Fictional Solar System

I'm trying to make a fictional solar system without a lot of astronomy knowledge, can Veeky Forums help me out?

>Can planets have asteroid belts?

>If not, if I have an asteroid belt around the star is it plausible that a planet with an appropriate elliptical orbit will draw in some asteroids during some parts of the year as the path of its orbit takes it near to the belt? It'd be nice to have a "meteor shower" season for the setting.

Other urls found in this thread:

en.wikipedia.org/wiki/Meteor_shower
en.wikipedia.org/wiki/Perseids
youtube.com/watch?v=3ME5jhsgmB4
twitter.com/NSFWRedditVideo

Additionally, what's a method of space travel that'd get you to other planets in the solar system in a matter or hours or days? I'm trying to avoid FTL travel via warping or anything like that.

Asteroid belt is a big word for planets, it's usually just called a ring. You know saturn's ring.
If the moon got destroyed somehow the earth would get a natural ring too.

If the planets in your system all gt space elevators you can use them as slings to get around pretty quickly and cheap.

Earth isn't massive enough for rings

So can a terrestrial planet get rings? And could you explain how a space elevator sling system might work?

it's all a question of how much thrust you can apply and how much velocity budget you have.

we could set up a trajectory that would send a craft basically straight to mars, but it would fly by or crash and burn spectacularly if it didn't have the means to get into a proper orbit. doing that requires enough propellant to do the job and also an engine with enough thrust to do it properly.

Look up VASIMR engines, that's the closest thing we have that we think is workable for a short trip to mars and doesn't require magic to explain like EMdrive.

Rings come from smaller rocky planets breaking up and getting caught in a bigger planet's gravity well. Saturn probably got its ring from two moons colliding or simply breaking from saturn's gravity being too great.

And space lifts use the planet's spin to "throw" things like a sling. Go up the lift, sit in a shuttle and let go of the lift at the right angle to fly off.

The gravity well has to be big enough for there to be Roche limit for the planet to have rings, Saturn got it's rings from things within the Roche limit getting pulverized by tidal forces

Do pic related

I guess it was more a question of "can terrestrial planets be massive enough to sustain rings" since going by our own solar system one would think to be more massive you need to be gaseous.

So can you dock onto a space lift from orbit and just ride it around until you're in line with the planet you want to go to?

I'll look into those engines. Thanks user

>is it plausible that a planet with an appropriate elliptical orbit will draw in some asteroids during some parts of the year as the path of its orbit takes it near to the belt? It'd be nice to have a "meteor shower" season for the setting.

This already happens to the Earth:

en.wikipedia.org/wiki/Meteor_shower
en.wikipedia.org/wiki/Perseids

Not sure if you're goal is routine catastrophic shit happening...meteor showers are just pretty.

routine catastrophes is what you'd get if Jupiter wasn't there to clear away most of the comets

saturn's rings - the ones that need shepherd moons to exist like they do

"meteor" showers are cause by dead comet debris try again cuck

Anything large enough to have one asteroid is big enough for an entire belt as long as it hasn't been there for long. General astronomy rule: anything can work as long as it doesn't need to be sustainable.

Also, unless you want magic space engines that can get 5gs of acceleration for hours and not run out of fuel, , or FTL, there is no way to do interplanetary in days.

actually those snarky quotes were unnecessary (I meant to say "asteroid")

also, if you plan to have manned ships do the slingshot effect they did to accelerate the voyager probes, best not to do it unless you have some magic technology in place to allow humans to withstand enormous g-force acceleration

>Can planets have asteroid belts?
Saturn

>Can planets have asteroid belts
Kind of, rings are believed to be uncommon on rocky exoplanets but they have been observed, probabaly. Eventually they would probably form a moon but if your planet has recently taken a hit from space or had a moon that got took an impact then it's not unlikely.

>Meteor shower
Happens all the time here.

You can'y go FTL without Sci-Fi warping of some kind. A big fuck off engine will get you there faster than a little engine but you're not going to get anywhere near hourly interplanetary travel without a dash of sci-fi magic.

>Trying to make a fictional
>can it have

YES OF COURSE IT CAN.

So what's a more realistic travel time between planets in a solar system (with planets comfortably close to each other) without getting too outlandish in my travel tech?

I want going to another planet to be a real commitment but I don't want it to take months or years to do so.

