wumpus

Yep. Maximum thrust. Now plug that thrust into the rocket equation and see how much delta-v you get.

Slightly more in the absolute scale. Hugely more on the relative scale. Which strongly implies that all spacecraft/satellite/whatever damage comes from man-made items whizzing around space.

Prevention: use mylar/Al foil as a screen. Dust particles hit the screen and explode, hopefully into pieces too small to bother the craft. As far as I know, this is already in use. And I'm not sure any craft has ever needed evasive action while going through the asteroid belt (early ones couldn't perform any). If you need assistance finding the leak (presumably by sound), duct tape will work fine. And you probably have the aero-grade tape on board, which should be even more effective. Air pressure will hold it in place, but I'm sure somebody will want a "permanent fix". Said fix will likely lose more air (assuming you remove the patch) than the patch would ever leak out. Also removing the patch may be difficult. It is unfortunate that the only steel hulls I've heard of in space are all stainless steel. Otherwise I'd recommend using a magnet as a short term patch.

I think the real question is how do you decelerate an orbital craft (more likely yet another staged specific vehicle) down to the venusian wind speed, capture the payload from the balloon, and then accelerate back to orbital velocity and dock with the main craft? This at least breaks down the number of stages significantly (and reduces the amount that has to be shielded from the full wrath of Venus's heat) but really doesn't reduce the total delta-v needed. The sample return is a huge addition to the problem. It adds huge amounts of delta-v and requires all kinds of thrust as well. Also fun if you have to deal with the heat of a Mercury approach with virtually the entire ship. As an aside, if you want the entire vessel to see at least 8 planets, you want to launch well before 1972 to get to Venus/Mercury/Mars first. I think the size of Apollo-era guidance computer was a good sized cubesat on its own, and the mechanism to grab a return sample won't be that small (note that "obtaining samples" has been notoriously hard in practice).

Thoughts on 1972 tech: Wasn't that roughly the time the nuclear thermal rocket was grandfathered into the current readiness state? That makes it a lot easier. You really don't want to do this without a NTR. Communications to and from 1972 tech would be iffy. Pretty sure the only reason they can still communicate with one of the Voyager probes is thanks to some extreme (old school) hacking that updated the radio coding. Trying to get put control and communications for the return sample will require a fairly hefty return vehicle. "Return sample". Picking a particle out of a ring of a gas giant is one thing, but if you require a ground sample from Venus you are asking for something well beyond 1972 tech, and likely 2022 tech. Look what has gone into just getting a sample back from Mars, and remember that you have to sample and return almost immediately to your entire rocket melting. You also have scaling working against you (see the fun in landing on Eve in KSP), so will need a significantly bigger rocket than the smaller (pre-1972) rockets used to escape Earth's atmosphere. I'd also assume that such a rocket would have to be hypergolic (how are you going to keep cryogenic fuel liquid during the descent and ascent on Venus)? Which means a huge amount of hypergolics launched from Earth (try to sneak in before the clean water act...). Calculating the trajectories: pretty sure you are limited to patched conics, just like KSP. The fancier orbital tricks (interplanetary highway) wouldn't be discovered until later, and your most powerful computer available is the CDC7600 (Cray 1 was 1975). 34MHz, less than 4M (Meg, not Gig) of RAM, 10MFlops.

In the space race, there were hard deadlines. You couldn't get the customer to make changes and then bloat the time and materials budget changing them left and right (exception that proves the rule: there were massive changes after Apollo 1, but the deadline didn't move). Also there was still competition among defense contractors. The contractor who let us lose to the USSR would not be popular in getting massive Congressional handouts. I'm less sure about blaming NASA management. Most of the big disasters (budgetary and literal) are in the high profile cases that brings excessive congressional oversight. The low visibility missions seem to work much better. If management works better with less micromanaging, I'd have a hard time thinking they are the problem (unless the problematic managers all get themselves promoted into high visibility roles, a common problem for any organization as it scales up).

