K^2

Zvezda, Poisk, and Rassvet have docking ports compatible with Soyuz and Progress craft. Pirs used to have one too, but has been decommissioned. While Chinese spacecraft started out heavily based on Soyuz, I don't know if they would have kept up with any modifications related to ISS and/or went off on their own path for their own station. Keep in mind that it's not just whether or not the ports themselves fit, but everything involved in aligning the two craft together for the docking to happen safely. If the ports themselves are identical, but the alignment guides are installed differently, you're not going to be able to dock. And even if the two systems are completely identical, and you want to take on the risk of manual docking, it's still something entirely untested with any number of potential problems arising. Honestly, if things were that dire, a better option might be a space walk.

I mean, even if the Starliner was completely DOA, it's not like there is no way to get the crew home. They might be stuck on ISS longer than planned, but you could always work the rotation of the future launches in a way that gets them home soon enough, and lets the normal schedule resume shortly thereafter. Back when the Soyuz was having issues, people were even talking about adding extra seats to the dragon, which it's been designed to handle at least on paper, so something like that would be an option in a genuine emergency. It's just fun to poke fun at Boeing, and how they're trying to be nonchalant about the whole thing a little too hard, given all the RP disasters they're in the middle of. If it weren't for all the other problems the company has been having, we probably wouldn't even be discussing this beyond the, "Oh, they're going to take a closer look at what's up before heading home." And yeah, I don't think anyone currently aboard the ISS minds the mission extension. It's not like there's nothing to do or the crew is stuck alone without resources.

Hypothetically speaking, if you were able to make a mirror that reflects any wavelength with near enough to 100% efficiency, you could build a tiny star that sits comfortably in an enclosure that fits in your pocket and can power your car, yes. The reason you can't has to do with how electrons in matter interact with electromagnetic radiation at such short wavelengths. I can see some kind of hypothetical superconducting degenerate matter being able to do that without flatly breaking known physics, but the kinds of pressures that involves already require being in a core of a star, so that seems entirely moot for any practical purpose.

I don't think there was ever a Vandenberg launch that my area wasn't overcast for. I'll keep an eye out, but I'm pretty sure I'll only see clouds.

I saw this dig by Futurism, and couldn't scroll past that title. Nothing new of substance, but sharing for the title anyways. https://futurism.com/the-byte/boeing-starliner-astronauts-stranded

We all know that cats can survive a fall from an arbitrary height. Things they land on, however, aren't as lucky. This cat, evidently, fell from pretty high up. Possibly an airplane.

