Bussard Collector

[Crazy Eddie]

Gonna need help on this one!

In trying to figure out the refuel rate of a starship, I hit a little snag when I looked up data on the interstellar medium and found a density of about 10^-18g of hydrogen per cubic kilometer. Crunching a few numbers, I figured out that a starship equipped with a ramscoop would have to therefore sweep an area of 10^14 cubic kilometers every second in order to obtain one gram of hydrogen.

So now I'm sitting here trying to figure out how exactly such a device is supposed to fuel a warp driven starship. I crunch the numbers and I get that a starship should probably produce a magnetic field about 200,000 kilometers in diameter, so the ship has to travel 500 million kilometers for every gram of hydrogen collected. This works out nicely since in the TNG scale this is a speed of about warp 9...

One gram of hydrogen (combined with one gram of antimatter) is worth about nine terawatts of energy. What I can't figure out is just how much energy does it take to produce a magnetic field that can trap hydrogen atoms at a distance of 100,000km. I need the wisdom of some of our local physics gurus here, because I have no fraking idea how to do calculations for magnetic fields of this type.

 

[Cary L. Brown]

Gonna need help on this one!

In trying to figure out the refuel rate of a starship, I hit a little snag when I looked up data on the interstellar medium and found a density of about 10^-18g of hydrogen per cubic kilometer. Crunching a few numbers, I figured out that a starship equipped with a ramscoop would have to therefore sweep an area of 10^14 cubic kilometers every second in order to obtain one gram of hydrogen.

So now I'm sitting here trying to figure out how exactly such a device is supposed to fuel a warp driven starship. I crunch the numbers and I get that a starship should probably produce a magnetic field about 200,000 kilometers in diameter, so the ship has to travel 500 million kilometers for every gram of hydrogen collected. This works out nicely since in the TNG scale this is a speed of about warp 9...

One gram of hydrogen (combined with one gram of antimatter) is worth about nine terawatts of energy. What I can't figure out is just how much energy does it take to produce a magnetic field that can trap hydrogen atoms at a distance of 100,000km. I need the wisdom of some of our local physics gurus here, because I have no fraking idea how to do calculations for magnetic fields of this type.

What you need to do is change your context a little bit.

You know the "average hydrogen density." And you know the speed of the ship (or rather, that is one of your inputs).

What you should be doing is looking at is creating a relationship, based upon that, of the radius of the "projected scoop diameter" versus the power-generation capability. It'll be a pretty simple equation, and you've done 2/3 of it already.

The only difficulty, really, is that there are two unknowns which require "pure guesswork" to determine.

The first is "how much energy is required by the propulsion system?" If we're talking "pure impulse" than this is trivial to determine (basic kinetic energy equations... and remember, when delta-V is zero, no matter how fast you're going, there's zero energy required, of course... only delta-v matters). If we're talking "subspace-assisted impulse," well... this is going to be a "magic" calculation, no real science behind it (though you could probably fudge something from Sternbach and Okuda's book). If we're talking "warp drive" all bets are off, too.

The second is "what sort of force-field does the bussard system use?"

Really, a magnetic field, by itself, does NOTHING to uncharged hydrogen atoms. So, you either need to be ionizing those atoms, or using something else besides a "simple magnetic field." A "real" bussard device uses a real scoop (or so the concept goes). A Trekkian one is, again, largely "magic" and there's no real science behind it whatsoever. So, you can pick any number which seems practical.

Sorry not to be more help, but without a reasonable basis for the energy requirements we're talking about, the equation simply can't be solved. At best, you can determine the total energy output of the system, determine how much energy you get (total) and how much you need for "known" consumption, and then divide the remainder up proportionally.

Your basic equation works nicely... to determine how much hydrogen you can get per-second, with any "scoop diameter." And if you ignore the energy cost to "flip" hydrogen into anti-hydrogen (or assume some nice round number like "10% total output"), you can get a nice energy-output number versus scoop diameter and speed.

But for the rest? No clue...

