NERVAfan

If it were performed entirely by NASA, developing all the hardware from scratch, like they did for Apollo? Probably yes. If someone (NASA or otherwise) paid a comparatively "lean" private company or group of private companies (like SpaceX) to do it, that would be entirely different. And I don't know how much overhead the Chinese space program has.

OK, thank you. I did mean in-flight, sorry.

I don't see why it should. If the lunar lander (and service module if it exists) use storable propellants (which seems likely as Draco/SuperDraco do and it would probably save development just to use a SuperDraco for the lunar lander), why can't they wait in orbit for a month or so before the crew/Command Module arrive? EDIT: And making new pads would be expensive, but SpaceX is doing it now and I doubt they have more than a couple of billion at the absolute outside to spend. We're still talking enormously cheaper than Apollo.

Can you, actually? I've read that jet fuel is too variable for rockets, though that book was talking about the situation in the 50s/60s when orbital rockets were first being figured out - maybe modern jet fuels are more uniform in composition? Theoretically, they could also increase the atmospheric pressure (and thus density) or gravity at Kerbin's surface... I doubt they would, though, since that would break the Earth-analogue nature of Kerbin.

Using mass-inefficient fuselages/tanks makes sense, though. A NTR using pure hydrogen would have much more volume per mass of propellant than even a hydrogen/oxygen chemical rocket, much less a hydrocarbon/oxygen one.

I bet you could to something like that with 3 Falcon Heavy launches once FH is flying, and use commercial crew Dragon for the Command Module. You'd have to develop a totally new lander/lunar module still, though, and improve Dragon's life-support endurance and probably communications and delta-v capacity (or give it an outright Service Module). I think it would still be vastly cheaper than Apollo though. Apollo had to develop pretty much everything from scratch. Dunno how much it would cost for SpaceX to develop a lunar lander, but they seem to be good at doing things cheaply.

Actually I never ever used an OKTO2 for anything because it was so thin that it was hard to click on successfully in the VAB (when I wanted to move the whole ship). The formerly (I think) 0.01 ton difference between it and the much bigger Stayputnik was never worth the inconvenience.

Can you connect two docking ports of different sizes, like a 1.25m (regular) and a 2.5m (Sr) one? Also, how do you release something from a cargo bay? It seems to just stay in when I open the bay in space (this is still 0.25 if that matters).

Yeah the ship design is probably the most realistic interstellar ship ever seen in a major movie.

Also, a rocket that could reach 100km would probably be more expensive and certainly much more difficult than a cubesat.

SSTOs are pretty borderline on Earth - even the small advantage from Venus's lower gravity makes a big difference. (I'm pretty sure you could do an SSTO quite easily with engines with Merlin 1D's TWR and the old Atlas' balloon tank construction. It would just have less payload than a F9 so not much point... and the structure would probably be too light to re-use so F9 is probably cheaper in the long run.) I think balloon launchers would work just fine on Earth, the advantage over regular launchers just isn't big enough to be worth it. If you leave your earth return vehicle in Venus orbit, you wouldn't need the rocket to be all that big - you could use a quite small capsule since you'd only have to be in it just for launch and docking. F9 can launch Dragon (which can carry up to 7 people IIRC) on Earth, so you could use something significantly smaller to launch say a 4 person capsule on Venus. Sulfuric acid has hydrogen in it - H2SO4 - and there's more of it. (You don't necessarily see it listed on the Venus atmosphere composition in the same way you don't generally see water vapor listed for Earth -- because it's so variable, whereas all the other gases are very well mixed so the composition is quite uniform up to very high altitudes). I don't see any real point to mining on Venus. If we ever have a permanent colony there -- not just a temporary mission or an ISS sized outpost -- we will probably have asteroid mining by then anyway. I don't know about that. Do we have any good pictures of what it looks like at the 50-55km level? It might be more like "luminous clouds" than "murky haze" - remember the sunlight is 2x more intense at Venus' distance from the sun.

I don't think it's quite that clear-cut, but there definitely is an argument in that direction -- but only a long-term human presence would make the difference, IMO, flags-and-footprints probably won't (just as Apollo didn't). Right now there's very little funding because politicians don't consider space important. A long-term human presence might change that if it was seen as important by the public (part of the problem of Apollo IMO is that the goal was stated as just 'get to the moon' so there was no clear direction after that was achieved). So there is not a "zero-sum" fixed amount of money available to space stuff that can be applied either to manned or unmanned projects. Politicians will never value unmanned missions very highly unless, perhaps, they relate clearly and directly to a near-term goal (not "people on Mars by 2040, maybe" but something like Apollo's "this decade").

