ED: Just saw your second paragraph. But the things you speculate on are not exactly common on Titan, if they even exist on the surface at all (it's an icy crust ,not a rocky one). And either way, it'd be much easier with compounds other than methane.

And no, there doesn't seem to be meaningful amounts of nitrates in the atmosphere at least. You can see a list here. Nitrogen compounds are cyanide and nitrile compounds.

Metabolized with what oxidizer?

It's just the opposite - methane on Titan is like nitrogen on Earth; it's things like acetylene and free hydrogen that are the potential energy sources, and to a lesser extent the more common (but less reactive) higher mass alkanes, etc.

The main problem is that LAWKI isn't even remotely compatible with existing in the cryogenic environment of Titan. There are a lot of interesting alternative chemistries, but they require basically redesigning life from scratch. We're simply not up to this task with our current technology.

Sadly it's being launched to near the equator, not the poles :( The geophysicists won out over the geochemists...

Freedom is great and neglectable, until you very suddenly don't have it.

History has not ended. The world order that makes life nice and comfy for you is not a given into the future.

It's funny how we so strongly disagree further down in the comments, but I 100% agree with you here.

0,38g being largely fine for health is... I mean, if I had to bet, I'd put my money on it probably being true, but it's anything but guaranteed. There was a private project to test this, the Mars Gravity Biosatellite, but it ran out of funding; I'm not aware of any similar experiments that have been conducted. There've been a variety of attempts to simulate various gravity on Earth, such as having people lie on tilted beds or hanging them from cranes at an angle or whatnot, but they all have obvious weaknesses.

There's not just the question of adults who visit from Earth, but also children who grow up on 0,38g, and what impact that would have to their physiology.

Venus is hot, but it's not *that* hot... ;)

NASA is getting there

It most definitely is not. Are you being deliberately obtuse?

one can do for more than a few minutes before shit implodes and burns

You clearly didn't read anything I wrote, so why should I even bother responding? (A) Literally nobody was talking about settling the surface, and (B) It's been repeatedly pointed out that basically indefinite lifespans can be achieved for surface vehicles, as backed up by peer-reviewed research from NASA. And "christoban on Slashdot disagrees with peer-reviewed research from NASA" isn't exactly a compelling argument.

B) building floating cities, which would probably take another century of engineering and investment before we could do so reliably.

We were flying balloons on Venus almost 40 years before we flew a helicopter on Mars. We directly sampled Venus's atmosphere 4 years before we sampled Mars. We successfully landed and transmitted data either 1 or 6 years (depending on your definition) from the surface of Venus vs. Mars.

Your incredulity about levels of difficulty doesn't translate to actual levels of difficulty.

That book presented a nonstop stream of pseudoscience as if it were hard sci-fi, and it's unfortunate that it's spread so many myths as a result.

I think your confusion stems from analogy to baking clay or ceramics. But what's happening there is sintering. You have extremely fine grains, and you're leading certain crystals to soften and merge as a "glue" between grains, so that the grains stay together.

While sintering is important in the formation of some types of sedimentary rock, this has nothing whatsoever to do with igneous rock. It's already as "together" as it's ever going to be when it a lava flow solidifies. The only thing its grains can ever become is "less together".

And even ignoring that, by definition, you're not going to be sintering something that formed at Venus temperatures, by exposing them to Venus temperatures. The process of sintering requires a radical change in conditions.

We are not capable of building anything that can withstand the surface pressures and temperatures for very long

The Venera probes have likely still not experienced any sort of crushing. You seem to be confused about how pressure works. If you don't exert stress pass the yield point of a material, the length of time until something crushes is "infinite". Which is why, say, almost all rocks buried in Earth's crust are able to remain intact over millions to billions of years.

You build of a thickness that the yield point at the design temperature is well above the amount of pressure-induced stress. The Venera probes' pressure vessels - uninsulated - hit surface temperature quite quickly (indeed, mostly during the descent itself). This did not make them crush, because their engineers were not morons who didn't do the math first when determining the probes' required specs.

