Propulsion in a Vacuum

[wwswimming]

i think if you ask a lot of people how to build a propulsion system to travel long distances - outside of the solar system - they might say, "i don't know !"

i think it helps to think of this as a 2 part problem.

* you need an energy source which would appear near-infinite from our perspective.

* you need a propulsion system which can deliver the thrust you need when you're accelerating. the klystrons at SLAC get particles up to .99 c (the speed of light), so i don't think it's unrealistic to perform calcs. based on a exhaust velocity of .05 to .10 c.

so, why wait to develop the energy source, before you develop the propulsion system ? why not start developing the propulsion system, acknowledging that you would need a power source that does not exist (at least not in university or industry labs) today ?

to date, one of the most promising propulsion systems for this is ion propulsion. most of the lab prototypes are lightweight creations (i'm not impugning the technology, i mean they don't weigh very much.)

in addition to the ion propulsion techniques, i think travelling wave tubes, which are commonly used as microwave amplifiers, hold some promise. i've worked for 2 different tube houses.

the TWT's involve stacks of supermagnets. now, those are fixed in place.

i've also worked on YiG oscillators. with those we built supermagnets using high nickel content steel that was a bitch to machine.

so, it's simple. you need something to drive out the end of the nozzle. it has to be something which you can accelerate to a very high speed, in order to get decent thrust.

one material that fits the bill is - water, after electrolysis. H+ and O-- molecules, i think. a single H+ molecule is the companion molecule to what they accelerate at SLAC (stanford linear accelerator ... worked there too) -- the simple electron. H+ = proton, or a proton and a neutron.

to propel it, you need an electric field. a massive electric field.

That would be my primary proposal if i was asked to task this project.

so, if you were propulsion system to be a companion to a near-infinite energy source, how would you do it ?

i think if you said you were going to build a rail gun to shoot magnetic particles out the nozzle end of the space-ship, you wouldn't be too far off.

 

[Evadman]

What about casting some type of giant energy field in 'front' of the space craft to gather the atoms that are in intersteller space, pull them into an accelerator engine, and push them out the rear of the craft at accelerated speed. That is roughly how a jet engine works, except with more mass (atoms being puleld in and out) and a lower exaust speed.

that way, the propellnt itself doesn't need to be accelerated as well. If the engine also used H for fuel (fusion reactor) it would be possible to gather fuel at the same time. Perhaps some kind of seperator that hept H on board, and passed everything else out as exaust.

 

[PowerEngineer]

Originally posted by: Evadman
What about casting some type of giant energy field in 'front' of the space craft to gather the atoms that are in intersteller space, pull them into an accelerator engine, and push them out the rear of the craft at accelerated speed. That is roughly how a jet engine works, except with more mass (atoms being puleld in and out) and a lower exaust speed.

that way, the propellnt itself doesn't need to be accelerated as well. If the engine also used H for fuel (fusion reactor) it would be possible to gather fuel at the same time. Perhaps some kind of seperator that hept H on board, and passed everything else out as exaust.

And maybe we can call it a Bussard ramjet

 

[AlabamaCajun]

Change that thought: Why emit matter, it's too expensive for the amount of mass you need to move. Warping space is somewhat more understood. Einstein knew of it. All known space has particles in it. Particles emit a weak force. It's the collective effect of these forces that hold planets together, in orbit and us to the Plant. We have to figure out how to build the gravity wave generator, aka Warp Drive, to solve interstellar space. You will still need a stellar amount of energy as these energy fields won't come cheap. I know someone will blast this with "you watch too much sci-fi" but think again, where does this sci-fi come from? I could post more technical details but a lot of people read this late at night.

"First we have to learn to live together and stop blowing up other nations on this planet before we can expect to meet other planets." AC.

