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Is interstellar travel possible?


Dinokilla45
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The topic about interstellar travel is scarcely spoken of within the scientific community. Even though, it should be one of the most debated and heated engagements of scientists across the world. This is because eventually mankind will have to seek the stars for support and sustenance for when we empty this planet of ours of resources. I want to know what you all think about this topic, is interstellar travel possible, and how soon would it be possible for mankind to seek other systems to live in?

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... when the time comes, the stars will become too far for us to even reach.

If you are thinking of the cosmic expansion, it only separates things at the supercluster level... groups of galaxies about 200 million light years or greater apart.

 

The topic about interstellar travel is scarcely spoken of within the scientific community. Even though, it should be one of the most debated and heated engagements of scientists across the world. This is because eventually mankind will have to seek the stars for support and sustenance for when we empty this planet of ours of resources. I want to know what you all think about this topic, is interstellar travel possible, and how soon would it be possible for mankind to seek other systems to live in?

We aren't going to be moving boatloads of people off this planet ever... the best we can hope to achieve is to sustain samples of Earth-life, including humans, by sending them away into space, like airborne spores, in the hope that they will land on hospitable terrain.and propagate.

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The topic about interstellar travel is scarcely spoken of within the scientific community.

 

I don't agree with this statement.

 

There is frequent discussion within appropriate segments of the scientific community. Interstellar travel has little scientific relevance to most scientists. Interstellar destinations would be mightily relevant, but the means of getting their is quite unimportant. There are several thousand hits in Google Scholar for Interstellar Travel - I don't see how that equates to scarcely spoken of.

 

Even though, it should be one of the most debated and heated engagements of scientists across the world.

I strongly disagree with this statement. The decision to leave the planet is a political and social decision, not a scientific one. Scientific knowledge and engineering expertise may inform the decision, but it is not a scientific decision and therefore scientists have no more part to play in discussing it than any other human.

 

This is because eventually mankind will have to seek the stars for support and sustenance for when we empty this planet of ours of resources

 

This is questionable. We currently employ a hughely wasteful approach to supporting a material and energy intensive culture. Use of renewable energy and effective recycling can be great solutions in this regard. After that we have a whole solar system at our disposal. The reasons for interstellar travel are twofold:

1. Don't put all your eggs in one basket

2. I wonder what is on the other side of the hill.

 

These are different from - and, I think more important than - your proposed motivation.

 

is interstellar travel possible

 

Yes, but rather difficult. Generation ships, using hollowed out asteroids seem the easiest route. Or a combination of von Neumann devices, AIs and frozen embryos.

 

how soon would it be possible for mankind to seek other systems to live in

 

We are doing that already. Within twenty years we will have positively identified likely candidates. Within a millenium the first interstellar colonies will be established.

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The book,The Millennial Project: Colonizing the Galaxy in Eight Easy Steps by Marshal T. Savage, is a good read and describes how humanity may colonize the galaxy. It is "hard" science fiction, and describes some science that is incorrect in detail, yet reasonable in concept. For example, his idea of using seacrete to make floating cities is probably not possible, but a Dutch architect envisions floating cities as a possible response to rising sea levels. Regardless of whether the ideas presented by Savage are developed exactly as described or not is unimportant, the ideas are generally sound, IMO and others.

 

In addition to the idea of people actually migrating into space throughout our Galaxy, this thread has links to a news article and paper that physicists wrote that explain how replicating machines with AGI can launch ships to carry the seeds of humanity throughout the Universe.

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"Is interstellar travel possible?"

 

That is a vague question, but interesting. Interstellar travel for robotic probes is now possible and Voyager is a success story, however traveling at a very slow speed relative to the great distances.

 

We can accelerate small robotic probes to MUCH higher speeds than we can accelerate humans with their many tons of life support per person. I think the Orion drive (long series of tiny nuclear explosions measured in hundreds of pounds of TNT rather than megatons), would be great for accelerating small robotic ships to very high speeds (like 50%C). After these probes reach a star system, they slow down using Orion drive and get into orbit around the star, and send back pictures and info so we can decide if there is a very nice Earth-like planet there. After reaching the star, you can use small rockets and Impulse power for fine tuning.

 

When it comes to sending humans to other stars, you will first need to be able to build space colonies where people can live indefinitely. Multi-generational star ships will be necessary to transport humans to other stars because the trip will take a LONG time, probably thousands of years.

Edited by Airbrush
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  • 3 weeks later...

If the science is able to generate gravitational waves,it won't be necessary to reach hundreds years other stars, it is possible to turn itself into a clot of gravitational waves and to send with velocite of light to other stars, then also return.

Are you sure?

