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

[nec209]

If you watch CNN about NASA payload is always the problem.The government is always looking at new material to make it strong and lightweight.. Well fuel is big problem it TAKES more fuel than the payload !!!

 

I'm sure in the future we will have strong and lightweight material and advances in chemistry and nanotechnology will help.

 

But the big problem is fuel .It takes more fuel than the payload .

 

Ion rockets or plasma rockets have low thrust .So as of right now, they could never lift anything from earth do to the low thrust .

 

Not sure about nuclear or fusion but I think they have low thrust too.Well Ion rockets , plasma rockets , nuclear or fusion have long burn low thrust so can be use to travel almost the speed of light.

 

Well chemical rocket have high thrust but use up the fuel very very very fast .

 

The fuel they use now is just not powerful enough so need lots and lots of fuel just to lift 15% of the rocket into space and shedding the 85% empty fuel tank.

[Moontanman]

Nuclear = low thrust? Not really see this link.

 

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

[skyhook]

I have been thinking, this energy used to power shuttles into space. It is lost in space instead of recycled on earth. If one day, space travel becomes common, will this depletes earth's resources ?

Edited March 10, 2010 by skyhook
correction

[Phi for All]

You can save payload and thus fuel by dropping the idea of manned missions. Robots and drones will probably be the near future of space exploration. It just takes too much of a ship's resources to accommodate fragile humans.

[Moontanman]

I have been thinking, this energy used to power shuttles into space. It is lost in space instead of recycled on earth. If one day, space travel becomes common, will this depletes earth's resources ?

 

I would have to assume that at some point all resources have the potential to become limited, space travel would have to be quite frequent to deplete all the nuclear energy on the planet and I would also have to assume there would be off planet sources of nuclear materials. It shouldn't take long before off planet sources of nuclear materials replace Earth based sources if for no other reason they would easier to exploit.

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Consecutive posts merged

You can save payload and thus fuel by dropping the idea of manned missions. Robots and drones will probably be the near future of space exploration. It just takes too much of a ship's resources to accommodate fragile humans.

 

I think that manned missions are far more flexible than robotic missions, having an actual human being, boots on the ground, is more than valuable enough to make sure that eventually men will have to travel in space.

 

Exploitation of resources in space as well as expansion of humanity will require humans in space, probably in orbiting colonies, I honestly expect there will be more humans in space than on planet Earth in 1000 years.

[Phi for All]

I think that manned missions are far more flexible than robotic missions, having an actual human being, boots on the ground, is more than valuable enough to make sure that eventually men will have to travel in space.

Eventually, sure. Travel, absolutely. But exploration takes time that our current technology doesn't handle well in terms of human life support.

 

Exploitation of resources in space as well as expansion of humanity will require humans in space, probably in orbiting colonies, I honestly expect there will be more humans in space than on planet Earth in 1000 years.

In the long run, it will happen. For the near future, robot ships with the best AI we've got will probably play the largest part.

 

I'm reading an interesting story right now where an enhanced Caribbean reef squid is operating the waldoes on a drone ship controlled from earth. Their mission is simple; head for an asteroid and set up small remote factories to process whatever the rock is made of. The squid is already adapted to a weightless environment, so maybe a compromise between a full manned mission and a robot drone would work well.

[nec209]

The space program is joke now:eek: In the 60's and 70's and little in 80's was years of hard money going into space program.

 

The cold war was year of money going into space program like money coming from trees.There was lots of exotic spaceships and drawings that got cut and never tested or got cut after some tests.

 

We would have moon base and gone to mars by now if the cold war was still on.Going in space cost money and it cost money to do research that coutries just do not want to do unless war time.

 

Look at coil,oil and gas same thing .No one wants to do research .In fact running out of coil,oil and gas and starting ww3 over energy would be good thing has much research would go into exotic programs to find new energy .

 

It true spending money on improving medicine is more imported than going to the moon or mars .But spending trillions of money on space program every year may spark revolution break through to make going in space cheap ,safe and easy like going on plane from LA to New York.This may help with extracting energy from space (fusion or hydrogen) and space mining where has of now it cost more to get up in space than what they will bring back has of now.

 

And earth population overflow problem where people can live on the moon or mars. Finding water and ice and other resources out there.

