Is going to space really going to be a pipe dream and for scfi due to this?

[InigoMontoya]

You can use waste materials as mass to change your orbits, mag fields to use this mass in mass drivers.

So? You still need the deltaV. A mass driver may be more efficient than a rocket, but you still need 2.5 km/s of deltaV. That's never going to be free.

Are you sure you don't mean interplanetary space?

Ack! Yes. Thanks for the correction.

[Moontanman]

So? You still need the deltaV. A mass driver may be more efficient than a rocket, but you still need 2.5 km/s of deltaV. That's never going to be free.

 

Ack! Yes. Thanks for the correction.

 

I didn't mean to say it would be easier , it just means we don't need volatile chemicals or exotic materials, we can just use our factory slag as reaction mass.

[Phi for All]

I think you guys are focusing on what is brought to Earth back rather than what is not used from Earth. Heavy materials with engineering uses can stay in space for continuing colonization, while rarer items with more wealth to mass ratios can be sent back. And don't forget the really valuable stuff doesn't weigh anything; the scientific knowledge and technological breakthroughs and new discoveries are of incalculable value.

[Mr Skeptic]

I think you guys are focusing on what is brought to Earth back rather than what is not used from Earth. Heavy materials with engineering uses can stay in space for continuing colonization, while rarer items with more wealth to mass ratios can be sent back. And don't forget the really valuable stuff doesn't weigh anything; the scientific knowledge and technological breakthroughs and new discoveries are of incalculable value.

 

That, and energy. Space solar is the most abundant form of energy available in the solar system, and can be "imported" as microwaves.

[Phi for All]

That, and energy. Space solar is the most abundant form of energy available in the solar system, and can be "imported" as microwaves.

Exactly. I envision a craft that gets boosted chemically out into space and then uses solar for electric propulsion to reach the asteroid belt. From there, robots programmed to grab and process whatever they come across bring materials back just inside the belt and build more robots for more processing. As long as the AI is sufficient to keep the system self-sustaining and ever-growing, we could eventually have a chain of supply stretching all the way back to Earth. Any manned missions would be paid for before they even started, and could include suitable habitats already put in place by the robots.

[nec209]

Already stated, but no, it's just pushing a hot gas through a nozzle. Same concept as chemical propulsion the only difference is the source of the heat (burning something vs. running it through a heat exchanger powered by fission reaction).

 

 

 

I don't know the difference of burning something vs. running it through a heat exchanger and what is better. Well pushing a hot gas through a nozzle is good idea but the question is what gas has more thrust and last longer with out the fuel used up

 

 

Light gases work better. Not gonna get anything lighter than hydrogen. For the purpose of fission-powered nuclear rockets, the fact that hydrogen is useful in fusion is irrelevant.

 

 

 

 

What do you mean.

 

 

 

 

Irrelevant. If you're looking to expand to the stars to save the planet from human overpopulation you're barking up the wrong tree. Right now it costs on the order of $5,000 per pound to get to GSO. That's not even to the Moon, but it's a useful benchmark.

 

Suppose that tomorrow there was some breakthrough that lowered that to $50 per pound. A reduction in cost by two orders of magnitude!

 

What would that mean?

 

 

 

 

Has of now the only people that can go in space is astronauts and just may be the rich.The lower income ,middle income ,upper income do not have enough money to go in space.Only the astronauts and may be the rich if the private sector can pull it off.

 

The only way we can deel with overpopulation is spend trillion of money on rocket research and hope revolution spark can bring the cost down has going on plane ticket from LA to New York.If the laws of physics does not allow it than no one will be going in space other than astronauts and may be the rich in crude way.

 

 

 

Well, the Apollo command module weighed about 5,000 pounds. That supported 3 guys for what, 1 week? A Mars mission is going to take a lot more support and such. I'll be VERY nice and say that a Mars habitat would weigh 9,000 pounds for 3 guys for - what is it to Mars? - 6 months? In any event... Call it 3,000 pounds per person. Again, this is insanely generous if we're talking a resettlement and not just a flyby of Mars. Still, let's run with it....

 

If there is a revolution sparks that say in 10 years that can bring the cost down to 1,000 per person than I and you have enough money to go to mars.If there is revolution sparks it may allow up 500 people or 1,000 people per rocket to mars .Has of now nothing is over 10 .