 

[TIN_MAN]

Well without doing the math (ugh) a couple of points.
-You have to remember that the ship is traveling extremely fast, at such speeds that the relatively rarified semi-vacuum of space becomes a dense particle 'sea' akin to an atmosphere or hydrosphere, because the ship is running into so many particles per split second! This is, in fact, a good explanation for why Star Trek ships are so streamlined and 'aerodynamic' looking, so as to reduce the 'drag' that would be encountered at warp speeds. Which leads to the next point...
-Actual Bussard collector designs Do use magnetic fields in addition to scoops, this has led to criticism that such designs would actually be more effective as 'brakes' for future starships because of the aforementioned density of the interstellar medium at high speeds! This is good news for ST fans, however, as it answers the age old question of "how does the Enterprise slow down", although I'm sure the big 'E' uses some sort of techno-babble force field instead of a magnetic field? But a magnetic field would work (theoretically) the idea is that a layered magnetic field would allow for the atoms encountering the first foemost field to be ionized (if they aren't ions already) and the secondary etc. fields would funnel them into the 'ramjet'. Of course the Bussard ramscoops don't have to be 'on' all the time and depending on speed, fuel needs, and braking, the fields could be adjusted accordingly?

 

[Trekker4747]

The ramscoops, also aren't meant to fully fuel the ship. The ship has a massive hydrogen fuel tank in her. The ramscoops aren't meant to keep this full just add to it every once in a great while.

It may also be possible for the ramscoops to get more hydrogen by going through a dense nebula or high orbit around a star. But the ramscoops were never meant to fully fuel the ship jsut sort of "augment it", like driving down the road and scooping up particles of unburned gasoline coming our of other cars' exhaust. It's not going to fill your tank, but it's not going to hurt to collect it either.

 

[Cary L. Brown]

The ramscoops, also aren't meant to fully fuel the ship. The ship has a massive hydrogen fuel tank in her. The ramscoops aren't meant to keep this full just add to it every once in a great while.

It may also be possible for the ramscoops to get more hydrogen by going through a dense nebula or high orbit around a star. But the ramscoops were never meant to fully fuel the ship jsut sort of "augment it", like driving down the road and scooping up particles of unburned gasoline coming our of other cars' exhaust. It's not going to fill your tank, but it's not going to hurt to collect it either.

That's per the TNG tech manual, of course, talking specifically about the Galaxy.

That was actually a bit of a contradiction of prior Trek tech, however. I'm sure that the rationale of saying that was to eliminate what Sternbach and Okuda saw as something akin to a "perpetual motion machine starship." But the idea of "harvesting" your fuel as you go isn't really like that at all. It's more like thinking of a steam-driven naval vessel capable of burning wood... and sailing along a forested coastline.

As far as I'm concerned, the ship has the ability to "harvest" enough hydrogen to fully meet all power requirements. At least, the TOS ship did.

Your mileage may vary, but it's important not to state "opinion" about a fictional concept as though it's doctrinal.

A true statement would be "according to the TNG technical manual, the ramscoops weren't meant to fully fuel the Galaxy class." Beyond that, we don't know anything, really... do we?

Now... considering the mission role of the Galaxy as it was ORIGINALLY intended (which was well prior to the TNG tech manual being created)... the Galaxy was intended to sail beyond Federation borders for as long as 30 years at a time.

The need to "fill'er up" at the local Federation "Shell station" seems to preclude that, doesn't it?

 

[Mr. B]

It's worth noting the bussard collectors would not be used at warp since the main deflector will be... deflecting any and all matter which may or may not exist in subspace.

 

[Cary L. Brown]

It's worth noting the bussard collectors would not be used at warp since the main deflector will be... deflecting any and all matter which may or may not exist in subspace.

Not necessarily so...

We don't know exactly how the deflector works. Is it possible to make it porous to hydrogen (and ONLY to hydrogen)? Why not? It's "magic."

On the other hand... is the deflector a constant beam? Or is it more like a radar beam, sweeping back and forth to deflect larger objects out of the path of the ship when it encounters them, but not necessarily projecting a constant "space broom" which sweeps away EVERYTHING.