 

If there is no revolution spark in space rockets than humans where not meant to go any where but the moon or mars just to vist and going space will be not ever and I mean ever be safe and will be very very very costly and big challenge.

 

 

Most likely if we cannot find new energy source and run out of mining on earth and no revolution spark in space rockets this will set back to medieval time if not worse.It up to now to spend mony on new energy source and space rockets to try to fix this problem.

 

 

May be the laws of physics was not meant for a country or corporation to go space but all countries . Where every country gives x number of money to go in space where the cost is not so bad that way.

 

I hope there is revolution spark in space rockets if not we are going no where in space but the moon and may be mars just to vist.If we cannot find new energy source and no revolution spark in space rockets we are doomed.

[Moontanman]

Actually nec, the cost of space travel is quite small when compared to the money we spend on the military, the Iraq war cost more money in just a few days that the entire NASA budget for a year. Space travel is pitifully under funded.

[Mr Skeptic]

Well fuel is big problem it TAKES more fuel than the payload !!!

...

The fuel they use now is just not powerful enough so need lots and lots of fuel just to lift 15% of the rocket into space and shedding the 85% empty fuel tank.

 

Actually, it is the oxidizer that is the most massive component. The oxygen oxidizer for a hydrogen-oxygen engine is 8 times heavier than its hydrogen fuel.

 

Not sure about nuclear or fusion but I think they have low thrust too.

 

There are many ways one can use nuclear energy for space travel. In space, yes the plasma/ion/whatever with a low thrust but high specific impulse would be the best. However those would not function for liftoff. However, nuclear energy can also be used in lieu of chemical energy. Rather than burning hydrogen with oxygen, you can pass it through a nuclear reactor to heat it up. This allows huge thrust and also a reasonable specific impulse. Also, there would be no need for an oxygen tank; this could run on hydrogen only.

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I have been thinking, this energy used to power shuttles into space. It is lost in space instead of recycled on earth. If one day, space travel becomes common, will this depletes earth's resources ?

 

Not likely. Earth's mass is continuously increasing from space dust and micrometeorites falling constantly to Earth. We'd have to take some huge amounts of stuff up, or extremely rare materials, to deplete anything. In any case, energy used on Earth is the same as energy used in space; it will be lost anyways.

[Airbrush]

Robotic missions can accomplish most of the things manned missions can at much lower cost. With nano technology, maybe tiny probes can hover or glide over an alien landscape. In the future the controller for these tiny robot explorers on any moon, planet, or asteroids/comets, could have hi-def cameras so that the controller would feel like he is actually there, virtually. In fact maybe the video feeds could be available to the general public someday so you could explore Mars, Europa, or Titan in 3-D on your home TV.

Edited March 10, 2010 by Airbrush

[nec209]

Actually, it is the oxidizer that is the most massive component. The oxygen oxidizer for a hydrogen-oxygen engine is 8 times heavier than its hydrogen fuel.

 

How much weight does the oxygen tank take up ? 20% or 30%?

 

Rather than burning hydrogen with oxygen, you can pass it through a nuclear reactor to heat it up. This allows huge thrust and also a reasonable specific impulse. Also, there would be no need for an oxygen tank; this could run on hydrogen only.

 

 

 

That is fusion you are talking about.

 

 

Robotic missions can accomplish most of the things manned missions can at much lower cost. With nano technology, maybe tiny probes can hover or glide over an alien landscape. In the future the controller for these tiny robot explorers on any moon, planet, or asteroids/comets, could have hi-def cameras so that the controller would feel like he is actually there, virtually. In fact maybe the video feeds could be available to the general public someday so you could explore Mars, Europa, or Titan in 3-D on your home TV.

 

what do you want do to wait to 2040 and we have no more coil,oil and gas and running low on mining on earth and population of 10 billion. We will be lucky if we have enough coil,oil and gas to for other 40 years from now .Than say okay that spend trillions of money on rocket research every year.And it to late at that time..

 

It is up to now to spend money on rocket research and finding a new energy source.After this critical problem is fixed than you can make nice TV's ,virtual reality ,learning about planets and stars not to say the universe and deep ocean on earth and rain forest.

 

 

To than water, food ,mining ,new energy ,overpopulation ,improving medicine and not running low on resources is priority number 1. Well entertainment and Knowledge of science that does not deel with the priority number 1 is at a much lower priority on the list.