Find a table of the solar system and do some of the math. Your question is ambiguous, because "going to another planet" could be (ignoring differences caused by the orbits being slightly elliptical) traveling between Venus and Earth when they at conjunction on the same side of the sun (0.3 AU), Mars vs Earth when at conjunction on opposite sides of the Sun, (3 AU). Jupiter is 5.2 AU from the Sun, so the distance to Earth could range from 5.2+1 to 5.2-1 AU. Travel from Neptune to Earth could be 30 AU, and if Uranus is opposite side of the sun from Neptune, it could be 50 AU to travel between those gas giants.
A speed which takes a day to travel 1 AU could take any where from 12 hours to 2.5 days to reach Mars, or take a month to reach Neptune. If the time to travel 1 AU becomes a month, travel from Earth to Jupiter takes from 4-6 months, and Earth to Neptune increases from that 1 month to become 2.5 years.

Make it a really small system like Trappist 1, where all the planets are virtually on top of each other but still habitable by virtue of the sun being tiny.

You can have cool stuff like free transfer orbits between planets when they're at the right location, that only take a week or two. Also all the planets will be enormous in the skies of each other and look aesthetic as fuck.

Bretty cool knowledge bomb my man

Play that shitty ksp game for a while and you'll get the hang of how things work. As for the story, just set up the fanfic in jupiter style moon setting instead of planets and you are mostly done. Or go with boats/cars/ww1planes in fantasy space setting since that is commonly understood as scifi.

Could use some binary planet pairs. Jumping between the planets in pair would be pretty short, but jumping between different binary groups would be much longer.

Basically imagine the moon was a bit further from earth and nearly the same size as earth. Then at mars you could put another binary pair. So would take a week on 1970s era tech to move from Earth to Earth 2, or from Mars to Mars 2, but a year or 2 to travel between the Earth pair and the Mars pair.

You could handwavey put this in a smaller system, too, like the Trappist 1 system. You'll just want to make the planets in pair smaller and closer together a bit to make it seem more plausible.

OP here, that's actually a pretty cool idea. I didn't look into Tappist 1 as much but I will now. Thank you.

Yeah I see your point about the orbits. I'm just unaware of how realistically fast a vessel can go in space. One AU in 12 hours is over 7 million miles an hour, closer to 8 million. If you're traveling in a vacuum do you notice speeds like that?

Wow is the diameter of the orbit of the most outer planet of trappist 1 really only 0.11AU?

Speed isn't a problem as much as acceleration is. You spend much of the time traveling accelerating, and people only can handle so much acceleration.

And you typically can only accelerate towards your destination for half of the trip max, after that you have to decelerate so that you don't hit a planet a 8 million miles per hour.

So long as your max acceleration is around ~3g, your passengers will probably be OK for several hours. Much more than that however and some people will start to get rather uncomfortable before the trip ends. A bit higher than that is still survivalable however, if you just don't care about passenger comfort.

There are multiple asteroids in our solar system with significant ring systems. Look up Charyklo, it's the first small object discovered to have rings.

A planet cannot have an asteroid belt because by definition an asteroid belt orbits a star. A planet *can* have rings and captured asteroids; all four of the Gas giants have both. Some theories posit that Mars' moons are both captured asteroids. Phobos will eventually be torn apart into a ring system around Mars.

Your hypothetical planet could easily be set up to have a few significantly large (10 to 100 km range) captured asteroid moons AND a significant ring system. One thing you're going to have to consider is the fact that any civilization attempting to launch satellites to orbit is going to have them shredded by orbital-velocity ring particulates unless they either stay low enough as to pass entirely under the ring, or launch on a significant inclination and on a highly eccentric orbit that passes entirely over the ring, then circularize while above it. The ring will act as a massive road block making the transport of any vehicles beyond very low orbits much more complicated and difficult. The ring material itself would contain very little to no volatiles (water, CO2, methane, nitrogen), but the captured asteroid moons may have some volatiles depending on their size and albedo.

The asteroid moons would be in fairly circular, equatorial orbits close to the planet, and in more eccentric and inclined orbits further out, as the close ones would have been more strongly influenced by the tidal forces of the planet's gravity.

>enormous g-force acceleration

During a gravitational slingshot a vehicle is in free fall. It feels zero gravity.

That Armageddon movie is not an accurate source.