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Ah, but then we can expand "us" to include everyone on earth, something we couldn't do without having a "them" off our planet. I really do think going into space will unify Earth, at least a little. (If done internationally or independently.) Also, we'll once again have a frontier, rather than having to fight others for territory.

 

 

What are you talking about .No one can go in space other than the astronauts and may be the rich in the future.

 

Living on mars the moon ,space station sound nice but put it simple the technology and money does not allow it now.

 

Space mining ,looking for other resources and energy in space sound cool but the technology just does not allow it ,It cost more just to get there in energy than what we will bring back.

 

 

The only way this can happen is a revolution in space rockets.Where it is cheap has getting on air plane and the technology that can do it.

 

 

Put it simple we are going in space in rafts not even columbus ship.

[InigoMontoya]

I don't know the difference of burning something vs. running it through a heat exchanger and what is better. Well pushing a hot gas through a nozzle is good idea but the question is what gas has more thrust and last longer with out the fuel used up

In the simplest terms, rockets work by pushing gaseous matter in one direction. The thrust of a rocket is nothing more than the instantaneous massflow multiplied by the velocity at which the gas is being pushed away.

 

So how do you push gas fast?

 

1) Heat it up (which also jacks up the pressure).

3) Run it through a nozzle.

 

Running it through a nozzle is straight forward. So how do you heat it up? Well, traditional rockets do it by burning stuff. Nuclear rockets do it by simple heat transfer.

 

What do you mean.

But all gases are not created equal. It turns out that all else being equal (ie, pressure and temperature), gases with low molecular weights (ie, "light" gases) go through a nozzle faster than gases with high molecular weights (ie, "heavy" gases).

 

Remember the part where I said thrust was related to the velocity at which the gases are exiting? Notice how I just said light gases move through nozzles faster? Voila, your connection.

 

So... What's the lightest gas out there? Hydrogen. Thus, when we say that Hydrogen's ability to undergo fusion is irrelevant to nuclear rockets, it's because we're refering to Hydrogen's properties as a gas, not as an individual molecule.

 

 

The only way we can deel with overpopulation is spend trillion of money on rocket research and hope revolution spark can bring the cost down has going on plane ticket from LA to New York.If the laws of physics does not allow it than no one will be going in space other than astronauts and may be the rich in crude way.

Disagree.

 

The only way we can (benignly) deal with over population is birth control. Of course, there's also war, famine, and disease, but those aren't quite as friendly as mere birth control (FWIW, my money is on famine. One day a drought will hit a couple continents simultaneously. Major crops will fail. Billions will die. That's my prediction. Man seems to be too stupid to go the birth control route (exception: China gets it)).

 

Not that your thought of reducing the cost of space travel to that of a plane ticket doesn't sound nice. It does. I just don't happen to believe it's achievable within the next couple hundred years (if ever). I say this as someone who's livelihood depends on his knowledge and familiarity with rocket motors.

 

If there is a revolution sparks that say in 10 years that can bring the cost down to 1,000 per person than I and you have enough money to go to mars.

And right now not even the wildest, craziest far out dreamers in the industry think in such terms. When I came up with the number $150k earlier in the thread that was using crazy-optimistic assumptions. Laughable assumptions, really. The development of a technology that would allow a trip to Mars for $15M per person would be deemed an AMAZING revolution in propulsion. Even it would be "off the charts." And you want $1k? Not gonna happen even in your great grandchildren's lifetime.

Edited March 12, 2010 by InigoMontoya

[nec209]

And right now not even the wildest, craziest far out dreamers in the industry think in such terms. When I came up with the number $150k earlier in the thread that was using crazy-optimistic assumptions. Laughable assumptions, really. The development of a technology that would allow a trip to Mars for $15M per person would be deemed an AMAZING revolution in propulsion. Even it would be "off the charts." And you want $1k? Not gonna happen even in your great grandchildren's lifetime.

 

 

Okay what about plasma propulsion,antimatter propulsion ,laser propulsion,explosion propulsion or fusion propulsion that are very much scfi now and if there was a breakthrough in these technology to allow it , could this not bring the cost down and take up more payload.

