The Nuclear Dilemma in Starfinder


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Losobal wrote:

Half snark/Half Serious.

If PC's can get a hold of nukes, so can the bosses. And if the boss is supposed to be a threat to the PC Party, and have better resources, they should have better missile defense than the PCs.

Its the old thing of, "Look, anything you can do or think of, so can the bad guys. There's a reason I'm not having them nuke YOU while you sleep." or in this example, "There's a reason why the Boss doesn't just decide "hey, I should send a nuke through a portal and tele-f*ck that PC"

The notion that the PCs have come up with a omg total pwnz idea that no one else has ever considered, especially when its on the level of, "Why not do massive over-reaction level damage?" is kinda silly.

If the PCs want to play on that level of overwhelm, its only fair the badguys do the same. Alternately something that blatant means the actual CR isn't that high and they shouldn't get anything tangible out of it.

"Nuke Planet" doesn't mean you get millions of xp.

This is the opposite of a solution - you're just rephrasing the question differently. We know you can't just teleport nukes in to take out your enemies - the Vesk and the Pact Worlds are both still alive, after having fought a war, and that's impossible otherwise. The question is, what stops you? The answer to that question helps you fill in your world, making it more immersive. It's bad form to just tell your PCs, "this can't work because if it did you'd already be dead, so just trust me that it doesn't", with no further explanation. It's absolutely fine, on the other hand, to say, "this can't work because if it did you'd already be dead, but your character doesn't know why it can't work", provided you're prepared to give a fuller answer when and if the party chases the red ball down that rabbit hole.


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Jasque wrote:
I once played a game where a fellow PC killed the final boss with an interdimensional ballistic missile (IDBM) with a nuclear warhead.

Was his character's name Waldorf?

Dark Archive

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Cthulhudrew wrote:
Jasque wrote:
I once played a game where a fellow PC killed the final boss with an interdimensional ballistic missile (IDBM) with a nuclear warhead.
Was his character's name Waldorf?

I had to look up that reference, and I'm glad I did! Stories of Waldorf might just crop up if my PCs investigate the cause of the Gap.

The Tale of Waldorf:

Dragon Magazine, Issue 137, September 1988 wrote:

Dear Dragon,

Recently my AD&D® game character, Waldorf, a 358th-level magic-user, created the nuclear bomb. Due to this action, all of Greyhawk has been utterly obliterated, except for a 3 × 4 mile island with a castle called Castle Waldorf. All creatures from the Monster Manuals were destroyed due to large amounts of nuclear fallout. All the deities work in a salt mine under Waldorf’s castle. I would greatly appreciate it if everyone would mail their character sheets to me so that I may tally up Waldorf’s experience. All of the game manuals and modules are now totally false and untrue. Any profit made from TSR’s merchandise from this day onward should be mailed to Waldorf’s castle (in gold pieces, of course).

Waldorf Comic


Every planet except maybe Akitosh should have some kind of orbital defense matrix. Now if you're somehow teleporting the nuke directly into the BBEG's base...that's hard to defend. Also consider, however, that while a nuke vs modern materials is pretty much a done deal, Starfinder materials are much more resilient. So a nuke might only deal some damage.


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Especially since we *know* that Starfinder tends to have a lot of stuff built from adamantine-alloys and other super materials.


I think Herbert's Dune series had an in-universe law about how nukes can be used. Maybe it could be applied in SF too. Retaliation only.


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Shadowcat48 wrote:

why bother with a nuke? you can do really entertaining things with big rocks dropped from orbit, or fired by a Mass Driver... think Babylon 5 and what the Centauri did to the Narn home world... nukes have uses... such as a bug infested planet like in Starship Troopers...

No need for nukes when Sir Isaac Newton is the deadliest son of a b%$*@ in Space


Newton? You have enough runway to easily quadruple or more a projectile's mass from relativity, and you're betting on Newton?


The Sideromancer wrote:
Newton? You have enough runway to easily quadruple or more a projectile's mass from relativity, and you're betting on Newton?

Yeah, pretty much. Newton's the way to go.

It's mass times velocity squared. Quadrupling the mass is pretty irrelevant compared to the increase in kinetic energy from velocity squared.


And unless you're shooting your guns supraluminously, there's a hard limit to the velocity. As well, the impact force is closely tied to the momentum, which scales linearly with both mass and speed. This is why hammers are more effective against armour than swords, even if a sword is moving fast enough to have higher kinetic energy, the mace is much harder to stop from continuing to go in its original direction.