All probes are designed to their environment. There is nothing magical about the nominal 92 MPa / 464 C of Venus's mean surface (note: this is for the mean surface; the highlands are significantly lower pressure and significantly cooler) that makes it impossible while, say, designing a lander to operate in the cryogenic conditions of Titan or whatnot is easy. This is 1960s tech. Steel alloys usually melt at up to 1400 C or so. Titanium at 1670 C. Tungsten at 3422 C. Some ceramics don't decompose until nearly 4000C. And pressure increases melting points. Now, it's not just the melting point that matters - higher temperatures mean lower yield strengths, so you have to design with the high temperature yield strengths in mind, not room temperature ones. But the simple fact is that various alloys and compounds can operate fine at WAY above Venus surface temperatures. It's not even close. The pressure vessel needed for the Venera probes was just a thin skin.

And to repeat: if the stress doesn't don't go above the yield point, the time to crushing is infinite. Same as any other pressure vessel, from aerosol cans to propane tanks to spacecraft in space (-1 atm).

And I'll repeat: with the same trivially-simple 1960s-tech method as the Venera probes, you can get surface residence times of a couple hours. With heat pumps, indefinitely. And "Baron_Yam at Slashdot" isn't going to override the actual NASA researchers who have worked on this topic.

The rock of Venus is dry-baked to incredible strength

The fact that you think that rock can be "baked to incredible strength" is itself a boggling concept. Not even accounting for the fact that we can literally see sand and gravel in the Venera images, and the Venera probes literally took surface samples. We can see dunes from orbit on radar. Just the very concept that you think that if you heat rock to a couple hundred celsius that makes it super hard, when the rock formed from vastly-hotter lava. Heat makes rock softer, not harder. And subliming away compounds or chemically eroding rocks makes them weaker, not stronger.

From a bulk composition perspective, Venus's surface is mostly just basalt - though there's some probable rhyolitic flows in places, possibly some unusual flows rare or nonexistent on Earth, and there's speculation that some of the highlands may contain residual granitic continental crust. The specific details of said rocks can be quite interesting, but from a bulk perspective, it's like oceanic crust. We know this because we've literally sampled it..

That's a lot of text to not mention the need to build floating cities and not die on the surface, which even NASA has not been able to do for more than a few minutes

In case you didn't notice, NASA also hasn't built cities on Mars either, despite spending two orders of magnitude more money on it in recent decades than Venus.

Anyway, we don't need the most Earthlike atmosphere, we need to survive in an environment where we actually know how to do that.

Which requires creating Earthlike conditions. Starting with reasonably Earthlike conditions certainly is a good start.

I was extremely disappointed by Three Body problem. I thought some of the concepts were pretty cool (I actually thought the part where the Trisolarians build the Sophons was great) and the the story through the lens of the Cultural Revolution was an interesting viewpoint. But damn, the writing sucked. Like you, I plodded on hoping it would get better and like you, I wondered if it was just the translation, or because I didn't have the right cultural background to get the cues, but ultimately... it's some good ideas that are just awfully executed.

Counterpoint.

Venus's middle cloud layer is the most Earthlike place in the solar system apart from Earth**, is energy-abundant, has favourable orbital dynamics, easy entry, and the simple act of storing electricity for the night via reversible fuel cells - if plumbed in a cascade - can enrich deuterium (2 1/2 orders of magnitude more abundant on Venus), a natural export commodity, if launch costs are sufficiently low. The atmosphere contains CHONP, S, Cl, F, noble gases, and even small amounts of iron. Pretty much everything you need to build a floating habitat, which can be lofted by normal Earth air, aka people can live inside the envelope. Aka, unlike on Mars, where you live in a tiny tin can pressure vessel where any access to the outside tracks in toxic electrostatic dust and you waste away from low gravity, on Venus you'd be in a massive, brightly lit hanging garden, where you could live half a kilometer from a crewmate if they really got on your nerves.