 

Gravitational waves are presently described as transverse quadripolar waves. Shall they have an axial effect? Through the axial gradient of a circularly polarized wave acting on a rotating, transversally elongated mass? That would multiply again by zero dot nothing.

 

Up to now, no single one has been observed despite the unimaginable sensitivity of the detectors. Shall they bring matter to light-years?

 

Human technology doesn't produce gravitational waves, even at the strength that we could detect. So if you know a means, just tell!

[...]I think the Orion drive (long series of tiny nuclear explosions [...]) would be great for accelerating small robotic ships to very high speeds (like 50%C). [...]

The Orion drive is science-fiction, not technology.

It cannot achieve 50% c (even if it were working) because nuclear energy isn't that much concentrated.

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This is because eventually mankind will have to seek the stars for support and sustenance for when we empty this planet of ours of resources.

 

People believe that we are emptying our planet. It's incorrect thinking. Atoms that were in oil are still in our planet. They just changed from one molecule of hydrocarbon to another molecule of hydrocarbon (e.g. plastic), or to water and CO2 while burning. These atoms nowhere go outside of our planet! The less will be oil, the more technologies of reusing old materials will be in common use. In capitalism, what is cheaper wins. If flying to asteroid and bringing it here would be cheap, everybody would be doing it.

 

and how soon would it be possible for mankind to seek other systems to live in?

 

 

It's just a matter of money..

 

People that build Saturn V etc. didn't lost knowledge how to build them.

They stopped building them because there was no more money from government to sustain conquest of cosmic space.

Edited by Sensei
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"...The Orion drive is science-fiction, not technology. It cannot achieve 50% c (even if it were working) because nuclear energy isn't that much concentrated."

 

Why don't they plan robotic missions using nuclear pulse propulsion? If they could accelerate an 800,000 ton spaceship to high speeds, imagine how fast they could get a light-weight robotic probe traveling. Also high acceleration will hurt people, but not damage a very robust-built robot.

 

"Project Orion was the first serious attempt to design a nuclear pulse rocket. The design effort was carried out at General Atomics in the late 1950s and early 1960s. The idea of Orion was to react small directional nuclear explosives against a large steel pusher plate attached to the spacecraft with shock absorbers. Efficient directional explosives maximized the momentum transfer, leading to specific impulses in the range of 6,000 seconds, or about thirteen times that of the Space Shuttle Main Engine. With refinements a theoretical maximum of 100,000 seconds (1 MN·s/kg) might be possible. Thrusts were in the millions of tons, allowing spacecraft larger than 800,000 tons to be built with 1958 materials.[3]"

 

http://en.wikipedia.org/wiki/Orion_drive

Edited by Airbrush
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If we can get past our preoccupation with Faster Than Light travel we could leave for the stars any time. A much more urgent matter is to learn how to live on alien planets of all types. Our thinking has been constrained to 'Earthlike' planets and so we presuppose people cannot have gratifying lives elsewhere - including life on board a generation ship. As long as we continue to insist on planets like Earth or Mars as targets for interstellar settlers, we very likely will have no real incentive to go.

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"...The Orion drive is science-fiction, not technology. It cannot achieve 50% c (even if it were working) because nuclear energy isn't that much concentrated."

 

Why don't they plan robotic missions using nuclear pulse propulsion? If they could accelerate an 800,000 ton spaceship to high speeds, imagine how fast they could get a light-weight robotic probe traveling. Also high acceleration will hurt people, but not damage a very robust-built robot.

 

"Project Orion was the first serious attempt to design a nuclear pulse rocket. The design effort was carried out at General Atomics in the late 1950s and early 1960s. The idea of Orion was to react small directional nuclear explosives against a large steel pusher plate attached to the spacecraft with shock absorbers. Efficient directional explosives maximized the momentum transfer, leading to specific impulses in the range of 6,000 seconds, or about thirteen times that of the Space Shuttle Main Engine. With refinements a theoretical maximum of 100,000 seconds (1 MN·s/kg) might be possible. Thrusts were in the millions of tons, allowing spacecraft larger than 800,000 tons to be built with 1958 materials.[3]"

 

http://en.wikipedia.org/wiki/Orion_drive

The advantage that Orion has over other propulsion methods is its ability to provide a large thrust to move huge payloads. For a small probe, you are better off using something like the VASIMR which has a predicted maximum of 120,000 sec. This would allow for a lower mass ration for the same speed. ( for example, to reach 0.01c with Orion requires a mass of ratio of 21 while with VASIMR it only requires one of 13. IOW, Orion would take 2/3 again more fuel/reaction mass to reach the same speed.