That is wildly exaggerated, TBH. Your typical interplanetary transfer is in tens of km/s. A 2RPM rotation involves a rotation around a point 250m from the center of mass (this can be more or less than 500m of cable, depending on your counterweight, naturally) and has velocity w.r.t. combined CoM of only 50m/s. This is well within the mid-course correction burns you'll be doing anyways. Likewise, loss of gravity, while disorienting, is about as dangerous as riding on a drop tower at an amusement park. You do still have the spin of the rocket itself, but it's likely to be a fairly stable rotation and the resulting centrifugal effects will be minor enough for this to be at worst comparable to a slip-and fall on flat ground. You can never exclude a risk of injury in any sort of a fall, but you can also slam your hand closing a hatch, so you know. What is a real risk is the cable snap-back. Back of an envelope estimate, a lot of materials you'd consider for a cable would stretch by about ~10% before failing. You want a good safety margin, so you're probably going to be looking at a little less than 5%. Call it a 10m stretch from CoM, where the cable's most likely to snap. A fully-fueled Starship is 5kT, which means you're looking at 1/2 * 50MN * 10m = 250MJ of energy stored in the cables. It's not a LOT, but it's enough to get the tip of the cable flying at you at a decent speed. (Yes, I know the energy is split between multiple cables, but so is the mass of the cable you have to get moving...) With a very rough estimate of 20T of cables in there, you'd get something like 50m/s average speed, but the tip is likely to be traveling closer to the speed of a bullet. The odds of that tip hitting the ship are not zero, and it will absolutely slice clean through. There are safety measures you can take. The tension wave will propagate at the speed of sound through steel, which is on the order of a few km/s. That technically gives you enough delay for emergency severing of the cable. If you put accelerometers everywhere along the length of the cable, you can cut all the cables from the ship, causing both ends to snap together instead, resulting in very low chance of any part of the cable hitting the ship with significant velocity. You obviously want this system to be rock solid, but what emergency system isn't? And we are looking after a catastrophic failure, which is very unlikely to begin with. We build suspension bridges using essentially the same tech. All of that said, when people talk about testing a centrifuge on ISS, people do talk about small radius centrifuge. As mentioned earlier in this thread, we do now have strong evidence that even a sub-5m radius centrifuge is viable for artificial gravity with a trained crew. Especially if you don't mind ramping up the speed over a few days when the trip starts, and winding it down on arrival. And that is an entirely different structure. Something with a revolution period of about 4 seconds and compact enough to fit in the inner hull of the Starship. If we're going to see artificial gravity on a trip to Mars, that is far more viable than any tethered design. And it's also something we can comfortably test on the ISS with very reasonable expense. I mean, it's still a full sized module requiring some amount of orbital assembly with current launchers, but again, if we're looking at testing this for interior of a Starship, the best way to test it would be to assemble one within the Starship, dock it to ISS, and just keep it docked for a few months. What better proof of Starship's capability to take a crew to Mars could you possibly ask for?

Our water never gets warm enough for a swim without a wetsuit. Otherwise, I'd probably be doing a lot of the same. There are a few bays not far from here that do heat up by end of July-August, but they all involve a bit of driving. And when the weather's good, also lots of standing in traffic to get to them. For anyone who doesn't mind a wetsuit and into surfing, though, these are some of the best locations. (Though, I suspect, same can be said about your area.)

I really want a rogue planet Easter egg. Something that looks like a once habitable (or even industrialized?) world that got flung out of its ancestral home eons ago and has been floating through the void of space ever since, its atmosphere having condensed and subsequently frozen as vast "oceans" between the elevated areas that were once its continents. Because it would be far enough out from Kerbol, it would make sense for it to be uncharted and nearly undetectable, but it can also stay entirely fixed. Though, I do recall some speculation sparked by the discussion of the stellar movement being a factor Intercept is considering, potentially indicating Kerbol being part of a binary with a nearby star. That would both be a great excuse to bring in the nearby star system closer to Kerbol, as 0.1ly or even smaller distances aren't unusual for such configurations, and would allow the formerly rogue planet to be a Kerbol capture, still being absurdly far away and entirely uncharted until you put an effort into it, but nonetheless, being on orbital rails, making it a little easier to plan transfers to it. Again, not a bad way to bring all of the concepts and planet work already done by the authors of this thread into KSP1. (Edit: Though, I'll be honest. I'm growing more and more tempted to build an engine in Unreal as a proof of concept.)

Yeah, especially if you throw in some outer planets with longer periods, and have to manage Hohmann transfers to these at the same time to reduce overhead of supplying colonies. It would make years and decades a more natural scale for the colony progression, which is probably not unrealistic. What I don't know is if it's the right choice for everyone. Not being a game designer professionally, one thing I never learned is the skill of making a game that's fun to play for a given target demographic. Making a game that's fun for the team that works on it is a great strategy for an indy studio, and we did get KSP1 out of that kind of strategy, but KSP2 was rather larger and more expensive, meaning Intercept was solving a fundamentally different problem than you and I are thinking of when trying to balance the game. To bring this back to the thread topic, for anyone trying to mod Debdeb into KSP1, yeah, I think that's the right strategy. You just don't have the tools to mold KSP1 into something that would let you deal with centuries and millennia time scales efficiently. So smaller interstellar distances would make something a lot more playable. Especially when 100k time warp is already pushing the system if you have enough debris floating about.

