wumpus

When I read the title, I couldn't help but think of the spaceships from the Hitchhiker's Guide to the Galaxy. The ones that would surf solar flares during a Disaster Area concert. Fortunately, this research is completely unrelated (but expect prototype naming to remember it). I'm guessing it is one of those things where we wouldn't need any new physics, but the engineering and the finance needed would be out of this world. You'd need a fission reactor to power it, and a fusion spherical torus (and someway to cool both).

Reality check: 5000mph = 2200 m/s Using a 50m radius, I get 10k g-forces. Good luck building a rocket that can take that (especially laterally). Next, they want to push it through the atmosphere at over Mach 6 (might be mach 7 depending on where they build it, but I'd suggest Leadville, CO as it is "two miles high"). Smallsat launchers have issues with aerodynamic drag, and this only makes things much, much worse. If you could possibly make this work, I'd expect to be bought out by Spacex to scale it up again and fling propellant into LEO. Successful smallsat launchers so far (success means achieved orbit, not financial success): Orbital: air launched Spacex (Falcon 1): ground launched Rocket Labs: ground launched Virgin Orbital: air launched So far, it looks like half the companies have gone to extreme measures to minimize air resistance. Orbital used 3 stages, so I doubt that they were as concerned with matching nozzel size to atmospheric pressure. No idea about Virgin Orbit. But even so, I think the real issue is that 10k g-force.

Presumably the rigidity of the cable (it won't need much) will prevent any issue with the cable wanting to orbit on its own (it will be stable just hanging there). The real fun begins when you hit atmospheric winds. Sats will have to avoid the cable. Lots of fun cleaning up space junk (especially Project West Ford: the one with half a million needles in space).

I'd assume you assemble a space elevator in space, although plenty of prototypes demand a self-assembling tower. Presumably the CW starts in geosync and slowly winds out to its final position, keeping the center of mass (I think "center of gravity" may be technically correct in this case, and they might be in slightly different orbits). I've always assumed you'd launch from geosync, but going higher may well be a more efficient way to gain velocity (as efficient as an electric motor).

As mentioned, they worked alongside their Soviet counterparts. Granted, when the war ended, Korolev and Glushko were in the GULAG. But I suspect that they were before they joined the German scientists. Oddly enough, in Rockets and People, Chertok mentions that they had more food in the GULAG than his family had in Moscow. Chertok was specifically tasked with grabbing all the German rocket people and tech he could, and specifically writes that they were especially happy to bring the test stands and jigs home. And "worse"? In 1945 that was all too easy. https://www.nasa.gov/connect/ebooks/rockets_people_vol1_detail.html

Not true. Nuclear energy has wide use in thermoelectric generators that simply use the energy that radioactive materials actively radiate. These are more or less mandatory on any probe going past Mars. There have also been a few devices (https://en.wikipedia.org/wiki/BES-5) that appear to be the same idea, but "kicked up" a little with an additional neutron supply. More likely the biggest difficulty with putting a reactor approaching criticality would be getting the budget for such a massive undertaking (not so much the reactor as whatever *needed* that much power put in space), although I'd admit that cooling such a beast would require heroic engineering for cooling (including possible comet capture to allow sufficient cooling fluid mass).

I'd have to wonder if this would lead to the use of parachutes. Not so much to rescue the passengers during a disaster (although it might be sold as such), but to act similar to the parachutes used by drag racers to extend the runway and hopefully use a smaller airport.

I'm pretty sure the Vogon planet destroyer (which destroyed Earth to make way for an intersteller bypass and famously hovered "like bricks don't") hovered at a similar altitude or lower. Visibility was key. And almost on a level with the Vogons. The important bits are visual (or audio for HHGTG), which far outweigh the science in the director's eyes.

I'd have to assume mass would be a big reason.

What would you want the power for anyway? The challenge is harnessing the energy of the Orion without melting the spacecraft. The amount of energy is the problem, not the fact that you waste nearly all of it. The point was figuring out a way to *use* that enormous [low mass] energy in *some* way. Also the only real reason you would want this is for "Fallout" [US 1950's "gas-punk" retro future] styling. Of course, you'd have to make it a V-8. Don't forget that every Watt of power that isn't being used as a spring (Orion needs dampers, doesn't it? Those produce nearly all the heat anyway) will heat up the spacecraft eventually. I'd probably try to tap the waste heat of the dampers myself... Same as acceleration. Exhaust velocity would have to be considerably faster than ship velocity, so I wouldn't expect to see the exhaust again. Just don't ever think about landing on a planet.

