Hard Science Fiction

Wherein I post and reblog scientifically plausible fictional spacecraft. (Header image by Theo Bouvier; avatar by VolusRus)

[hardspaceships]

The "official" purpose of this blog is to encourage the creation of hard sci-fi in art and such

The *real* purpose is to curate a collection of kickass hard sci-fi art so I can keep it all in one place

Feel free to recommend creators (read: pleasepleaseplease I'm so normal about this I swear).

You can ask me anything related to hard SF through my inbox. I like reviewing spaceships.

[hardspaceships]

Heya! I guess I'm another person asking about their own setting here! I've got a somewhat hard setting but one of the two main concessions I'm giving myself is with the engines like The Expanse. Here there is a highly energetic, but extremely reactive (and therefore dangerous) fuel compound which is used in most warships and other vessels desiring high thrust and efficiency, but can take the tradeoff of oxygen leaks into the fuel lines causing a full hull loss. A number of cargo ships and slow, inner system craft craft prefer plain DFD drives as they are much safer and provide enough power while under thrust to put their reactors on minimal power or completely shut them off. And of course if you are utterly insane and have no budget a Nuclear Salt Water Rocket is also there but their use is highly discouraged outside of completely unpopulated areas of space. Anyway, the hyper fuel. The main issue I have is the most reasonable engine type to use the fuel with to make low grade torch drives that works as a light explanation hand wave. Considering that it can also be used as a chemical fuel (No need for separate RCS or shuttle fuel). So far I have them use NTRs but I'm aware of the radiation exposure for the crew, which would get pretty bad I feel if retrograde engines are also included. The other alternative I think would either be some electro-nuclear system or a fusion based drive with the heavier hyper fuel heated and expanded by the plasmified fusion fuel. I know this might be a little too soft for your liking but I would still like to get your thoughts, as outside of my free cards I'm trying to make the setting fairly hard.

We're talking about ✨unobtanium✨, which means anything goes as long as we don't get caught up in the causes of your fictional chemical.

Unless you plan on consulting with actual chemists/rocket engineers (of which I am neither) to work out precisely how you are breaking physics to get what you want, the first thing you want to do is shove your hyper-chemical into a black box, where nobody can see why it does what it does. It just works.

With that out of the way, let's focus on effects.

From what you described, you have a fictional chemical that can be used as both chemical rocket fuel and fission/fusion propellant. This is reasonable, since hydrazine has been used/tested in similar ways, as both the Space Shuttle's RCS propellant and DRACO's NTR propellant.

Fusion drives already exist in your setting, so you can therefore invent a military-grade fusion torch that uses this high-density-yet-high-efficiency chemical as propellant.

Everything else is a matter of determining torchship performance, and so I will direct you to Atomic Rockets for the mathy bits.

Basically, the level of performance you want from your torch should be based on how quickly you want your ships to get from point A to point B. 0.3g will get you most places in our solar system within weeks, 0.03g within months.

Also, by having your drive "shift gears" between, say, 0.3g and 1.5g, you can have a "cruise mode" and a "combat mode"

Anyways, the difference between handwavium and unobtanium is that we can model the effects of unobtainium using real-world physics. As long as you're focusing on effects instead of causes, you can get away with a lot more implausibility.

Postscript: I'm a writer, not an engineer, so advice I give is geared towards what I call "plausibility," not realism. I don't measure the sizes of the radiators on the ships I post to make sure they're big enough to cool the MICF drive, I just check to see that they're there. If I can tell that the creator cares about presenting a high-plausibility ship/setting, then I'm happy.

[hardspaceships]

Ryland-class Exploratory Cruiser

Original concept art by Sir_Lazz

Model by u/DOOMSIR1337

[hardspaceships]

What r ur toughts on "Aether" from the midnight sky? It looks really cool, and some clips of it shows it have lots a feature in and out of it

Let's see what this movie is abou-

Ok, so I read the phrase "habitable moon of Jupiter" and briefly blacked out due to dangerous levels of "what" (also, apparently one of the astronauts is pregnant? Who let that happen?!?)

But I'm going to muster all of my willpower and only focus on the spaceship.

The Aether!

(Art by Jonathan Opgenhaffen)

First things first: This is another example of Hollywood building ships in modules like the ISS. Nothing newsworthy, apart from the fact that they did some really cool design work on the various bits.

We also get this:

(Art by Jonathan Opgenhaffen)

This is extremely helpful for people like me! I get to nitpick in much greater detail!

Ion engines, plus xenon tanks. Good. Also, hydrazine tanks for the maneuvering thrusters. However, those radiators are clearly based on the ISS EATC system. I'm not an expert, but I'm pretty sure those aren't designed to bleed off the heat from two nuclear reactors.

