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wumpus

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Everything posted by wumpus

  1. While the microbes may be mutating quickly, I'd also expect the ISS to leak to vacuum within a year or so without supplemental air. Between the Van Allen belts and the vacuum, I doubt the "new improved" microbes will avoid extinction. I also can't imagine anyone bothering to lift it to significant orbit, or maintain its orbit until such is a possibility. Although it might make an excellent test/demonstration of any high Isp thruster (I think that there was a dropped plan to add VASIMR a few years ago. Perhaps it would be easier to stick them on an uncrewed ISS).
  2. While that was the agreement during the first flight, NASA has relented and allows reuse. https://spacenews.com/spacex-to-reuse-dragon-capsules-on-cargo-missions/ https://spaceflightnow.com/2020/06/23/nasa-agrees-to-fly-astronauts-on-reused-crew-dragon-spacecraft/ [no idea of the quality of the links, but I'm pretty sure I'd heard they were re-using them for cargo].
  3. While this doesn't apply to SpaceX, I have to wonder just how much the semiconductor example I used for "manufacturing where 10% failures would be a godsend" will apply to the companies that are 3d printing entire rockets. The main reason that yields are what they are in semiconductors is that there is simply no way to test a chip from the moment the wafer goes in the fab until the chips are all baked on the wafers (before they are sliced and diced). 3d printing will have a similar issue, and probably require some sort of constant visual inspection, with likely other forms of RF (X-ray?) inspection done during printing.
  4. I'd assume that they test tanks before putting them in in rockets. Blowing up 10% of their rockets would be odd, but once they committed to mass producing rockets this became an option. Since nobody else is mass producing rockets (including the Falcon 9 line), this would be a disaster anywhere else. Anyone who can get Intel's 10nm process (allegedly in production since 2018) to 10% failure will immediately be made a senior Intel fellow (it was likely 90% in 2018). I'd be impressed if the old workhorse 14nm++++++++ process fails less often than 10%, certainly TSMC's competing 7nm process isn't 10%. And those are shipped as Intel's main product. Not that I could imagine a company surviving building 11 aircraft for every 10 it shipped, but in rocketry I'd have to expect that most of the costs are NRE. This certainly helps Soyuz (all development costs are long since paid). Blowing up 10% of rockets is hardly unknown, although typically that happens in flight. Spacex lost the first three Falcon [1] flights, than had 21 successful flights (for the primary payload, if not the secondary). Then they blew up another spacecraft, making sure that they wouldn't get below 10% failure rate before Falcon 9 launch 40 or so. If 10% of your aircraft failed, not only would heads roll over the costs, I'd assume that it would be a safety issue worse than the 737MAX fiasco. With all the flights everyday, sooner or later you'd see the same thing with crewed flights. With new rockets, failure is to be expected and if you *aren't* losing a few you probably have far too much margin. Crewed flight is different, and also some markets have unbelievably expensive cargo. Hint, hint ESA, don't blow up Weber.
  5. That appears to be an overstatement. Any input from the spysat people was *extremely* limited (although NASA does have a spare keyhole lens/mirror). I remember a letter in the WashingtonPost from an alleged NRO (or whoever was in charge of the spysats in the late 1980s) whining that APL (who built/ran Hubble) didn't listen to suggestions that differential heating might be a problem. Note, apparently anything more was far to secret to tell them, and APL was only interested in real data. So Hubble had this issue when it transitioned from sunlight to "night" (no idea of the long term effects). You can certainly say that the Shuttle payload bay was sized to fit the spysats (KH-11) and Hubble was designed to fit the payload bay, so there are a lot of similarities. If they used the real (at that time extremely secret, but anyone who know the size of KH-11 and a little physics new what they were up to) secret tech from the spysats they wouldn't have needed most of what Hubble could do.
  6. Do all these manufacturing companies have the mass margins of space? Sure, Boeing might take mass in their airplane business as the strictly space bit of aerospace, but it makes a lot of sense to push the process as far as it would go. Elon might decide that if you don't blow up 10% of your tanks you could easily save a few kg. Granted, part of this is thanks to using stainless steel as opposed to carbon. Not sure if it would be worth it with carbon tanks. I think sometime in the 1990s, silicon chip manufacture finally got yields (100-failure rate) from around 30-40% yields to somewhere north of 80%. I wouldn't be surprised if modern yields have been creeping back down (they are some of the strictest secrets in the business). You really want to compare apples to apples (although your experience with aircraft is probably closest). If they wrote that, then I'm guessing that the EPA regulations are designed to be impossible to not to pass (but will generate paperwork that will require the EPA to be continually funded, especially in the districts of powerful congresscritters). According to the links below, that's the annual CO2 output of ~3,000 Americans. Since they employ ~10,000 Americans, it seems hard to claim that they are emitting "too much" (compared to all other US companies). https://www.macrotrends.net/countries/USA/united-states/carbon-co2-emissions confirmed here https://ourworldindata.org/co2/country/united-states
  7. I'm all but certain that the R7 was sold entirely as an ICBM. Deploying satellites was likely something Korolev didn't even try suggesting until the Americans suggested launching a satellite and he could point out the benefits of beating them to orbit. Few countries have science budgets that approach the war budget, and none of them are space-faring. If the Soyuz engine is so superior, why haven't later engines used such a design? It seems to be in the "too good to ECO, not good enough to use elsewhere" region. In many ways, that isn't all that lucky. Also SpaceX's luck seems to center on how deep the Merlin can throttle, if it was half as strong it would require nearly 18 engines to lift off (ok, maybe 15-16 since the first Falcon9 went to orbit on 8 engines). Musk seems to think that the difficult/critical tech is in mass producing something, not what you can build a one-off in the lab. Probably learned that the hard way with the Telsa model 3. See the Everyday Astronaut interview (probably end of part 2 or in part 3).
