wumpus

I remember a discussion on USENET back when China launched its first taikonaut back in 2003. Somebody categorically denied that this could possibly result in a space race, but I suggested confirming that with India (I don't think anyone believed that any other nation felt a need to prove themselves this way). Oddly enough, both SpaceX and ULA are "racing" to be the first commercial vessel to bring astronauts to the ISS. Winner gets to keep the flag that the last Shuttle brought. Of course this largely rests on NASA letting one of them launch first (plus, of course actually bringing them to the ISS). But nobody expects to see either of these expand their military via winning. Anyone who heard Sputnik's distinctive "beep" knew they were in range of Soviet nuclear missiles. Without understanding this, you can't understand a "space race" Musk has stated that he feels he is competing with the Chinese to pioneer space (and presumably Mars). But a "space race" is all about PR (listen to why JFK "choose to go to the Moon" if you have any doubts https://www.youtube.com/watch?v=kwFvJog2dMw Bezos appears to feel a rivalry with Musk (see the "welcome to the club" tweet exchange), but that hardly is a "space race". Also anyone trying to break into the small sat market has to compete with Rocket Lab. This isn't a "space race", but a bog standard "price and reliability" commercial market. Being first helps, but also lets others see your mistakes. That's all well and good, but the only reason NASA had the money to go to the moon was to prove the point. Go listen to Kennedy speech1: he explicitly says that we choose to go to the Moon to prove that the American way of life allows us to meet challenges that Communism couldn't. That was the entire reason for Apollo. Certainly NASA had a roadmap before that, but it was mostly torn up and replaced with this awesome goal. And the JFK roadmap more or less stopped after we "bring them home again". Once Apollo 11 landed, that goal was complete and there were other places that Nixon desperately wanted to spend tax dollars. The Viet Nam war was obvious, and Nixon (and presumably the American public) saw Apollo as a Kennedy victory, something Nixon didn't want to pay for2. Note that the Saturn V didn't quite die with the Moon program. Skylab was launched on one of them, and both manned Skylab missions and Apollo-Soyez launched on Saturn 1B rockets. Then it died. And part of the reason it was "dead dead" instead of "mostly dead" was that the only way it was getting funding was to just go to the Moon. The thing was never documented enough to build on its own (probably standard procedure for government contracts, to protect the contract) and required extensive machinist notes on the blueprints to complete (although presumably if you wanted to build one badly enough, enough machinists could learn how to build one after a few tries. A F1-B was printed/built well enough to test fire for SLS). Another issue was that by 1980 or so we couldn't launch the remaining Saturn V if we wanted to: the countdown routine wasn't documented enough and the original technicians weren't all available or capable of doing it. Note that this doesn't confirm the "NASA destroyed the plans" myth. In complex systems, there's a lot of specific know how to get the job done that for various reasons isn't entered into configuration management (probably because there's no system for the machinist to submit them. Just the engineers. Also don't ever believe that all redlines are fully captured. Not on a 6 million pound behemoth). So we have 99% of the plans. Which was enough to base a modified F1-B and testfire the thing, but don't try to "build to print" an entire Saturn V. 1. My speakers aren't working, so I can't confirm that includes the right parts of the speech. 2. This is 50 years old, and hopefully falls under "history" and not "politics".

Was the plan to not fill them in peacetime? Or more realistically, outside of an active warzone or otherwise likely to come down on enemy territory? Or was it more of a pain to have non-permenantly sealed hypergolics that the techs would have to drain and refuel?

This surprised me, as the R-7 uses kerosene and LOX not vodka and LOX. But those engines otherwise look suspiciously like A-4 engines, including turbopumps driven by hydrogen peroxide. And as far as I can tell, doesn't have an additional stage, although the Vostok appears to have yet another A-4 on top of the previous 5 A-4s.

Soyuz first flew in 1966, and has 1700+ flights. Boeing 737 first flew (commercially) in 1968, although Boeing appears to be breaking that classic design. The goal for Starship is to be like Soyuz, and if success blocks the next generation then so be it. Perhaps Elon will simply design another, or simply go and do something else.