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Actually, no, there isn't a hard limit. Or rather, there's a hard limit on velocity, but you can keep cranking the actual energy ( and thus damage ) delivered, by accelerating your projectile closer and closer to C.

That said, do we have any idea whether Starfinder STL drives actually do hit high fractions of C? I mean, you don't need to be traveling at 99% the speed of light to do WMD damage if you're an asteroid, but it makes a big difference in whether or not every random starship is a doomsday weapon. I'm inclined to say "No, not normally", precisely for that reason. Its not *really* prudent to have every single tramp freighter be a planet-killer if you crash it.


I'm just saying that the upper bound on energy is in Einstein's wheelhouse, not Newton's.

Normal Starfinder engines don't normally reach high fractions of C. In-system travel by thrusters takes 1d6+2 days, but at C it would take four hours to go from Earth to Neptune (making the thrusters moving at between 6%c and 2%c for this journey).


The Sideromancer wrote:
And unless you're shooting your guns supraluminously, there's a hard limit to the velocity. As well, the impact force is closely tied to the momentum, which scales linearly with both mass and speed. This is why hammers are more effective against armour than swords, even if a sword is moving fast enough to have higher kinetic energy, the mace is much harder to stop from continuing to go in its original direction.

That's because increase in velocity for the sword is small relative to the difference in mass.

By the time you've got your projectile moving fast enough to quadruple its relativistic mass, the velocity is ~0.87c. The only reason you really care about anything aside from Newton at that point is that it's starting to get harder to accelerate it more.


Metaphysician wrote:

Actually, no, there isn't a hard limit. Or rather, there's a hard limit on velocity, but you can keep cranking the actual energy ( and thus damage ) delivered, by accelerating your projectile closer and closer to C.

That said, do we have any idea whether Starfinder STL drives actually do hit high fractions of C? I mean, you don't need to be traveling at 99% the speed of light to do WMD damage if you're an asteroid, but it makes a big difference in whether or not every random starship is a doomsday weapon. I'm inclined to say "No, not normally", precisely for that reason. Its not *really* prudent to have every single tramp freighter be a planet-killer if you crash it.

You can travel between any two planets in the same system without using Drift drives in 1d6+2 days. If we apply this rule to our own solar system, this means that, on average, you can go from Mercury to Pluto in ~5 and a half days, round up to 6 days. On average these two planets are about 149.5 million km from each other. This comes out to about 29.9 million km/day, 1,245,833.33- km/h, 346.065 m/s. About 0.000115% the speed of light if my math is right. Not actually that impressive TBTH.


1 km/h=1000 m/h=100/6 m/min=10/36 m/s. Dropping four orders of magnitude between km/h and m/s is an error.


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Look, all I want is a way to kill Deathwebs from orbit because spiders driving a giant undead mecha-spider is not something that should be dealt with while you're on the same planet...


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Shinigami02 wrote:
Metaphysician wrote:

Actually, no, there isn't a hard limit. Or rather, there's a hard limit on velocity, but you can keep cranking the actual energy ( and thus damage ) delivered, by accelerating your projectile closer and closer to C.

That said, do we have any idea whether Starfinder STL drives actually do hit high fractions of C? I mean, you don't need to be traveling at 99% the speed of light to do WMD damage if you're an asteroid, but it makes a big difference in whether or not every random starship is a doomsday weapon. I'm inclined to say "No, not normally", precisely for that reason. Its not *really* prudent to have every single tramp freighter be a planet-killer if you crash it.

You can travel between any two planets in the same system without using Drift drives in 1d6+2 days. If we apply this rule to our own solar system, this means that, on average, you can go from Mercury to Pluto in ~5 and a half days, round up to 6 days. On average these two planets are about 149.5 million km from each other. This comes out to about 29.9 million km/day, 1,245,833.33- km/h, 346.065 m/s. About 0.000115% the speed of light if my math is right. Not actually that impressive TBTH.

If you can travel between any two planets in the same system in 1d6+2 days, there's obviously no meaningful velocity you're travelling at.

Not only can you go from Mercury to Pluto in 5 and a half days on average, it takes just as long on average between the closest two planets.

You might be able to handwave something about acceleration taking most of the time, but I'd hesitate to try to draw any conclusions.