Sustainer stage reuse was routine from 1981-2011, albeit with extreme refurbishing costs. And the 50-66% almost certainly isn't just the rocket, the upper stage has a single engine (10% of the engine costs) and far less mass (not to mention fairing reuse). 30-40% of those costs have to be in the launch, with the army of highly trained professionals launching the thing, not to mention all the costs bringing the booster back and various tests needed. Much of the key to the success of Falcon 9 reuse is that the booster doesn't get anywhere near orbital velocity. So it doesn't need a heat shield (although it does need a back-burn) and all the issues the shuttle had with tiles (as far as I know, Starship is using tiles as well. Different tiles, but they couldn't find a better solution even with the warning of Shuttle experience.

The SSMEs provided 1,180,000lbs of thrust for ship weighing 4,480,000 lbs (the SRBs provided most of the thrust). I'd recommend the RD-170s instead (or a new methane engine). Sure, the SSMEs are refurbishable, but that really isn't going to happen with SSTOs. SSTO with reuse is significantly less in reach (so much I keep telling Spacescifi that he needs "magic" Isp to do it). Getting the SSTO to orbit requires significant rocket science. Getting it down so it can fly again requires much, much more. Neither the means of surviving re-entry nor the means of landing can be done without adding mass. And the current state of the art requires a lot of mass, especially for the landing. You're arguing that just getting to orbit (with some payload) is possible but hardly showing any way to land the SSTO. Without reuse, SSTO makes no sense. If you are throwing away the rocket, what good is it to throw it all away at once as opposed to in pieces? You'll always have more payload and less rocket required with TSTO. And with reuse it is currently impossible.

SSTOs can reach orbit. But you have to subtract the weight of all the launch engines (that provide a TWR>1, so a lot of mass) as well as all fuel tanks that could be discarded in a TSTO. At least one TSTO rocket can recover 90% of the engines and 90% of the mass of the (empty) rocket. At least one TSTO rocket in production should reach 100% for both. SSTO can carry minimal payload (if that). They certainly don't allow for the mass of a heat shield to cover the entire (massive, if any significant payload is considered) rocket, nor any means of landing. The "means of landing" is critical: Falcon 9 stages need to be around 10% full for recovery. Try to find a SSTO that has a payload anywhere near 10% of its total mass, and try replacing it with fuel (and don't forget the mass of the heat shield). So SSTO is only considered for expendable rockets where payload is not a consideration, nor the extra cost of the overpowerful engines needed to lift the silly thing into orbit. And they will inevitably be much more expensive for the same payload as a TSTO. Sounds like a NOGO for the foreseeable future.

To be honest, the original question can be answered with some physics and roughly a single guessable parameter. Step 1: figure out just how powerful "navigational shields" are. These shields have to withstand constant bombardment of various particles (electrons, protons, alpha particles) hitting the ship at nearly the speed of light (granted, we really don't know how fast federation ships go before they switch to warp drive. Perhaps the aren't impressive). Step 2: guess how much stronger "shields" are than "navigational shields". It should be fairly significant. Step 3: calculate how many particles would hit the shield and what their energies are. Since a 25th century craft should survive a 20th century attack (surely the klingons/romulans/borg/villain-of-the-series have access to nukes), you really can use this to establish a lower bound for how much stronger "shields" are than "navigational shields".

A lot would depend on whether you could get ink to copy from bronze/clay/whatever to papyrus. It would be a lot easier in Mesopotamia as they wrote on hardened clay (unfortunately I think Summerians/Babalyonians cuniform would require too many stamps, Egyptian might have worked). In fact, there was at least one Greek artifact (a vase? some sort of pottery) that appears to have text on it that was printed via individual stamps. But just one such piece of pottery, and didn't seem to take off. Don't underestimate the complexity of moveable type, it took a lot of modifications to get from the wine press to moveable type (check the length of time between the Chinese "whole sheet" printing press and the Korean "moveable type" press). Some of this may be exaggerated: I remember reading that the printing press required special ink, but it sounds almost identical to scribe's ink. Maybe the proportions changed? Was there ever a case where that wasn't suicide? There was one such attempt in the US civil war. The Captain kept the hatch open to see what he was attacking, and the resulting wave sunk the boat.

The point of "battleships" was the construction of thick armor plating. Building that pusher plate would take relearning some lost skills. The size of the thing wouldn't matter, except that you'd presumably make it in Antarctica (or possibly build it on a barge and tow it to a soon-to-be ice free arctic summer).