  8. Just to put these volumes of questions in perspective, does anybody know the percentage of space science fiction readers that have/haven't played KSP? I'd think that a significant percentage of them have, and it teaches the rocket equation even more thoroughly than orbital mechanics. For those who have played enough to get into orbit, you would be better off having the characters teleport to Mars (or wherever) than a SSTO. Replacing SF with magic somehow is a lot easier to get away with than amazingly bad science. The most critical thing about space travel is always mass. This is the decree of our most tyrannical overlord, the rocket equation: Vdelta=Isp*ln(Mf/Me) So the big heavy engines increase the dry mass of the rocket. And don't forget that if you are lifting civilian passengers, you probably don't want excessive g forces, so maybe 2 gees top (don't forget to add gravity, and do you really want to experience weighing three times your current body weight)? So you'll waste 33% of the thrust and 33% of the fuel until you start going sideways. Expect to require even more "magic Isp fuels" than the typical "magic fuel" needed for SSTO. And don't neglect where all those neutrons are going if you are using fusion or something. Not to mention that I, as a regular on this forum and vastly more interested in the internals of jet engines than the general public, recently flew commercially and my only thoughts about the engine on said plane was to be glad it was a turbofan instead of a turboprop (a commuter flight between two fairly small cities). A "as you know, Bob" infodump would be completely unnecessary to describe my flight. I'd suggest describing space flight in terms of liftoff, a boring wait to get there, and finally reentry and landing. Or teleports. If you have to describe the staging at all, you better finally break down and learn how the rocket equation works, and playing KSP is probably the easiest way to *get* it in a way most of your potential readers already have. Otherwise they will know you can't be bothered to learn basic facts about science and any "hard sci-fi" cred goes out the window (far worse that if you had merely used a 15th level wizard to cast the teleport spell...). This isn't to say that SSTO will never replace TSTO. Maybe we will one day have enough ISP and enough thrust in a single engine to make staging appear as quaint as the steam engine is now. But expect enough R&D work to go into making staging as easy as joining freight train cars is today long before we ever get these magic fuels. At that point the inertia of staged design becomes hard to replace, although if the powerful engines are cheap enough to make than eventually they should replace the TSTO. Perhaps your character can discuss the politics of why the "rocket catcher" companies lobbying effectively makes SSTO illegal, even though the rockets could easily make orbit on their own. And until you learn the rocket equation, you will be miseducating even worse than most (and yes, learning orbital mechanics in the process might help as well. But far more of your questions are out of ignorance of the rocket equation rather than orbital mechanics). So if you don't pick up KSP, see if you can find the demo. Or just use the teleporter (having it transport at the speed of light would be a scientific improvement on nearly all space fantasy science fiction).
  9. I really have to wonder just how much more influence the other Senator Ballast had over his Mercury capsule than he did over the shuttle. Wiki mentions that he had photo/videography duties as well as was used for medical research tests.
  10. They'd effectively be an "invasive species", although I'd expect them to thrive unless some humans decide to hunt them to extinction again.
  11. With the right conditions you should get something like convergent evolution to a similar ecosystem. Maybe. Or maybe not. It really will be a random chance toward all somewhat possible stable ecosystems (and who knows how long you have to feed the mammoths until you get one that feeds the mammoths) and you probably don't know enough about the ancient ones to produce a close copy. I remember reading an otherwise excellent book on current ecological damage. Unfortunately the suggested changes were impossible. Not only politically, but the author simply never thought through that you can't have a complex modern society without the tools of industrialization, and those tools have an ecology similar to life. Gut the energy use, and suddenly you are back in the 18th century in nearly *all* ways. After explaining that trying to create an elephant sustaining ecology with tiny habitats with long "elephant corridors" between them, it shouldn't be hard to see that a phone system has similar requirements (don't ask about the chemicals needed to make chips).
  12. I'd have to wonder just how much easier it would be just to launch a probe with an RTG and an ion thruster. Sure, you won't have the thrust of 100GW of lasers, but you can keep accelerating as long as you want (as opposed to somewhere between Mars and Jupiter when the lasers can't focus on a 4km target). Use Americium if you want longer power (and more easily ignore the anti-nuke brigade), although I don't expect an ion thruster to outlast a Pu RTG. Consider using Krypton or Argon as well, you'll want a *lot* of propellant, and won't get close to .1c (or whatever Starshot is claiming with an unlimited budget). But really, Orion shall rise!