And suppose that the ship is flying in this "subspace bubble" through real-space. Is this really in a totally separate realm of existence, or do objects have the ability to "fall into" the bubble if they're in your path, and to "fall out" of the bubble at the aft end? I mean, within the bubble, you're essentially inertia-less relative to the real universe, but that means "conservation of momentum" would still apply... an object that enters the "bubble" with some amount of momentum won't necessarily give up all momentum, will it?

If either of those situations were the case, you could just fly the ship (at warp) right through planets, suns, asteroids, giant planet-eating doomsday machines... you name it.

In "Starwarsian" concepts like Hyperspace, it's a totally separate realm of reality. But in Star Trek, "subspace" is ALMOST "real space/time." And they interact in real-time, so you can see in, or out, of your little bubble (ST'09's silly "arrival at Vulcan" scene notwithstanding).

 

[xraydeltaone]

And suppose that the ship is flying in this "subspace bubble" through real-space. Is this really in a totally separate realm of existence, or do objects have the ability to "fall into" the bubble if they're in your path, and to "fall out" of the bubble at the aft end? I mean, within the bubble, you're essentially inertia-less relative to the real universe, but that means "conservation of momentum" would still apply... an object that enters the "bubble" with some amount of momentum won't necessarily give up all momentum, will it?

If either of those situations were the case, you could just fly the ship (at warp) right through planets, suns, asteroids, giant planet-eating doomsday machines... you name it.

I never liked the idea that the subspace bubble surrounding the ship completely removed it from "real space". It always seemed more like a region of intense distortion around the ship. I like the Alcubierre drive model - it seems to fit what we see pretty well, while being somewhat plausible.
Having said that, if the warp field does work like an Alcubierre drive, compressing the space in front of the ship and expanding it behind, would the ship even being moving in a Newtonian sense while at warp? I'm guessing it would have to have some velocity, but not necessarily that much, certainly no more than standard impulse speeds. If this was the case, any particles that "fell into" the warp field could be dealt with as easily as those the ship encountered while on impulse drive.

 

[Mr. B]

It's worth noting the bussard collectors would not be used at warp since the main deflector will be... deflecting any and all matter which may or may not exist in subspace.

Not necessarily so...

We don't know exactly how the deflector works. Is it possible to make it porous to hydrogen (and ONLY to hydrogen)? Why not? It's "magic."

If those minuscule particles pose grave danger to a ship at warp, it stands to reason they could inflict damage on the collector just like the rest of the ship.

 

[Crazy Eddie]

It's worth noting the bussard collectors would not be used at warp since the main deflector will be... deflecting any and all matter which may or may not exist in subspace.

1) Starships don't travel through "subspace" at warp, so that's not an issue.

2) Apparently the navigational deflector only comes active when it runs into something big enough to be a threat to the ship; everything else gets gobbled up by the collectors.

Of course, as I already posted, the ship would HAVE to be moving at warp for the ramscoop to be of any use. There isn't alot of hydrogen floating around in space.

 

[Crazy Eddie]

The only difficulty, really, is that there are two unknowns which require "pure guesswork" to determine.

The first is "how much energy is required by the propulsion system?"

Yeah, but my whole reason for doing this is (well, WAS) trying to gage the engine's power requirements based on how much matter the bussard collectors can draw from space vs. how much energy the collectors/deflectors consume. I would assume the engines use 90% of the leftover energy and only a tiny fraction (if any) is leftover for the EPS taps.

The second is "what sort of force-field does the bussard system use?"

I'm only using electromagnetic fields because we know how to generate them and somebody out there (hopefully, somebody IN HERE) knows something about the energy requirements of electromagnets, particularly an electromagnet that has to generate a field of an intensity of at least 1 gauss at a distance of 100,000km. I would just assume that an unobtanium forcefield that affects all matter uniformly would be similar--power wise--to a simple magnetic field.

Your basic equation works nicely... to determine how much hydrogen you can get per-second, with any "scoop diameter." And if you ignore the energy cost to "flip" hydrogen into anti-hydrogen (or assume some nice round number like "10% total output"), you can get a nice energy-output number versus scoop diameter and speed.

