Bill Phil

There's stuff out there that we just haven't seen yet. And to me, one of the weirdest things is the Bootes Void. https://en.wikipedia.org/wiki/Boötes_void It's not strictly empty, but it's a huge region that's relatively devoid in galaxies. Almost like a supercluster or two got deleted or something.

Probably steam, I'm not too aware of how pressure or state affects electrolysis.

Yeah fusion power reactors will definitely be similar, but it seems like they'll operate at lower temperatures in the working fluid, since the reactors need to be larger for a given power output iirc. So it seems like fission would be better suited. The problem with hydroelectric is that there just isn't all that much capacity in it from my understanding. And you're going to need a lot of capacity to electrolyze hydrogen at the needed scales.

I don't think there's much reason to. It's certainly something interesting, though.

Actually I would say that water splitting is more suited to fission reactors, since most fusion reactors (even tokamaks) will likely be pulsed in nature at least somewhat, among other issues that fusion has. Fission on the other hand can continuously operate at high temperatures... which reduces the electricity need for water electrolysis. Electrolyzing hot water takes less electrical energy than electrolyzing room temperature water. This can be done with the heat from fission reactors. Meanwhile I'm not sure that fusion reactors will be as capable, not to mention more complex, for the task. Though you just need cheap heat, and there are a lot of sources of that. But nuclear fission reactors are a technology that can provide that heat, and fission reactors work now.

Yeah IIRC there's a rule where they have to have multiple companies involved. So they'll probably end up launching crew on both Dragon and CST-100.

Rocket fuel isn’t all that expensive as is

I'm aware of the instability issues with Z-Pinch. Modern concepts are quite capable however and sheared flow stabilization could make it work. It's still decidedly non-trivial and new problems are likely to crop up, but even besides that the Z-machine did good work up until fairly recently, though I haven't looked into recent news on that front. Still, through experiment and bettering our understanding it could work. Looks like they're doing experiments for MagLIF, sort of like fast ignition for Z-Pinch systems. And from what I can find they've massively increased their neutron output in recent years. Looks promising, though using the word "promising" for any fusion system is problematic in its own way. Yeah, it's a yikers. Other facilities and scientists are working on confirming the claim or at least verifying as much as they can.

I’m more optimistic for inertial confinement, seems like NIF doubled their energy yield recently as well. Maybe not but that’s a possibility. Z-Pinch could work, and there are some cool concepts out there. As for doing it in a magnetic field like a tokamak... well, it probably won’t do much for power, and will mostly be of interest for research purposes. For space propulsion either inertial confinement or Z-Pinch is probably the way to go. Sustaining the conditions for fusion just seems out of our reach. @KSK Fission powerplant costs are dominated by legal fees and financial weirdness, not the complexity or difficulty of building the reactor. That said better standardization of reactor designs would help significantly as well as addressing the other issues. But that depends on large scale deployment of reactors. France seemed to manage it reasonably.

The Saturn V was pretty sweet, and even SLS can't quite beat it (despite claims that SLS is more powerful).

Yoooooooo. I remember that show. Crazy.

Well in a sense if you can get photons to provide current (say, in a solar panel) and then power an electromagnet you’ve converted light into magnetism.

IR astronomy? Huh. Might be something to do with elemental abundance on the surface... but then again it could be something else entirely.

From what I recall it's the binding energy between the quarks, but that can be construed to be kinetic energy as well.

I've heard "gas giant planet" before.

I've seen planemo (planetary mass object) tossed around for anything that would otherwise be considered a planet but isn't due to not orbiting a star. Could also be construed as a portmanteau of planet and moon. For that example, sure. But when it comes to planets all we're doing is using external factors to distinguish between planet and dwarf planet. The actual physical processes on the bodies involved though have enough similarities that it's questionable to make dwarf planet a completely separate category of object.

There are many fields that conflict in their terminology. It's not really a problem. And in this case using the term planet to describe objects that are physically similar and have similar processes would be beneficial. In astronomy the definition could be anything, though I do believe that major and dwarf planets should be a subset of planet. Some merging of astronomy and planetary science might call large moons like Ganymede "planet-like moons" since they're just that large. Planetes described wandering stars. The original intent was for anything of that sort. Under that intention then asteroids constitute planets as well since even with reasonably powerful telescopes they look like stars. It's not too big of a deal, and having objects like Pluto (and Ceres, plus a lot more) be counted as planets (though given the modifier minor or dwarf depending on their significance in the system) isn't a problem either.

Well I would only call them planets in certain contexts. They're moons as well, I just think that planet would make more sense to describe certain properties like hydrostatic equilibrium in a non-fusing body. This is because there are processes and properties that can be found on these moons that are similar to what happens on (what are commonly accepted to be) planets, like cryovolcanism. Basically they're planets in the context of planetary science, but moons in the context of astronomy. As for Pluto-Charon, I'd call it a double planet, along with other bodies orbiting the Sun that are non-fusing and in hydrostatic equilibrium being planets. My problem with the IAU definition is that dwarf-planet is a distinct class from planet, and not a sub-class. But it should be other way around - major planets being ones that dominate their orbit and dwarf planets being ones that don't, with both falling under the planet category. The IAU definition is just weird. I feel as if they just really wanted to make Pluto not a planet, and didn't much care for the whole thing being sensible.

I don't have a problem with calling the Galilean moons planets. Though they would generally be referred to as moons (since they are moons) but I don't see why planet wouldn't be acceptable if it's physically accurate.

I'd call it a planet. I believe we should use properties of the body in question and not external properties. Essentially, "clearing an orbit" doesn't really make sense for defining something.

IIRC there was a book like that where we build a starship around 1492.

Lol. Guess I'm too honest.

I would but it seems to want my location. Not like it can't get it already but still.

Didn't they serve on the city council or something? I'm sure they could sell some of their inventions if need be.

Yeah that would be pretty cool. Maybe you could argue that the normal tanks have separate structural elements from the tanks themselves. Combining the two creates much better tanks. Keep in mind that delta-v limitation is only for one stage. Multi-stage vehicles or vehicles with drop tanks are much less limited.