No love for abysall lurker? These might be obsolete now (they were all done with pre 1.0 installations), but the missions were amazing... https://www.youtube.com/user/ablu444 Another great one who stopped recording is Bob Fitch. His "Project Alexandria" (a recreation of space from 0-1969 in RSS) was amazing. I think his Apollo 11 was far too much work for the views (go watch it, it's great) and he stopped soon afterwards. https://www.youtube.com/watch?v=SZeoHfONUxA&list=PLBhKowDYZ822XxTabtoYup81ZLsrgA4be Scott Manley doesn't claim to be the best pilot in KSP (and then lands extremely long rockets on their exhaust bell on the Mun, without them falling over). I didn't know why until I checked out Abysal lurker and others... He certainly knows his orbital mechanics and space history, and especially keeps the patter on such subjects going during the tedium between burns (which makes his videos so great).

Especially before the "moar boosters" pack, I'd often build larger rockets with multiple kickback stages. I also remember that was the favorite strategy for low cost to orbit with expendable boosters (a forum competition). One strategy I used for a long time was to have a pair of boosters to one side, and connect all other boosters to that stage. This was more important with hammers (and somewhat with thumpers) as the cost of the decouplers was often more than the booster. With the current options, it makes more sense to go simply use larger engines (and even more huge boosters) rather than adding more boosters.

I can't tell if the Popular Mechanics ships carry jet or propeller aircraft. It might have worked for propeller craft, but there really isn't any reason to build a carrier that can't carry MiGs. I heard that during the early part of the Iraq War, the US parked an empty carrier in the Indian Ocean. Perhaps they later replaced it with a similar sized container ship (especially during an economic downturn), but it was effectively a "floating base". Just make sure you haven't deployed on while fighting an enemy with an effective navy (read: has submarines).

I'm going to have to study that slide deck, if only for all the other information for air-breathers it appeared to have (mostly trajectory analysis). If you want one of these, I'd start with an air-augmented rocket. Even side boosters can justify work learning how to build intakes that work on at least one mode of the multitude of modes that NTR requires. By the time you can build the intakes, perhaps nuclear power won't be quite so demonized.

On the reusability of lunar rockets (taken from the Solar metro map the Kerbal metro map was based on)... Sealevel - LEO: 9400 m/s - presumably reusable (although I don't think Falcon 9 reuses parts that supply more than 3000m/s, and the shuttle probably reused engines that provided less overall relative thrust) LEO - LLO: ~4000 m/s reusable if and only if you aerobrake on Earth, you almost certainly leave the craft in orbit, and you resupply the propellant (and everything else you need) in orbit. LLO - Lunar Surface - LLO: ~3500m/s and would be left in Lunar orbit (presumably not docked to any space tollbooth). All the propellant issues from LEO-LLO, plus the need to haul them to LLO (ions might come in handy, as long as none of the fuel is cryogenic). Note that if you *are* using ions to haul non-cryogenic propellant to the Moon, it might also make sense to build a fuel-depot in an elliptical Earth orbit with ~1500m/s delta-v. This will require a two more trips through the Van Allen belts, but it greatly reduces the mass of fuel needed. But it also is more than a bit silly just for getting to the Moon. If the Chinese (trying to stay on topic) do this, I'd expect they are doing so with their sights clearly set on leaving the Earth's sphere of influence.

I'll have to read it again. I was going to make a comment about obeying the rocket equation, but I'm not sure it has to (it gets its momentum a bit differently). PS: the book is by George Dyson, the late Freeman's son. Highly recommended. https://www.goodreads.com/book/show/21243.Project_Orion

When they needed a crash deep dive to test *everything* and found a show stopper mid-flight does not bode well. Certainly the vast majority will be minor. It is how many that endanger the crew & mission and how likely they are to occur is the big deal. I suspect they knew they had lousy tests, designed to meet contract requirements. That they found real problems with real tests that quickly shows that they need to do the whole thing over again with real testing. Of course, the fact that in the end the crew would have survived implies that it probably isn't all that bad (not Apollo 1 or Soyuz 1), but still needs some real testing and a lot of fixes.

