Spacecraft question

[Stormonu]

Um, if you have gravity devices on planetary scale (especially that big - you may not understand the amount of energy you'd need to maintain the scenario you're describing - it is equivalent to having an entire planet "under thrust", permanently), you don't get to claim the culture is "on the verge" of the graviometic age.

I guess a better term would be infancy. The technology is on the scale of 60's mainframes vs. iPads. It took several of these "engines" to do the job and only a couple were left on-planet for course-correction afterward (they remainder are being moved to Venus to "fix" that planet next). I'd gone with the assumption once they'd brought the orbit in line with Earth (and stabilized it) they did not need to keep the engines running - they'd somehow figured out how to keep the orbit from drifting or changing).

You have fusion torches. You don't need artificial gravity. Just arrange the deck so that the torch pushes up on people's feet, and so long as you're under thrust, you've got "gravity".

Hadn't considered that, though What happens when the ship start deaccelerating? Does the ship need to do a 180 to pull negative G's?

You realize that whoever owns this device owns the solar system, right? Hitting a planet with a largish object going 0.9C or better is an extinction-level event.

Ow. I can see the Jihad factions wanting to get control of the Hypergun for this very reason. Of course, aiming this thing from way out near Jupiter would be a task unto itself (there's currently only one gun, and its an over-budget prototype right now).

On a side note, you never see something like Star Wars or Star Trek simply aim a Star Destroyer, Cruiser or even a warp/hyperspace torpedo at a planet or enemy and rely on the pure speed destroying the target. So for game/story purposes, I think I'm in the clear for not considering this.

 

[Stormonu]

[MENTION=33447]Storm[/MENTION]omu I think that you have your tech levels mixed up there. Moving a planet is a very high tech level solution and there are a lot of lower tech solutions. Terraforming would take a long time and you would have at least a few tech levels during that process.

That's the funny thing - future tech levels are a guess, we don't really know what will get evolved first. On Romeworld Mars, terraforming has been underway for about 500 years, the orbit synchronization happened about 160 years ago.

Keep in mind that once you have artificial gravity you also would likely have inertial compensators so that your crew is not effected by the acceleration in the first place. They would be both effects of controlling gravitic fields (assuming that it is possible in the first place).

The problem Romeworld is contending with is the delay between first motion and the counteracting of that motion. With acceleration to extreme speeds occuring in less than a second, even a fraction of a delay in arresting that motion is deadly to any organic being. Its basically a technology limitation - when your circuitry is more-or-less light based, how do you control objects moving at near light-speed?

There is also a huge leap from colonizing the outer planets to colonizing another solar system. It is a few orders of magnitude higher (AUs to light years to kiloparsecs).

Yep, Romeworld is still working on the speed barriers involved - they have not discovered a FTL drive that makes anything short of generation ships even a viable idea.

 

[slobster]

[MENTION=33447]
There is also a huge leap from colonizing the outer planets to colonizing another solar system. It is a few orders of magnitude higher (AUs to light years to kiloparsecs).

In distance, yes. On the other hand, it might be much easier to travel great distances (perhaps abetted by advanced drive systems and suspended animation) and colonize a hospitable world in the Goldilocks zone than it would be to terraform the cold, sterile, microgravity outer planets.

I guess a better term would be infancy. The technology is on the scale of 60's mainframes vs. iPads. It took several of these "engines" to do the job and only a couple were left on-planet for course-correction afterward (they remainder are being moved to Venus to "fix" that planet next). I'd gone with the assumption once they'd brought the orbit in line with Earth (and stabilized it) they did not need to keep the engines running - they'd somehow figured out how to keep the orbit from drifting or changing).

Well a planet's orbital period is directly dependent on its distance from the sun. The upshot of that is, if Mars is further out from the sun form earth, but you want it to have the same orbital period (same year length, such that it keeps pace with earth), you have to apply constant force. A lot of force. It would take far more energy than could be produced by detonating every nuclear weapon ever made at once, every second, to keep that planet in its orbit.

If you want a scifi setting that has the technology to do this have at it, but keep in mind it's not very "hard" science fiction.

Hadn't considered that, though What happens when the ship start deaccelerating? Does the ship need to do a 180 to pull negative G's?

Yup, just pull a 180 halfway through and decelerate for the rest of the trip. Other than the weightless period at the middle of the voyage, everyone on board experiences an entire trip at normal gravity (or more accurately, gravity equal to the acceleration your ship is pulling; 9.8 meters per second per second is earth-normal).