Anything deeper into star trek tech pretty much leads to bad TV show tropes. The writers just write "tech the tech" and the science consultants fill in reasonable/consistent technobabble. No idea if they've burned away too much good will away to keep this up at a high level. http://www.bryanreesman.com/2009/10/09/captain-picard-the-tech-is-overteching/ Focusing on the technology is pretty pointless. Society and maybe weird fundamental bits of science make more sense. And one thing I learned from a fairly deep study of the history of science and tech (not to mention watching more of it happen than I care to admit) is that "inspired inventions" aren't the key to technology. Technology depends on the infrastructure. "Steam engine time" is merely the condition of having enough infrastructure to support steam engines. If you don't have it, it doesn't matter how good an engineer Hero of Alexandria was. You don't get steam engines other than toys.

Domestication was a long process. Some have speculated that the cat was the first domesticated species, which more or less "self domesticated" by hunting mice around granaries. The cats that tolerated humans being close were more likely to thrive in such places, outcompeting more human-averse strains. On the other hand, dogs were likely domesticated pre-agriculture (wolves, like humans, are persistence hunters see Joe's first notes. So wolves were much more useful for less agrarian people), although humans lived using both technologies (direct food production and hunter/gathering) for a long, long time. Often with peoples shifting back and forth over the years. In either event, starting with an easier animal lead people to try to domesticate anything that appeared useful. There is even a painting from ancient Egypt (presumably from a temple/pyramid/tomb) of somebody attempting to train/domesticate(?) a jackal.

It is an interplanetary (allegedly interstellar) craft of massive size that can be constructed with 1960s tech (might even be a bit harder now that everybody who has ever built a battleship is easily 90+ if not dead). What more do you want? Catches are that it requires a large number of nuclear explosive devices (the smaller the craft, the smaller and more numerous the nukes), and that thanks to a mistake in ignoring the magnetosphere, the original calculations for safety only work if you launch/build the thing in Antarctica (otherwise all the "fallout" comes back to Earth and lots of people die). Great book on the subject: https://www.goodreads.com/book/show/21243.Project_Orion

Not sure why North America was spared the horror of neolithic cities (outside a few short lived places). Presumably huge swaths of land had abundant food, unlike the narrow fertile valleys civilization first grew in. The catch was once farmers monopolized the region, the shear number/density of farmers could fight off hunter/gatherers trying to live off the farmer's land. But presumably there were small patches of fertile land in Aztek/Mayan lands, and presumably farming terraces was the only way to produce food in the Andes. So those areas it was possible to force nearby people to farm, but less so in North America. But there was certainly plenty of farming: I'm pretty sure the pilgrims would have died out had they not been able to squat on fields cleared by a native population wiped out by smallpox. Corn was already widespread (native to and cultivated in what is now Mexico). No idea what percentage of food came from farming, and one alleged real motive for farming [scrubbed by forum rules] wasn't known above the Rio Grande. And it wasn't just idiotic hard to be a farmer in neolithic times. Plenty of people simply left "western civilization" and "went native" with the nearby tribes (presumably starting with Roanoke). Between taxes, interest, and other middlemen fees the hunter gatherer life was particularly attractive at least until the mid 19th century (which coincided with all current hunter gatherers confined to some of the least fertile parts of the USA). And ironically enough, horses aren't the only way for "hunter gatherer societies" to mass enough warriors to defeat farming societies, the Vikings managed to locally mass warriors in huge numbers by longships. I think the big catch is that Lief Erikson's crew in the Vineland Saga was more a farming/trading/brewing mission than a full out "Viking raid", so the locals were able to deliver themselves from the "fury of the northmen", while all the monasteries of Europe (at least nearby seas and rivers, although they nearly took all of England) were praying "from the fury of the northmen, deliver us oh Lord".

When has SLS/Artimis *not* been open ended? And won't Boeing have to design a "new" SLS, then build it for Artimis 3? That sounds more like a decade at Boeing's pace than a year.

