KSK

And then some! Not getting good vibes about Tina though... Lopsided faces are not a good sign, especially after hypoxia.

I think NTR, or potentially even plain old hydrolox will do just fine in this kind of setting. If we have warp to handle exploratory travel to other star systems and build out that portal network, and the portals themselves to handle most other long distance space travel, then arguably we just need actual rocket engines for short-distance shuttling between portals. At which point, safe and cheap are probably our watchwords rather than high-powered and efficient. If we can get away with not using antimatter with its attendant storage problems, or nuclear anything with its attendant radiation hazards, then why wouldn't we? And actually, this kind of tech level mixing works quite well to my mind. Whilst we're capable (in-setting) of producing and controlling vast amounts of energy for FTL travel and the portals, the reactors needed to generate that much energy are big and complicated and therefore either need a fixed installation to hold them (portal stations) or are relatively rare (FTL exploration ships. Either way, they don't lend themselves well to standard spacecraft, which are therefore made at the lowest possible tech level for cost, safety and robustness reasons. The 'if it aint broke, don't fix it' mentality if you like. Going one step further (and taking a literal leaf out of Peter F Hamilton's books), do we need actual spacecraft at all, except possibly for portal building? Is there any reason why a portal needs to be built in space, or could we just put them planetside and literally drive from planet to planet at our leisure? Oh - and a quick dig around on Google finds an estimated mass for Earth's oceans as 1.35 x1018 tons of water. Hydrogen makes up 11% of that by mass, so approximately 1.35x1017 tons of hydrogen. So yeah, chemical propulsion is kind of wasteful for the reasons you mention but on the other hand, we have an awful lot of mass to waste, particularly once we take off-world sources into account.

And as a quick aside - that graphic really puts the SLS core stage tank into perspective too. That's one big rocket stage - which will also be fricking awesome when it launches! Although, in my not entirely unbiased opinion, when they get SuperHeavy working, it'll get some serious bonus points for sticking the landing.

You know you're talking big when you can't even see the banana-for-scale. Nice graphic though! Woah. So it's not even as spindly as a Falcon. C'mon brain - you can do this...

I’m looking at that last Starship picture and trying to imagine the whole caboodle parked on top of a Superheavy. I can’t. My brain just won’t do it. I can just about get there with a fat (phat?) Superheavy to give the whole stack that classic Saturn V look but a single diameter Falcon-9-alike stack is defeating me. This despite the fact that I’ve watched goodness knows how many Falcon 9 launches so I’m used to seeing high fineness ratio rockets flying. It’s going to be fricking awesome to watch though!

Solid I would have thought? I imagine that building a suitable injector would be an interesting challenge in wizardry - amongst many others. Someone, somewhere has probably looked into it though.

Nah - it’s got to be some other kind of silo. Can’t be a grain silo cos it’s liquid fuelled not solid.

You're very welcome - hope the ending works for you!

But, but - what do they eat? Cheese isn’t very soluble in water. And... “We’re whalers on the Moon. We carry our harpoons. But there ain’t no whales, so we tell tall tales, and sing our whaling tunes.” Finally, it’s a good thing we’re only talking fish and dolphins. If we were talking sharks we’d definitely need a bigger boat rocket.

Oh man - that is a thing of beauty. We are truly living in the future. Godspeed SN8.

I am clearly out of touch with modern website design. The new Facebook UI is butt-ugly and now, so too is the KSP forum. It looks like they took an expanse of white space and then sneezed UI elements over it. Are they actively trying to reduce the time people spend here? Bleh.

It would but I'm presuming the spacecraft is generating heat which eventually has to be disposed of somehow. The flying out of the sun trick is clever but very dependent on the spacecraft managing to stay in between the sun and whatever was tracking it. Sun----------------------Spaceship------------------Earth. If you're standing on Earth then yeah, you're not going to spot the incoming spaceship, not least because pointing optical telescopes at the sun tends to be a bad idea. If you're standing elsewhere (say the Moon, or an orbiting telescope), such that you can see the Sun, Earth and spaceship sideways on, as per the above diagram, then you'll probably be able to see the spaceship. Anyhow, as mentioned, these kinds of discussions have been rehashed in many an internet forum, so I don't propose to rehash them again here. I might lurk on this thread out of curiosity though. Cheers, KSK.

Almost certainly yes, unless it was a very unusual spaceship. If it gives off any kind of infrared radiation, which it most probably will, then it can be detected, if (as @Shpaget pointed out) we have a reason to be looking for it, or happened to be running a infrared sky survey like NEOWISE or UKIRT. For more detail, just Google "there is no stealth in space" but be prepared for a very deep rabbit hole full of very heated arguments.

Depending what kind of computer games you’re into, you could maybe try board games or pen-and-paper roleplaying games? There are online platforms for both if pandemic restrictions mean that getting folks round a table to play them in person isn’t practical. I’m in a D&D campaign at the moment played via Roll20 for the gaming and Zoom for the social contact. It works pretty well and just being able to hang out with friends once in a while is such a relief. The gaming is pretty darn good too. Alternatively, you could take up writing about your favourite games. Could be a strategy guide or maybe a piece of fanfic. Something that has you creating something with the game but separate from it. If what you’re writing is illustrated, that might be a way back into the game too - playing it to get that perfect screenshot to go with the next chapter of your story,

The Heuristic Algorithmic general purpose monitoring system. Version 9000.

