sevenperforce

I wonder if they will leave the Roadster bolted to the PAF, like they did with Ratsat on the first successful Falcon 1 launch, or if they will figure out a way to deploy it? Falcon 9 can provide a payload with a small angula momentum before deployment using its nitrogen thrusters, for pointing and so forth. It would be cool if the Roadster was given a cable with a camera on the end and a touch of rotation, so the cable would unfurl and you'd have a camera pointing at the Roadster from some distance away as it rolled slowly through space.

Define "base"?

Correct. Pressure differential is gauge; if the tire can handle 45 psi at sea level, it can handle 30 psi in space. SES-8 packs an 8 kWh battery but it also has a solar array that produces 5 kW whenever it is in sunlight, so the 56 kWh of the Roadster battery could only power the SES-8 for about 11 hours before dying. Of course, the SES-8 comsat probably has much higher power requirements than whatever our spacebound Roadster needs to do. Actually the first-Gen roadster will fit horizontally on the payload adapter inside the fairing.

The point was the illustration of metric expansion and bounded/unbounded/observable. Not trying to get at the mechanics of it, hah.

No, in the analogy the vapor in the bubbles represents empty space between galaxies and galaxy clusters while the surfaces of the bubbles represent matter.

Some people are asking if he is drunk on his twitter feed. I do believe he is serious.

Unfortunately no. I believe that even if the boosters were only usable twice, it would still be a huge money-saver.

The curvature of the universe is only meaningful at the scale of cosmic filamentary structures; everything smaller is dominated by local gravitational effects. The question is this: when you zoom out to the largest levels, where you're looking at galaxy cluster filaments, is there any overall curvature? Is there warping around a preferential axis? Are the cosmic filaments aligned, or are they being pulled in one direction more than any other direction? As far as we're able to tell, the answer is no. Supercluster filaments are randomly-distributed and have no particular alignment; redshift measurements show no bias in any given direction. This means the exouniverse is hundreds of times larger than the observable endouniverse. If it wasn't -- if, for example, the endouniverse was a sphere with an edge only a few billion lightyears outside our observations at the nearest -- then there would be a dramatic bias in observed redshift, because gravity would be pulling everything toward the endouniverse's original center. We would see galactic redshift at one extreme much higher than galactic redshift in the opposite direction. Yet we do not. In addition to redshift, this also matches our calculations of the values for dark energy. Our measurements indicate that if the exouniverse is finite and bounded, it must be have a volume at least 100 times greater than the endouniverse in order for its curvature to be "hidden" in our experimental error. Yeah, sorry. Typo fixed. And yes, I just came up with those two terms yesterday, because I was trying to express things concretely in this thread. For all intents and purposes, the microbe can't tell that it's "going up" so much as it can only tell that everything is moving away from it. Yeah, my analogy doesn't include anything for the speed of light, lol.

To say that at the Big Bang the "whole universe" was "compressed to an infinitesimal point" isn't entirely inaccurate but it's not as accurate as it could be. The fact is, we don't know the shape of the exouniverse. The endouniverse we CAN observe is relatively flat (in terms of gravitational curvature), so even if the exouniverse isn't not infinite, we're definitely only seeing a very small portion of it. The exouniverse could be infinite, or it could be an amorphous sphere, or it could be a long thin squiggly line, or it could be a four-dimensional hypertoroid, or any other conceivable bounded or unbounded shape. Whatever that shape was, originally, was compressed down to its smallest possible definition at the Big Bang. Everything we see was just a very tiny "infinitesimal point" within the greater exouniverse.

You know when you're cooking pasta on the stove and the pot starts to fill up and overflow, because more bubbles are being formed each second at the surface (aided by starch) than can pop? The expansion of the universe is like that. Let's say you're a microbe inside one of those bubbles somewhere in the middle of the layer of foam rising larger and larger in the pot. You don't know where in the pot you are; you don't know how large or small it is, or where the edge is, or if there even is an edge. All you know is that suddenly, all the bubbles around you are swelling and getting bigger, and everything is moving away from everything else. That's how metric expansion works. Everything is expanding in every direction; there is no particular "center", at least not one we're aware of.