Speaking of which, as cool as the solar panels look, they are A.) uneccessary in the face of said nuclear reactors, and B.) not going to be worth much for a mission to Jupiter, where solar panels operate at 4% efficiency.

Now, uh, all that being said, there's one thing that is absolutely baffling to me.

What in the world is that "shield" supposed to be, and what is it doing right in the middle of the payload section? I genuinely can't think of its purpose. Is it protecting the stuff behind it? From what? Why isn't it in front of the spin hab? Is it supposed to protect the hab from the reactor's radiation? That would make sense (and I would give it extra points) if it was situated all the way at the back of the ship, behind the radiators. Also, it's transparent? I really don't know what it is.

I might do a post someday about "hard-aesthetic" SF vs "hard-setting" SF vs "hard-genre" SF, but the Aether is 100% built for a realistic aesthetic, with a minimal amount of actual realism involved. I like the style, but I wish it made more sense.

[hardspaceships]

your blog is a treasure trove, thank you. also thoughts on the phoenix from for all mankind? if you haven't rated it already.

(also got any hard sci fi media faves to rec?)

I'm currently reading Exodus: The Archimedes Engine by Peter F. Hamilton, which is the tie-in novel for the upcoming Mass Effect spiritual successor Exodus. It's way better than a video game tie-in novel has any right to be, and somehow features a space opera setting with no FTL at all. I'm having a lot of fun with it so far.

My favorite hard SF novel of all time thus far is 2001: A Space Odyssey. I've only recently started reading more SF, so it might be a minute before I have something to recommend that isn't already well-known.

If you play TTRPGs, though, I endorse 2300AD and Orbital 2100, which are both built on the bones of Traveller.

2300AD features an interstellar setting where Earth hasn't unified under one world government, which is a surprisingly rare development. Also, the speculative biology of the aliens is very good.

Orbital 2100 is a plausible mid-future "rocketpunk" setting like The Expanse, but with nuclear rocket engines and an alternate future history beginning in the 1980s.

Anyways, on to the Phoenix:

Honestly, not much to say about this one. According to the wiki, it uses methalox engines, which means they'll have to use a high-effiency-but-incredibly-slow trajectory.

No indication of a nuclear reactor on board, so while those two radiators feel... insufficient for a vessel of that size, the lack of big glowing fins isn't a problem.

Ideally, if you're going to be taking chemical thrusters to Mars, you'll want some propellant depots in place (one in LEO, one in Mars orbit) to make things cheaper. I can forgive the show for not going to that detail, especially since they're pressed for time, and the Phoenix stays put after going out there.

They have interface vehicles for landing on Mars, which is expected, but no indication of how they got on board in the first place. I understand they likely used the Polaris shuttle to get the astronauts up, but if they were planning on coming back to Earth in that thing, I would rather the Earth re-entry vehicle be on-board, both as a lifeboat and to cut down on potential points of failure.

Lastly, no heat shield. That's free delta-v you're leaving on the table! I won't penalize them for it, but it's a thing I want to see more often.

All together, pretty solid design. Nothing groundbreaking, but For All Mankind isn't really going for that.

[hardspaceships]

have you seen the runaway? https://jayeaton.site/RunawayToTheStars/Characters/Bip very nice ship

The Runaway, from the hard-SF webcomic Runaway to the Stars

Model by Lily Harper

[hardspaceships]

Art by @hailsanta.bsky.social

[hardspaceships]

Dusty plasma radiators by @shisurn.bsky.social

[hardspaceships]

What r ur advice in making a Hardsf setting or spaceships?

To start with, go browse Atomic Rockets. I can find no better repository for information pertaining to hard SF.

Besides that, are you creating a setting for a novel/game/art, or are you worldbuilding for its own sake? This will affect the choices you make, including what liberties you take.

That's all I can offer without knowing more.

[hardspaceships]

Hardness ask - the Hermes from "The Martian" movie?

"The Martian" is a beloved comfort scifi watch of mine, and I love the design of the Hermes. It reminds me a lot of the Discovery from "2001: A Space Odyssey" 🤔

The Hermes!

The Martian is one of my favorite movies, and I got into it very early on in my hard SF journey.

To start, the Hermes is a cool ship for the aesthetic of the film, which is heavily NASA-coded. This checks out, because NASA was very enthusiastic about providing support for the film.

However, this NASA-inspired aesthetic doesn't necessarily mean it's the most realistic. The Hermes is very clearly based off the International Space Station, like so:

So, I have a few notes.

Let's start with the good:

The Hermes uses a VASIMR ion drive, which is notable in that it can "shift gears" between low-thrust, high efficiency mode and high(er) thrust and low(er) efficiency mode. This is all from the book, and perfectly acceptable for a very-near-future Mars mission.

If we get a slightly different angle on the Hermes...

...we can see that it has high-temperature radiators and propellant tanks. Very good. I honestly have no notes on that propulsion section.