You can get another factor of 3.4 by using Kerbin year. Orbital period for Kerbin is about 9Ms vs Earth's 31.6Ms. So you have a built in excuse for KSP interstellar distances to be 34 times shorter. Distance to Proxima would then map to something like 1.2x1015m. But yeah. All the problems you highlight persist. I'm sure the ISP and thrust of NPP would be pushed beyond reasonable as has happened with ions, and even so, we're looking at many decades, possibly centuries for transit. The colony gameplay has to work around that. You really have 3 options here. 1) You don't just fast-forward the transfer. You keep playing colony manager at 100k-1M time warp, checking in on your transfer progress occasionally. 2) Colonies don't "age", much like ships in KSP1. That means no life support or anything like that in the game. The only resource management gameplay for colonies is when you're expanding. 3) You make interstellar distances a lot shorter. Somebody was going to be upset with either pick, but there would be mods giving you all 3 options, I'm sure.

Intuition paired with critical thinking can be a very powerful tool. After all, checking if you got the correct answer is usually a lot easier than finding it in the first place. And even if after checking your answer you realized that your intuition was wrong, it probably gave you some insight in the process. The only real problem is when people go with their "gut" against the evidence. But you don't seem like the type to do that. Confirmation bias is also a thing, but that bites people in the rear regardless of whether they think they're following intuition or evidence, and in fact, the tunnel vision tends to get a lot narrower with the latter, due to misplaced confidence. Hence it's the critical thought that counts. Focusing on, "How can I be wrong about this?"

A thing a lot of people in analytics and machine learning know is that somebody reliably giving you guesses that are notably less than 50% correct, it's just as good as being correct more often than not. Because, as is easy to guess, you can always flip their predictions in the analysis. So reliably incorrect weather guessers can still give you a good prediction after correction.

We've seen some screenshots suggesting files were being edited for some of the planets that haven't been properly shown. It's very hard to say what state of completion things were in, but also it's pretty clear that art was ahead of engineering on KSP2, so it's entirely possible that most of the Debdeb system was already in an early alpha stage. The biggest blockers for getting Debdeb into KSP2 EA would have been the vast distances involved. They would require origin relocation to work smoothly across interstellar distances, larger rockets being launchable and stable, and time warp being able to go to something like 1M. All of this is... lets say problematic in the current state of KSP2. Having interplanetaries be built on orbital shipyards following the colonies update would solve one of these problems. Origin relocation seems to have been actively worked on. And the team was likely hoping this buys them time to clean up the performance in deep space and/or map at least a little to enable the ludicrous warp rates required. In which case, holding on to interstellar for a bit longer, even if planets and art are in good enough shape for EA, was a sensible choice. I was kind of hoping they'd drop these into the final patch, possibly a lot closer to Kerbol than initially planned, just so that we have something to explore. Heck, just getting a few planets that were shown dropped in as outer planets of Kerbol would have been nice.

Copper is a good target material for cheap sintering, so I get why it's desirable, but I'm impressed that it works. Even with cooling, I'd expect engine-rich exhaust from this thing. But hey, if this is good enough for one launch of an expendable craft and is cheap to print, I don't think anyone would complain.

Thanks for saving me the trouble of getting dressed up, I guess. And because this is 90% meme thread, apparently.... Ok, sure, but also to be fair, there's this data. https://www.carbonbrief.org/wp-content/uploads/2024/04/Screenshot_2024-04-23_at_13.33.12.png

I'm not saying it's a good strategy. Just that it's technically available. The failure mode's not so bad, though. Unlike a rigid body spinning near its intermediate axis, you're not going to have it flipping back and forward violently. Fluid would facilitate the migration of axis from longitudinal to transverse over a number of revolutions*, with the moment inertia now being along the major axis, drastically reducing angular velocity due to momentum conservation. You'd go from 15RPM and 1G to a few RPM and around ~0.1G. It's unlikely to cause serious injury if all large cargo is secured, and it'd be easy enough to reach some sort of controls to kill the rotation all together. A centrifuge internal to the cargo bay is still the best option for the starship, though. There's just absolutely no reason to spin the whole thing. * Edit: Solving equations of motion for both completely rigid and "fluid core" bodies is kind of interesting and illuminating. If you can handle very simple differential equations and some tensor algebra, I encourage you to run through them. The relevant equations of motion are Euler's Equations. (Yes, same name as the fluid dynamics ones, but the rigid body ones aren't nearly as scary. Euler sure has a lot of things named after him.)