[Moontanman]

That is fusion you are talking about.

 

No, it is not fusion, did you read think I provided about nuclear powered space craft?

 

what do you want do to wait to 2040 and we have no more coil,oil and gas and running low on mining on earth and population of 10 billion. We will be lucky if we have enough coil,oil and gas to for other 40 years from now .Than say okay that spend trillions of money on rocket research every year.And it to late at that time..

 

It is up to now to spend money on rocket research and finding a new energy source.After this critical problem is fixed than you can make nice TV's ,virtual reality ,learning about planets and stars not to say the universe and deep ocean on earth and rain forest.

 

 

To than water, food ,mining ,new energy ,overpopulation ,improving medicine and not running low on resources is priority number 1. Well entertainment and Knowledge of science that does not deel with the priority number 1 is at a much lower priority on the list.

 

I have to admit I generally agree, waiting for the correct technology is simply too risky, if Columbus had waited for steam ship technology where would we be now? It might have been better for my people but the new world and everything that came from it would be drastically different if someone had told Columbus, aww just wait we'll have better technology in a few hundred years. Well be able to fly over the Atlantic instead of months by sailing ship.

 

Anyway you look at it, research should not be stopped, the return on space technology has been tremendous, nearly our entire technological civilization depends on space related technology. Right now were spending a pittance on space travel, if we had spent just 20% of what we spent on killing each other since 1950 on space travel humans would already own the inner solar system and yes the resources of the inner solar system would make a big difference in our own lives.

[InigoMontoya]

That is fusion you are talking about.

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). 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 want do to wait to 2040 and we have no more coil,oil and gas and running low on mining on earth and population of 10 billion. We will be lucky if we have enough coil,oil and gas to for other 40 years from now .Than say okay that spend trillions of money on rocket research every year.And it to late at that time..

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?

 

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....

 

Cost to Mars? $150,000 per person.

 

Pretty damned cheap, right?

 

But you implied that you wanted to significantly evacuate Earth. How many people do we have to evacuate to make a significant dent? I mean, suppose we evacuated 1,000,000 people today (out of a population of 6 billion)? That leaves 5,999,000,000 people. Wooopty dooo! We just evacuated 0.017% of the population. How long do you think it will take to repopulate? Well, considering that the global population growth rate is about 1%, that implies it'll take a whopping week or so to replenish the Earth's population to pre-evacuation levels (6 billion) but I'll be generous and say it'll take a month since you're presumably taking prime breeding age folks off planet.

 

And at what cost?

 

Well.... $150,000 * 1,000,000.... Hmmm... $150 billion spent to set the Earth's population back a month. Just to keep the Earth's population steady state you're talking $1.8 trillion dollars PER YEAR.

 

And with all that money spent, what do you have to show for it with regards to decreased stress on our planet? Absolutely nothing. You're just treading water.

 

Even worse: Don't forget those numbers are using insanely generous assumptions! Reality is much, much worse.

 

Go to space because you think it's cool and you think mankind should explore the universe and such. But don't kid yourself: Going to space will do squat towards saving the planet.

Edited March 11, 2010 by InigoMontoya

[Mr Skeptic]

Go to space because you think it's cool and you think mankind should explore the universe and such. But don't kid yourself: Going to space will do squat towards saving the planet.

 

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.

[Moontanman]

No one is saying that space travel can be used to ease population pressure on the Earth any more than Spanish galleons could have been used to ease over crowding in Europe in the 15th century, even now it would be impractical to bring people from one continent to another faster than they could reproduce.

 

However resources, raw materials and even manufactured goods (no i have no idea what could be manufactured in orbit better than on the earth) could be brought to the earth not to mention colonies could and probably would be built in free orbit around the sun in around and near asteroids, around the gas giants and in the Trojan positions of those planets.

 

There is no way at this time to predict what theses colonies or even resources might contribute to the Earth but I am quite sure by then we will know.

[InigoMontoya]

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.

 

Do unified people eat less?

[Moontanman]

Robotic missions can accomplish most of the things manned missions can at much lower cost. With nano technology, maybe tiny probes can hover or glide over an alien landscape. In the future the controller for these tiny robot explorers on any moon, planet, or asteroids/comets, could have hi-def cameras so that the controller would feel like he is actually there, virtually. In fact maybe the video feeds could be available to the general public someday so you could explore Mars, Europa, or Titan in 3-D on your home TV.

