I'm currently in the early planning phase for a hard sci-fi campaign set solely within the Solar System. What I'd like to do is figure out some way to simplify orbital mechanics in a way that wouldn't require me to boot up Kerbal Space Program or manually figure out equations every time, if only because that ruins the pace of play. The Expanse RPG has some decent charts for communication times and brachistochrone trajectories but they rely on using torchships and I'd like to limit the use of those in-setting if possible. Has anyone here made or played with a ruleset or an external program that could allow for this? If not, any ideas as to how I could go about crafting one?
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>hard sci-fi
Yawn.
Stop breathing
I like the way that the Universal Century timeline of Gundam does it. There are human presences on Mars and Jupiter but they are months away from Earth and most of the action takes place within the bounds of the Earth, the moon and orbiting clusters of O'Neill cylinder colonies except for the one time a guy from Jupiter showed up in the middle of a civil war and completely changed the dynamic of the war or the whole Mars Zeon thing where Zeon true believers ran away to Mars where Earth authorities had less of a grip and surveillance so they made a new movement with a core of Zeon exiles who didn't sign up with the Axis Zeon faction who were based out of an asteroid mining station turned fortress that was just outside of Earth orbit.
Oh yeah I'm definitely going for the orbital habitat route, it's a great way to be able to slot in new locations and adventures without having to frick about with geopolitics elsewhere too much. I'm looking less for setting ideas as much as a way to make the orbital mechanics work well in a tabletop setting.
Huh, never thought about doing it that way. I was considering just using one of those subway-style delta-v maps but I was struggling to find a way to make that work well for Lagrange points and stations and I think that could work. My only concern is that I'd need to figure out some sort of way to abstract things like gravity assists and travel times but this seems like a decent starting point if nothing else
>a way to make the orbital mechanics work well in a tabletop setting
My point was communication wise, having it explicitly NOT work is a valid option. If the majority of the action takes place in the Earth sphere and the Earth authorities have nominal at best control over places like Venus, Mars and Jupiter, it would provide fertile ground for war criminals on the run and exiled members of past antagonist factions to retreat to and cultivate a new movement against the Earth government.
I wasn't really planning on having any single planet have a unified government anyway. I think it'd be more interesting to have major planets be fairly balkanized. Mars, for example, would have its own nations that are either entirely based on the planetside, in orbit via space habitats, or some combination thereof in addition to a few that are still nominally colonies of Earth-bound powers. It also allows a little more nuance to military conflicts because you there's actual risk to using high-velocity impactors to do all of the work for you
Instead of mapping the whole solar system and keeping it updated through the games, make relative abstract maps between the various powers.
Concentric circles should do. The inner point is your planet (or you if you are on a station, whatever) and each further sphere represent a "proximity layer". You can then subdivide layers to represent a specific planet or orbital or whatever. Going from one layer to another cost certain about of Delta V, and specific sublayers may cost more to represent adopting a harder orbit.
>hard sci-fi
noice
>orbital mechanics
double plus noice
What's your maximum speed? Also I think there is universe sandbox on steam or something.
I'd consider Universe Sandbox or Space Engine but I don't own them right now and I don't necessarily want to run them simultaneously with a VTT if I can avoid it
I feel stupid for not thinking of looking into the High Frontier ruleset with how often it gets cited on Atomic Rockets, thanks for the reminder. I'll probably include torchships of some kind at least for large governments or militaries but I'd like to keep them relatively uncommon so I'd like at least some supplemental rules for other ship types. As for location I did give some thought to the Jovian moons but I'm probably going to keep it to the inner solar system because they're yet to be heavily developed in the timeframe of the campaign. But yeah, I am 100% going to be keeping the interplanetary travel to a minimum where I can
I'll definitely look into this, thank you anon. As for what my campaign is about I'm still a little too early to have anything super concrete as I only have one player I know will be playing it with 100% certainty but the elevator pitch is that it's essentially space trucking with all that entails. I'm debating maybe having the players work directly with the government of an upstart asteroid belt habitat and trying to establish their long-term supply lines but I haven't committed 100% to it yet.
I think I saw this in a thread ages ago and forgot about it, I'll definitely give it a look
I tried looking for this while I was doing research but it's apparently the only GURPS thing on Da Archive that got DMCA'd, unless that's changed since I last looked
My guy, check out Aurora 4x
It's a Grand Strategy Hard SciFi Spreadsheat Simulator, but the big draw for you will be the map generation for the solar system. It's about 100x lower impact than anything like Sandbox or Space Engine, and also a fun game too if you ever want to get into it.
There should be some easy youtube tutorials on how to start a game, and once it's going it simulates orbits, distances, everything like that in the background, with as realistic as possible measurements between objects, variable orbits, all that great shit.