The winds are mostly east-west, though; staying on the equator shouldn't be difficult. According to this article there is zero north-south wind at the equator and a max of 10 m/s at 50 south latitude. It talks about slow (daily up to multiple years) changes in wind speed, but it's not clear to me if there are brief (minutes or seconds) and local (on the size scale of a big airship) differences, which are what would matter for this purpose. http://sci.esa.int/venus-express/51937-super-hurricane-force-winds-on-venus-are-getting-stronger/ Yeah the balloon would have to be made out of something nonreactive to sulfuric acid. But there are some plastics that can do that. (And I think more depending on how strong the acid is - Venus's cloud droplets in mostly CO2 would probably be a less harsh environment than total immersion in concentrated sulfuric acid.)

True... but it would be a lot easier if people didn't make the nuclear regulations quite so insane. Uranium itself is not THAT bad... it's toxic (like other heavy metals) and radioactive, sure, but there are many chemicals used regularly in industry that are vastly more dangerous (EDIT: and yet much less regulated). (Fission products are vastly more radioactive, but they aren't involved in the mining or refining... though there are some decay products in uranium ore. IIRC it's not all that much, though.)

Yeah, that's tiny on a planetary scale. I don't think solar is necessarily a good idea for cloudy high-latitude countries like the UK. We're talking about converting the entire world energy infrastructure; no matter what you do, it'll pretty much be a megaproject. I don't think water vapor is "a much more capable greenhouse gas" at least in the current situation. These things are situation dependent; when you have a tiny amount of a particular greenhouse gas, every little bit has a big effect. When you have tons, most of the radiation at those wavelengths is already absorbed, so adding a little bit more is insignificant. Adding 300 ppm CO2 would have a huge climate effect on Earth; it would be nothing on Venus. Most of the Earth's greenhouse effect is due to water vapor, but there is way more water vapor than CO2 in the Earth's atmosphere. I don't know - and I'm not really sure that anyone does. There is more than one kind of photovoltaic cell - which kind? Silicon? Ga-As? That probably matters a lot? Oh, I wasn't actually suggesting one giant megaproject. The comment about fitting in Nevada was just to illustrate that it's a tiny amount of land on a global scale, not that we should actually put all the world's power production in Nevada. I actually don't think solar-only is a good idea... it doesn't work well for high latitude countries with very little sunlight in winter, and for very cloudy areas. I personally would favor a combination of nuclear and solar, plus biofuels as a carbon-neutral fuel source to make up times when the solar isn't producing well and for applications where high density is important like aviation fuel.

Well, I would say "NASA is too risk averse" rather than that going to Mars is too risky. I don't think it would be unreasonably risky for exploring someplace totally new. Well, yes. IIRC one of the main points of ISS is learning about long-term human spaceflight (theoretically as a preparation for Mars or whatever, though we don't really seem to be moving in that direction). The other (probably the main point, at least for the politicians in charge of the funding) is as a demonstration of working together with other nations (especially US/Russia in the post-Cold War era). The actual science experiments are kind of an afterthought AFAIK.

The point of human spaceflight isn't purely science. Maybe not even mostly science. I think exploration has value as a human activity beyond pure science. And I'd argue that if there weren't humans in space, there would be much less human interest in space and thus less money for space science too. If there was no ISS, there's no realistic way politicians would spend all that money on science missions instead. I think one of the reason Mars gets more missions (disproportionately, according to some people) while Venus has relatively few is that we think of Mars, but not Venus, as a likely next destination for human exploration. If there was zero chance of humans ever going to Mars, there'd probably be less interest (and thus eventually less money) for Mars science.

I think "disinformation" is harsh. It's a case of the distinction between "survive" vs. "live actively" getting lost when the research gets publicized. That distinction is pretty common. E.g. for hyperthermophiles they distinguish between the temperature it can grow and reproduce at, and the temperature at which it merely survives. (But, as GregroxMun says, no Earth lifeform is adapted for surviving vacuum - tardigrades are just using the same mechanism they use to survive desiccation etc., IIRC. No living thing could live entirely or indefinitely in vacuum since it would have no way of replenishing its resources, but temporary active life is probably possible with enough selective pressure or genetic engineering.)