 

And right now not even the wildest, craziest far out dreamers in the industry think in such terms. When I came up with the number $150k earlier in the thread that was using crazy-optimistic assumptions. Laughable assumptions, really. The development of a technology that would allow a trip to Mars for $15M per person would be deemed an AMAZING revolution in propulsion. Even it would be "off the charts." And you want $1k? Not gonna happen even in your great grandchildren's lifetime.

 

Would it be possible to take up 50 people even with new technology coming out that are more scfi now and hope we run into no problem.I believe the most people taken up where on the space shuttle is 9.Would the technology allow to take up 50 people even with new technology they are working on now.

 

What about building a space station or space ship in space to take 50 or 100 people to the moon or mars in one trip ? Would this be possible? Take up 5 or 8 people in small rocket to the space station or bigger space ship and take the space station or space ship that can hold 50 or 100 people to the moon or mars in one trip .

Edited March 12, 2010 by nec209

[vordhosbn]

But all gases are not created equal. It turns out that all else being equal (ie, pressure and temperature), gases with low molecular weights (ie, "light" gases) go through a nozzle faster than gases with high molecular weights (ie, "heavy" gases).

 

But the force, created by the propulsion system is related to the momentum change of the gas, i.e. the impulse, not the velocity. So isn't the mass of the gas irrelevant (high mass gases will have lower velocity but identical momentum compared to low mass gases with higher velocity, that is provided mass and velocity change being proportional).

[Leader Bee]

Could we not avoid the cost of leaving earths gravity well with an orbital elevator??

[Mr Skeptic]

But the force, created by the propulsion system is related to the momentum change of the gas, i.e. the impulse, not the velocity. So isn't the mass of the gas irrelevant (high mass gases will have lower velocity but identical momentum compared to low mass gases with higher velocity, that is provided mass and velocity change being proportional).

 

Correct. However, the heavier gas also weighs more. So given the choice, a light gas that generates the same thrust is better.

[InigoMontoya]

Okay what about plasma propulsion,

Much better in space than traditional chemical propulsion, but still several orders of magnitude away from your requirements. And it does nothing to get you off the surface and to LEO.

 

antimatter propulsion,

We can't even contain the high energy soup required for sustain fusion and you want to talk antimatter? We can agree to disagree, but in my book that's beyond science fiction and into science fantasy.

 

laser propulsion,

Worth studying and shows some promise, but given how much work/money has gone into ABL, I'm inclined to believe that it's not the answer. That's not to say that it won't ever have a place or change the game. Rather, that's to say that it I don't believe it has the potential to be ENOUGH of a game changer to make space accessable to the common man.

 

explosion propulsion

I have no idea what you're talking about. IF, you mean something like pulse detonation wave engines.... I'm not that impressed with them. Sure, they operate very efficiently, but they come at one hell of a cost: Vibration. They are absolutely positively VIOLENT machines. Result? You have to shock mount them to the gills. Result? By the time you added all the extra bells and whistles required to get your vehicle to survive having a PDE strapped to it's back you could have gone with a traditional rocket with a slightly larger fuel tank and gotten similar system-level performance at a much lower cost.

 

fusion propulsion

Fusion has been "just around the corner" for 50 years. I predict that 150 years from now it will still be "just around the corner." I could be wrong, and it's promise warrants research.... But I wouldn't bet the farm on it.

 

if there was a breakthrough in these technology to allow it , could this not bring the cost down and take up more payload.

Sure such a breakthrough could bring the cost down. But could it bring the cost down ENOUGH? No, I don't believe so.

 

Would it be possible to take up 50 people even with new technology coming out that are more scfi now and hope we run into no problem.

That depends on your definition of "possible." Is it a violation of the laws of physics? No. Is it politically viable in any rationally foreseeable environment? No.

 

 

What about building a space station or space ship in space to take 50 or 100 people to the moon or mars in one trip ? Would this be possible? Take up 5 or 8 people in small rocket to the space station or bigger space ship and take the space station or space ship that can hold 50 or 100 people to the moon or mars in one trip .

