Interstellar travel

[karenatlan]

Interstellar space travel is unmanned or manned travel between stars. The concept of interstellar travel in starships is a staple of science fiction. Interstellar travel is tremendously more difficult than interplanetary travel. Intergalactic travel, the travel between different galaxies, is even more difficult.
Many scientific papers have been published about related concepts. Given sufficient travel time and engineering work, both unmanned and generational interstellar travel seem possible, though representing a very considerable technological and economic challenge unlikely to be met for some time, particularly for manned probes. NASA has been engaging in research into these topics for several years, and has accumulated a number of theoretical approaches.

 

[JeffreyNYA]

ok, so what's the point if this post?

 

[jimeagle]

Interstellar space travel is unmanned or manned travel between stars. The concept of interstellar travel in starships is a staple of science fiction. Interstellar travel is tremendously more difficult than interplanetary travel. Intergalactic travel, the travel between different galaxies, is even more difficult.
Many scientific papers have been published about related concepts. Given sufficient travel time and engineering work, both unmanned and generational interstellar travel seem possible, though representing a very considerable technological and economic challenge unlikely to be met for some time, particularly for manned probes. NASA has been engaging in research into these topics for several years, and has accumulated a number of theoretical approaches.

Although I can't dig out your thesis here, I can respond to a couple of things--in my lay person's way. Those "givens"--sufficient time and engineering--are not to be glossed over. I think they may be game-stoppers, "given" that they appear so far to be insurmountable. Long discussion, for another time. And worm holes are treacherous passages.

It is the idea of alternative modes of "transportation" that some solution may lay: teleportation, transkinesis, or some mode of disassembling, sending and reassembling particles (or whatever essences can be worked with--at the atomic level.....that may be the only viable method.

Now bringing the space-tripper back? Hmmmmmm... "beam me up, Scotty....please.

 

[karenatlan]

Ok the point of this post is the following..

Our nearest star is Alpha Centauri and it's 4.3 lightyears away...What do you think,can we reach this star or not?
Suffice to say that the technology i.e. the spaceships are ready to fly there

 

[MeteorWayne]

No, the spaceships or technology are NOT ready to fly there for many decades, or centuries to come.

 

[crazyeddie]

Ok the point of this post is the following..

Our nearest star is Alpha Centauri and it's 4.3 lightyears away...What do you think,can we reach this star or not?
Suffice to say that the technology i.e. the spaceships are ready to fly there

What technology would that be? Sure, we could send a probe to Alpha Centauri, but it would take 165,000 years to get there if we sent it with a conventional rocket. A little less if we used a nuclear thermal engine. We've never built a nuclear-pulse rocket, and a light sail could carry only a tiny payload, with current technology. No other type of faster propulsion exists that we could build today.

 

[bdewoody]

So this thread is about Science Fiction

 

[StarRider1701]

Our nearest star is Alpha Centauri and it's 4.3 lightyears away...What do you think,can we reach this star or not? Suffice to say that the technology i.e. the spaceships are ready to fly there

You totally missed the most important question - do we have a REASON for going to that particular solar system? Especially with a manned expedition? Just because it is the closest one to us is NOT reason enough to do more than send a few probes. Now should we discover a habitable planet there...

Then we would need to find your "...spaceships ... ready to fly there"!!! Because while we do know of some methods for travelling between solar systems, much of that technology is on paper only. We do NOT have any functional or practical designs for actual, real spaceships capable of carrying a viable colony of humans to another solar system.

As MW said, that will likely not happen for at least 100 if not a couple of hundred years from now. We've reached the point in time where we can truly SEE just how much will one day be possible. Too bad our technology has been far outstripped by our dreams.

 

[karenatlan]

Dear StarRider1701 I totally agree with you,because we don't know whether there are earthlike planets or not...NASA is waiting for the James Webb telescope which will launch in 2014 or 2015.It will open many doors to us.Being X-ray scanner and huge telescope it can send us information about the surface of Alpha Centauri.Based on this information NASA scientists will do many discoveries and it will be quite important..
More information in

http://www.youtube.com/watch?v=Zd5Zh_0HusI
http://www.youtube.com/watch?v=YPjXxKpM ... re=related

 

[bdewoody]

In my experience YouTube is rarely a source of valid reliable data on such matters

 

[ZenGalacticore]

If we could attain 1% the speed of light--which would be an astonishing achievement and milestone-- it would still take us 400 years to get to Alpha Centauri. (1,186 miles per/second.)

Probably in much less than 100 years, we'll know which nearby systems are worth going to, ie, systems with living planets or promising ones. But, even knowing which ones to go to, I doubt we'll be able to get there in any reasonable amount of time, or at all. (Within 100 years, that is.)