 

Or put another way, applying the large thust of Orion to a smaller probe just decreases the time it takes for the probe to reach its top speed than a VASIMR rocket would, however, given the same amount of fuel, the VASIMR will give you the greater top speed.

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[...]for example, to reach 0.01c with Orion requires a mass of ratio of 21 while with VASIMR it only requires one of 13 [...]

NO.

 

Your maths are way off. 0.01c is unattainable with isp=6000s, and is unrealistic with Vasimr because the energy source isn't concentrated enough. 120,000s refers to the ejected mass, but the required energy comes from a heavy fuel and reactor - this isp figure is just dishonest from its promoters and you got fooled by it.

 

Vasimr cannot move a big payload. Even if it had 100MWe available, at isp=120,000s and 100% energy efficiency it would provide only 170N. The cold sink at 500K for 100MWth (if the thermal conversion were 50% efficient from a hot temperature) would need 28,000m2. If this cold sink is material and weighs 1kg/m2, it adds 28t. A 50t ship accelerating at 6mm2/s would take 16 years to attain 0.01c, but 1GWe nuclear reactors weighing thousands of tonnes must be refilled yearly - impossible in deep space. Then, the nearest star is still 5 centuries away.

 

Even if the payload is smaller, the mass of the reactor and the fuel scales with the thrust, keeping such speeds impossible.

 

Oh, and just in case, I should like to remind that fusion reactors don't work.

 

Vasimr may be good to hop within the Solar system with careful trajectory planning. It should be excellent to put satellites in geostationary orbit. But it's incapable of joining the next star.

Why don't they plan robotic missions using nuclear pulse propulsion? [...] Thrusts were in the millions of tons, allowing spacecraft larger than 800,000 tons to be built with 1958 materials.

Because, again, it does not exist. Nor is it even feasible.

 

You're mixing what has been vaguely imagined, what is possible, and what exists. Science-fiction is not science.

Edited by Enthalpy
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NO.

 

Your maths are way off. 0.01c is unattainable with isp=6000s, and is unrealistic with Vasimr because the energy source isn't concentrated enough. 120,000s refers to the ejected mass, but the required energy comes from a heavy fuel and reactor - this isp figure is just dishonest from its promoters and you got fooled by it.

 

Vasimr cannot move a big payload. Even if it had 100MWe available, at isp=120,000s and 100% energy efficiency it would provide only 170N. The cold sink at 500K for 100MWth (if the thermal conversion were 50% efficient from a hot temperature) would need 28,000m2. If this cold sink is material and weighs 1kg/m2, it adds 28t. A 50t ship accelerating at 6mm2/s would take 16 years to attain 0.01c, but 1GWe nuclear reactors weighing thousands of tonnes must be refilled yearly - impossible in deep space. Then, the nearest star is still 5 centuries away.

 

Even if the payload is smaller, the mass of the reactor and the fuel scales with the thrust, keeping such speeds impossible.

 

Oh, and just in case, I should like to remind that fusion reactors don't work.

 

Vasimr may be good to hop within the Solar system with careful trajectory planning. It should be excellent to put satellites in geostationary orbit. But it's incapable of joining the next star.

Because, again, it does not exist. Nor is it even feasible.

 

You're mixing what has been vaguely imagined, what is possible, and what exists. Science-fiction is not science.

I wasn't actually promoting VASIMR as an interstellar drive, I just used it as an example of a drive with a higher ISP; Comparing its "theorectical limit" with that of Orion. I'm sure that the 100,000 sec ISP given for Orion is overly optimistic also. The point I was trying to make was that higher thrust doesn't automatically lead to greater final speed. Probably I could have been more clear on that.

 

I am well aware that 6000 sec is far too low to reach even 0.01c, and never said that it was( 6000 sec would give a mass ratio of ~1.4e22). So I can't see where you say my "math" is way off, as the only math I did was comparing mass ratios for ISPs of 100,000 sec and 120,000 sec. Granted, I did not take into account the relative engine to payload ratios of the two, Which would severely limit things in practical terms, But then again, I wasn't actually trying to deal with this aspect. Again,I should have been more clear.

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So, in your opinion, what will be the propulsion method to send unmanned probes to the nearest stars?

None. With presently extrapolable technology, we have no method at all.

 

The best feasible method I see (though not desireable!) is to cover a thin film with a superthin alpha emitter to catch the recoil. But it's incapable to send anything to the nearest star within, say, one full human life.

 

It would need to carry an energy source more concentrated than radioactivity, fission, fusion - something like antimatter. Or to find energy in situ or bring it there - how?