It's excellent too because you really don't even have to play the game, to my knowledge there is no real failstate once the simulation starts. Just watch the system swirl around.
I actually have tried and failed to get into Aurora before, never really thought to use it as a tool for running a campaign. If you have any specific videos that do a good job of making a proper tutorial for it I'm all ears, but from my personal experience it seems like the kind of game that'd require just as much prep to learn as running a campaign on its own
Thanks Anon, I found it there. I don't know how the frick I missed it the first time I looked, I must have been tired and just skimmed through it
Aurora isn't suitable for any hard sci-fi shortcut-model of interplanetary spacecraft transits or interactions because it uses a non-Newtonian propulsion gimmick to sidestep and simplify its emulation of spacecraft movement into Terrestrial Navies in Space.
But honestly, I think the concept of actively needing to figure out the precise orbital mechanics of planetary bodies and spacecraft in our Solar System in the middle of a TTRPG session is kind of strange and superfluous. Why is this necessary in the first place, what exactly is the focus and content here? If it's "ship combat", everything will get bogged down if you don't just settle for approximations and intuitive Newtonian outcomes to player actions regardless. A genuine attempt to move past this with a hard sci-fi modeling of content will inevitably ruin the pace of play, there are too many relevant variables to keep track of once you peel off the top layers of abstraction.
Yeah, that's why I'm just trying to shorthand it. I want to try and keep some facsimile of it though for a couple of reasons, mostly tied to the longer travel times:
>Less direct control of space colonies from Earth
>Colonies have time to develop as their own nations and cultures as a result
>Ships have to put in more time and commitment to travelling interplanetary distances so players have more reason to be on the surface or in space stations doing odd jobs and gathering cargo contracts for their next journey rather than just refueling and fricking off
>Outer solar system is hard to access and is less developed as a result
>Allows me to slowly introduce torchships as a paradigm shift that sets up for military conflicts, colonization rushes for Jupiter's moons, and other potential plot hooks later down the line
>it's apparently the only GURPS thing on Da Archive that got DMCA'd
Check the PDF in the OP of the GURPS general
Save yourself a headache and go for Expanse-like torchships. That will save you the hassle of orbital planning. Just use a nomogram like pic to plan transit times..
https://projectrho.com/public_html/rocket/
this website has everything you need for hard SF, including gamey-like modelisation.
Look up High Frontier and learn the rules for a game-ready orbit transfer trip planner.
But really, interplanetary travel should be a rare occurence or an in-between sessions thing. I recommend setting your adventure around the Jovian moons, loads of places to visit and very short transit (hours at most) between moons. Also, this place has loads of opportunities for geopolitic and colonail chicanery.
>to boot up Kerbal Space Program
That's actually not a bad idea and I wish I could think of a better one. Will be monitoring this thread.
Space Engine would probably be lighter and easier to use
THS is a source setting to get a general idea how the 22th century might look like and how space might get developed. I personally would also add space factories creating RT superconductors for more fun laser time and greater push for space. What will your campaign be about?
Orbital 2100, a setting for the Cepheus Engine (basic license-free Traveller), specifically exists to adapt the rules to a more realistic near-future solar system traversed by fission-powered NTRs. It has extensive rules for travelling between the inner planets, outward to the gas giants, and to each Lagrange point around Luna. Fuel is laid out too. It's probably the most detail I would go into without Kerbal.
>solar system traversed by fission-powered NTRs
Never thought cuckery would be the key to space travel.
GURPS Spaceships is predicated on hard science primarily, with reactionless drives as an optional afterthought. It's a fantastic resource in general, but these two tables specifically should be exactly what you're looking for
>pay X deltav to change orbits
Space is like a railway. Strategic travel is changing lines and tactical travel is more of a knife-fight in the engine room.
Aren't those values are for slow-ass hohmann transfers? Should be able to spend excess deltaV to get there faster but that sounds like a whole lot of autism.
You could theoretically make your burns at a suboptimal time to leave sooner, sure, but you'll probably not save much time in terms of the time it takes in transit on its own because it will still look functionally identical. Really the only way to avoid having slow travel times is to have torch ships or something close to them like an orion drive.
Without having some really fancy future tech that is both more efficient and more effective. Even the expanse, popcultures "hard sci-fi" lovechild handwaves it with "something something magnets, something something plasma"
No, not really.
Yes. Spending more DV than the literal minimum possible to do a transfer reduces travel time massively. Travelling to mars in weeks instead of months, hohmann transfers are used because they're the cheapest way.
It costs 3.9k DV to do a 260 day transfer to mars when they're aligned.
If you have 12k DV to spend the trip only takes 70 days (NASA proposal for a Earth-Mars tug)