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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?

#321

Post by Melatonic »

eru wrote: post #54
codq wrote: post #24

Earlier quoted context omitted.

Without tectonics, is terraforming Mars even possible as a long term solution? This "Mars colonization" strategy seems like a pipe dream, no?

The lack of tectonics would only be a problem if you want your terraforming to be 'one and done'. If you admit that terraforming, even after it's 'done', will require an ongoing maintenance effort, it's simple (but not easy). Eg you can use satellites to spin up an artificial magnetic field to shield against solar wind. However, I suspect terraforming planets is a waste. Far more bang for your buck to build habitats…

Seems like Mercury could be a good opportunity for automated drones and research

Re: Why is Venus hell and Earth an Eden?

#322

Post by potato3732842 »

techdmn wrote: post #307
pbmonster wrote: post #268

Earlier quoted context omitted.

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

Only free if you discount the costs involved in carrying out genocide against the existing inhabitants. But your point stands, that cost was frequently born by the government, so from the perspective of individual settlers it was often free.

> But your point stands, that cost was frequently born by the government,

Who paid this government?

Re: Why is Venus hell and Earth an Eden?

#323

Post by jsbisviewtiful »

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…

Wow thank you for laying out this info. I've always read the theories on the Venus floating colony but the info on pressure and temp I had no idea about.

Re: Why is Venus hell and Earth an Eden?

#324

Post by dredmorbius »

shrx wrote: post #216
bryanrasmussen wrote: post #186

Earlier quoted context omitted.

>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…

Launching the rocket from a balloon is not a problem. You can have a platform with a hole underneath the rocket's exhaust and the balloon itself can be a torus through which the rocket flies upwards. There would be minimal impact of a rocket launch on the platform if designed properly.

Heck, you could just drop the rocket and have it ignite (one hopes) with lateral thrust, clearing the launch aerostat.

Or consider the aerostat disposable (at a significant replacement cost, see: https://news.ycombinator.com/item?id=45333674>).

But either way it's a bit less the firey-burney-explodey problem than the sudden loss of a few thousands tonnes of mass that would displace the equilibrium of the launch platform, should you care to re-use that, or the means by which such platforms (capable of supporting said thousands of tonnes of mass).

Just to put some hard numbers on it, a crewed Falcon9 (Crew Dragon) has a launch mass north of a half-million kilograms, or 500 tonnes.

The Russian Soyuz-FG, also human capable, has a launch mass of slightly over 300 tonnes.

If this spacecraft is only a shuttle to low-Venus orbit with another transfer craft for the flight back to Earth (or other points of interest) that should suffice. If the launch craft is intended for the full return trip of 100--250 days, things could get a bit cozy and interesting depending on the number, disposition, and fragrance of inhabitants.

Re: Why is Venus hell and Earth an Eden?

#325

Post by dredmorbius »

losvedir wrote: post #267
NoMoreNicksLeft wrote: post #258

Earlier quoted context omitted.

>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…

Last I heard, though acidic, the Venusian atmosphere is not made of oil and vinegar. Nor does it have hard strata lines.

Suddenly losing or gaining a few hundred tonnes of mass will do interesting things to a free-floating aerostat.

Re: Why is Venus hell and Earth an Eden?

#326

Post by dredmorbius »

potato3732842 wrote: post #279
dredmorbius wrote: post #261

Earlier quoted context omitted.

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…

>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. Now explain weather balloons. Why don't they rise to infinite altitude? Like I said, the numbers are all wonky, but the principals are the same. If there is too little mass for the amount of bouncy just compress your gas and hold some reserve buoyancy/balloons to inflate…

Weather balloons reach a stable equilibrium altitude because 1) they're designed to expand as they rise (at quite an impressive ratio) and 2) they're not suddenly gaining or losing 100s of tonnes of mass.

At least one if not both those prereqs is missing from the observed case. Though discussing the matter further has lost virtually all appeal.

Re: Why is Venus hell and Earth an Eden?

#327

Post by dredmorbius »

SwtCyber wrote: post #313

What stuck out to me is how fragile Earth's long-term stability actually is. We've gotten insanely lucky with things like plate tectonics, subduction, and just the right volcanic activity to keep CO2 cycling.

And over sufficiently long terms, the Earth's not been all that stable.

There've been multiple Snowball Earths (based on geological evidence), and a few episodes in which (even had land-based life existed) the continents were barely habitable.

Even today large expanses (Antarctica, the Sahara and other deserts) are only barely habitable. Still Edens compared with the rest of the Solar System.

Re: Why is Venus hell and Earth an Eden?

#328

Post by dredmorbius »

tasty_freeze wrote: post #95
WalterBright wrote: post #53

Earlier quoted context omitted.

The crazy ones are the ones that get sh*t done. Musk was initially written off initially as crazy for every one of his successful business ventures. And it's his money to spend as he sees fit.

Walter, I never said he couldn't spend his money how he wants, so that really isn't a counter argument to what I was claiming. Personally, I think most people (Musk is just one) who thinks terraforming Mars is realistic have read too much science fiction and are more enamored of the cool Robinson Crusoe aspect more than it would really serve any purpose. As for "every one" of his successful business ventures being ca…

Agreed, and adding: Hyperloop wasn't original to Musk (other than name). RAND explored the concept in the 1970s, and there are further earlier concepts:

Look up Robert M. Salter at RAND:

"The Very High Speed Transit System" (August, 1972)

"Trans-Planetary Subway Systems -- A Burgeoning Capability" (February, 1978)

http://www.rand.org/pubs/papers/P4874.html> PDF: http://www.rand.org/content/dam/rand/pubs/papers/2008/P4874....>

http://www.rand.org/pubs/papers/P6092.html> PDF: http://www.rand.org/content/dam/rand/pubs/papers/2009/P6092....>

Similar / more: http://en.academic.ru/dic.nsf/enwiki/6107059>

Re: Why is Venus hell and Earth an Eden?

#330

Post by jrussino »

dredmorbius wrote: post #177
eru wrote: post #51

Earlier quoted context omitted.

Yes, first everything rusted, and then the excess oxygen collected in the atmosphere. Many of our iron ore deposits we still mine today are from that rusting. (That iron used to be mostly dissolved in the oceans.)

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…

Human civilization feels so much more fragile to me since I realized how much we owe our technological progress to the accumulated effects of biological processes over geological timescales. Fossil fuels seem like the most obvious part of this story. If we had to start over "from scratch", would it even be possible? Or have we already so thoroughly exhausted the low-hanging energy stores that a second "industrial revolution" would be effectively impossible if our present civilization collapsed deeply enough?

I wasn't aware that concentrated stores of iron are also an important part of this story!

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