Only after our own Solar System is almost fully explored and utilized, will people get serious about voyaging through interstellar space to other star systems. And it may take 1,000 years or more before we fully explore our own system.

This of course presumes that we will not destroy our civilization, or indeed, our very selves. And just because the Cold War is over, is no guarantee that we won't destroy our own civilization, or our own species. (Or most of the life on this planet.)

And if we keep exponentiating our numbers, all we're going to be doing is digging a hole in the sand. IOWs, going nowhere mighty fast. All resources will be allocated to a "welfare planet" that survives, but excels at nothing.

 

[crazyeddie]

If we could attain 1% the speed of light--which would be an astonishing achievement and milestone-- it would still take us 400 years to get to Alpha Centauri. (1,186 miles per/second.)

Probably in much less than 100 years, we'll know which nearby systems are worth going to, ie, systems with living planets or promising ones. But, even knowing which ones to go to, I doubt we'll be able to get there in any reasonable amount of time, or at all. (Within 100 years, that is.)

Only after our own Solar System is almost fully explored and utilized, will people get serious about voyaging through interstellar space to other star systems. And it may take 1,000 years or more before we fully explore our own system.

This of course presumes that we will not destroy our civilization, or indeed, our very selves. And just because the Cold War is over, is no guarantee that we won't destroy our own civilization, or our own species. (Or most of the life on this planet.)

And if we keep exponentiating our numbers, all we're going to be doing is digging a hole in the sand. IOWs, going nowhere mighty fast. All resources will be allocated to a "welfare planet" that survives, but excels at nothing.

I agree. Unless there is some kind of hitherto-unknown method of circumventing the speed of light, it's doubtful that we will have the technology or economic resources to send a manned mission to even the nearest star within the next couple of hundred years. And then there's always that problem: once interstellar travel is barely possible, do you send a mission right away, or do you wait for the technology to improve? It doesn't make much sense to send a slow manned mission that takes 100 years to get to Alpha Centauri, if a couple of decades worth of development will get you a ship that will get you there in 50 or 25 years.

 

[jimeagle]

Ok the point of this post is the following..

Our nearest star is Alpha Centauri and it's 4.3 lightyears away...What do you think,can we reach this star or not?
Suffice to say that the technology i.e. the spaceships are ready to fly there

What technology would that be? Sure, we could send a probe to Alpha Centauri, but it would take 165,000 years to get there if we sent it with a conventional rocket. A little less if we used a nuclear thermal engine. We've never built a nuclear-pulse rocket, and a light sail could carry only a tiny payload, with current technology. No other type of faster propulsion exists that we could build today.

Good points.

I was not being completely facetious when I mentioned teleportation as possible the only possible means for intergalactic travel. It is being taken very seriously and is apparently within the realm of possibility--maybe even probability. http://www.popsci.com/science/artic...e-teleportation-energy-theoretically-possible

 

[MeteorWayne]

Dear StarRider1701 I totally agree with you,because we don't know whether there are earthlike planets or not...NASA is waiting for the James Webb telescope which will launch in 2014 or 2015.It will open many doors to us.Being X-ray scanner and

Uhhh, bzzzzzzzzzt no it is not looking at X-rays:

Due to a combination of redshift, dust obscuration, and the low temperatures of many of the sources to be studied, the JWST must operate at infrared wavelengths to see deeply into dust or distance. Its present design spans the wavelength range from 0.6 (near the cutoff between red and near-infrared) to 28 micrometres (deep infrared which corresponds to temperatures of about 100 kelvins).

That's about as far as you can get from X-Rays....

 

[StarRider1701]

Probably in much less than 100 years, we'll know which nearby systems are worth going to, ie, systems with living planets or promising ones.
Only after our own Solar System is almost fully explored and utilized, will people get serious about voyaging through interstellar space to other star systems. And it may take 1,000 years or more ...

I beg to differ, Zen. We already know that there is no other place in our solar system where humans can live without protection from the elements and breathing apparatus. While I am a strong proponent of "you must crawl before you can walk and walk before you can run" - and our space efforts are currently in "crawl" stage, I think we will be looking outward and wanting leave this system as quickly as physically possible. Yes, some folk will move out into and begin utilizing other places here, but I don't agree with your "we must fill up this solar system before anyone will want to go elsewhere" concept. Other than the Mars groups, we already want to go elsewhere because most of us know there is no real satisfactory place for us to live here in this solar system.

Actually, you can keep Mars, if I were going to live somewhere in this system I think I might pick Europa.

Ok, so there are a few interesting places here, since we can't go anywhere else!

 

[karenatlan]

Proposed methods of interstellar travel

If a spaceship could average 10 percent of light speed, this would be enough to reach Proxima Centauri in forty years. Several propulsion systems are conceivably able to achieve this, but none of them are ready for near-term (few decades) development at acceptable cost.