The scenario as given isn't limited to natural evolution, so yeah, I think active life in vacuum is quite possible... for a while anyway. The main reason conventional Earth life can't survive in vacuum is that a) it needs to breathe and as part of that need to breathe, the lifeform is constantly "open to" the surrounding air or water, so when exposed to vacuum, it loses what it does have (in the case of a human, not only are you not getting any new oxygen, you actually lose oxygen). So a living thing that could close itself out from the ambient environment (IE airtight shutters over eyes/nose/mouth/etc equivalents) could survive and be active... until its stored oxygen (or whatever it uses, for an anaerobic species) runs out. (This could be quite a while, some whales can go over an hour on air stored in their lungs, and I think some underwater reptiles may be able to go even longer...) There are other secondary problems but with the same level of 'directed evolution' that could be handled too. UV exposure is probably the worst ... have the outermost level of skin and the 'shutters' be opaque to UV and made of non-living tissue, like hair or bark, so the skin isn't itself killed.) Pressure difference... I'm pretty sure a tough skin could be developed that could hold at least 1atm pressure difference... proteins can be very strong (eg spider silk). Human skin exposed to vacuum doesn't actually rupture, just swells up hugely (though lung tissue can rupture... that's why you need the shutters). If our skin was reinforced with a web of thick spider-silk-protein strands every tenth of a millimeter or so... (Also, you could probably get away with an internal pressure much less than 1atm... birds can fly very high, and they've got to be pretty much equalized with the outside pressure. A Ruppell's vulture collided with an airplane at 37000 feet, and the pressure there is ~0.21 atm.)

Mercury bigger than Gemini? Are you sure? (Googling "Mercury habitable volume" I get 1.56 m3 and 1.70 m3)

This is why you need cellulosic biofuels. Grain crops throw away most of the plant (stem/leaves), if that could be converted to biofuel... (it can, but it's not industrial-scale yet, IIRC).

Actually, not quite; if the rover has a sharply limited lifespan, a short communication loop lets you get more done/make better use of the time. Is that such a difficult problem? Sulfuric acid is a well-known industrial chemical... I think protection against it is well-understood. The dirigible envelope itself (which needs to be light and might be plastics that would have trouble outgassing in vacuum) never needs to be exposed to vacuum, so being in space shouldn't really matter.

Right Yeah, undersea machines deal with pressures like that (1 atm is about 10m underwater, so that's about what you'd get 1km down in the ocean). Exactly. Well, there was a recent wind power proposal for Venus rovers. Wind speed at Venus's surface is low but the high density of the atmosphere means it has significant force.

There are tons of resources in Venus's atmosphere! It has the major elements (CHON) necessary for life (carbon and oxygen in carbon dioxide, nitrogen in nitrogen gas, hydrogen and oxygen in sulfuric acid), so you can make water and breathing air. These are also the elements needed to make many plastics. The only thing that can't be practically gotten at is minerals/metals, but if you were talking about building something on the scale of a permanent city, realistically we'd have an asteroid industry by then, which could complement the Venus city's gas extraction. As for things to gain... Venus' atmosphere is very much worth studying in its own right. Sure, you can't pick up rocks, but that just makes this a meteorology mission rather than geology. There's a mysterious unknown substance in Venus' atmosphere that absorbs UV, and a bizarre cold layer, etc. (And there might even be microbial life in floating droplets...) On the other hand, the pressure outside is Earthlike, so that a pressure loss will be slow and give you plenty of time to work on it, rather than rapid and quickly deadly. The hurricane level winds aren't necessarily a problem for a balloon since the balloon is moving with the wind - only relative speeds matter. The question is how uniform those winds are. Launching a rocket from the air is an existing technology - the Pegasus rocket does it. Launching from balloons is well-known too, lots of sounding rockets were done that way, though nothing orbital IIRC. Protecting stuff from sulfuric acid is also well-known technology. There's a lot they could do, they'd just be doing "lab" things analyzing the atmosphere etc. not "field geology" things.

Actually that land use doesn't sound that bad for powering the entire world - 24.4 million hectares = 244,000 sq km is smaller than Nevada and only a tiny fraction of the world's land. As for the water... does it have to be pure or fresh water? That amount would be nothing if you could use salt water. As for the molten salt... that might be an issue, I don't know what total world production of nitrates is like. OTOH there are other ways to store energy eg pumping water uphill. The water vapor shouldn't make much difference, it's tiny in comparison to what evaporates from the ocean.