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The nuclear thermometric battery of a Voyager is expected to last till 2020 curiosities is expected to last 14 years. So any probe launched on a giant conventional rocket would be dead long before the million year arrival date. Something larger with a more exotic energy and propulsion source like nuclear fusion is needed. So with current technology, no, if fusion power becomes cheap ask again.

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Do any of you take serious the possibility of going faster than light travel by use of Alcubierre drives or worm holes. Nasa is actually working on warping space for subatomic particles. http://www.extremetech.com/extreme/164326-nasa-discusses-its-warp-drive-research-prepares-to-create-a-warp-bubble-in-the-lab. And theoretical physicists and astronomers have been trying to see if wormholes could be used for decades. http://www.youtube.com/watch?v=lhp2_RqOxCw.

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How many years before we will have a propulsion method that will allow an unmanned probe, weighing less than a ton, to reach a nearby star within a century of launch?

 

I still think there is promise for nuclear pulse propulsion, either through an Orion or Medusa type drive, or other nuclear power method. If nanotechnology allows us to build unmanned probes that are very small, then very little mass must be accelerated to high speeds and it will be easier to accelerate such a small object faster.

Edited by Airbrush
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I honestly believe that we will go to other solar systems. It will not be in any of our lifetimes but it will happen. We do not have the technology to go to the edge of our own solar system yet so i don't think we will get there any time soon.

 

This is all talking about manned missions just so everybody knows.

Edited by Persius
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We hear estimates of when we will have simple bases on the Moon and Mars. We hear about unmanned missions to the outer planets and bigger and better space telescopes. But I have never heard an estimate of when will we send unmanned probes to other stars. Who cares about missions that could not bear fruit for a hundred years or more from launch? That would be a case of very delayed gratification for the human race.

Edited by Airbrush
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I still think there is promise for nuclear pulse propulsion, either through an Orion or Medusa type drive, or other nuclear power method.

You think what you want, but figures are strictly against, whatever the method is.

[...] hundred years from launch? That would be a very delayed gratification for the human race.

Cathedrals take several lifespans to build, and though, humans do build them, including right now.

 

One argument for cathedrals is that one sees them progress through his work. An other is that people working on them hope to deserve better chance for Paradise.

 

Drawing the parallel, you should invent a new religion that gives some kind of reason like Paradise for people to develop interstellar probes that take centuries to reach their goal, or even for people to board such a vessel. Some countries won't jail you for that.

 

Fine, because religion is more adequate than science to justify such an undertaking.

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"The 100 Year Starship (100YSS) is the name of the overall effort that will, over the next century, work toward achieving interstellar travel. The effort will also go by the moniker 100YSS. The 100 Year Starship study is the name of a one year project to assess the attributes of and lay the groundwork for an organization that can carry forward the 100 Year Starship vision.

 

Dr. Harold ("Sonny") White[54] from NASA's Johnson Space Center is a member of Icarus Interstellar,[55] the nonprofit foundation whose mission is to realize interstellar flight before the year 2100. At the 2012 meeting of 100YSS, he reported using a laser to try to warp spacetime by 1 part in 10 million with the aim of helping to make interstellar travel possible.[56] Related to the use of lasers is the optical effect which was confirmed by Yale University’s 2009 electrical-engineering experiment.[57] The Optical Effect says that, on silicon chip-and transistor-scales, light can attract and repel itself like electric charges/magnets. Albert Einstein, as well as other scientists, had the aim of uniting electromagnetism (light is one form of this) and gravitation.[58] Achievement of Einstein's Gravitational-Electromagnetic Equivalence means gravity could, on quantum levels, also attract and repel itself. General relativity says gravity is the warping of spacetime (the union of space and time into one entity called spacetime was first formulated by the mathematics professor Hermann Minkowski),[59] so space and time could be made to attract and repel at quantum levels. Prof. Max Tegmark [60] of MIT believes quantum levels make up all spacetime (he has said "You are made up of quantum particles, so if they can be in two places at once, so can you.")[61] Spacetime attracting and repelling at quantum distances which add up to the existence of the whole universe throughout all time means this: distances between points billions of light years apart could be eliminated in space (if Tegmark is correct; you could be here on Earth, and billions of light years away, at the same time). Since there is no separate space and time but only "spacetime", distances between the past and future would therefore also be eliminated (according to Prof. Tegmark, enabling you simultaneously to be in the past and future). This validates the work of physicist Ronald Mallett[62] whose use of lasers to warp spacetime for the purpose of time travel might, like the work of Harold White and Icarus Interstellar, see fulfillment if it builds on the theory of gravitational-electromagnetic equivalence and the optical experiment conducted at Yale University."

 

http://en.wikipedia.org/wiki/Interstellar_travel

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