Again, not a violation of the laws of physics, but it does nothing to address the cost. Right now it costs (to use recent historical numbers) $20M for a person to get to the ISS. Even if the ISS was a teleportation device that sent the guy to Alpha Centari for free, you're STILL talking $20M per trip. Until you figure out a way to get to LEO on the cheap and easy, NOTHING about space will be cheap and easy.

[Moontanman]

I don't know if nec209 visited the site i gave a link to but a nuclear light bulb rocket could out preform chemical rockets by a factor of 10, but as it says in the article to maintain reliability figure about 6 or 7 times the best chemical rockets. if you had read the link I provided you would have seen the idea of a rocket that could lift 8 times what the Saturn 5 moon rocket lifted in one shot, one stage ground to orbit, reusable and it can land under power.

 

http://www.nuclearspace.com/Liberty_ship_menupg.aspx

 

There are ways to get into space that are far better than what we are doing today or in 1969.

 

One thousand tons from ground to orbit in one reusable rocket is pretty impressive.

[InigoMontoya]

Could we not avoid the cost of leaving earths gravity well with an orbital elevator??

An orbital elevator not only requires engineering on a scale that has never even been attempted before, it also requires a massive counterweight at a very high orbit. How are you going to get that counterweight up there?

 

There are no free lunches.

[Mr Skeptic]

We can't even contain the high energy soup required for sustain fusion and you want to talk antimatter? We can agree to disagree, but in my book that's beyond science fiction and into science fantasy.

 

We can contain antimatter just fine, as far as I know. Producing it, on the other hand, is much harder. Last I read they were talking about having produced it at a very high efficiency... something like 0.00001% efficiency.

 

Fusion has been "just around the corner" for 50 years. I predict that 150 years from now it will still be "just around the corner." I could be wrong, and it's promise warrants research.... But I wouldn't bet the farm on it.

 

Eh, we could have been using fusion propulsion decades ago. Check out Project Orion (not to be confused by the shuttle program of the same name). Heavy lift capability (millions of tons) combined with potential for interstellar travel. It does have a drawback or two however...

[InigoMontoya]

Eh, we could have been using fusion propulsion decades ago. Check out Project Orion (not to be confused by the shuttle program of the same name). Heavy lift capability (millions of tons) combined with potential for interstellar travel. It does have a drawback or two however...

I'm well aware of Orion, but I find the words "it does have a drawback or two" to be the understatement of the year.

[nec209]

Would it be possible to take up 50 people even with new technology coming out that are more scfi now and hope we run into no problem.

 

That depends on your definition of "possible." Is it a violation of the laws of physics? No. Is it politically viable in any rationally foreseeable environment? No.

 

No I mean the cutting edge technology that is coming out is it possible.The technology we have now does not allow more than 8 people to go up in space at a time on a rocket.

 

What about building a space station or space ship in space to take 50 or 100 people to the moon or mars in one trip ? Would this be possible? Take up 5 or 8 people in small rocket to the space station or bigger space ship and take the space station or space ship that can hold 50 or 100 people to the moon or mars in one trip .

 

Again, not a violation of the laws of physics, but it does nothing to address the cost. Right now it costs (to use recent historical numbers) $20M for a person to get to the ISS. Even if the ISS was a teleportation device that sent the guy to Alpha Centari for free, you're STILL talking $20M per trip. Until you figure out a way to get to LEO on the cheap and easy, NOTHING about space will be cheap and easy.

 

Is it even possible with todays technology or cutting edge technology coming out the pipe to built a space ship or space station to take 50 or 100 people to mars..

 

Sure such a breakthrough could bring the cost down. But could it bring the cost down ENOUGH? No, I don't believe so.

 

From what I read plasma propulsion,antimatter propulsion ,laser propulsion,explosion propulsion or fusion propulsion or ion not to say fission have low thrust and high inpulse and can never lift any thing from earth.

 

Only the orion project and daedalus project have high thrust and high inpulse .

 

From what I read none of the things we have now or cutting edge technology coming out like plasma propulsion,antimatter propulsion ,laser propulsion, explosion propulsion, fusion propulsion , ion propulsion or fission deal with fact that they can never lift any thing from earth and will not bring cost down.

 

Nothing on the drawing board seem to fix the problem.The future looks sad. On less there was some breakthrough in atigravity:eek::eek: space is for the astronauts and may be the rich in the future.