Actually, I was kind of assuming that the ship has a limited supply of antimatter on board that has to be replenished from time to time. The problem is a different set of numbers I've been playing with has proven this to be basically infeasible for the kinds of missions a starship is involved with, so I'm at the point now of dropping the bussard collectors completely and moving it into the navigational deflector, where it can also be used like a vacuum cleaner/drill rig to extract hydrogen from the atmospheres of gas giants.

At this point, it's just for the sake of argument, since we've had these bussard collectors foisted on us all these years and now I'm trying to figure out how they were supposed to have worked all this time.

 

[xraydeltaone]

The problem is a different set of numbers I've been playing with has proven this to be basically infeasible for the kinds of missions a starship is involved with, so I'm at the point now of dropping the bussard collectors completely and moving it into the navigational deflector, where it can also be used like a vacuum cleaner/drill rig to extract hydrogen from the atmospheres of gas giants.

At this point, it's just for the sake of argument, since we've had these bussard collectors foisted on us all these years and now I'm trying to figure out how they were supposed to have worked all this time.

Personally I think that the giant vacuum cleaner idea is just as likely to be used for refueling purposes. If you have the ability to ionize interstellar gas at hundreds of thousands of kilometers from the ships (using some sort of huge ionizing radiation emitter, possibly something like a gamma ray laser), then pull that diffuse cloud of ions into the ship, you can do the same from the orbit of a gas giant.

The ramscoop idea is handy if you want to collect 'free' fuel as you go however.

If you want numbers, the wikipedia article has some. There's some good info on the Atomic Rocket site too.

 

[Myasishchev]

Another thing to think about regarding the bussard collectors and interstellar hydrogen is how thin that medium must be getting at this point, with hundreds or thousands of years of FTL travel on well-established lines (well, curves) between points of interest. Not counting all the now-dead but long-lived space empires like the Tkon, who would have utilized that interstellar hydrogen if it had been profitable to do so.

I mean, if I plow through space collecting all the hydrogen in front of me, the guy behind me isn't going to get any hydrogen at all. And if a frontage of hundreds of thousands of kilometers is necessary to get any significant amount of it, any convenient route between points of interest is going to be rapidly (cosmologically speaking) exhausted.

I'm liking that idea that bussard collectors are for solar/gas giant atmosphere sampling more and more. Jupiter probably has billions of times more hydrogen than the whole trip to Vulcan would provide.

 

[Mr. B]

1) Starships don't travel through "subspace" at warp, so that's not an issue.

Subspace is a nebulous issue but every description of warp drive leads one to believe a ship at warp is not necessarily traveling in normal space.

2) Apparently the navigational deflector only comes active when it runs into something big enough to be a threat to the ship; everything else gets gobbled up by the collectors.

Even a microscopic particle could threaten a ship. It doesn't make any sense for the navigational deflector to be toggled on and off during warp flight. You would be depending on the sensors to detect every object several orders of magnitude smaller than a grain of sand up to 4 billion miles ahead (distance traveled in one second at warp 9.9).

 

[Crazy Eddie]

I'm liking that idea that bussard collectors are for solar/gas giant atmosphere sampling more and more. Jupiter probably has billions of times more hydrogen than the whole trip to Vulcan would provide.

That was my thought too. The interstellar medium is incredibly diffuse, but planets and nebula and even stars are thick clouds of gas--thick in a non-cosmological sense--and would probably be alot more efficient for refueling purposes. Especially if the ship makes its own antimatter, which--depending on the efficiency of the generator--might require the ship to take in six or seven grams of hydrogen for every gram of matter and antimatter stored.

 

[Crazy Eddie]

1) Starships don't travel through "subspace" at warp, so that's not an issue.

Subspace is a nebulous issue but every description of warp drive leads one to believe a ship at warp is not necessarily traveling in normal space.

Except for the fact that ships at warp can be tracked by ships not at warp, and sometimes can even fire on ships that are not at warp. This isn't possible if they are somehow flying through some kind of Star Warsian/Babylon 5 hyperspace realm.

And then there are references in TOS where ships traveling at warp drive are actually visible to ships at sublight. I think it's pretty clear that "subspace" isn't an alternate dimension as much as it is some kind of substrate of the physical universe, like "aether" or something like it.