 

Actually, no, we cannot control robots on alien planets, even at the distance of the moon, time delay due to the speed of light prevents any real control over robots.

[Phi for All]

Actually, no, we cannot control robots on alien planets, even at the distance of the moon, time delay due to the speed of light prevents any real control over robots.

Agreed. Programmed AI is the best way to use robots off planet. They would need to find a chunk of asteroid to cannibalize, and use the materials to build whatever they needed to keep going further out.

[InigoMontoya]

However resources, raw materials and even manufactured goods (no i have no idea what could be manufactured in orbit better than on the earth) could be brought to the earth not to mention colonies could and probably would be built in free orbit around the sun in around and near asteroids, around the gas giants and in the Trojan positions of those planets.

 

There is no way at this time to predict what theses colonies or even resources might contribute to the Earth but I am quite sure by then we will know.

 

If it costs $50/pound to get from Earth to intersteller space (remember, very generous), then it's going to cost something similar to return something from interesteller space to Earth. First you'll have to alter your helio-centric orbit and then you'll have to slow for decent (After all, it does you no good to come it at full orbital velocity.). You'll burn up in the atmosphere and all that. You'll need rockets of one flavor or another. Blah blah blah.

 

So unless we find an asteroid made of gold...

 

What is there in space that's worth $50/pound to bring back in significant quantities?

 

Water?

Iron?

Nickel?

 

None of those qualify.

 

It's a serious question. The colonial economics argument requires that you be bringing in raw materials from off world for significantly cheaper than they can be produced on world. Even with our freakishly cheap transportation system, we're not even close to making a valid economic argument.

[Moontanman]

Do unified people eat less?

 

No they do not, but taking mining and as much heavy industry as possible off planet certainly would ease the burden on the environment but over population is not really part of the reason for or against space travel.

 

Over population is a separate issue and over population just might eventually result in the extinction of humanity but if we have many space colonies humanity will go on.

 

Space colonies also have the possibility of providing places for various groups or even individuals who no longer feel comfortable on the earth, possibly those who want to live under various forms of government, say for instance a pure capitalist society or pure socialist or what ever from religious communities to anarchies, colonies might provide a place for such people to go.

 

I predict societies that are nothing but human carcinomas to pastoral squalor will eventually live in space colonies and when they fail use free vacuum to sterilize them refit them and sell them to someone else. Sounds like a real estate developers Paradise

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If it costs $50/pound to get from Earth to intersteller space (remember, very generous), then it's going to cost something similar to return something from interesteller space to Earth. First you'll have to alter your helio-centric orbit and then you'll have to slow for decent (After all, it does you no good to come it at full orbital velocity.). You'll burn up in the atmosphere and all that. You'll need rockets of one flavor or another. Blah blah blah.

 

So unless we find an asteroid made of gold...

 

What is there in space that's worth $50/pound to bring back in significant quantities?

 

Water?

Iron?

Nickel?

 

None of those qualify.

 

It's a serious question. The colonial economics argument requires that you be bringing in raw materials from off world for significantly cheaper than they can be produced on world. Even with our freakishly cheap transportation system, we're not even close to making a valid economic argument.

 

I does not take $50 a pound to bring stuff to the Earth and atmospheric reentry is not as difficult as you seem to think. Bringing something to the Earth is quite cheap. I once read that a 10 mile nickle iron asteroid contains enough precious metals like platinum group metals, gold silver and such to make every man woman and child on the earth wealthy. of course it wouldn't work that way but it illustrates just how much "stuff" is out there.

Edited March 11, 2010 by Moontanman
Consecutive posts merged.

[Mr Skeptic]

Do unified people eat less?

 

No, but we'd kill each other off less. So there! (Also, we'd start caring more about "our" planet rather than "the" planet and whether we should reduce pollution if it will weaken us compared to "them" other countries.)