Lastly, the spin habitat is just plain cool. Any crewed mission to Mars is going to need a way to keep the astronauts' muscles from deteriorating.

Okay, now let's get to the artistic liberties:

First, the size. This thing is very big.

Essentially, the Hermes in the movie is a collection of modules, assembled in orbit, with a series of sheet solar panels and some low-temperature radiators, like the ISS. Then, it adds a cockpit, a propulsion section, and a huge spin habitat.

Now, to be fair, the difference between a space station and a space ship is the existence of a propulsion section, so in that regard the Hermes is right on the money. But the ISS is rather large, as space stations go. Lining up a ship the length of the Hermes and pushing it is going to cost a lot of energy, and when every gram counts, having a ship that size is gonna cost a lot, in terms of both delta-v and money.

Speaking of which, those huge sheet solar panels are unneccessary when you've already got a nuclear reactor on board. They'll just be extra mass, and solar panel efficiency will decrease the farther you get from the sun. It's certainly not as bad as solar panels on interstellar spaceships (something I've seen), but it's obviously a product of Hollywood's habit of designing spaceships based on the ISS. This is something I mentioned in my write-up of the Hail Mary, as well.

Another lore-visual discrepancy is the lack of a forward-mounted heat shield. For reference, here's what the Hermes looks like according to the book:

The spacecraft spins to produce gravity, then pulls those two halves in to provide a cone-shaped shield as it decelerates using Mars' atmosphere. This is, by the way, how real-life probes save propellant when decelerating into Martian orbit.

The Hermes, in both book and movie, uses the ion drives to accelerate, then uses the Martian atmosphere to decelerate for maximum efficiency. Movie Hermes does not reflect this.

My last nitpick is that the spin habitat would either need to spin much faster or be much larger to achieve the 0.4g that the book establishes the Hermes spin gravity to be. Based on the radius of the movie Hermes' spin hab, and the rate it appears to be spinning, the on-board gravity would be 0.02g, which is, not a lot [source].

Wait, actually, one more thing: Where is the crew capsule? I've been scouring whatever images I can find of the ship, and I can't find anything that looks like an Orion. Those astronauts got up to the Hermes somehow.

Conclusion:

Aesthetically, the Hermes absolutely nails it. It, just like everything else in the movie, looks like something that should have been designed by NASA. The vibes are immaculate.

Mechanically, it's the ISS with a spin habitat and a nuclear electric drive, and not much more than that. It's not perfect, but it definitely ain't nothing.

Either way, I love it.

[yodawgiheardyoulikemecha]

Ian Stead

[hardspaceships]

Some of you may be familiar with TV Tropes' "Mohs Scale of Science Fiction Hardness," and while it's certainly workable, it's also very linear.

My system is also linear, but it extends in two different directions, instead of just being "soft" vs. "hard." I think this is important because some science fiction settings combine realistic physics with implausible technology, or realistic technology with fictional physics, and I wanted to distinguish them.

So, because I should put it somewhere, here it is:

The Official(ish) Hardspaceships pH Scale of Science Fiction Hardness!

Acidic Science Fiction

Acidic SF violates the laws of physics in some significant, unpardonable capacity. The nature of the violation becomes more precise as pH increases.

0-1: Technology is whatever looks cool on screen. Technobabble abounds. Spaceships bank in space and blasters go "pew". This is where you find Star Wars, Doctor Who, and Hitchhiker's Guide to the Galaxy.

2-3: Certain laws of physics are acknowledged, but liberally-applied handwavium technology helpfully ignores anything that gets in the way of the story. Space is probably silent, at least. Star Trek goes here, as does the Lancer RPG.

4-5: The laws of physics are now assumed to reign supreme, but we use handwavium to tweak our setting into the form we desire. Battlestar Galactica, Babylon 5, and Firefly all go here.

6: We take the real world, change it, and justify our changes with precisely-engineered handwavium, with clearly-articulated effects. Hard magic systems, basically. Mass Effect and Mobile Suit Gundam go here.

Neutral Science Fiction

7: Apart from our "free pass", we aren't breaking the laws of physics at all. We aren't taking pains to implement realistic technology, either. The Expanse is my go-to example here.

Alkaline Science Fiction

Alkaline SF incorporates realistic technology. The overall realism of the technology increases with pH.

8-9: This is where you see technology that is purely speculative. Quantum radiators, black-hole drives, Dyson spheres/lasers, etc. We can't even begin to know how to pull these off, but we can consistently model their effects using real-world physics. High-concept and distant-future SF resides here.

10-11: This is where you see technologies that have had papers written on them, and may have fields of study dedicated to making it work. Fusion reactors/drives, Nuclear Salt-Water Rockets, nuke-pumped lasers, etc. Most "hard" SF is probably going to wind up here, where things are realistic-yet-still-speculative.