Ships aren't assumed to be travelling at significant fractions of light speed. Ships in combat are assumed to be moving roughly the same speed and to be able to turn and alter that velocity quickly. Don't think to hard about it.


Valamuur wrote:
Look, all I want is a way to kill Deathwebs from orbit because spiders driving a giant undead mecha-spider is not something that should be dealt with while you're on the same planet...

Of course they should be. "Take off and nuke the site from orbit" might be the best plan, but it doesn't make the best adventure. There's always a reason it doesn't work.


The Sideromancer wrote:
1 km/h=1000 m/h=100/6 m/min=10/36 m/s. Dropping four orders of magnitude between km/h and m/s is an error.

I... yeah I completely forgot to convert km > m. I did convert days to seconds appropriately though. That said, it does throw my math off.


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thejeff wrote:

Not only can you go from Mercury to Pluto in 5 and a half days on average, it takes just as long on average between the closest two planets.

You might be able to handwave something about acceleration taking most of the time, but I'd hesitate to try to draw any conclusions.

Ships aren't assumed to be travelling at significant fractions of light speed. Ships in combat are assumed to be moving roughly the same speed and to be able to turn and alter that velocity quickly. Don't think to hard about it.

Drift engines don’t go fast. They shift into another dimension (The Drift) where distances are shorter and then shift back.

You can even hand-wave the time requirements as being mostly about the transitions back and forth. Note that to enter or exit the drift you need to be stopped (with no indication of stoped relative to what).

All of the methods of extreme distance travel have involved either teleportation or dimensional travel tricks.


Puts it to ~0.1% of c?
Not sure that's right either. Pluto's ~330 light minutes out from the Sun. (Mercury's close enough to the Sun it can be ignored for this back of the envelope*)

So at light speed it would take 330 minutes - 5.5 hours. That's convenient, since the average transit time is 5.5 days, we can see at a glance it takes 24 times as long, so the average velocity could be 1/24th the speed of light -> 0.04c

Anyway, I still maintain it's not really a meaningful question, since I could do an estimate of a Mercury Venus trip to get a wildly different speed, but we know the trips take the same random time.

distance:
Mercury's about 3 minutes out, less than 1% of Pluto's distance, so that can certainly be ignored, but can't the average distance between any two planets be approximated as the average orbit of the outermost one? They would be closest when they're both in line on the same side of the sun and farthest when they're in line on opposite sides, so the average of those two distances would be the distance to the sun.
All assuming simple circular orbits of course. Pluto's orbit is massively non-circular and out of the plane of the rest of the system so that would throw it off.


Starfinder Superscriber

The way travel in this game works makes my head hurt. I'm on board with there being variables, so that I don't have to build a working 4d model of the solar system, but the idea that the closest planet and the farthest planet take the same time to reach makes me want to face palm.


BretI wrote:
thejeff wrote:

Not only can you go from Mercury to Pluto in 5 and a half days on average, it takes just as long on average between the closest two planets.

You might be able to handwave something about acceleration taking most of the time, but I'd hesitate to try to draw any conclusions.

Ships aren't assumed to be travelling at significant fractions of light speed. Ships in combat are assumed to be moving roughly the same speed and to be able to turn and alter that velocity quickly. Don't think to hard about it.

Drift engines don’t go fast. They shift into another dimension (The Drift) where distances are shorter and then shift back.

You can even hand-wave the time requirements as being mostly about the transitions back and forth. Note that to enter or exit the drift you need to be stopped (with no indication of stoped relative to what).

All of the methods of extreme distance travel have involved either teleportation or dimensional travel tricks.

We're talking about in-system, non-Drift travel. I didn't double check, cause I don't have the book on my here, but we started with Shinigami02's "You can travel between any two planets in the same system without using Drift drives in 1d6+2 days."


pithica42 wrote:
The way travel in this game works makes my head hurt. I'm on board with there being variables, so that I don't have to build a working 4d model of the solar system, but the idea that the closest planet and the farthest planet take the same time to reach makes me want to face palm.

Assume that it's a difference in the available orbits and that you're under acceleration the whole way so the longer trips reach much higher speeds.

It's handwavy as hell and you might want to at least tweak it so that similar ships making the same trip at roughly the same time take about the same time, but you can make it look a little better than it seems at first glance.


Starfinder Superscriber

I was considering house-ruling it to be something different if my players balk.