Most Earthlike? Yes. Temperature, pressure, gravity, etc all similar. Natural radiation shielding equivalent to half a dozen meters or so of water over your head. Even storms seem to be of an Earthlike distribution. The "sulfuric acid" is overblown; it's a sparse vog, with visibility of several kilometers; with a face mask, you could probably stand outside in shirtsleeves, feeling an alien wind on your skin, only risking dermatitis if you stayed outside for too long.

Indeed, it'd actually be useful if the sulfuric vog was more common (to be fair, it's still unclear whether precipitation happens, and if so, whether rains or snows; the Vega data is disputed). Why? Because it's your main source of hydrogen. Highly hygroscopic and easily electrostatically attracted, so readily scrubbed through your propulsion system. First releases free water vapour when heated, then decomposes to more water plus SO3, and if you want you can further decompose the SO3 over a vanadium pentoxide catalyst to O2 + SO2, or you can reinject it into the scrubber as a conditioning agent to seed more water vapour. Of course, if precipitation happens, collection possibilities are basically limitless.

The surface is certainly hostile, but even 1960s Soviet technology was landing on it (also, contrary to popular myth, there is no acid at the surface; it's unstable at those temperatures, the sulfur inventory is only SO2 there). But in many ways, the surface is very gentle. Mars eats probes with its hard landings, but one Venera probe outright lost its parachute during descent and still landed intact, as the dense atmosphere slows one's fall. It's been calculated that with the right trajectory, a simple hollow titanium sphere launched from Earth could arrive at Venus, enter, descend and land all intact. Simple thermal inertia (insulation + a phase change material) can keep an object cool for a couple hours; with heat pumps, indefinitely (and yes, heat pumps and power sources for the surface conditions have been designed). Even humans could walk there with insulated hard suits, like atmospheric diving suits. Indeed, some of the first space suits NASA designed for the moon (ultimately ditched for weight reasons, despite the superior mobility performance) were similarly jointed hard-shell suits.

On Venus's surface, a lander or explorer can literally fly, via a compressible metal bellows balloon. Small wings / fins can allow for long glide ratios. Loose surface material can be dredged rather than requiring physical excavation, potentially with the same fan used for propulsion. Reversible ascent back to altitude can be done with phase change balloons - that is, at altitude, a lifting gas condenses and is collected in a valved container, and the craft can descend; at the surface, when one desires to rise, the valve is opened and the gas re-lofts the lander.

On Mars, you're stuck in one location. The problem is that all minerals aren't found in the same spot; different processes concentrate different minerals. And you can't exactly just get on a train to some other spot on the planet; long-distance travel requires rockets, and all their consumables. But on Venus the atmosphere superrotates every several days (rate depending on altitude and latitude), while latitude shifts in a floating habitat or lander can be done with minimal motor requirements. So vast swaths of the planet are available to you. Furthermore, Venus is far more dramatic in terms of natural enrichment processes; wide ranges of minerals are sublimated or eaten out of rocks and then recondensed elsewhere. Temperatures and pressures vary greatly between the highlands and lowlands as well. There even appear to be outright semiconductor frosts on parts of the planet. Lava flows show signs of long cooling times, which promotes fractionalization and pegmatites. Volcanism is common, primarily basaltic but also potentially secondary rhyolitic sources. A variety of unusual flows with no earth analogies (or only rare ones) show signs of existing, including the longest "river" channel in the solar system (Baltis Vallis). While there's no global tectonic activity, there appear to be areas of intense local buckling between microplates. The surface conditions of the planet also appear to have been very different at many times in the past. It's all a perfect setup for having diverse mineral enrichment processes. Yet there's almost no overburden (unlike Mars, which is covered in thick overburden on most of the planet).