12-13: This is where you find technology that has actually been tested in real life. The Orion Drive, Nuclear Thermal Rocket engines, ion drives, etc. Typically the realm of near-future SF, like The Martian and 2001: A Space Odyssey.

14: Essentially reality, with no speculative elements. Space Brothers and Gravity go here.

This is mostly just vibes, and it would probably work better as a four-quadrant chart, but I do think it's worthwhile to distinguish between physics and technology when analyzing "realism" in science fiction.

I've always held that "hard" isn't a binary, and what it even means can be different for different people (I've heard people call Starfield "hard sci-fi" when it's a 3 at best). I might write about that in the future.

Hopefully this provides some insight into how I think about science fiction.

[hardspaceships]

How do you rate the ships of 'The Expanse' as a hard spaceship? Barring the absolute lack of radiators , what else?

Before I answer that, let me yap a bit about how I approach scientific hardness in SF:

My grading system for hard/soft science fiction exists along a scale that resembles the pH scale.

"Basic" science fiction (pH 0-6) invents fictional physics at the higher end, and ignores physics entirely at the lower end. Eezo, Minovsky Particles, and Handwavium/Phlebotinum generally.

"Acidic" science fiction (8-14) makes use of realistic, or at the very least, plausible technology. Radiators, nuclear thermal rockets, Orion drives, that sort of thing.

The Expanse is (excluding the protomolecule, but every hard SF property gets one handwavium pass) what I call "neutral" science fiction, where a general lack of rubber science is combined with implausible technology. A neat middle ground between breaking the laws of physics and being forced to read NASA white papers.

The spaceships, therefore, follow suit. Expanse ships have unreasonably powerful torch drives, but don't use gravimetrics. They don't have radiators (apart from a few mentions of open-cycle cooling in the later novels), but they don't have inertial dampeners either. They don't use laser weapons, but neither do they use energy shields.

Instead, we get orthogonal deck layouts (as God and Robert Heinlein intended), artificial gravity thanks to Newton, and travel times measured in days (early writing mistakes notwithstanding). Voila! Space opera that doesn't exclude the physicists!

So, no, I don't consider the ships of the Expanse to be particularly plausible, but they are squarely neutral: following the laws of physics, but not doing any more math than is necessary for the story.

In my opinion, It'd be cool if science fiction recalibrated itself around the Expanse, making it the new baseline for how to categorize SF. Anything more "acidic" than the Expanse is hard SF, anything more "basic" is soft SF.

[rocket-enjoyer]

you got the pH scale flipped.

[hardspaceships]

[hardspaceships]

How do you rate the ships of 'The Expanse' as a hard spaceship? Barring the absolute lack of radiators , what else?

Before I answer that, let me yap a bit about how I approach scientific hardness in SF:

My grading system for hard/soft science fiction exists along a scale that resembles the pH scale.

"Basic" science fiction (pH 0-6) invents fictional physics at the higher end, and ignores physics entirely at the lower end. Eezo, Minovsky Particles, and Handwavium/Phlebotinum generally.

"Acidic" science fiction (8-14) makes use of realistic, or at the very least, plausible technology. Radiators, nuclear thermal rockets, Orion drives, that sort of thing.

The Expanse is (excluding the protomolecule, but every hard SF property gets one handwavium pass) what I call "neutral" science fiction, where a general lack of rubber science is combined with implausible technology. A neat middle ground between breaking the laws of physics and being forced to read NASA white papers.

The spaceships, therefore, follow suit. Expanse ships have unreasonably powerful torch drives, but don't use gravimetrics. They don't have radiators (apart from a few mentions of open-cycle cooling in the later novels), but they don't have inertial dampeners either. They don't use laser weapons, but neither do they use energy shields.

Instead, we get orthogonal deck layouts (as God and Robert Heinlein intended), artificial gravity thanks to Newton, and travel times measured in days (early writing mistakes notwithstanding). Voila! Space opera that doesn't exclude the physicists!

So, no, I don't consider the ships of the Expanse to be particularly plausible, but they are squarely neutral: following the laws of physics, but not doing any more math than is necessary for the story.

In my opinion, It'd be cool if science fiction recalibrated itself around the Expanse, making it the new baseline for how to categorize SF. Anything more "acidic" than the Expanse is hard SF, anything more "basic" is soft SF.

[hardspaceships]

Transfer Over Ceres, by u/nolan-void

[zandoarts]

Galilean fast attack craft fly low over Titan in a show of force. These are much older spacecraft, predating the Galilean Revolution. When analysts refer to the Green Fleet of Jove, they’re usually referring to the newer constellations. Nonetheless, these legacy craft still bear the colors of their sister groups and still pose a significant threat to Titanian sovereignty.

[hardspaceships]

The LREF Endeavor and LREF Astrid, by u/Sir_Lazz