But if they don't, my explanation for why you could possibly go from Mercury to Saturn faster than Mercury to Mars was that M&M happened to be on opposite sides of the sun when you rolled, and M&S were on the same side. Even that is probably too much for the longer distances though. I don't think there is any position of Mercury and Pluto that's closer/faster than Mercury to Venus, even if they're at their furthest points.

I like the acceleration idea as an explanation, but then the pedants in the group may ask how they are able to easily move around the ship while constantly accelerating/decelerating. I really don't want to have to say "inertial dampers".

Meh, I'm probably just tilting at windmills again. I'm probably the only one in my group that cares.


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pithica42 wrote:

I was considering house-ruling it to be something different if my players balk.

But if they don't, my explanation for why you could possibly go from Mercury to Saturn faster than Mercury to Mars was that M&M happened to be on opposite sides of the sun when you rolled, and M&S were on the same side. Even that is probably too much for the longer distances though. I don't think there is any position of Mercury and Pluto that's closer/faster than Mercury to Venus, even if they're at their furthest points.

I like the acceleration idea as an explanation, but then the pedants in the group may ask how they are able to easily move around the ship while constantly accelerating/decelerating. I really don't want to have to say "inertial dampers".

Meh, I'm probably just tilting at windmills again. I'm probably the only one in my group that cares.

Hopefully. :)

Cause there's a giant pile of worms waiting at the bottom of any attempt to handle spaceflight realistically in anything like real time. :)

I mean, you'd really have to throw out the starship combat rules entirely. They have spaceships using a "speed", not acceleration. Ships are assumed to start any battle essentially at rest relative to each other, I guess? Even though that makes no sense at all.


why does everybody argue about non drift travel times in a system, as if the speed a ship can get through their thrust is relevant to the speed of a bullet shot from said ship?

Like, cannonballs from sail powered galleons didn't travel at 10 miles per hour, did they?

And yes, at 1.3% of C (the speed of ammunition in the Mass Effect video example), Newton is going to do a ton of damage


Well, the original discussion that sparked the discussion about non-drift travel times was about not using bullets from the ship but ramming the ship itself into something.


gustavo iglesias wrote:

why does everybody argue about non drift travel times in a system, as if the speed a ship can get through their thrust is relevant to the speed of a bullet shot from said ship?

Like, cannonballs from sail powered galleons didn't travel at 10 miles per hour, did they?

And yes, at 1.3% of C (the speed of ammunition in the Mass Effect video example), Newton is going to do a ton of damage

Well, if you're aiming at planetary targets and you're capable of reaching even small fractions of c, you don't need guns or ramming. You can just get up to speed, drop a decent size rock and then brake and start your turn.

Calculations for hitting a planet or even a city on a planet aren't hard and intercepting something moving at speed would be difficult.

And it might well be much easier to accelerate a ship to that speed - over a period of hours or days than to fire a smaller projectile, which would need to be accelerated in seconds at most.

Still, it's largely irrelevant to the game - that's not how starships or starship combat work.


Shinigami02 wrote:
Well, the original discussion that sparked the discussion about non-drift travel times was about not using bullets from the ship but ramming the ship itself into something.

The thread itself is about nuclear weapons. Any projectile accelerated to something as low as 1% of C would be a WMD. That's pretty much ever single weapon in the starshhip table that shoots projectiles, because projectiles slower than that would be useless against fast moving spaceships. That means «the nuclear dilemma» becomes the «any weapon in a spacesip dilemma». Nukes themselves aren't much more dangerous than a coilgun, specially if you take in account coilguns don't have limited ammo.


It's fairly clear that starship combat works on original series Star Wars physics plus rule of cool. I'm not sure that any of real life nukes, relative velocity, relativity, the lack of atmosphere or a surface for ships to use to maneuver with, or mass times velocity squared were considered at any point in the system design. Extrapolating them from this starship combat system seems futile. If you want to include them you'd want to start from a different system, not here.


Yes, reading my post again, it sounds as if I'm advocating for "more realism" or whatever. Bad writing, my fault.

My point is: "anything could be used for the same effect than nuclear weapons. The point of the game is not that, tho, and any sensible gaming group will understand that if the GM talks to them about what does he want to achieve in game."