 

The laws of physics just seem to paint space is for astronauts and may be and I use the word may be the rich and cost lots and lots of $$$$$ and we will never be able to send up more than 8 people on rocket and never send more than 8 people to the moon or mars on craft.

 

The fuel will be a big problem and it TAKE MORE fuel than the payload :eek:The fuel they use now is just not powerful enough so need lots and lots of fuel just to lift 10% of the rocket into space and shedding the 90% empty fuel tank.

 

And from what I read it sad but plasma propulsion,antimatter propulsion ,laser propulsion, explosion propulsion, fusion propulsion , ion propulsion or fission will not fix the problem I talk about.

[Moontanman]

I'm curious, project Orion which used nuclear detonations to launch a space craft into orbit is being considered as usable technology but the idea of gaseous fusion (nuclear light bulb variant) which could, with relative ease, lift 1000 tons into orbit and return under power one stage, reusable, ground to orbit and back, is not even considered?

 

That's 1000 tons payload by the way.

 

http://www.nuclearspace.com/Liberty_ship_menupg.aspx

Edited March 20, 2010 by Moontanman

[nec209]

I'm curious, project Orion which used nuclear detonations to launch a space craft into orbit is being considered as usable technology but the idea of gaseous fusion (nuclear light bulb variant) which could, with relative ease, lift 1000 tons into orbit and return under power one stage, reusable, ground to orbit and back, is not even considered?

 

Sorry what do you mean ? There is no fusion power station or fusion rocket just like there is no plasma rocket.

 

The orion project and daedalus project was testing they where doing but than stoped .None of the above propulsion talked about here deal with the problems talked about here.

 

 

The plasma propulsion,antimatter propulsion ,laser propulsion, explosion propulsion, fusion propulsion , ion propulsion or fission was on the drawing board to deal with trevel close to the speed of light and does not deal with cost or liffing from earth .It was not replacement to chemical rockets.

 

When it came to the first boats and airplanes they where dirt cheap and the physics allowed over time to build bigger and bigger boats and airplanes and this not the case with rockets .

 

If the boats and airplanes of today will not allow more than 4 people and cost $1,000,000 per person we would not have this too!!! The physics of going in space is very costly and does not allow more than 8 people to go in space on a rocket .So payload will be big problem and cost.This was not the case boats and airplanes .

 

You do not see a big cruise ship just to move small raft.This is the case of rockets.

 

The rocket is like a big cruise ship just to move payload like small raft in space.

[Moontanman]

Possibly you missed the link I provided?

[Icefire]

one of the main problems is that the current way of getting stuff up there is by going straight up, which is done by essentially building a high-pressure column of air faster than it can dissipate.

If the space elevator by some sort of miracle becomes a reality, then it would be a whole lot easier.

[Moontanman]

one of the main problems is that the current way of getting stuff up there is by going straight up, which is done by essentially building a high-pressure column of air faster than it can dissipate.

If the space elevator by some sort of miracle becomes a reality, then it would be a whole lot easier.

 

Building gaseous fission nuclear powered rockets would be much easier and cheaper than a space elevator.

[Radical Edward]

Building gaseous fission nuclear powered rockets would be much easier and cheaper than a space elevator.

 

it might. It depends on the materials. We could build a lunar space elevator with current materials if we wanted.

also, you really don't want a nuclear powered rocket for lifting things from earth into space. you really don't.

[Moontanman]

it might. It depends on the materials. We could build a lunar space elevator with current materials if we wanted.

 

I'm not so sure, a space elevator implies an orbit that allows the anchor of the elevator to be stationary over the surface of the object it rises from, a 28 day orbit would mean a very tall, much taller than from the earth, elevator.

 

also, you really don't want a nuclear powered rocket for lifting things from earth into space. you really don't.

 

 

And why would that be? Risk mitigation can deal with any risks involved.

[Icefire]

 

I'm not so sure, a space elevator implies an orbit that allows the anchor of the elevator to be stationary over the surface of the object it rises from, a 28 day orbit would mean a very tall, much taller than from the earth, elevator.

 

 

 

 

And why would that be? Risk mitigation can deal with any risks involved.

 

A flying Chernobyl?