Piscator

Pointing out that this drive would violate the third law seems a bit besides the point when the whole thing is based on the assumption that it is actually only a guideline. I think it highly unlikely that they're onto something, but it's at least nice to see their theory tested. No need to argue about it. Just let the universe be the umpire.

Well, assuming your smart cooling system works, you could just add a pair of giant stylish angel wings to your suit to increase the radiative surface. Or you could carry an equally stylish parasol.

Not really. I know that the original poster mainly uses this forum to storm his brain and our input isn't really required, but I guess I'm bored.

That's exactly what I was just thinking about. Space is big and literally contains everything. There's always a place suitable to manufacture a certain product "in space". Unless you specify an approximate region and tech level, the whole discussion is pretty meaningless.

This entirely depends on the technological limitations you are willing to accept in your scenario. All atoms found on earth can be found in space, so there's nothing fundamental keeping you from arranging them as you please. So, yes: everything.

I'm pretty sure scramjets only reach this kind of Isp because they get a large part of their reaction mass for free. After all, when calculating Isp you only have to take the propellant into account that you actually have on board. If you were carrying your own air supply, the number would drop considerably.

It's above the cabin pressure in airliners, so I guess it would be sufficient. There's not really a need to use the ISS standard, is there?

Wait, wait, wait, isn't the advantage of jet engines that you don't have to bring the air along and thus get a lot of your reaction mass for free? Making your intake air from a liquid air storage seems to defeat the purpose and would very likely result in a system massively less efficient than a dedicated rocket engine. Also "generating hydrogen in flight" is a very strange idea. The reason why you use fuel, is so that you have a nice energy storage medium without having to carry the infrastructure around that generated the energy in the first place. Or looked at it the other way round, if you had a sufficiently strong and portable energy source, you could do more efficient things with it than somehow collect water, split it and then recombine it in an engine.

Same thing, really. Whether Triton lost Pluto or Pluto lost Triton is merely a matter of perspective. The important question is whether an event strong enough to separate a hypothetical Pluto-Triton binary would leave Pluto's sub-moons untouched. Since the Plutonian system is apparently rather compact, this doesn't seem completely out of the question and as mentioned, there's always the possibility that Pluto acquired its moons in a later collision event. It doesn't make the whole idea more likely though, especially since there's little evidence pointing to Pluto in the first place. After all, there are more than a dozen objects that pretty much share Pluto's orbital characteristics and there are a whole lot more with perihelia inside Neptune's orbit which would be as likely candidates. And this doesn't even take the possibility into account that Tritons mysterious partner was simply lost or destroyed - either during the separation event itself or during a later encounter with Neptune - which seems far more likely.

At least today, Pluto doesn't come very close to Neptune due to different inclinations of their orbits. Also, Pluto would have had to acquire its current set of moons afterwards as the system wouldn't have survived the encounter. It seems more likely that Tritons hypothetical binary partner met its fate during one of the subsequent encounters with Neptune and was either ejected out of the solar system or inwards where it either disintegrated or collided with another body.

According to my very quick search, further purification involves repeated fractional distillation of volatile silicon compounds. So if you need a second step anyway, it probably doesn't matter very much where your raw silicon is coming from. Especially since this process typically uses feedstock of much lower purity. According to my somewhat more involved search, solar-grade silicon may be as impure as 99.9999%, so the cited "more than 99.999%" might actually be pretty close to being usable without further refining. Apparently, there is also some potential for getting away with even less pure silicon.

I was tempted to interpret "coolest" literally and pick Pluto, but then I chose Earth after all. It's where all the interesting biology is happenening.

Is that a crewed demo of a landing or a demo of a crewed landing? In the second case, you wouldn't necessarily have to have people on board. It would probably suffice to have life support and so on working flawlessly.

Yeah, it looked very different to me in the wide angle view as well. I guess both boosters slowing down so much before touchdown gave me a wrong impression.

I'm not a 100% sure I remember this correctly (well, actually not even 90%), but the difference in timing of the two boosters might only seem more pronounced this time, because they accidentally showed footage from the same booster on one of the previous occasions. The external footage of the two boosters coming down didn't seem much different from earlier flights.

It's also quite noticeable that Webb doesn't see just more, but also different stars than Hubble. The "blue" stars in the Webb image correspond to the "red" stars in the Hubble version pretty closely. But even the most prominent of Webb's "yellow" objects don't seem to show up in the other image at all. That's of course to be expected but it's still interesting to see.

Luckily we don't need to worry about the environmental impact of methane as a lifting gas since it's completely unfeasible in this role anyway. Half the lifting capacity doesn't sound too bad at first, but simply building your airship twice as large is only a solution if you somehow manage to keep the structural weight the same. Which is of course impossible. Even if the square-cube-law works in your favour - and I'm not convinced it does in this case - you would likely end up with a monstrosity of a vessel just to get of the ground.

Couldn't you basically cover the planet (or at least the tidally challenged parts) with subterranean artificial gravity generators to keep the water from falling into the sky? PS Would be possibly quite interesting to have a planet that would naturally self-destruct if there was ever a major power outage.

Thanks for confirming my back-of-the-napkin calculations. I was using a dry mass closer to 100 tons but I also took the additional ~1000 cubic meters of payload volume into account. Since Wikipedia gives slightly higher surface densities for Venus' atmosphere at ground level (probably due to not being an ideal gas and/or being supercritical) and since it can also be assumed that the tank's contents will warm somewhat during decent, things might in fact even look a bit more favourably. Since Starship wouldn't have to be stripped down too much, re-entering form interplanetary velocities might not actually be much of a problem. That's what it's designed to do anyway, if I'm not mistaken. If push comes to shove, there should be a sufficient delta-V budget to slow down propulsively.

If it’s light enough, large enough, and stiff enough, it will deorbit with just fine with minimal heat shielding required. Actually, we might be close to the point where we can try this. Depending on the final figures for dry mass, internal volume and how you pressurize said internal volume, Starship (usual disclaimers apply) might be just buoyant enough to float in the lower parts of Venus' atmosphere. It wouldn't excatly qualify as an airship and would likely have not practical value whatsoever, but it might not touch the ground for a while either.

Using an alloy that's liquid or close to liquid at room temperature makes for a pretty lousy hybrid rocket, I'd assume. Probably depends on what your local room temperature is, though. That said, I can see a use case for metal/oxygen (rich) hybrid rockets on worlds without readily available hydrogen and low delta-V requirements like e.g. the moon.

If I remember correctly, it was considered to send Dawn on a fly-by mission to a third object in the asteroid belt, but in the end they decided to do some additional cool stuff around Ceres instead. Also rovers regularly seem to find themselves with enough delta-Wheel left for an extended mission.

Just figuring out all the launch windows until 2023 doesn't mean they intend to launch in 2023.

Maybe they should switch to ethanol fuel then. Even friendlier to the environment and more fun to "eat the sledge dogs".