Ow. I can see the Jihad factions wanting to get control of the Hypergun for this very reason. Of course, aiming this thing from way out near Jupiter would be a task unto itself (there's currently only one gun, and its an over-budget prototype right now).

On a side note, you never see something like Star Wars or Star Trek simply aim a Star Destroyer, Cruiser or even a warp/hyperspace torpedo at a planet or enemy and rely on the pure speed destroying the target. So for game/story purposes, I think I'm in the clear for not considering this.

Yeah, genre conventions back you up in not considering efficient drive systems to be weapons of mass destruction (as they would be). If you are trying to simulate the scifi genre as opposed to obsessing over hard scifi projection, do it. I've played games like that, and they are great.

As an aside, your hypergun would be a terrifying weapon, but it doesn't really do anything that the other drive systems you have talked about wouldn't. A drive capable of sustaining a 1G acceleration for the entirety of the trip from Earth to Mars would be capable of accelerating a spacecraft to such speeds that, if it just pointed itself at a planet, it would also be an extinction-level event.

Space travel tech is scary!

 

[Umbran]

I guess a better term would be infancy. The technology is on the scale of 60's mainframes vs. iPads.

Doing *anything* on a planetary scale requires either huge amounts of power, or sophistication. 1960s mainframes had neither.

It is your universe, mind you. I'm just telling you where you deviate from real-world science, as your players may notice...

It took several of these "engines" to do the job and only a couple were left on-planet for course-correction afterward (they remainder are being moved to Venus to "fix" that planet next). I'd gone with the assumption once they'd brought the orbit in line with Earth (and stabilized it) they did not need to keep the engines running - they'd somehow figured out how to keep the orbit from drifting or changing).

Here's the thing: for something like Earth or Mars (meaning, a body that is small compared to the Sun), the orbital period is a function of the radius of the orbit. In order to "synchronize" so the distance from Earth to Mars is constant, Mars must be pulled into the same orbital path as the Earth! And, since Mars is of size and mass comparable to the Earth, you wouldn't get to simply park it in a Lagrange point. Now, Both planets would need massive forces applied to them pretty constantly to avoid catastophe.

Hadn't considered that, though What happens when the ship start deaccelerating? Does the ship need to do a 180 to pull negative G's?

Yep. You just flip it around, and come at your destination torch-first. Easy-peasy, for someone who can manage a fusion torch.

Ow. I can see the Jihad factions wanting to get control of the Hypergun for this very reason. Of course, aiming this thing from way out near Jupiter would be a task unto itself (there's currently only one gun, and its an over-budget prototype right now).

Dude, we can hit a distant planet *today*. If you've got the fancy computers that can run such a beast, hitting a planet should be child's play.

On a side note, you never see something like Star Wars or Star Trek simply aim a Star Destroyer, Cruiser or even a warp/hyperspace torpedo at a planet or enemy and rely on the pure speed destroying the target.

In Star Wars, there's a simple defense - the hyperspace drives don't work in the gravity field of a planet, and the ships only come out of hyperspace with the momentum they went in with. Star Wars hyperspace drives cannot produce a relativistic Kinetic Energy weapon. So, they have to build Death Stars.

Star Trek has no excuse. If the Romulans or klingons really hated Earth, they just needed to slap a bunch of drives on an asteroid, and point it at Earth. None of this "red matter" crud

Mind you, they have a script and writers that can force nobody to think of it. Meanwhile, you have *players*, who are not beholden to a script. Just sit back and hope that none of them realize that you've put the mother of all Chekhov's Guns on stage...

 

[Stormonu]

Mind you, they have a script and writers that can force nobody to think of it. Meanwhile, you have *players*, who are not beholden to a script. Just sit back and hope that none of them realize that you've put the mother of all Chekhov's Guns on stage...

Thanks for at least pointing it out; even though I'd put "gun" into the name, it never crossed my mind of somebody using it as a kinetic weapon. I'm guessing the area is going to need the security level of a nuclear silo or area 51 - and it's probably moved every so often to make it a little more difficult to locate.

Still, there are some factions in the game world who'd probably either love to get their hands on the original or its blueprints. I'll have to ponder on that, as there's only one faction that might have the resources to replicate it; the rest would have to settle for theft.

 

[tomBitonti]

For the motion to work, wouldn't there need to be a transfer of energy (and linear momentum and angular momentum) on a truly massive scale? Seems to be possible only if you could transfer all of the above from Mars to a different planet.