Ideally, players would not use orbital bombardment to skip adventures for the simple reason that playing the adventure is more fun. IF (and only IF) the players are adamant in their intention to skip the adventure with orbital bombardment, then nukes aren't more a problem than basically everything else in the game. The first book in the first official AP in a certain moment have the PC flying a cargo ship that is towing a huge meteor. Accelerate against a planet, let the cargo crash it, and you have a extinction level weapon of mass destruction. At levels 1-4, without nuclear weaponry. That's not the point of the Adventure, tho.


Pathfinder Maps, Pawns Subscriber; Pathfinder Roleplaying Game Superscriber; Starfinder Charter Superscriber

Anyone read the Bobiverse series?

Humanity was nearly wiped out by terrorists dropping meteors on the earth. Later, humanity was saved from a superior alien enemy that was wiped out by having two planetoids dropped onto their home star from opposite directions at near light speed velocities, starting off a supernova-like chain reaction.

That was done with near-future tech, not like what's available in Starfinder. With nihilistic cults like in Dead Suns #2, it amazed me there is a Pact Worlds at all.


Ravingdork wrote:

Anyone read the Bobiverse series?

Humanity was nearly wiped out by terrorists dropping meteors on the earth. Later, humanity was saved from a superior alien enemy that was wiped out by having two planetoids dropped onto their home star from opposite directions at near light speed velocities, starting off a supernova-like chain reaction.

That was done with near-future tech, not like what's available in Starfinder. With nihilistic cults like in Dead Suns #2, it amazed me there is a Pact Worlds at all.

Because it's not a hard science setting. It's space opera. Deal with it.

Ships can fly from planet to planet in reasonable times. Ships can't be used effectively as suicide weapons or dropping high speed rocks, etc. Hand wave it, assume defences, whatever you please.

I'm also not sure how you accelerate planetoids to near light speed with anything I'd consider near-future tech. :)


thejeff wrote:

I'm also not sure how you accelerate planetoids to near light speed with anything I'd consider near-future tech. :)

It's actually not that hard, you just need a lot of thrusters. Preferably rotatable so you can use the same ones to counter the spin before using them to start pushing.


Starfinder Superscriber

Wait, what? What kind of near future thrusters can do that? I think even theoretical fusion rockets are generally fuel limited to extremely low percentages (like <1-5%) of c, unless you can somehow carry a whole star's worth of hydrogen around with you.


It's more the cost (incredible!) than the tech advancement. I mean, you could bankrupt a near-future Earth before you got to the planetoid-pushing point, I'm sure.

Moving little nickel-iron asteroids around may pay for itself and may be affordable for a big consortium now. Thankfully terrorists aren't technically sophisticated, and even ISIS never had access to that sort of money or facilities. You wouldn't need near-C velocities to wipe out a large chunk of humanity.


Shinigami02 wrote:
thejeff wrote:

I'm also not sure how you accelerate planetoids to near light speed with anything I'd consider near-future tech. :)

It's actually not that hard, you just need a lot of thrusters. Preferably rotatable so you can use the same ones to counter the spin before using them to start pushing.

Theoretically, sure.

Given sufficient fuel, plenty of time* and a long distance. You're in space, push on anything long enough it'll go really fast.
Conventional fuel would probably need multiple times the mass of the planetoid. Even with fusion for power, you're still going to be throwing a lot of reaction mass away to get up to speed. And fusion's been a near-future tech for my whole life time.:)

I'd expect a matter of years and probably light years of run up.

Countering spin and any existing orbit are relatively minor problems.


Starfinder Superscriber

To be clear, I agree that moving a rock around is easy enough. Strapping a rocket to an asteroid and slamming it into another rock is just a few years to decades away if we try. Getting it to hit a city or other valuable target on a specific rock is just some vector addition/multiplication, and you only have to be close for it to work.

What I was responding to what that thejeff explicitly said accelerating to near C was not "near future tech" and Shinigami02 said you could do it with "a lot of thrusters". That's what I was balking at.

There are theoretical engine designs that we believe are possible and can get you to relativistic speeds (low percent of C), but they're all fuel/time limited. They either accelerate VERY slowly (like millennia) or require VAST fuel reserves (like whole planets), and usually both and they're all probably impossible, practically anyway. I can't think of even a theoretical design that could get a planetoid near C and slam it into another planet. So I don't think that's "near future" if we haven't even formulated an idea for doing it yet.