2) Apparently the navigational deflector only comes active when it runs into something big enough to be a threat to the ship; everything else gets gobbled up by the collectors.

Even a microscopic particle could threaten a ship.

Probably not at warp. The warp field itself would deflect that particle, considering said particle would instantly be accelerated to FTL velocities along with the ship it's about to collide with. Furthermore, there is precedent to believe this is the case, since in "The Battle" Data is able to track the Stargazer by tracking the compression of interstellar gas in front of it. Since Stargazer is traveling at warp nine at this point, one of two things is happening: either the navigational deflector is compressing that gas (which is what it's designed NOT to do) or the gas is crashing into the leading edge of the warp field and forming a bow shock phenomenon. I think the latter is more likely, considering there are all kinds of things in this galaxy that form similar shockwaves in the ISM.

It doesn't make any sense for the navigational deflector to be toggled on and off during warp flight.

Andy Probert seemed to think differently. Or did you ever wonder why the deflector dish of the TMP enterprise only glows blue when it's at warp and orange at impulse power? Or did you not catch that line in the wormhole scene where Ilia reports "Navigational deflector coming up sir..." and seconds later, "Navigational deflector inoperative, Captain!" this just to deflect an asteroid, which is probably the deflector's main function: Enterprise is an ICEBREAKER, so it needs to be able to handle large debris for its exploration mission. Klingon battlecruisers and birds of prey don't, which is why they don't have navigational deflectors.

 

[Myasishchev]

^

in "The Battle" Data is able to track the Stargazer by tracking the compression of interstellar gas in front of it.

Heh, all 10^-16 atoms of it.

Must be the same sensors that can detect the infrared signature of life forms instantly from light years away.

 

[Crazy Eddie]

Well they were in a solar system when it happened, so maybe he was tracking displacement of solar winds?

Although, you're right, it's probably just technobabble.

 

[Mr. B]

Except for the fact that ships at warp can be tracked by ships not at warp, and sometimes can even fire on ships that are not at warp. This isn't possible if they are somehow flying through some kind of Star Warsian/Babylon 5 hyperspace realm.

I don't believe the ability to interact with subspace while in normal space (i.e. subspace radio) negates whatever properties it might have.

Probably not at warp. The warp field itself would deflect that particle, considering said particle would instantly be accelerated to FTL velocities along with the ship it's about to collide with.

If that was the case, and I don't believe it is as the TNG tech manual and Memory-Alpha are quite clear on the necessity of the deflector, how are the bussard collectors supposed to collect something at warp if all interstellar particles are being deflected by the warp field?

Andy Probert seemed to think differently. Or did you ever wonder why the deflector dish of the TMP enterprise only glows blue when it's at warp and orange at impulse power?

That would be a valid point if there was a change during warp flight. I don't doubt deflectors are unnecessary during sublight travel.

 

[Crazy Eddie]

Except for the fact that ships at warp can be tracked by ships not at warp, and sometimes can even fire on ships that are not at warp. This isn't possible if they are somehow flying through some kind of Star Warsian/Babylon 5 hyperspace realm.

I don't believe the ability to interact with subspace while in normal space (i.e. subspace radio) negates whatever properties it might have.

Of course not. It simply negates any motion that a ship is "in" subspace. If it's interacting with things in normal space, then for all intents and purposes it is in normal space.

If that was the case, and I don't believe it is as the TNG tech manual and Memory-Alpha are quite clear on the necessity of the deflector, how are the bussard collectors supposed to collect something at warp if all interstellar particles are being deflected by the warp field?

The field produced by a bussard collector would have to be hundreds of thousands of kilometers in diameter in order to be of any use at all, extending far beyond the confines of the warp bubble.

Of course the warp field will accelerate any in-falling matter TO warp speeds, but it won't deflect it away from the ship. Locally--meaning inside the warp bubble--the ship will encounter interstellar particles at something like orbital velocities... it's just that, well, you don't want to run into things like asteroids and large rocks at orbital velocities.

That would be a valid point if there was a change during warp flight. I don't doubt deflectors are unnecessary during sublight travel.

As do I, but there still remains the fact that most non-Starfleet vessels don't have navigational deflectors.