 

[MrDudeMan]

Originally posted by: AlabamaCajun
Change that thought: Why emit matter, it's too expensive for the amount of mass you need to move. Warping space is somewhat more understood. Einstein knew of it. All known space has particles in it. Particles emit a weak force. It's the collective effect of these forces that hold planets together, in orbit and us to the Plant. We have to figure out how to build the gravity wave generator, aka Warp Drive, to solve interstellar space. You will still need a stellar amount of energy as these energy fields won't come cheap. I know someone will blast this with "you watch too much sci-fi" but think again, where does this sci-fi come from? I could post more technical details but a lot of people read this late at night.

"First we have to learn to live together and stop blowing up other nations on this planet before we can expect to meet other planets." AC.

i dont think you watch too much star trek. bending space is definitely the answer. proplusion like the OP is suggesting is way too primitive IMO to travel outside of the solar system. i say that because you would have to accelerate slowly enough that the humans inside dont die, and you would have to start decelerating half way to your destination to stop in time. it just isnt practical.

 

[AlabamaCajun]

The current issue of Popsci July 2006 has a clip on page 44 that mentions using 10 milligrams of antimatter to fuel a ship to run to mars and back in 6 months for the round trip. Not Warp but fast. The clip mentions the power of antimater as "Releasing millions of time the fusion reaction of particles on the Sun" (PS). This is one of those furture headlines meaning it's not real but a spectulation of what might be a real article by then. Below is a link to one of the "recent" articles on the study of antimatter.

http://www.popsci.com/popsci/science/10...fa84010vgnvcm1000004eecbccdrcrd/3.html

Why I started with mentioning this clip is because it may be the answer to how to create the wrap field. Building the reactor and engines is outside of our abilities at this time (Barring a Vulcan might show up to give us the plans or sell them to us). Serveral obsticles remain.
1) The amount of energy this device emits would destroy most materials we make here on earth.
2) Storing antimatter would be so dangerous that a couple of loose particles would more than likely vaporize a city (Oops... poof ****)
3) Turning one of the most powerful energy sources that man could hope to produce into a propulsion wave.
4) Building the engine with what?
This is a stretch and really would eat up some major resources to produce so blowing one up would suck.

MrDudeMan, thanks for you acknoledgement. The effect on living organisms could be a real problem as using the amount of energy it takes to send matter from A to B would be deadly without shielding from the energy and the effects. If it works, then acceleration is not mearly propulsion but more of just taking a group of matter, ship, people, food and gear in tact and for a designated timeframe eliminating inertia. By this I mean eleminating the effect of all gravity outside the ship and moving the matter to a new location. I don't think it's something we unstand but it Einsteins theories move to production them this would be what he was telling us. We won't be talking propulsion which requires emmision of some sort. What we would be doing instead is altering the universe by disrupting the gravitational effect on our matter. Contents of the ship are enveloped in the field and thus by theory not feel accelaration since the matter is nulled from outside forces. Like moving a fishbowl would be the closest I can thing to describe it. The density of the water keeps the fish from slamming into the rear of the bowl. One effect is that people may not be able to move but held in stasis during the trasition. This may freak out a lot of people but virtually all signs of life on the ship would be non-exsistant during this travel. No one would be breathing, hear beating, drinking martinis just a stange sensation like a deja voux event. One second you see earth outside the window and the next mars. Earth observser might actually see you leave and weeks on months later say hello when you reach orbit. Another scenario from the sci fi movies is that you experiance a slowmotion period until you reach equlibrium with the wave distortion generator that moves you through space. All of this is from my understanding of the theory of relativity and the physics of space travel and energy systems. All we can do is theororize on this stuff and hope it inspires a reader to get an idea and produce one of these things.

 

[DrPizza]

I think it'd take more than a "couple of loose particles" to blow up a city. Quite a bit more than "a couple" - relatively simple E=mc^2; double the mass of your antimatter particles, since they're going to "poof" out the existence of regular matter particles in a 1 to 1 ratio.