If I'm wrong and that idea exists and I just haven't read the paper, and I hope it does cause it would be super neat, I'd like to know, because that's awesome.


avr wrote:

It's more the cost (incredible!) than the tech advancement. I mean, you could bankrupt a near-future Earth before you got to the planetoid-pushing point, I'm sure.

Moving little nickel-iron asteroids around may pay for itself and may be affordable for a big consortium now. Thankfully terrorists aren't technically sophisticated, and even ISIS never had access to that sort of money or facilities. You wouldn't need near-C velocities to wipe out a large chunk of humanity.

I'm not sure where the profit comes from in a little nickel-iron asteroid. Certainly not to pay for itself.

We may have the tech, but nothing like the infrastructure. We can reach orbit reliably and send little robots out, but not much more.

And anything out there is expensive.


thejeff wrote:

I'm not sure where the profit comes from in a little nickel-iron asteroid. Certainly not to pay for itself.

We may have the tech, but nothing like the infrastructure. We can reach orbit reliably and send little robots out, but not much more.

And anything out there is expensive.

Asteroid mining.

There's asteroids out there which could easily cover the costs if the prices of platinum etc. didn't take a dive when it reaches the point where it looks likely to work. if they drop 30-50% as expected then no, it wouldn't pay for itself. They'd drop further with more mining too, though by then the bleeding edge cost would come down.

There's a couple of companies trying to develop the prospecting tech at least, Planetary Resources and Deep Space Industries.


pithica42 wrote:

To be clear, I agree that moving a rock around is easy enough. Strapping a rocket to an asteroid and slamming it into another rock is just a few years to decades away if we try. Getting it to hit a city or other valuable target on a specific rock is just some vector addition/multiplication, and you only have to be close for it to work.

What I was responding to what that thejeff explicitly said accelerating to near C was not "near future tech" and Shinigami02 said you could do it with "a lot of thrusters". That's what I was balking at.

There are theoretical engine designs that we believe are possible and can get you to relativistic speeds (low percent of C), but they're all fuel/time limited. They either accelerate VERY slowly (like millennia) or require VAST fuel reserves (like whole planets), and usually both and they're all probably impossible, practically anyway. I can't think of even a theoretical design that could get a planetoid near C and slam it into another planet. So I don't think that's "near future" if we haven't even formulated an idea for doing it yet.

If I'm wrong and that idea exists and I just haven't read the paper, and I hope it does cause it would be super neat, I'd like to know, because that's awesome.

I'm actually going to use an argument that someone in my own group has actually used on pretty much this very same argument: It's not practical. It's not feasible. It would take a ton of resources. But I never claimed otherwise. I'm just saying, it is possible with modern tech, given enough time and resources.


Starfinder Superscriber

There are only three currently used 'thrusters' using modern technology, in space travel. Chemical Rockets, Ion engines, and Impulse drives. A fourth type of engine was tested in the 50-60s, nuclear pulse propulsion, but it's illegal now.

Chemical rockets can never get you to relativistic speeds. The stuff coming out of the back isn't going fast enough. No matter how much fuel you add, there's a top speed because of this. Even if you burn the mass of the entire universe as fuel, you're looking at 0.2% the speed of light. reference math The practical top speed, based on how much fuel you can actually strap into a rocket, is much, much, much lower.

I don't remember the specific impulse of Ion or Impulse drives off the top of my head, but I know they require less mass. They have higher theoretical top speeds, but they accelerate a LOT more slowly, because the mass coming out the back is so low (but going really fast). Even still, the practical top speed of these things (short of burning up the entire universe as fuel), is only about five times that of chemical rockets, as far as I know.

Nuclear Pulse propulsion involves throwing nuclear bombs out the back of your ship, setting them off, and riding the shock wave. The US Air Force actually did this in the 50s-60s, but the project was shut down around the time of the Nuclear Test Ban of the early 70s. Look up Project Orion or Daedalus if you're interested, those guys were insane. I read a report on the math a long time ago, and if you burn the entire universe as fuel, I think you still only get up to 10% C. With what you can put on a ship, you're looking at probably double what the ion drive can do.

There are fusion engine designs that are faster, but they're theoretical, they've never been built or tested as far as I know, because we've only gotten fusion to work one way so far (Hydrogen Bombs).

Sure, you could make the argument that if you had all the mass of the universe to use as fuel and the entire history of the universe to accelerate, it's possible to get a rock up to those speeds using a known drive type (Daedelus), but you've already destroyed your target by burning it as fuel, so really, what's the point?


