considerations of launch-capable structures. Existing aerostats and rockets operate at the outer limits of engineering design capabilities, and still go boom with some regularity, often due to exceeded structural tolerances.

Re: Why is Venus hell and Earth an Eden?

#262

Post by emilecantin »

NoMoreNicksLeft wrote: post #258
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…

>Literally how floating works. Yes, ignoring momentum. Do parachutes just get stuck in the air halfway down? When do you inflate it? If you inflate it, can you even deorbit? Do those pop when you deorbit? Do you cover the balloon with big heavy heat shield tiles? I'm not claiming I understand this at all, but you seem to have some child's grasp of "how floating works". > By launching your rocket from the ballon city…

> If I can't get the materials to repair my building in a hurry, I go outside and I wait. Or I stay inside and I wait. And if I can't do that for my Venusian balloon city, I slowly sink into a zone that melts lead and bakes me alive. And if I get the materials after it has stared sinking, repairing it won't reinflate the balloon and have it rise again, because some significant fraction of the air has leaked out.

It's more similar to a boat than a house. If your boat has a leak, you need to repair it very quickly or it ends up at the bottom of the ocean. Yet we've managed to do it relatively reliably.

Re: Why is Venus hell and Earth an Eden?

#263

Post by abduhl »

bryant wrote: post #254
ubermonkey wrote: post #250

Earlier quoted context omitted.

A shockingly useful "quick and dirty" estimate for C to F for temps humans are likely to encounter is 2x + 30. It's not precise at all, but for purposes of "what does that feel like outside" or "should I bring a sweater" it works pretty well. 21C would, by this estimate, be 72F. The true conversion is just shy of 70F, so, again, it's not correct but it's close enough for this kind of conversation.

for what it's worth: add 9 degrees F (or 18 if it's easier to remember) for every 5 degrees C (10 C, easier), and peg 32F to 0C. You get: -40F=-40C -22F=-30C -4F =-20C 14F =-10C 32F = 0C 50F = 10C 68F = 20C 86F = 30C 104F= 40C and then approximate in between from there. It's quick enough for me now that I skip the 2x+30.

In this HN subthread: users slowly converge on the conversion formula for Celsius to Fahrenheit (32+9C/5) in greater and greater precision while calling it an “approximation.”

Re: Why is Venus hell and Earth an Eden?

#264

Post by thomastjeffery »

a3w wrote: post #229
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…

Venus is room temperature with low radiation, if you dig in. Living on Venus was floating around as an easier alternative to living on the Mars surface. Room temperature is 21°C, I have no idea how many freedom fries units that is.

The irony is that (at least I'm pretty sure) the concept of "room temperature" was originally pinned to 70° Freedom Degrees. Your 21°C reference unit is probably a rounded conversion, which explains the sibling comment arguing 23°-25°C as potentially inferior alternatives. An accurate conversion would be 21.1̅°C.

Re: Why is Venus hell and Earth an Eden?

#265

Post by yndoendo »

bryant wrote: post #255
ZYbCRq22HbJ2y7 wrote: post #231

Earlier quoted context omitted.

> Room temperature is 21°C Debated, was 23 or 25 in my college textbooks: https://en.wikipedia.org/wiki/Room_temperature > I have no idea how many freedom fries units that is. Kind of a bad attempt at humor? Imperial units is fine.

Imperialist here. Freedom fries was funny.

Had to add metric to an imperial unit application since it is to be sold internationally. I live in a Fahrenheit country so I set my phone, computer, and car to Celsius to learn how the the temperatures readings feel.

I 100% agree, "Freedom Fries Units" is quite fitting.

Turns out I prefer Celsius over Fahrenheit in day to day usage.

Re: Why is Venus hell and Earth an Eden?

#266

Post by glenstein »

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…

Exactly right, and it's a fascinating prospect. Earth like temperature and atmospheric pressure, and better protection from radiation than even Earth. Major advantages Venus has over Mars are that (1) it's closer, (2) aforementioned radiation protection, (3) no issue of aggressive bone decalcification.

Radiation on Mars is brutal and it doesn't get talked about enough. Anyone without sufficient protection from surface rays would have 5-10 years before they come down with some form of terminal cancer.

When Andy Weier went on book tour for Artemis he talked about how cities have to have an economic rationale for existing, which is why in his story, the Moon would be oriented around tourism. Venus seems to be disadvantaged in terms of having practically no access to rare or heavy metals because you can't safely get to the surface and even if you can, is basalt (which in many ways is great and chemically diverse and rich, like the nutritious potato of surface rocks, but it won't yield concentrated veins of valuable metal).