Of course, all of these are in particular resonances ... which would then readjust to new stable points.

Hmm, what would happen if you did Mars and Venus both at the same time? Different sizes and different orbits, so still some leftovers. How much would be left over?

Thx!

TomB

Btw, lots of interesting info out there. E.g.:

Types of motions in the rectilinear three-body problem with unequal masses | ResearchGate

 

[kronos182]

@ Umbran : Actually.. I think the reason no one in Star Trek uses something like an asteroid with a warp drive attached to it as a kinetic kill weapon, is due to warp drive dynamics, stresses, and all that other fun stuff. Traveling at warp speed is kind of like traveling in air.. there are stresses that must be over come, through hull shape, the shape of the warp bubble/field created by the nacelles, and structural integrity fields.
One of the rules of warp flight is 'faster than light, no left or right'.. well not a DEFINITE rule, the straighter the flight path, the better, with gentle curves over light hours of distance are fine, but sharp turns require dropping out of warp.
An asteroid requires too much work to make it warp capable especially over a long distance flight to a target. Have to install the nacelles, an anti-matter/matter power source, deflector fields, structural integrity field projectors if you're launching it any distance, computer for flight control and navigation..

Also I think there's a limit to how much mass a warp system can move, so a really good asteroid which will outweigh even the largest starship might not be able to be launched to warp speeds due to limitations in technology.

So yaeh... big long answer.. oh.. and also because it's 'uncivilized' and probably violates a number of treaties of types of weapons that are allowable in war, like we have today.. and it'll destroy a massive amount of infrastructure and resources you'll want to capture.

 

[Nellisir]

You might check out the sci-fi fiction of CJ Cherryh, particularly the Chanur saga and the books around Hellburner (Tripoint Station and...there might be another one) for a good viewpoint on high-speed combat.

In short, her starships have a "jump" drive that utilizes energy from another dimension to attain a high rate of speed and "jump" into that dimension. When they come out, they're moving at a significant fraction of the speed of light, and have to dump speed/energy through "vanes" on the ship.

Vessels moving at superhigh speeds are particularly high-risk, as the lag between information on the vessel and the vessel itself can be very small if the ship doesn't dump V. It's also possible for a ship to propel or carry an asteroid or similar through jump space and release it after exiting jump. The ship can decelerate, but the asteroid keeps going, impacting the target only a few minutes after the light wavefront passes by.

It's not a commonly used tactic because there's no defense against it, and occupiable real estate is fairly rare.

 

[Umbran]

An asteroid requires too much work to make it warp capable especially over a long distance flight to a target. Have to install the nacelles, an anti-matter/matter power source, deflector fields, structural integrity field projectors if you're launching it any distance, computer for flight control and navigation..

All of which you have to do for a normal starship anyway.

Think of it slightly differently - build a cargo starship. Fill it with concrete or lead. Point it at a planet. Kaboom!

The typical no-prize way out of this is to say that Trek Warp drives don't add to kinetic energy in the usual Einsteinian way. But, Trek *impluse* drives are generally rated to get a ship up to almost C, and that's all you need.

Also I think there's a limit to how much mass a warp system can move

Yes and no. The engines on the Enterprise will only move a mass so big - but Trek has established that the upper limit is a matter of practical engineering, not of theory.

"Too much work?" Really? Since when have cultures at real total war balked at doing work? Emperor Palpatine *built* a moon that could move. Certainly making an already-existing moon is less work than building one from scratch.

and also because it's 'uncivilized'

'Cause Kllingons and Romulans and others have proved themselves to be oh, so concerned with offending Terran concepts of civilization in the past?

and it'll destroy a massive amount of infrastructure and resources you'll want to capture.

Well, yo don't get to capture *anything* if you lose. Blow away the "home" planet, and you get to capture all the colonies without blood.

 

[Mishihari Lord]

I am working on my fusion age game in Nexus D20 and my brain is too tired from work this week to think straight. I want to have the ships have a high acceleration rate 10-20 gs with everyone in shock gel and controlling the ship through VR. The problem is that I can't think of a good justification for the ship to have a high Acceleration and a fairly low burn endurance. Fuel wise would that be a bad idea or would it be basically the same as a low acceleration/high burn endurance engine?

The first thing that comes to mind is that hi-g capability is needed for some reason, perhaps to dodge hostiles. Then say that the hi-g engine is difficult to adapt to efficient low-g use.