The only pre-Columbian method I've heard of to hunt buffalo was to spook them and get them to charge off a cliff. It took horses and later muskets/rifles to even the odds. Pretty sure there aren't any cliffs near St. Louis. Don't underestimate the size of the herds either. A fairly large herd could outnumber even ~40,000 native americans, although they might only gather this large in rutting season (not enough scientists out west before anti-indian policy demanded the [near] extinction of buffalo). Best guess is that they *did* hunt the buffalo. But I'm curious how they did it pre-horses. Maybe they drowned them in the Mississippi (or there is a cliff nearby) and after a few centuries the buffalo learned (and Chokia faded).

It is always suspicious that sudden extinction events always seem to happen when humans show up. And those humans presumably killed the mastodons and mammoths with nothing more than Clovis* tools, rarely if ever dying even if hunting such obviously dangerous game (the groups simply couldn't survive losing many hunters at all). Don't forget Cahokia had a population of ~40,000 (presumably at peak). Probably had to both fish the Mississippi and grow corn. What I'd like to know is how they kept the buffalo (bison) out of the crops? Those herds were immense, and a little fence wasn't going to stop them. Andes (and Mexican/central American) culture might have resembled bronze/iron age civilizations, but if such cultures existed in North America, they didn't survive smallpox (or died out earlier, like Cahokia and the Anasazi). * not sure about the state of pre-Clovis artifacts/evidence. Wouldn't be surprised if an earlier wave had wiped out the other megafauna and it wasn't until the arrival (or development of) Clovis people/tech that the locals could hunt/wipe out the mastodons and mammoths (and thus have the food for the population to leave evidence of their passing).

Extreme? Sounds more like sane, with a slight improvement on what the French have been doing for decades.

But is it "exposure to air is an immediate danger" for all 10, or would it be possible to have two levels of pools. One built to "nuke standards" (to prevent any leaks that might cause the fuel to go critical) and one for economical efforts.

The question implies that all functions are going to be done close together. Current practice appears to ignore it. Launching rockets: you typically want coastal areas as close to the Equator as possible, with clear ranges west and south (if you focus on southern routes, lattitude matters much less). Elevation would be a plus as well, but only if you are free to crash things west and south of you. Constructing rockets: You want areas more tolerant to "overpressure events", probably less densely populated. Local wages are likely less important than most other industries, as you want highly specialized labor and might have to relocate a good chunk of you workforce. Designing rockets: Geography becomes irrelevant (except if you have send your people to the other two sites regularly). Labor is even more specialized, and probably found in big cities. College towns might also be preferred, as you presumably can get your highly educated workforce to move there and often have a lower cost of living. Other considerations: Since rockets, like airplanes, run on money you might want to locate as many of the above in political districts that like to shower rocket companies with pork/tax breaks. This starts out huge as any fundraising angle is critical, and a successful rocket program will almost certainly make plenty of lobbying connections.

Leaving the rods in water makes a lot of sense for the first several years after they've been decommissioned. It allows the worst stuff with the shortest half lives to decay, and has limited effect on the water. I have know idea if there is ever a point where you'd want to transport the stuff *then* put it back under water. Don't forget to have enough electricity for vitrification (see below) when you fish them out for good. It might make sense to have two (or more) levels of storage pools. Start them in highly secure pools that can survive earthquakes and artillery and later (once they can be left in the air with minimal issues) move them to pools closer to normal swimming pools After that, vitrification is your best bet, presumably including (semi-accessible) underground storage. Vitrification turns the stuff into glass (or crystal), and thus makes erosion issues *much* slower and less of an issue. Making it less accessible to modern humans might be needed from a proliferation standpoint, but there's always the issue that you are locking up the fuel supply needed by future generations. Sure, vitrification takes a lot of electricity, but is typically done with a handy nuclear plant nearby. https://mo-sci.com/vitrification-nuclear-waste-management/

Pressure is irrelevant, there is no conservation of pressure. Momentum is the key, and is pretty much set for each photon. And since the energy =hc/λ and momentum = h/λ, it shouldn't matter what wavelength you are emitting, you get the same (tiny) momentum per Joule of energy. And while this might maximize the Isp of your starship, the energy efficiency isn't going to enough to make it a good choice.

I think that's the whole point of going to Stanford (previously Harvard). Lots of money gets thrown around to all sorts of startups.