  13. This is also why the Shuttle (and presumably other hydrolox engines) run fuel rich. The extra hydrogen maintains the higher exhaust velocity and also helps cool the combustion chamber down below its melting point. Exhaust momentum is the critical issue. If you get exhaust velocity from heat (like chemical and nuclear rockets) you want low mass [per molecule] exhaust propellants. If you are using electricity to directly accelerate your propellant (ions, hall effect) you want high mass per molecule (and inert as well, to keep from destroying your engine. Inert like Xeon, Krypton, Argon).
  14. Why in the world would a gel have a greater energy/power content than a solid? Other than an even greater propensity to explode? And then you have all the issues of a solid. In a liquid rocket, the combustion chamber is a part of the engine. In a sold or gel rocket, the entire "fuel tank" becomes the combustion chamber. And since the pressure of the combustion chamber directly effects the power and efficiency of the rocket (if you want that much pressure at the throat of the combustion chamber, you need to make sure the rest of the combustion chamber can withstand that pressure), expect a heavy rocket. Shuttle SRBs are ~100 ton steel tubes, so any SSTO based on a shuttle SRB will have 100 tons less payload (per booster) than a well designed TSTO. I've only heard of gels being used in hybrid rockets, where the oxidizer was fed separately and the gel was entirely fuel. Best bet is to read Ignition! to see what happened to gels and why.
  15. Compilation by Scott Manley (music by Skye)
  16. From the Everyday Astronaut videos, it looks like the load points consist of small rods jutting out from the rocket. That "flat, slippery surface" likely either is a mesh to make it easy to trap the rods or some sort of support for something strong enough to support the rods.
  17. KSP staging: Explosive staging because the couplers are three times the cost of the [original] solid boosters and you are feeling cheap. Or back when career mode let you get to space/orbit that way and you hadn't unlocked couplers. Bamboo staging with the last stage. Note this isn't "real" bamboo staging as that is unstable, but involves putting a stage (or two) on top of the capsule and magically transferring the fuel to the working engine. Note that while in real life, the RL-10 is extremely expensive (supposedly redesigned to be cheaper to make, but ULA probably bought Rocketdyne to get the budget for the Starliner launch undercontrol), the LV-909 is pretty cheap (and light) making this a marginal improvement. Still one of my favorite tricks for getting a ton of Isp out of the last stage.
  18. They are going beyond that, and bringing in their best lobbyists. https://arstechnica.com/science/2021/09/blue-origin-hires-advisory-firm-linked-to-messy-jedi-contract-process/
  19. Is KSP docking ten or one hundred times as fast as real life? On the one hand the countdown is timed for a straight shot to the ISS (and computer controlled for the right trajectory), but on the other hand the relative velocity of docking is measured in cm/s.
  20. I'd assume that Spacex is only going to the Moon in a NASA program. So it won't happen until all the lawsuits are settled and STS is either ready for the big day or has been replaced in Artemis. Artemis was designed first and foremost as something that Congress would be willing to fund (although much of the lander fun is because they didn't fund it enough to actually do it, but don't tell the Congressmen paid by Bezos that).
  21. Musk sees the Moon as a distraction, but is willing to do it for the money that NASA is waving around. Or are you talking about the tourist "around the Moon" trip chartered awhile ago (poll says "land", so no)? And when is "complete?" KSP (1.x) is "complete", and took over 10 years to get to "final approach". But it only took 4 years from first compile to "1.0 release" (of course, with all the changes rushed in, it took until at least 1.0.3 to be playable again). Star Citizen appears to be what happens when a software project has fuzzy goals (like any game) and a vastly inflated budget. And it doesn't help that the most profitable thing they can do is to produce more DLC starships.
  22. Can we have a full blown Sputnik (and Vostok) style American reaction? Now would be a particularly good time to push science and the rest of STEM in school and industry.
  23. Hubby didn't live long enough to get (or at least die from) cancer. He was run over by a horse carriage.
  24. You don't need a quantum computer AI to run a corporation. People (preferably psychopaths, but that is more a feature than a requirement) do it fine already. Although perhaps the AI will be able to put more effort into maximizing control of the workforce and market and be less concerned with board level politics.
  25. SSTO (from Earth) more or less requires air breathers. With three-digit Isp (or similar "magic"), Earth SSTO becomes a possibility. Of course, it might still be more effective to use TSTO even with an airbreather, moreso with something like a SABER, less so if you get something like a X-43 engine taking you to mach 10. Of course, X-43 only really made it to mach 6.8 under its own power and only barely maintained mach 10 (positive acceleration was in the center of the error bars, not outside them). And "either rocketry or bombs for thrust then they will wreck the launch site"? You really need to try this game called "Kerbal Space Program" (I heard they finally finished development): it will teach you about the difference between thrust and delta-v. You need "magic" Isp for SSTO. Thrust really doesn't enter into the rocket equation (while it helps use a bit less fuel at first as your effective thrust is 1-TWR, big engines are the enemy of SSTO).
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