Yes, if fluids are involved. You just need active compensation to keep the axis alogned.

The tumbling is due to intermediate axis. Longitudinal axis is usually the minor axis, which can be stabilized. It is, actually, stable for a perfectly rigid body, but anything with fluids, moving cargo, or people inside would result in destabilization, requiring active correction. It's not hard, though. That said, there is no reason to spin the entire craft. That would cause all sorts of additional complications. A "cage" for crew quarters would be relatively easy to integrate, which is what I was basing my analysis on. There would be a bit of an air drag, but you just need a tiny amount of motor torque to compensate.

Same thing happened to me, and likewise. (Edit: I do think that whether T2 is hoping to resume work on Kerbal games or sell off the brand, community is a big part of the sales pitch, so there's a good reason to keep the forums running, but you never know.)

It's rough. For the most part, shielding's about either diverting or stopping the particles. The latter scales roughly with how much matter you can put in the way. Earth's atmosphere is density-equivalent to 10m deep pool of water and blocks about as much radiation, and that's after the Earth's magnetic field has a go. Carrying 10 tons of shielding for every square meter you want protected is... well, not entirely unfeasible, but it's problematic. We're going to need more research on what's the threshold going to be. We clearly can't get everything, but neither does Earth's protection. Somewhere between ISS and Earth there's a "safe enough" threshold. And we might be able to help by blocking more of the radiation that's easy to block. Hard UV, for example, is blocked by a sheet of foil better than by all of Earth's atmosphere. On the other hand, UV isn't the thing that was going to damage someone's kidneys. Next on the list are going to be charged particles. Earth's magnetic field is kind of wimpy. It acts in volume. We have superconductors. Flying with a tiny Jupiter on your ship will create all sorts of engineering challenges, but it should be safe to the crew. The protons and other nuclei that are both abundant in the solar wind and dangerous to the crew are going to be in the 1MeV/amu range. Taking worst case scenario on charge (e.g. alpha particles) of 0.5q/amu, this gives cyclotron radius of about 30cm at 1 Tesla. So magnetic shielding isn't out of the question on basic principles, but that still leaves engineering the system, flying tests, etc. Worst part is that it's a system that's hard to both build and test at small scale, and it needs to be flown beyond Earth's bow shock before we can be properly sure that it's not going to collapse on an interplanetary voyage. Normally, I'd say we're two decades if we start working now. The growing evidence that we need it for a flight to Mars might cause people to hurry it up, but we have to start gearing up for tests now. Finally, if we're trying to combine shielding with centrifuge, the complexity skyrockets. (And it was bad already.) Here we have a modicum of good news. Recent research strongly suggests that while untrained individuals do poorly in AG environments above 2rpm, almost anybody can be acclimated to up to 20rpm. This brings the centrifuge radius requirement from 250m radius (half a kilometer in diameter!) which is viable only in a tethered configuration, which sucks for both magnetic and bulk shielding options, down to merely 2.5m, which means an entire centrifuge could fit inside a Skylab workshop. (And in fact, it sort of has...) Or, I guess, more relevant to the future missions, Starship's 9m hull can easily fit a small centrifuge inside its cargo compartment. Given all the other equipment that has to be brought, space is going to be at a premium, but if, say, a 3m section of it can be dedicated to the living quarters, with floor diameter probably ending up closer to 4m from center, you can have sleeping cots at floor level, where you'd probably have full 1g, and standing up, your head would be down to about 0.5g. That might not be enough to fully remove negative effects of low g on your eyes, but it's not catastrophic even at 0g for a year, so hopefully good enough? And you can have slightly better conditions sitting down to do any computer work. This would bring centrifuge speed to 15rpm, or a quarter of a revolution per second. Not terribly fast, slow enough to go to the center transfer ring by ladder, and for the crew to use hand grabs to cancel/start their rotation. The transfer tubes to enter the nose or aft storage would have to be pretty narrow to reduce air drag, but they can still easily be similar in size to ISS connectors, making them easy enough to navigate and bring equipment through. The nose section can have the jump-seats for the takeoff and landing portions of the flight, research equipment for use in flight, as well any lighter cargo. With this sort of the configuration, you can have the engines, a significant amount of fuel on the outbound leg, and most of your heavier cargo/equipment serving as part of the bulk shielding from the solar radiation. Slightly thicker foil on outer wall, and floor of the centrifuge would have to be enough for most of the rest. Toroidal magnetic shield a few meters outside the centrifuge would help reduce effects from radiation coming from the sides reducing the work the ship's walls and centrifuge wall have to do. This won't be enough to bring the background to Earth levels, but it'd be way better than what the ISS is averaging. Hopefully, that's enough, but a lot of test and engineering needs to go into it. Obviously, a mission like what I'm describing is not even close to what Elon's pitching. It will require a better built Spaceship with a lot of very expensive interior and exterior hardware, as well as several pieces of equipment that have to be engineered and proven to work. But also, I haven't been very optimistic about the promises for cheap flights to Mars both on general principles and based on previous promises from the same people. Nonetheless, I do suspect that Starship and Super Heavy will have to converge on something functional due to being critical to Artemis in its current plan, so the ship and the rocket will likely be available, with the rest to be filled in at the later time. If some of the relevant research is fast-tracked, 2040's is still a realistic goal. Whether any of this actually materializes remains to be seen.