Also, concerning acceleration; given that we can safely accelerate at 9.81 m/s/s (in fact, we'd probably enjoy a space craft that simulated gravity in this manner), it would take 3.0*10^8 m/s divided by 9.81 m/s/s to give us about a year to reach the speed of light (which we wouldn't reach) (And, ignoring relativity, since I'm pretty tired tonight)
Regardless, with an acceleration in space of 1 g, we can get moving pretty quickly in very little time.

 

[sao123]

Originally posted by: DrPizza
I think it'd take more than a "couple of loose particles" to blow up a city. Quite a bit more than "a couple" - relatively simple E=mc^2; double the mass of your antimatter particles, since they're going to "poof" out the existence of regular matter particles in a 1 to 1 ratio.

Also, concerning acceleration; given that we can safely accelerate at 9.81 m/s/s (in fact, we'd probably enjoy a space craft that simulated gravity in this manner), it would take 3.0*10^8 m/s divided by 9.81 m/s/s to give us about a year to reach the speed of light (which we wouldn't reach) (And, ignoring relativity, since I'm pretty tired tonight)
Regardless, with an acceleration in space of 1 g, we can get moving pretty quickly in very little time.

Theoretically, if we could remove inertia from a an object, wouldn't it take less force to accelerate it?
After all in F= MA... M for M is really a fundamental value for Intertia of the Mass. We can use M, because up till now M & I were locked in a 1:1 ratio.

 

[BucsMAN3K]

Originally posted by: MrDudeMan

Originally posted by: AlabamaCajun
Change that thought: Why emit matter, it's too expensive for the amount of mass you need to move. Warping space is somewhat more understood. Einstein knew of it. All known space has particles in it. Particles emit a weak force. It's the collective effect of these forces that hold planets together, in orbit and us to the Plant. We have to figure out how to build the gravity wave generator, aka Warp Drive, to solve interstellar space. You will still need a stellar amount of energy as these energy fields won't come cheap. I know someone will blast this with "you watch too much sci-fi" but think again, where does this sci-fi come from? I could post more technical details but a lot of people read this late at night.

"First we have to learn to live together and stop blowing up other nations on this planet before we can expect to meet other planets." AC.

i dont think you watch too much star trek. bending space is definitely the answer. proplusion like the OP is suggesting is way too primitive IMO to travel outside of the solar system. i say that because you would have to accelerate slowly enough that the humans inside dont die, and you would have to start decelerating half way to your destination to stop in time. it just isnt practical.

Even if we could "bend" space, would there be anything on the other side, or would you just get caught in a neverending story...I mean hole.

Anyways, I think that the resolutions of telescopes are going to advance much quicker than any plans for travel outside the solar sytem. Then we will see if its even worth doing.

 

[spikespiegal]

Theoretically, if we could remove inertia from a an object, wouldn't it take less force to accelerate it?

That would mean hiding it's mass somwehere (hyperspace maybe?), which I believe one physicist theorized that the object would then fly apart in a cloud of randomly moving particles at near the speed of light if mass wre reduced to zero.

Larry Niven has written some pretty cool stories about traveling to the core of the galaxy and back with bussard ramjets, and also staying as true to conventional science as possible. Neat stuff to read and far more technically fulfilling than Star Trek.

 

[sourshishke]

We need to harness dark energy ,it must be a key part.Did you ever see the Hubble pic
of gravity being bent?Text
If link does not work Google Abell 1689

 

[OSX]

I was going to come in here and say something about the third law of motion, and feel quite clever, sadly that seems way more basic then this topic.

 

[wwswimming]

well i appreciate the theoretical comments as well as the down-to-earth comments.

what i meant was, what would you do if you were going to start building today, using known technology, for the propulsion system ?

as one of my engineering managers used to say, "run what you brung".

then, to put the thing in orbit, you would need about 5 miles of high voltage wire arranged in a spiral fashion, and you would need to make sure it wasn't looped around someone's toe on takeoff.