Those laws are written by more or less the same crew that keep shoveling money into SLS (well, the Senate is the main source, thus Senate Launch System, but it can't keep going without the House along for the ride).

Intercepting an orbit ("first one") means not only being in the same spot, but having the same orbit (otherwise you'd be moving at different velocities). A fast ISS intercept has the advantage in that you are actually waiting arbitrarily long for the ISS to be in the right position for you launch pad before you "start the clock" at liftoff. Fastest possible intercept is flying toward the ISS at full speed (whatever that is, obviously less than c), followed by a "suicide burn" that corrects your orbital velocity and hopefully doesn't spray the ISS or ISS orbital path with exhaust particles. In KSP, you typically trade fuel for quick intercepts where make significant changes in orbital periods for one spacecraft to catch up to the other and then burn off (or re-apply) said speed. I don't think this is the case with NASA vs. ROSCOSMOS: the delta-v is almost cm/s for the NASA approach. More likely that is how they did it the first time with the shuttle, and that is how they know how to do it.

Check yo' staging

I've heard that crossbows were used to a limited extent in the Korean War (but probably not since). Back when I was a boy scout, I learned that crossbows were more regulated than rifles in my home state. Most of this was likely that they could easily restrict crossbows (and modern ones look scary), but also that they are silent, penetrate soft body armor, and have no muzzle flash (but do point back to their shooter when they stick in something). https://www.youtube.com/watch?v=NTJnyQ-bZLU The ancient weapons segment of youtube went crazy over this set of videos. A mad German engineer developed a "repeating bow" he named the "instant Legolas". Expect 6 to 10 well aimed shots in well under 20 seconds, but don't expect the power of the 15th century bow/archer (although last I saw, they were trying to find ways to get even that. But even just the repeating bow would have been on the edge of 15th century craftsmanship).

Analog computers work on integrals (which reduce noise) and avoid derivatives (which amplify noise). With less complicated equations you just integrate them until the derivatives go away, but I'm not sure about yours. To be honest, the only time I've ever heard about analog electrical computers was as a pre-req for DSP type courses (it introduced the fourier transform and used analog computers as an example of the systems you needed to emulate). To even have a prayer of getting the analog computer in the same class of a digital one (even a cheap desktop CPU), you'd almost certainly have to built the thing entirely on a chip. And then have fun matching capacitance values. Analog computers may be revived in the neural net (AI/machine learning/whatever the latest buzzword is) craze, but I that's the only place I can imagine a comeback.

Sounds like what happens to marathon runners after mile 20 or so. The human body can only store so much glucose, so after about 20 miles or so you run out and it starts to tear apart the rest of the body for more energy (although even the most serious runner has enough fat to last >>100 miles.

I'm pretty sure there are a few more issues, like cost of catalysts and the efficiency of cracking methane (water is only cracked for PR purposes). But you're right in that there would likely be enough work done to make it happen if the really tough issue (hydrogen transportation and storage) went away.

And according to Musk, to validate the design of the factory as much if not more than the design of the rocket. After having issues scaling up Tesla model 3, he's trying to be more like Henry Ford (as interested in the factory design as the car itself. He might even have to increase the "crank level" a bit to match Ford).

Is there any significant part of "US old space" now that isn't owned by ULA directly or by Boeing or Lockheed Martin? I'm sure they both have subcontractors, some with visibility at the contract level, but nothing that would change any of NASA's decisions.