Good catch.

Gimballing is obvious due to the lack of verniers; probably single-axis since we have two engines but it could always be more. I'm really interested, however, in how you know it's using a single preburner/turbine for two chambers, as opposed to two completely separate engine assemblies.

South Korean analysts have asserted that the Hwasong-15 uses a pair of the Hwasong-14 engines. https://www.nytimes.com/2017/11/30/world/asia/north-korea-missile-test.html Gimballing previously-fixed engines is pretty impressive, if true. Do you have any basis for the claim that the Hwasong-15 uses a single staged-combustion preburner and turbopump feeding two chambers?

Paradoxically, a physically smaller bomb requires a greater amount of fissile material.

Yeah, this is seriously not good. https://www.washingtonpost.com/news/worldviews/wp/2017/11/30/north-korea-has-shown-us-its-new-missile-and-its-scarier-than-we-thought/?utm_term=.1fc320a92106 It appears that the Hwasong-15 is a completely new missile...perhaps sharing the same first-stage tank and upper-stage engine, but otherwise hugely different. New first-stage engine(s) for higher thrust, much heavier upper stage. Currently running a frame-by-frame analysis to estimate launch TWR.

That's not good. [snip]

Any idea what the putative difference between Hwasong-14 and Hwasong-15 is? I see three possibilities: This is just Hwasong-14 flying without a payload This is a Hwasong-14, but they are adjusting the mixture ratios in-flight to maximize thrust at launch and maximize ISP before S1 burnout This is a Hwasong-14 with a new upper stage engine

48 tonnes after reaching orbit.

Using the "clip tanks inside fairings" and "cancel tail drag by attaching, rotating, and offsetting engines" tricks, I can put a 48-tonne SSTO into LKO with four RAPIERs, one nuke, 1292 units of oxidizer, and 6928 units of liquid fuel. Did it pretty easily, too, so if you need more margin I can try again. Is that enough to make it to Tylo, land, orbit, and return? The SSTO has wheels, Jeb in a command seat, wings, and control surfaces, so it can land deadstick as long as it can get a good Kerbin aerocapture trajectory.

Bingo. Rockets are flying metal balloons; trying to up their structural integrity to allow for a high-gee catapult wouldn't work so well.

I don't believe so. The iron in your blood is bonded to oxygen; it is, essentially, rust. Rust is not ferromagnetic. Even the un-rusted iron in the hemoglobin in your veins is, I believe, still bound to something and so the ferromagnetic metal-metal bond structure isn't there.

Quantum communication still requires old-fashioned signals being sent back and forth via photons or smoke signals or whatever else. The trick is that the data itself is encrypted by quantum entanglement so only the intended recipient has the "key" to unlock the data. On an unrelated note: If the continents had moved from the original position (Rodinia supercontinent) to their intermediate position (Pangaea) and then to their current position in the span of a single year (as proposed by certain young-earth creationists), the heat release would be enough to boil the oceans and leave behind bare basins.

Going in the opposite direction... How much does gear mass, exactly? I'm just thinking: gear is really only needed on takeoff. You don't actually even need it on landing; you can ditch in the ocean at survivable speeds if you're careful enough and you do a little design work. For the rest of the trip, it's dead weight. What if you take off the landing gear, make it a tailsitter VTOL, and add a single Dart? Might be a slight increase in mass, but that Dart will give you a HUGE advantage for your landing burn over RAPIERs alone, both in terms of isp and in terms of terminal TWR. A tailsitter VTOL can have a TWR of 1.001; you just punch all the engines and then slowly tilt forward until you build up enough forward speed for lift to take over. Then you'd have a TWR of closer to 3-4 by the time you get to Tylo.

Looks like a no go then. Love the mission patch though.

Here's the Generous Spirit: https://ufile.io/8c56t Here's the Transcendent Spirit: https://ufile.io/orje2