But what Venus does have is enough carbon ready to be processed into liquid fuel, while skipping complicated mining and extracting and refining processes that complicate the matter on Earth and would similarly complicate it from any other source in the solar system. You would have to source hydrogen from somewhere to synthesize fuel. But in a way that's an advantage, because you could source it from an asteroid, keep it in space, and just send up the carbon feedstock from Venus. You'd probably rather do it that way anyway, avoiding some of the more brutal costs of sending water weight in and out of the gravity well. So you pull the carbon feedstock from Venus, you synthesize fuel in space, and you're the premiere source of rocket fuel in the solar system. Economic rationale! The pin that might burst this bubble is that Venus's carbon feedstock advantage might not matter, because the water rather than the carbon maybe the more critical variable, and the second best options for sourcing carbon (mining, processing) may be good enough that Venus's advantage doesn't matter.

Then there's the buoyancy, another extreme eyebrow raising advantage given Venus's hellscape on the surface. It's remarkably easier to be buoyant on Venus than Earth, in some ways you could consider it an ocean planet, but it's an ocean of extremely thick air. Which is not only extremely important for any hypothesized floating settlements, but might open the door to buoyancy based passive dragnets to scrape and retrieve raw materials from the surface. But that too would hinge on having incredibly powerful carbon weaves netting and economics making it worth it. But still, there's something intriguing there.

Anyway, I feel like there's a wiiiide open lane in public communication and in hard sci-fi for a deep dive on Venus colonization, Kim Stanley Robinson style, and I just want someone to occupy that damn lane already.

Re: Why is Venus hell and Earth an Eden?

#267

Post by losvedir »

NoMoreNicksLeft wrote: post #258
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…

>Literally how floating works. Yes, ignoring momentum. Do parachutes just get stuck in the air halfway down? When do you inflate it? If you inflate it, can you even deorbit? Do those pop when you deorbit? Do you cover the balloon with big heavy heat shield tiles? I'm not claiming I understand this at all, but you seem to have some child's grasp of "how floating works". > By launching your rocket from the ballon city…

The guy you're responding to is an aerospace expert, iirc.

Anyway, the balloon would be relatively stable. The atmosphere gets increasingly dense as you go towards the surface, while the balloon has a particular density which is more than the wispy far atmosphere and less than the dense low atmosphere. Therefore, if you were to drop it at the top, it would fall (while it's more heavy) then approach the altitude where it's equally dense, and start bobbing around there, until it settles at its equilibrium.

Picture a glass cylinder of water and oil. It's cleanly separated with the denser water on the bottom and oil on top. Then drop an ice cube in. It will sink through the oil and then float, in the middle of the cylinder, on the water.

Re: Why is Venus hell and Earth an Eden?

#268

Post by pbmonster »

potato3732842 wrote: post #224
eloisant wrote: post #181

Earlier quoted context omitted.

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.

Because it's cheaper to live on a f-ed up half-built construction site of a planet than it is to fight with entrenched interests on earth. Same reason North America got colonized by religious extremists and weirdos.

The free, abundant land choke full of natural resources was probably more important.

Re: Why is Venus hell and Earth an Eden?

#269

Post by glenstein »

thomastjeffery wrote: post #264
a3w wrote: post #229

Earlier quoted context omitted.

Venus is room temperature with low radiation, if you dig in. Living on Venus was floating around as an easier alternative to living on the Mars surface. Room temperature is 21°C, I have no idea how many freedom fries units that is.

The irony is that (at least I'm pretty sure) the concept of "room temperature" was originally pinned to 70° Freedom Degrees. Your 21°C reference unit is probably a rounded conversion, which explains the sibling comment arguing 23°-25°C as potentially inferior alternatives. An accurate conversion would be 21.1̅°C.

Conceivably, if you had an umbrella to protect yourself from the acid rain, an oxygen mask, and were on a very safe floating platform in the upper atmosphere, you could walk around in a t-shirt and be just fine.

Re: Why is Venus hell and Earth an Eden?

#270

Post by lolive »

chasil wrote: post #8

Venus does not have a molten core, and there is no magnetic field protecting the atmosphere from the solar winds. This is not likely the sole reason, but it must be a factor. Mercury does have a magnetic field, Mars does not.

[Not to bore its audience, the Bible had to be brief on that part of the process, but] God iterated several version before delivering.

Inner thought: here come the downvotes, baby!

Post reply on HN