If you could snap your fingers and have your ship moving at any speed, the speed wouldn't make a difference for the crew. In free fall in vacuum, there's no difference between eight miles per hour and eight million miles per hour.

However you can't snap your fingers and be moving at any speed, you need to accelerate. The speeds at which interplanetary travel would take several days or hours are so high that even accelerating constantly would mean exerting dozens of Gs on the crew for the entire trip. This is obviously bad.

You really only have two solutions. One is to allow for longer trip times and deal with that. The other is to shrink your solar system, put it around a low mass red dwarf for example, or better yet instead of a planet make your setting a large habitable moon orbiting a gas giant. That way you can have other large moons, many captured asteroid moons, and even a large planetary ring system to use.

That's true for a regular gravity slingshot, but not true for an Oberth maneuver, in which you burn your rockets at maximum just as you swing past a planet, to amplify the effect. That might have been what the movie was showing.

How about Kalgash?

Yep, the entire system is tiny, and all seven planets are about as big as Earth. The star is about as big as Jupiter. It's so comfy.

>space lift

they are a meme mate

Even then you only feel the force exerted by your engines. That force feels the same to you whether you're deep inside a gravity well or far off in interplanetary space.

what is wrong with ksp?

the orbital physics seem legit

Not that guy, Ksp is past its golden age but it's still the best 'realistic' space game where you actually build rockets.

Orbital mechanics in Ksp are hugely simplified because of the use of rigid spheres of influence, but the difference compared to real life is not so huge that it makes much of a difference unless you're planning on doing anything to do with Lagrange points.

>space game where you actually build rockets.

You don't build rockets in ksp?

Have you ever tried rss+ro+real fuels?

Yes, my current install is a full realistic progression/realism overhaul/RSS setup.

You do build rockets in stock Ksp, it's just greatly simplified. In RP-0 you're just more involved with the finer details of launch vehicle construction.

I know so tell me about the more complex rocket builder/space games

>routine catastrophes is what you'd get if Jupiter wasn't there to clear away most of the comets
That is a rather mixed case. Sure Jupiter hoovers up a lot of junk but early on you had the late heavy bombardment. Also today Jupiter exerts enough gravitational pull to dislodge objects from the Oort cloud, sending them crashing through the inner parts of the solar system.

Ksp with Real Fuels, Realism Overhaul, and RSS installed. Weren't you listening?

You said you have a better game than ksp retard.

I already did everything in rss/ro

Have you seen pitch black? That's a good one.

The Vin Diesel one in the Riddick Univserse? I watched it as a teenager but didn't pay attention to any of the space stuff. Do they go into it a lot?

Thanks for breaking this down for me. My goal is to create some sort of run-down, lived-in solar system where space travel is akin to sailing on the ocean. I appreciate you description of rings and what kind of problems they might pose.

I think I'm gonna settle for a small solar system similar to trappist. Is this compatible with larger planets that have rings and moon systems? I could bump up the size a bit and fudge some numbers to make it work.

A few more questions: Do rings have to converge/condense or w/e along the equator? Couldn't you have rings running vertically (pole to pole) which frees up the majority of your non-polar surface area for launches? Would there still be too particulates near the ring that it'd shred passing vessels? Can satellites orbit perpendicular to a planets rotation? How does a planets rotation and the alignment of its rings correlate?

Your system would benefit from a large Jupiter-type planet some way outside the inner planets to eat all the debris that otherwise would rain down on the planets.

From what I understand a ring around the planet would have to be aligned with the equator. Mass distribution is always uneven and any misalignment would be dragged towards the equatorial plane.

If you want to keep planets close you could place a few in Lagrangian points L4 and L5 with respect to a huge gas giant.

>freeze them during the long journeys
>make the journeys short by having them only around moon(s)
>go with magic
I mean, it's not like there's THAT many choices, right? Either that or suck up the 3y travel time to jupiter and fill it with normalfag drama and slasher psychos.

Rings do typically follow the equator, this is due to tidal forces. As the planet spins under the rings, it drags the rocks in the ring along with it, some rocks are closer to the surface than others, and so get dragged more. This spreads the rocks out until the once pile of rocks becomes a ring.

Even if a ring was polar for circumstances I can't realistically image, it wouldn't be stable and over time would no longer be a polar ring. I can't say for sure if it would transition into a more equatorial ring or if it would just basically deorbit.