Fusion reactors spew neutrons willy-nilly, but I can't imagine the extra C14 in the atmosphere (or maybe even heavy hydrogen) to be an issue. It is even less of an issue burning near non-Earth locations. "It just makes it heavier, and again ISP will suffer." Delta-v will suffer (due to increase of dry mass). ISP describes fuel and engines. " you get to use pretty much any propellant you like since it doesn't need to be combustible." Note that for the three-digit ISPs of NTRs you need to exhaust hot hydrogen. If you use water, your Isp will be less than hydrolox. If you use anything else, expect even worse Isp (although this might not matter as ISRU is as easy as it gets. And you can always leave some hydrogen in reserve for high Isp "burns"). Granted, a lot of the reason NASA loves NTRs is that the tech is already grandfathered in as being "tech ready for humans", so politically/regulatory issues are lower (this ignores the politics of dragging a nuclear reactor into orbit and beyond. Try convincing people outside of this board that such is a great idea). But that Isp (800s with 1970s tech, probably higher today) is ideal for interplanetary travel. There aren't a whole lot of better engines for sci-fi spaceships (although if you are dealing with a situation where interplanetary travel is similar to current air travel, you might consider hydrolox with propellant delivered by ion thruster. "Climbing" up multiple depots (somewhat regularly replenished via ion-slowboat) would be almost as efficient as the ion-slowboat but as quick as hydrolox (except for the docking parts). You might even have an excuse to explain the technology as the narrator changes his seating arrangements (read/computer stuff/whatever) as he goes through bursts of acceleration (describing a NTR would make as much sense as the narrator bothering to inform the audience that the plane doesn't really use jet engines, but high-bypass turbofans are invariable called 'jets' by travellers).

Wasn't the Volt supposed to be on such a "versatile EV skateboard"? It still turned out fairly well, at least until canceled. I can't imagine GM really following the "gigafactory" strategy. GM would need a battery plant on a scale they couldn't imagine (and would have to pioneer* how to build one). Then they would need a crash program to expand it. "One of the problems of being a pioneer is you always make mistakes and I never, never want to be a pioneer. It’s always best to come second when you can look at the mistakes the pioneers made." - Seymour Cray (a guy who maintained the position of "designer of the world's most powerful computer" for multiple decades, back when that required designing a machine so fast your competitors couldn't build anything faster even with several years of technology improvements, and then doing the same thing all over again several times over).

Tens of millions of people would have a tough time rebuilding a technological infrastructure (although presumably they couldn't mine the cities of the sterilized half until the politics were at least functional). Don't forget that sterilizing a continent means deforestation, you'd probably have desert conditions across most of the sterilized half (typically after human caused deforestation they don't grow back from seeds fast enough, I'd assume natural causes would do the same).

If it was an issue of case ground vs. logic ground then the screw shouldn't have made a difference (unless part of the flow from case ground to logic ground or vice/versa) was going through said screw. It seems more likely the screw was used to ground to logic, but grounding to case is normally how to layout those boards. I normally tell those new to electrical troubleshooting that if the problem moves around and won't let you isolate it, check power and ground. Ground is great for a lot of intermittent errors, especially *different* ones. Isolating the problem to a single screw either means a physical issue with said screw (probably shorting out the wrong thing) or letting ground currents flow where they shouldn't flow (which is a "ground error", but not one you are likely to solve by replacing the power supply and improving your connection to ground).

It took me some googling to determine that the previously explody (possibly just "collapsed") "first Starship" was "Mrk 1" and this "SN 1" was a different Starship.

I've heard that a surprising amount of professional engineering applications (mostly electrical design and simulation, but I wouldn't be surprised if it was the same in other disciplines) are single threaded. The people who are plunking down thousands or more dollars want accurate results, and it getting remaining bugs out of multi-threaded code is wildly harder than single threaded code. As a side note, they also use double precision, something Unity (and any other game engine) avoids. This is the whole point of the "floating origin" was to kill the Kraken that using single point "floats" created. Unless Unity does some massive work on their physics engine, expect similar results as KSP1. We might hope for double precision, but unless they expect more "physics/science heavy simulations" (car racing won't cut it) don't expect Unity to bother.