As mentioned before, Venus has significantly superior orbital dynamics to Mars, due to the Oberth effect. Venus-Mars transfers are almost as fast and almost as low energy as Earth-Mars transfers. Venus-Earth transits are super-fast, esp. with extra delta-V added. The asteroid belt is, contrary to intuition, much more accessible from Venus than from Mars. Also, gravity assists are much more common around Venus - when we want to launch probes to the outer solar system, we generally start with sending them first inwards toward Venus, then back between Venus and Earth and outwards from there.

From a long term perspective, both Venus and Mars have problems with terraforming, with some things you can do "relatively easy", and some that require megascale engineering on scales best left to fantasy. You can boil off Mars's polar caps, but the amount of CO2 there is still quite limited, and there's just not that much nitrogen inventory on the planet (it's been lost to space), which also matters to plant cultivation. You could probably engineer active radiation shielding from orbit, maybe direct more light to the surface, but you can't increase the gravity. Etc.

With Venus, one of the earliest ideas for terraforming it was from Carl Sagan, before the planet was known well; he proposed seeding it with engineered bacteria to convert CO2 to graphite and release oxygen. He later rejected his idea, on the grounds that a high temperature surface of graphite and oxygen would be a bomb. Later studies showed that the timescales for said conversion would be tens of thousands to millions of years. But in a way, that is actually a savior to his idea, in that Venus's rocks contain unoxidized minerals. In analogy to the Great Oxygen Catastrophe on Earth that created our banded iron formations, slowly exposed to oxygen, Venus's rocks would weather and sequester the oxygen and deposited carbon. Hot, high-pressure high-oxygen conditions would never have a chance to exist.

Various faster methods have been proposed. A common one is that of the soletta, a thin orbital sunshade. Another is building an "alternative surface", aka propagating floating colonies to the point that they are the new surface - and indeed, below that surface, they could exclude sunlight to the below atmosphere. Regardless of the method, the cooler the atmosphere gets, the lower its pressure gets, to the point that you can start outright precipitating out the atmosphere out as icecaps.

Just like Mars will never have high gravity and probably never much nitrogen, Venus would probably never be fully Earthlike. It would have enough nitrogen that, barring loss to weathering, people would have a constant mild nitrogen narcosis, like always being ever so slightly tipsy. It would remain a desert planet, barring massive influxes of ice (which present their own challenges and problems), or of hydrogen (pre-cooling). But then again, the very concept of terraforming anything has always required one to put on thick rose-coloured glasses ;)

I don't say all this to diss on Mars. But our obsession with "surface conditions" has led us to ignore the fact that if you're going to the extremes of engineering an off-world habitat, having it be airborne is not that radical of an additional ask, esp. on a planet with such a big "fluffy" atmosphere as Venus. If Venus's atmosphere stopped at its Earthlike middle cloud layer, if there was a surface there, nobody would be talking about long-term habitation on Mars - the focus would have been entirely Venus. But we can still have habitats there. The habitat can, in whole or part, even potentially be its own reentry vehicle (ballute reentry), and certainly at least inflate and descend as a ballute (with a small supply of Earth-provided helium as a temporary lifting gas until an Earthlike atmosphere can be produced). Unlike with Mars entry, you're never going to be "off course", or "crash into something" because you got the location or altitude wrong.

(Getting back to orbit is certainly challenging from Venus - all that gravity that's good for your body has its downsides - but the TL/DR is, hybrid and/or air-augmented nuclear thermal rockets look by far to be the best option. Far less hydrogen needed than chemical rockets, far lighter relative to their deliverable payload, only a single stage needed, and in some designs have the ability to hover without consuming fuel. This is, of course, of great benefit for docking with a habitat, avoiding the need for descending rocket stages to deploy balloons and then to dock those to the habitat. The hydrogen and mass budgets involved are totally viable)

If you "sneak" amendments into an agreement, arguably said agreement would be invalid because you were duplicitous which prevented a meeting of the minds.