Environmental effects of various propulsion systems

[Nerys Ghemor]

Many stories have speculated there are reasons not to go to warp within a solar system...some say it's because you'll destabilize the star, others because you can't do so within a planet or star's gravity well without tearing your ship apart, and other reasons.

What about impulse? Have we ever seen a ship go to full impulse (rather than maneuvering thrusters) in atmosphere? If they did, would there be any environmental effects from doing so?

(On that note, impulse is assumed to be some form of ion drive, correct?)

 

[Santaman]

Impulse engines are a coil drive just like warpdrive except that they are specifically designed to operate at sub light speed, they are also driven by fusion reactors instead of matter/antimatter although some designs like the refit Constitution have a so called impulse deflection crystal that let impulse power to be augmented by energy from the matter/antimatter reactor.

The exhaust of impulse engines is probably waste heat and helium thats been expelled by the fusion reactors that power the drive.

As for enviromental concerns, I assume not that much since shuttles are flying around in atmospheres without any problems.

 

[Ronald Held]

If the impulse exhaust consists of energetic helium ions, I cannot see much of an impact in space.

 

[Cmdr Sho]

Impulse engines are a coil drive just like warpdrive except that they are specifically designed to operate at sub light speed, they are also driven by fusion reactors instead of matter/antimatter although some designs like the refit Constitution have a so called impulse deflection crystal that let impulse power to be augmented by energy from the matter/antimatter reactor.

The exhaust of impulse engines is probably waste heat and helium thats been expelled by the fusion reactors that power the drive.

As for enviromental concerns, I assume not that much since shuttles are flying around in atmospheres without any problems.

Well, you have to remeber that a shuttle is smaller than a starship. Voyager would have a harder time flying in the atomsphere of a planet under impulse than a shuttle... Not to metinion the force needed to move that big of a ship... It might not cause enviormental problems but I think it would cause problems for the starship more...

 

[Timo]

If the impulse exhaust consists of energetic helium ions, I cannot see much of an impact in space.

Or in an atmosphere. Unless the exhaust is a hypervelocity jet, which would be nice in vacuum but nasty in an atmosphere, causing undue shockwaves and all. But I agree that it doesn't seem as if impulse engines would be conventional rockets with propulsive exhausts.

Perhaps impulse engines cannot be used in atmospheres? After all, Kira in "The Siege" claimed that going down to the soup would negate the advantage that the impulse-capable interceptors had over her little sub-impulse craft. The shuttles might operate on some sort of gravitic systems down there, only turning on the impulse engines after getting sufficiently high up. Or then it's just a case of having to throttle down the impulse engines a bit. But if it's gravitics, those probably don't do environmental harm.

Warp fields are known to damage subspace if they are sufficiently intense, or applied often enough in one spot. But we might be speaking only of catastrophically big field eruptions, and of centuries of wear and tear.

Both impulse and warp are said to leave a trail that can be followed in vacuum. But even if that trail was very radioactive (as in "Pirates of Orion"), it need not be particularly dense, and even thousands of such trails might not make a difference in an atmosphere.

Timo Saloniemi

 

[Albertus]

It would seem reasonable that Impulse Drive would be operational within an atmosphere.....but....

It seems to me that the subspace driver coils, inherent in the Impulse Drive, require freedom from intense gravity wells in order to work effectively.

The starship thrusters seem to be orders of mangnitude beyond what we have at present. Voyager managed to negotiate an atmosphere and land successsfully without using Impulse Drive.......and take off again.

Impulse is for planets as Warp is for stars. Thrusters are the broomsticks that sweep them off the planet.

 

[Cmdr Sho]

It would seem reasonable that Impulse Drive would be operational within an atmosphere.....but....

It seems to me that the subspace driver coils, inherent in the Impulse Drive, require freedom from intense gravity wells in order to work effectively.

The starship thrusters seem to be orders of mangnitude beyond what we have at present. Voyager managed to negotiate an atmosphere and land successsfully without using Impulse Drive.......and take off again.

Impulse is for planets as Warp is for stars. Thrusters are the broomsticks that sweep them off the planet.

Very nice analogy!!! That is the easiest way to explain it!!

 

[Nerys Ghemor]

If the impulse exhaust consists of energetic helium ions, I cannot see much of an impact in space.

Or in an atmosphere. Unless the exhaust is a hypervelocity jet, which would be nice in vacuum but nasty in an atmosphere, causing undue shockwaves and all. But I agree that it doesn't seem as if impulse engines would be conventional rockets with propulsive exhausts.

Perhaps impulse engines cannot be used in atmospheres? After all, Kira in "The Siege" claimed that going down to the soup would negate the advantage that the impulse-capable interceptors had over her little sub-impulse craft. The shuttles might operate on some sort of gravitic systems down there, only turning on the impulse engines after getting sufficiently high up. Or then it's just a case of having to throttle down the impulse engines a bit. But if it's gravitics, those probably don't do environmental harm.

That's the episode I was thinking of!

That's why I was wondering if it might cause problems if somebody just gunned the impulse engines to full while in atmosphere. Especially if a really large ship did it (like a Galor-class...if there IS an environmental impact, I can't see a Federation starship doing it unless they're VERY desperate).

(As to how said ship got into the atmosphere in the first place and is going to get back up there without crashing...that's a different piece of physics that has something to do with shield configurations and a whole bunch of other jazz I still have to figure out.)