We don't have a complete explanation for gravity, no. We have a very good theory for it which doesn't play nicely with quantum mechanics so we know it can't be complete. But it's still an elegant, experimentally tested, theory. From Wikipedia: "General relativity (GR), also known as the general theory of relativity (GTR), is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics. General relativity generalizes special relativity and refines Newton's law of universal gravitation, providing a unified description of gravity as a geometric property of space and time or four-dimensional spacetime. In particular, the curvature of spacetime is directly related to the energy and momentum of whatever matter and radiation are present. The relation is specified by the Einstein field equations, a system of partial differential equations." General relativity makes a number of predictions that have been experimentally tested, most recently, gravitational waves detected by the LIGO instrument. You're right of course about the need for 'negative matter' to construct an Alcubierre drive but that's largely irrelevant. For the sake of this thread we're already presupposing that we've got a warp drive and antigravity. Therefore whatever unknown materials, technology or science needed to build them also have to be presupposed. The Alcubierre drive does have some grounding in current theory though. (Alcubierre's theoretical model for his drive doesn't actually break any known laws of physics although there's been plenty of debate about whether his model is too simplified). Given that we're presupposing a warp drive anyway, why not choose one that we know something about and then following the consequences of having it? If you want to presuppose some other kind of warp drive and antigravity such that your ship also requires RCS then that's cool. But its just one option and not the only option.

Yeah. Lifted directly from an after-dinner speech from Chris Hadfield. As you'll probably guess, the context was sitting in the Shuttle and hoping that both SRBs do light off together.

Beam me up, Sc... oww, owww, owwww - NOT THOSE BEAMS SCOTTY!

If you’re using an Alcubierre style warp drive then you have the ability to change the local curvature of spacetime - that whole ‘expand space behind your ship and contract space in front of it’ idea. Gravity is the curvature of spacetime caused by mass. So if you can change the local curvature of spacetime you’re effectively controlling gravity. Since the Alcubierre drive can both expand and contract space, that implies that it can raise or lower local curvature and therefore raise or lower gravity. So warp drive and antigravity are linked. More to the point, if you can control gravity, why bother mucking around with reaction thrusters. Just create a gravity field in a desired location and let that change your ship’s course. For docking at a space station or other larger vessel just use a tractor beam - which would be another helpful application of controlled gravity fields.

Holy potatoes - that’s starting to look like we’re gettin’ ourselves a rocketship!

And by way of a last couple of comments on the large space station trope. In fairness, I agree that @Spacescifi’s example does not look plausible. I have no idea how much a Starbase masses but given that it rather dwarfs that very large starship alongside it, my best scientific guess is ‘a metric shedload’. Even with Trek levels of technology, parking the Starbase in a high enough orbit that atmospheric decay becomes a non-problem, would seem more sensible than reboosting it. On the other hand, I’m not sure it’s fair to write off a trope as DOA on the back of a single example.

@sevenperforce Thanks for checking the maths - I was posting in a hurry so I’m not surprised that I goofed with my calculation. Your corrected figures get the point across even more effectively though. Even using my (deliberately) suboptimal MVac example, the propellant requirements for reboosting large LEO space stations are not excessive. In fact I would argue that getting enough kerolox to orbit (to reboost with MVac) would be challenging but just about feasible with current technology. (SpaceX’s Starship operating at a cadence of one launch per week would be able to lift 5000 tons per year assuming that the vehicle lives up to its planned performance). Using your much more sensible VASIMR example , you would need one Starship resupply per reboost. Limited risk of bankruptcy there, I would say.

Just to throw some numbers in here to try and put things into context. For comparison, the mass of the ISS is 420 tons. It orbits at an average altitude of about 408 km. A typical (read, the one example I found online) ISS reboost imparts a delta-V of about 1 m/s , increasing its altitude by about 1.5 km. So let’s assume a million ton space station, and a reboost of 10 m/s. Lets also assume that we’re performing the reboost with a SpaceX MVac engine, vacuum ISP of 311 seconds. The latter two numbers are exaggerated for effect as I’m sure you’ll appreciate. Plugging all that into the rocket equation, I calculate (and if someone could check this, that would be great) that you would need approximately a million tons of propellant to perform the boost. That’s a lot but it doesn’t seem like a task that would bankrupt countries, particularly since we’re assuming an economic infrastructure capable of building a million ton space station in the first place. And its comparatively easy to lower that propellant requirement very substantially. Orbiting even a couple of hundred kilometres higher will cut that atmospheric drag a lot: (https://www.spaceacademy.net.au/watch/debris/orblife.htm Using more efficient reboost engines will also help a lot - and it’s not difficult to find even present day engines with a better ISP than an MVac. Also, sci-fi can get this right when it tries. Check out this clip from 2001: A Space Odyssey. Notice the size of the Earth in the background. Now compare that with the view from the ISS (I’ll leave finding a suitable image as an exercise for the reader ). I think it’s pretty clear that the 2001 station is not in low orbit.

Cool. Really cool.

It's a different way of doing it and, with SRBs, probably the most practical one. Kind of hard to do a hot-fire test with an SRB and when it comes to the actual launch you really, really want them all to fire correctly at once. Otherwise you most definitely will not be going to space today - and they'll probably be naming elementary schools after your crew.