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There was a different form of nuclear propulsion, tested in labs if not in space - look up NERVA. Rather less insane it used a more stable nuclear reactor to heat gas which could expand out the back to provide propulsion IIRC. It was dropped due to the risk of launch pad fires or other failures spreading uranium all over the area.


Pathfinder Maps, Pawns Subscriber; Pathfinder Roleplaying Game Superscriber; Starfinder Charter Superscriber

Sorry, I probably should have spoilered my first post.

Further Bobiverse Spoilers:

I don't recall the type of propulsion used, but the planetoids were basically moved with lots of thrusters.

The guy who set it up was a human named "Bob" who had his brain transplanted into a spaceship computer. He could build copies of himself and mine far away celestial bodies for materials to build whatever he needed. He had years to maximized his self-expansion/other work ratio to get his job done quickly and efficiently. So he built a bunch of thrusters, attached them to a few planet-sized or near-planet-sized objects, did the math, and launched them at humanity's enemy. By the time they arrived on target, they had spent so much time accelerating that they just obliterated everything.


pithica42 wrote:
Wait, what? What kind of near future thrusters can do that? I think even theoretical fusion rockets are generally fuel limited to extremely low percentages (like <1-5%) of c, unless you can somehow carry a whole star's worth of hydrogen around with you.

The kind of near future thrusters that use technomagic.

In game we have artificial gravity. There's a nig chance that means mass effect fields such as in Video game franchise Mass Effect. It is pretty easy to accelerate things thstt have no mass.


avr wrote:
There was a different form of nuclear propulsion, tested in labs if not in space - look up NERVA. Rather less insane it used a more stable nuclear reactor to heat gas which could expand out the back to provide propulsion IIRC. It was dropped due to the risk of launch pad fires or other failures spreading uranium all over the area.

No. NERVA was dropped because the vibrations caused by passing the Reaction Mass (water) through the Fuel Rods would knock off bits of the Rods. Those bits would be carried away by the exhaust, making it highly radioactive. A modern version might involve passing the reaction mass through a Heat Exchanger, with a (theoretically) slight decrease in the Specific Impulse.


Shinigami02 wrote:
thejeff wrote:

I'm also not sure how you accelerate planetoids to near light speed with anything I'd consider near-future tech. :)

It's actually not that hard, you just need a lot of thrusters. Preferably rotatable so you can use the same ones to counter the spin before using them to start pushing.

Solar sails seem much more economically efficient than thrusters, even if they'll be much slower. They even have the benefit of being reusable once your asteroid has been brought where you need it.


gustavo iglesias wrote:
pithica42 wrote:
Wait, what? What kind of near future thrusters can do that? I think even theoretical fusion rockets are generally fuel limited to extremely low percentages (like <1-5%) of c, unless you can somehow carry a whole star's worth of hydrogen around with you.

The kind of near future thrusters that use technomagic.

In game we have artificial gravity. There's a nig chance that means mass effect fields such as in Video game franchise Mass Effect. It is pretty easy to accelerate things thstt have no mass.

That's not near-future tech.

This particular line of conversation was spun off a reference to another work where they used near-c planetoids as weapons with "near-future tech".

For Starfinder, the details of in-system propulsion or of artificial gravity aren't specified. You don't have to assume they're the same as Mass Effect if that leads to consequences you don't want in the game - like it being easy to use asteroids as planetkillers.
Incidentally, I wonder if this is part of the reason science fiction table top RPGs don't seem as popular as fantasy ones. Players being players they try to exploit things and in SF RPGs you have not just the rules, but the scientific consequences of those to abuse. Magic just works like the rules say and you can't really extrapolate much beyond those rules. In science fiction you easily can, as we see in this discussion.

I know I've had assumption clashes with GMs in science fiction games in the past - partly due to knowing more real world science.


Bluenose wrote:
Shinigami02 wrote:
thejeff wrote:

I'm also not sure how you accelerate planetoids to near light speed with anything I'd consider near-future tech. :)

It's actually not that hard, you just need a lot of thrusters. Preferably rotatable so you can use the same ones to counter the spin before using them to start pushing.
Solar sails seem much more economically efficient than thrusters, even if they'll be much slower. They even have the benefit of being reusable once your asteroid has been brought where you need it.

Useful for moving around, but not so much for weaponizing them.

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