 

[GodThingFormerly]

I imagine that the NCC-1701 Refit's M/AM-energized impulse engines would need to be slightly "defocused" (with a communsurate loss of propulsion efficiency due to the increased exhaust cone-angle) in order to avoid accidentally gamma-irradiating planetary biospheres/space vehicles/space habitats that could be lightyears away at the moment of a particularly violent impulse maneuver and thus be affected years in the future.

TGT

 

[Timo]

So that's what those bursts in the sky are all about!

What is the basis for assuming that those engines produce gamma emissions? Let alone directional ones?

Timo Saloniemi

 

[GodThingFormerly]

What is the basis for assuming that those engines produce gamma emissions?

Scotty (ST:TMP): "Intermix set, bridge. Impulse power at your discretion." Uh, and protons + anti-protons = pions > muons > electrons/positrons/neutrinos > gamma rays.

Let alone directional ones?

The ship's impulse engine bells only point in one direction.

TGT

 

[Timo]

But why would the gamma rays escape? They are still an important way in which power is derived from the reaction, so naturally the machinery would have a means of capturing them or it would be inefficient.

And Treknology must be capable of stopping gamma, or starships wouldn't last for a second in battle. OTOH, if such a means doesn't exist, then it wouldn't make a difference where the engine bells point, now would it? Assuming that those are engine bells at all, of course, or other features connected by suitable geometry to the annihilation location.

Timo Saloniemi

 

[GodThingFormerly]

But why would the gamma rays escape?

The same reason water vapor is permitted to "escape" from an Ariane 5's Vulcain cryogenic rocket engine: To provide thrust.

They are still an important way in which power is derived from the reaction, so naturally the machinery would have a means of capturing them or it would be inefficient.

The gamma ray photons need to be directionalized for optimal thrust, not captured.

And Treknology must be capable of stopping gamma, or starships wouldn't last for a second in battle.

Sure, and I have long argued that forcefield technology is employed to redirect the impulse exhaust along the flight vector for braking maneuvers.

OTOH, if such a means doesn't exist, then it wouldn't make a difference where the engine bells point, now would it? Assuming that those are engine bells at all, of course, or other features connected by suitable geometry to the annihilation location.

I have absolutely no interest in derailing this thread by arguing over the impulse engine's mode of operation on either the NCC-1701 or her Refit. You know my position on the subject.

TGT

 

[Timo]

Hmm. But shouldn't this be a powerful argument against the engine being a gamma ray rocket? That is, evidently the engine doesn't pose any sort of a radiation risk to things astern, as evidenced by various chase scenes, application of the engine near inhabited planets and space installations, and so forth.

Timo Saloniemi

 

[GodThingFormerly]

Hmm. But shouldn't this be a powerful argument against the engine being a gamma ray rocket? That is, evidently the engine doesn't pose any sort of a radiation risk to things astern, as evidenced by various chase scenes, application of the engine near inhabited planets and space installations, and so forth.

ST:TMP depicted the Enterprise employing maneuvering thrusters to clear dry dock, and presumably Sulu would be cognizant of standard procedures concerning safe operation of the new impulse engines in a relatively crowded MEO environment (i.e., point them away from Earth and any nearby orbital facilities during departure). The later films are, of course, absolutely none of my concern.

TGT

 

[Timo]

I'm not sure the distinction helps. That is, if this is boresight:

http://movies.trekcore.com/gallery/albums/tmp/themotionpicture0420.jpg



Timo Saloniemi

 

[Cmdr Sho]

I'm not sure the distinction helps. That is, if this is boresight:

http://movies.trekcore.com/gallery/albums/tmp/themotionpicture0420.jpg



Timo Saloniemi

the image on the screen is a rear view....to me they were far enough away in order to use the impulse engines... but even if they did use gamma, then why do 24th century starships impluse in and out from orbit and solar systems???

 

[GodThingFormerly]

I'm not sure the distinction helps. That is, if this is boresight:

http://movies.trekcore.com/gallery/albums/tmp/themotionpicture0420.jpg



Timo Saloniemi

Oooooh, good one! Although it must be noted Sharpline Arts replaced that particular visual effect with CGI for absolutely no reason in their bastard DE (why couldn't you have put something in the SOC viewports instead, Dochterman? ). If I may post the first frame of that scene and then the last one captured from a 720p24 bootleg of the 1979 cut, you will kindly notice a definite lateral movement of Earth on the viewscreen. I think that this detail (along with Lt. Ilia's "Orbital departure on plot, sir.", an untested warp drive and the overriding mission requirement for a rapid intercept of The Intruder) is all the fudge factor I need to get away with my assertion vis-à-vis restricted launch windows for gamma-spewing starships.

TGT

 

[Nerys Ghemor]

Sorry to bump my old thread here, but I had a question.

Would it be possible that, if someone went full impulse in atmosphere that the ionization effects could trigger a really intense version of St. Elmo's fire--something that might even be damaging to other ships in the area?

This may not be strictly scientifically possible...but to be totally honest, what I'm looking for is for something that makes a good story effect without being so TOTALLY impossible as to jar the reader out of the story. I am NOT looking for 100% real-world accuracy here.

 

[Herkimer Jitty]

Yeah, full impulse is what, .25c? The thrust from that is gonna be pretty ugly.