Another thing you seem to miss in these continual questions about the Orion. Pulse engines simply aren't a good system. The reason the Orion was developed to use pulsed explosions was that nuclear explosives were the only known way to produce the energy needed for [interstellar] space travel without the fuel mass where that lets the rocket equation stop you from getting there. There are [were] pulsed jets. Think like a ramjet, only with pulses. The V1 "buzz bomb" was such a thing. But once the ramjet was developed, nobody would think of making such an inefficient design as a pulsed jet. Likewise, if you simply increased the mass (and thus ruined the rocket equation), you could presumably build a de Laval nozzle to efficiently shape your exhaust velocity (it would have to be a massive nozzle to survive atomic explosions, but hey, you wanted to increase mass!). Similarly, if you refused to use a piston, you would want to reduce the size of the explosion as much as possible, and possibly increase the frequency. Perhaps something like laser ignition. And you seem to like anti-matter based tricks. But anything to have a reasonably efficient explosion that is much smaller than traditional. I'm a huge fan of the original Orion. But the whole point of the thing was that it could harness the fusion (or possibly just fission) that we already had in the 1960s to take us to space and possibly the stars (I'm not remotely convinced that the Isp is there for the delta-v I keep seeing for Orion). But there really was no intention (or ability) to make the whole thing efficient. There wasn't a real point: the nukes were simply so much more powerful than anything else humans could produce at the time (still are, although NTR are a something of a thing). Finally, at some point you will just have to stop and play KSP. It isn't on sale right now, so I'd suggest waiting a bit longer (steam should have plenty of post Christmas specials, but I have no idea if KSP will be one). But to understand space you need to understand delta-v and ISP (or at least the rocket equation), and KSP is easily the best way to learn that. These discussions would go a lot better if you understood the rocket equation at roughly KSP-player level.

I'm pretty sure that's how the 100mph delta-v de-orbit works. Of course *all* instantaneous delta-v reductions are about reducing the perigee, and 100mph is barely noticeable (presumably *just* hits the atmosphere). The "de-orbiting velocity" he talks about isn't about lowering perigee down to sea level.

Except in space. Then you get the whole arm...

From a Scott Manley video, you only need about 100mph (160km/h) delta-v to deorbit trash (presumably for trash that will burn up. Hitting the satellite burial grounds in the Pacific likely requires more precision). So a small pneumatic cannon should do the trick. Note: it might be a bit more than that. The answer was that you couldn't throw something fast enough (absolute top professional baseball pitchers could hit that range, but not in a space suit), could easily reach that velocity with a golf club and ball (although the space suit might make it problematic. And Alan Shepard (holder of the beyond-the-world record golf shot of 515 yards) is no longer with us to describe the difficulties of non-Earth golfing. I think the best answer was to put the trash in a ball and use a jai-alai "glove" to throw it. But it wouldn't require your pneumatic cannon to hit any significant "delta-v" (at least significant to a rocket scientist. Cannon makers used to shooting out t-shirts might have to scale up their designs). For such limited missions, I'd expect "put it in a bag and stick it to the outside" would be an option. But that would require and additional expensive airlock and probably make full spacesuits essential. So I'm not surprised it isn't an option (but might be considered for a Mars orbiting gateway).

Not for solar wind, but for bursts such as solar flares and whatnot. You probably don't need to maintain that attitude constantly (I think the real danger is ions emitted in a solar flare, or other such things with real warnings), but I'd keep it that way "just in case" the Sun decided to emit a large EM event in my direction without warning (since you have to be able to turn that way occasionally anyway). From memory, there was a real fear that the Apollo astronauts would be in real danger from such an event (although granted, a LEM is one of the flimsiest vehicles ever produced by humans). If there's a solid core (or at least a large chunk somewhere in the pile) that would be enough. Granted, that assumes you are capable of mining through the thing, and that you are digging out ore instead of breaking metal into useful sizes. Real asteroid mining may involve just sifting through the rubble looking for nearly entirely metal bits and melting them with minimal smelting.

After you develop that warp drive, could you deliver some Covid-19 vaccine to Wuhan around the start of this year? Because the entire reason that the speed limit = c is that any faster breaks causality. While there is the minor issue that increasing momentum only asymptotically increases velocity up to the speed of light, the real issue is that light travels at the speed of causality. Make warp drive and you made a time machine. I'm pretty sure that making the Star Trek universe cannonically non-casual was a fluke needed to fit Harlan Ellison's plot, but it does make their warp drives plausible. They just never bother to point out how bad warp drives (and ansible communication) really wreck chronological order (and how many timelines would get created right and left).