The important part is locking the carbon. We have ways of doing that with old plastics much better than vehicle exhaust. Also, with gasoline and natural gas demand down, these companies would have to build facilities to convert light fractions into plastics as well. That opens a door to eventually replacing crude with captured carbon, making plastics production carbon-negative. It's a long road to that, but non-fossil power production and electrification of our energy consumption is still a good first step.

There's been a wonderful graphic on the subject making rounds on the socials. In the market that's going up and up, Tesla is one of the few that are doing worse, and a lot of it is other car manufacturers eating into what used to be Tesla's niche with better offerings. Northern CA tends to lead a lot of the trends, and Model S has been overtaken by Taycan here already, with electric Macan starting to eat into the X market. It sounds like full electric 911 and Corvette E Ray is also going to make the market before Tesla releases a long-promised Roadster overhaul, which is likely to eat into the Model S market as well, simply because there was not another alternative in that price range previously. Of course, luxury market's not the main profit for the company. Tesla's holding a lot better in the 3/Y market, but the lead is decreasing rapidly. I am seeing a lot more Mach E showing up, suggesting it's probably eating into the Y market quite a bit, which would explain the decline of the popularity. And while Bolt and Leaf aren't exactly competing in the same niche as Model 3, they are effectively providing a cheaper alternative. Which is what was promised, but never delivered with 3. What Tesla needed was an update on their aging offerings which could continue to compete with the evolving market. What they dumped the resources into instead has been the Cybertruck. And while I'm seeing more of these eyesores on the streets than I'd like to, it's not even a competition with Rivian trucks which are absolutely everywhere. I think I'm seeing more Ford Lightnings than Cybertrucks, tbh. But I don't have concrete numbers for these, so take that with a grain of salt. The outcome is absolutely predictable.

I don't know if T2 would have pushed hard against using Unreal if a strong business case was laid out. Problem is, Intercept was built from a bunch of Unity devs who likely wouldn't have been recommending Unreal.