I worked with a tech that claimed to have been in a VW (bug)/Corvair race. Somebody who knew about it made a prank call (as the cops) to one of the participants homes claiming the police were aware of it. They were going to be charged with street racing (a serious offense) as it was almost certain that neither car exceeded the speed limit the entire "race" (it wasn't a "turbo" Corvair). - no idea which car the tech was driving.

I'd strongly believe that you couldn't see whatever was shorting out the board. But it is also quite possible that ground return noise was the problem. Most likely that ground current was flowing through your problem screw back into the power supply. This current happened to flow over some overly sensitive part of the circuit board and induction forces created a current going the opposite way. And that was enough to make the board not work (probably only sending the wrong bit once every million times, but that's easily enough to crash it in milliseconds)... You might want to google "ground loops" as well. Nasty little buggers. But if there really isn't anything touching where it isn't supposed to touch, and board designers love to use mounting screws as ground, weird grounding current issues are the most probably cause.

I only said they were bountiful. Not necessarily strong enough for whatever you want, but certainly there. And far, far, easier to manipulate than vacuum. But slowly changing orbits has been shown to work.

Back in the 90s there was some claim that a nanotech device managed to use the EM background radiation as a power source. Unfortunately it only managed to push a piston in a single direction and couldn't drive it the other way. I'm not even sure that thermodynamics allowed that much, but nobody was hoping for more than a localized nanotech power supply, and a weak one at that (think "solar" energy from 3K radiation). If you are limiting yourself to Earth's orbit you don't have to bother with vacuum. There is an abundant magnetic field that physics allows you to push against. At least one spacecraft has used it, although it was more of a proof of concept than an effective choice.

NASDAQ traded $172,530,291,288 today (google only wanted to tell me number of shares for NYSE, but it appears to be similar) And the whole point assumes you want to link it to at least one other exchange on a different continent (more trillions). A large percentage of that is going to be high speed trading (if only because the whole point is to trade a lot). Just how you segment the market so these customers will pay what the market will bear is out of my field, but there is much more money here than in standard users, no matter how many. Whether that is a good thing or not is out of the scope of this forum.

A bunch of reasons: 1. Historical and availability of hilarious fails as you learn rocket science. You'll note we saw it as a Squad trademark. Judging by past design choices, I think this is the real reason. 2. Allows for the possibility of recovery by staging parachutes on falling stages as the next stage is sequenced (this was really hard with the old "deletion zone", I'm not sure it is still remotely effective now. It does help mods). 3. The additional code has the chance of preventing hot staging and other side effects via bugs, not including it is safer. 4. It takes more man hours than you'd think, and Take2 doesn't want to fund KSP1.x more than they have to.

Not USA, but you have to ask yourself why Germany turned off their nuclear plants in the face of catastrophic global warming... In the USA I've personally made sure I selected an infra-red based smoke detector instead of a more effective radioactive-based detector. Although that was exclusively about fear of paperwork (it was for the Marines, so lots of military regulations*) than any other reason to choose the inferior method. * I had visions of writing "absolutely safe" over and over on a mountain of documentation...

Lorentz terms presumably divide by zero above c. And regardless of kinetic energy, anything with [rest*] mass should have infinite momentum at c, and greater than infinite** momentum. Kinetic energy should be even worse, but doesn't have any obvious proofs (unless there are real ways to convert momentum into kinetic energy). * "rest mass" is a bad term. Newton's laws work fine if you change F=ma to F=dp/dt. Then you don't have to worry about "relativistic mass" and don't fall into the fallacy of "how fast does something go to have enough relativistic mass to create a black hole?". ** see Cantor's diagonal argument for proof the existence of values for "greater than infinity". Although even 1015 times infinity will hardly rate an "alph 1" on the Cantor scale (assuming the momentum of an object at c is alph 0).