If you want, you can have a planet with a high axial tilt (with respect to the orbital plane). This would put the poles in line with the orbital plane of the rest of the planets around the star. But this is just finer details in orbital mechanics and doesn't really drive the story too much in such a small solar system. The dV savings would be minor for such a planet.

There would still be particulates and larger debris near the ring and elsewhere in orbit, but these would be very rare. In the shadow of the planet these would be nearly impossible to see or avoid, but otherwise inside the ring relative motion of the particulates and debris would be very small, and thus not all that dangerous. Overtime minor damage would build up, but short trips to the rings, or at least near by (or even through the rings) would be possible. Dangerous at high speeds, reasonable at low speeds. The rings are not very dense BTW. There are ~10s of km between the larger objects in the ring.

Satellites can orbit perpendicular, or opposite a planet's rotation, you'll determine the direction of orbit at launch during the gravity turn. On earth, if the rockets turns north or south during launch it will be a polar orbit. A westerly turn would be opposite the earth's rotation. These orbits require more dV, but for your universe where space travel == sailing it is a relatively minor increase

>The rings are not very dense BTW. There are ~10s of km between the larger objects in the ring.

What's the explanation for things like youtube.com/watch?v=3ME5jhsgmB4 where it's a dense asteroid field full of large debris? Recently destroyed large planet or something? I think in-universe it's just a ring around the planet geonosis but it seems much denser than you described, unless those aren't "larger objects" as you mentioned.

Also I want to thank you for all of your wisdom so far. Our interaction is only ever going to be temporary so do you have some good resources so I can try to study up on this stuff myself?

By larger objects I pretty much mean significantly larger than your ship. Like ~multi-story-building sized. There are a few mountain-sized rocks but these should be extremely rare. There is still a lot of meter-sized rocks and below. But as long as you pass through with low relative velocity, you should be able to easily avoid damage when traversing a ring.

For that scene, maybe shrinking down about 70% of the rocks to smaller than the ships and then triple or quadruple the amount of the new small rocks. There will be a lot of dust too. Traveling at high relative speeds like in this scene would likely be suicidal from the number of high speed small collisions. These smaller ones would be constant and shred the ship.

However at slower speeds the small stuff wouldn't be a problem. You are worried about pebbles hitting your car at highway speeds, but fist sized hail is another story. It'll be like that in the rings. Keep things slow to about ~10 m/s relative and there should be almost no damage at all.

Saturn's rings are 10m to 1km thick, and are primarily composed of particles between 1cm and 10m in size. Even at 10m/s, you'd pass through in less than 2 minutes. Unless you pick a really bad place to pass through.

Also, instead of the big rocks being solid, they are more than likely clumps of much smaller rocks being loosely held together by gravity. So most of the stuff bigger than your ship is probably just a handful of smaller rocks loosely floating together.


Study up in anything and astrodynamics orbital mechanics. Even just wikipedia articles. They'll give you a good enough basis of knowledge to let you get "close enough" for most audiences.

And finally, feel free to take some creative liberties. Don't get to bogged down in the finer physical details that the story suffers.

That 10m/s limit, can I bump that up a bit if I'm using armored vehicles instead of standard space construction practices (which I imagine are a bit more squishy)?

Again thank you for all your help user.

You can bump it up a bit, but much faster and you are almost guaranteed damage. It would be kind of like the heat shield tiles on the bottom of the space shuttles, they do their job most of the time, but can't really be reused, and in some cases, still result in loss of the vehicle.

However if you have complex optics you could possibly reason that the spacecraft aim for thin parts of the ring that is mostly dust when traversing and could reduce the chance of an accident down to about that of airplanes.

The problem with adding armor is that the craft is much heavier and thus needs alot more fuel to maneuver and is slower to accelerate when maneuvering. Fuel scales exponentially with weight, which is why most space vehicles would be as light as possible.

I think up to 100 m/s would be able as fast as realistically possible, but nobody is going to check your math if you go even faster than that. You could even push the speed higher in emergencies and just claim that got lucky. On average though the spacecraft should want to go through as slow as they can though because collisions are going to be very difficult to entirely avoid

I didn't say I had something better than Ksp retard, I said Ksp is the best despite being past its prime at this point. What is reading comprehension.