 

---

 

Also, I think $50 per pound is extremely cheap and your other estimates too high. Remember that the big portion of the cost here is to escape Earth's gravity well, and do so with huge thrust. Once we get stuff in space, we can shuttle it all over the place rather cheaply. Landing can be done without rockets by using a heat shield. We can have specialized shuttles to go back and forth between Earth and Mars, but not land there. If we can make fuel in space the costs for this will be vastly reduced. Liftoff could be done via specialized lifters, and space travel with more efficient engines such as ion or plasma. Even better, we could make something like a launch loop, which would make liftoff much cheaper than rockets.

[InigoMontoya]

I does not take $50 a pound to bring stuff to the Earth and atmospheric reentry is not as difficult as you seem to think. Bringing something to the Earth is quite cheap.

Just for fun I ran some numbers. The deltaV required for a Hohmann transfer orbit from Mars to Earth is approximately 2.5 km/s. By comparison, the orbital velocity required for geosynch orbit is 3.1 km/s. So while it's accurate to say that it takes more energy to get from Earth's surface to geosynch, I think it's fair to say that the cost to get from a similar-to-Mars orbit to Earth is going to be on the same order of magnitude.

 

Or do you somehow think that it's free/cheap/easy to get from the orbit of the asteroid you're mining back to Earth?

 

As for atmospheric re-entry being easy when entering Earth's atmosphere directly from intersteller space, I'd be curious as to what you're basing that statement on. Reentry from LEO and reentry from heliocentric orbit are two VERY different feats. Heck, it's only been done a handfull of times to my knowledge.

 

As for the basis of my statements: in a former life myself and 2 other guys designed, built, and flew an RV (well, technically the Air Force few the RV). I'm not totally ignorant on what it takes to survive re-entry (for those who doubt the claim... search for the word "chop").

 

I once read that a 10 mile nickle iron asteroid contains enough precious metals like platinum group metals, gold silver and such to make every man woman and child on the earth wealthy. of course it wouldn't work that way but it illustrates just how much "stuff" is out there.

Show me a mine on Earth that has moved 525 cubic miles of material. It's not enough to say that there's a bunch precious metals there, it has to be easy to obtain. If it's a trace element in an essentially nickel/iron mass, you're killing your profit margin on the processing end (gotta get all the good stuff out of the junk iron/nickle).

Edited March 11, 2010 by InigoMontoya

[Moontanman]

It all depends on how fast you need to come to the earth, from the asteroids to the earth is quite cheap if you don't mind the travel time being a couple of years. processed metals do not need life support or gravity, they can be transferred over time in slow efficient orbits. No one is coming out of interstellar space. and processing in space can use solar power, not to mention automation. But the real deal is making space habitats not bringing platinum to the earth although by that time the need for many metals by that time just might justify a very large price. And mining in space would be much easier that moving the stuff out of the earth.

[InigoMontoya]

It all depends on how fast you need to come to the earth, from the asteroids to the earth is quite cheap if you don't mind the travel time being a couple of years. processed metals do not need life support or gravity, they can be transferred over time in slow efficient orbits.

Do the words, "Hohmann transfer orbit" mean anything to you? Barring gravity assist, it's the most efficient way to get from one orbit ot another...And with the lack of large bodies between Mars and Earth, I'm going to go out on a limb and say that gravity assist is questionable. In other words, regardless of how long you want it to take, you'll need on the order of 2.5 km/s of deltaV. There is no free lunch here. You can use any sort of exotic, low thrust, high efficiency thruster in your book. You can take 5,000 years to do it. But you'll still need 2.5 km/s worth of velocity change until you come up with new laws for orbital mechanics.

 

No one is coming out of interstellar space.

Then you're dealing with a niche market at best and any talk of exhaustion of Earth's resources being a motivator for space travel is totally irrelevant.

[Moontanman]

Do the words, "Hohmann transfer orbit" mean anything to you? Barring gravity assist, it's the most efficient way to get from one orbit ot another...And with the lack of large bodies between Mars and Earth, I'm going to go out on a limb and say that gravity assist is questionable. In other words, regardless of how long you want it to take, you'll need on the order of 2.5 km/s of deltaV. There is no free lunch here. You can use any sort of exotic, low thrust, high efficiency thruster in your book. You can take 5,000 years to do it. But you'll still need 2.5 km/s worth of velocity change until you come up with new laws for orbital mechanics.

 

 

Then you're dealing with a niche market at best.

 

You can use waste materials as mass to change your orbits, mag fields to use this mass in mass drivers. Are you sure you don't mean interplanetary space?