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Comment Re:Titan or Bust! (Score 1) 54

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.

Comment Re:Titan or Bust! (Score 1) 54

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..

Comment Re:Titan or Bust! (Score 1) 54

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.

Comment Re:Starship (Score 1) 26

Using an expendable cargo version starship, including a small rocket for launching the samples to orbit would be possible. That would also fit in with what SX wants. From there, ESA's return rocket would be able to bring them back. And this could be done in the next couple of years assuming that SX gets Starship done this year.

Comment Re:Titan or Bust! (Score 2) 54

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)

Comment Re:power (Score 2) 54

Titan's atmosphere is rather calm; not an issue. At the surface, the winds measured by Huygens were 0,3 m/s.

You actually can use solar power in extreme environments - even Venus's surface has been shown to be compatible with certain types solar, though you certainly get very poor power density. Dragonfly, as noted above, uses an RTG.

Comment Re:Second flying drone to explore another planet (Score 3) 54

Planetary scientists frequently refer to moons that are large enough to be in hydrostatic equilibrium as planets in the literature. Examples, just from a quick search:

"Locally enhanced precipitation organized by planetary-scale waves on Titan"

"3.3. Relevance to Other Planets" (section on Titan)

"Superrotation in Planetary Atmospheres" (article covers Titan alongside three other planets)

"All planets with substantial atmospheres (e.g., Earth, Venus, Mars, and Titan) have ionospheres which expand above the exobase"

"Clouds on Titan result from the condensation of methane and ethane and, as on other planets, are primarily structured by circulation of the atmosphere"

"... of the planet. However, rather than being scarred by volcanic features, Titan's surface is largely shaped..."

"Spectrophotometry of the Jovian Planets and Titan at 300- to 1000-nm Wavelength: The Methane Spectrum" (okay, it's mainly referring to the Jovian satellites as planets, but same point)

"Superrotation indices for Solar System and extrasolar atmospheres" - contains a table whose first column is "Planet", and has Titan in the list, alongside other planets

Etc. This is not to be confused with the phrase "minor planet", which is used for asteroids, etc. In general there's a big distinction in how commonly you see the large moons in hydrostatic equilibrium referred to as "planets" and with "planetary" adjectives, vs. smaller bodies not in hydrostatic equilibrium.

Comment Re:Titan or Bust! (Score 3, Informative) 54

Why?

NASA's obsession with Mars is weird, and it consumes the lion's share of their planetary exploration budget. We know vastly more about Mars than we know of everywhere else except Earth.

This news here is bittersweet for me. I *love* Titan - it and Venus are my two favourite worlds for further exploration, and dragonfly is a superb way to explore Titan. But there's some sadness in the fact that they're launching it to an equatorial site, so we don't get to see the fascinating hydrocarbon seas and the terrain sculpted by them near the poles. I REALLY wish they were going to the north pole instead :( In theory they could eventually get there, but the craft would have to survive far beyond design limits and get a lot of mission extensions. At a max pace of travel it might cover 600 meters or so per Earth day on average. So we're talking like 12 years to get to the first small hydrocarbon lakes and ~18 years to get to Ligeia Mare or Punga Mare (a bit further to Kraken Mare), *assuming* no detours, vs. a 2 1/2 year mission design. And that ignores the fact that they'll be going slower in the start - the nominal mission is only supposed to cover 175km, just a few percent of the way, under 200 metres per day. Sigh... Maybe it'll be possible to squeeze more range out of it once they're comfortable with its performance and reliability, but... it's a LONG way to the poles.

At least if it lasts for that long it'll have done a full transition between wet and dry cycles, which should last ~15 years. So maybe surface liquids will be common at certain points, rare in others.

Comment Yes and no. But mostly yes. (Score 1) 299

For the last 40 years, china has been at work destroying manufacturing foreign nations (which is a big part of why they are the world's worst polluter of all times).
They are somewhat copying Japan's and S. Korea's approach to their build-ups. Basically, high tariffs, heavy subsidies, then once up to par or better then others, heavy exports after dropping subsidies. The difference is that when China gets to the last part, they continue to subsidize, and the government makes heavy use of controlling the companies exports, manufacturing capabilities, etc. which are then dumped so as to destroy foreign, esp. western, industries. Steel is just one of many.

What is needed is for nations to say enough is enough and to raise strong tariffs or even block ALL imported items from China that are being dumped. For example, nations really should block ALL metals that China is trying to import directly or indirectly. Likewise, I was surprised that Biden was stupid enough to relax the PV imports from Chinese companies that simply moved to Viet Nam and other Asian nations on moderate terms with China. All of that needs to be 100% blocked.
Likewise, the batteries need a growing tariff, and to block them from manufacturing in the west, if not other nations esp with their dirty/corrupt supplies ( most of the child labor issues and low pay comes from Chinese-owned mines; this is why China and Russia are pushing coups in Africa ).

Comment Oh, well, change :) (Score 1) 22

Every change looks like corruption in the eyes of people who don't like it.

And corruption looks like evolution to some people.

Personally, I'm in favor of words meaning as much of the same thing over time as possible. It enhances communication and understanding. If you need a new meaning, you either need a new word or you need to explain yourself at a bit more length. Lest you "decimate" (cough) the listener's/reader's understanding... you get me?

Comment Re:I would even ban cruise control (Score 1) 86

I find cruise control a blessing on long drives. I can concentrate on other things, like the environment around me. Speeding tickets are also a non-issue.

My last rental car (in Texas for the eclipse) had adaptive cruise control, which I really like. I've looked in to retrofitting this to my own car (a 2016 Golf with dumb cruise control) but decided it's not worth the hassle. It also had lane assist. This showed me what it would be like to drive with an autopilot, though if it got angry with me if I took my hands off the wheel for more than 10 seconds. Nevertheless, I see the attraction.

...laura

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