Nuclear pulse propulsion

Since the 1960s it has been technically possible to build spaceships with nuclear pulse propulsion engines, i.e. ships driven by a series of nuclear explosions. This propulsion system contains the prospect of very high specific impulse (space travel's equivalent of fuel economy) and high speed, and therefore of reaching the nearest star in decades rather than centuries; construction and operational costs per unit of payload were expected to be similar to those of ships using chemical rockets.
Proposed interstellar spacecraft using nuclear pulse propulsion include Project Orion, which used nuclear bombs as propellant, and Project Longshot, which used inertial confinement fusion explosions. Orion is one of the very few known interstellar spacecraft proposals that could be built entirely with existing technology. However, interstellar travel would only be possible using advanced derivatives of the design with cruising speeds of 8%-10% c. Versions studied during the project had exhaust velocities of 20-30 km/sec, far too low to achieve reasonable interstellar cruising speeds.

Fusion rockets

Fusion rocket starships, using foreseeable fusion reactors, should be able to reach speeds of approximately 10 percent of that of light. These would "burn" such light element fuels as deuterium, tritium, or 3He. One proposal using a fusion rocket is Project Daedalus. Because fusion yields about 1% of the mass of the nuclear fuel as released energy, it is energetically more favorable than fission, which releases only about 0.1% of the fuel's mass-energy. However the most achievable fusion reactions release a large fraction of their energy as high-energy neutrons, which are not simple to use for propulsion.
A problem with all traditional rocket propulsion methods is that the spacecraft would need to carry its fuel with it, thus making it quite heavy. The following three methods attempt to solve this problem:

Interstellar ramjets

In 1960 Robert W. Bussard proposed the Bussard ramjet, a fusion rocket in which a huge scoop would collect the diffuse hydrogen in interstellar space, "burn" it on the fly using a proton-proton fusion reaction, and expel it out of the back. Though later calculations with more accurate estimates suggest that the thrust generated would be less than the drag caused by any conceivable scoop design, the idea is attractive because, as the fuel would be collected en route, the craft could theoretically accelerate to near the speed of light.

Antimatter rockets

An antimatter rocket would have a far higher energy density and specific impulse than any other proposed class of rocket. If energy resources and efficient production methods are found to make antimatter in the quantities required, it would be theoretically possible to reach speeds near that of light, where time dilation would become much more noticeable, thus making time pass at a slower rate for the travellers as perceived by an outside observer.

Beamed propulsion

This diagram illustrates Robert L. Forward's scheme for slowing down an interstellar light-sail at the destination star system.
A light sail or magnetic sail powered by a massive laser or particle accelerator in the home star system could potentially reach even greater speeds than rocket- or pulse propulsion methods, because it would not need to carry its own reaction mass and therefore would only need to accelerate the craft's payload. Robert L. Forward proposed a means for decelerating an interstellar light sail in the destination star system without requiring a laser array to be present in that system. In this scheme, a smaller secondary sail is deployed to the rear of the spacecraft, while the large primary sail is detached from the craft to keep moving forward on its own. Light is reflected from the large primary sail to the secondary sail, which is used to decelerate the secondary sail and the spacecraft payload.
A magnetic sail could also decelerate at its destination without depending on carried fuel or a driving beam in the destination system, by interacting with the plasma found in the solar wind of the destination star and the interstellar medium. Unlike Forward's light sail scheme, this would not require the action of the particle beam used for launching the craft. Alternately, a magnetic sail could be pushed by a particle beam or a plasma beam to reach high velocity, as proposed by Landis and Winglee.
Beamed propulsion seems to be the best interstellar travel technique presently available, since it uses known physics and known technology that is being developed for other purposes, and would be considerably cheaper than nuclear pulse propulsion

 

[a_lost_packet_]

Nuclear pulse propulsion...

We simply do not have enough fuel right now. It would take an enormous effort and exhaust current stockpiles for a trip to Mars and back using NPP. For interstellar distances, it's out of the question until we find other. more available, means of blowing things to bits... (It's one of my favorite projects, though.)

Fusion rockets...A problem with all traditional rocket propulsion methods is that the spacecraft would need to carry its fuel with it, thus making it quite heavy. The following three methods attempt to solve this problem:

As you say, it's quite inefficient on a long-term voyage like we're discussing. The fuel mass would be fairly large.

Interstellar ramjets... the fuel would be collected en route, the craft could theoretically accelerate to near the speed of light.

There may not be enough gas stations on the way... IOW, space may not have enough sources of fuel for a ramjet to make meaningful use of. We'd be solely dependent on "finding fuel" and that's not a really good idea.

Antimatter rockets

The most powerful, most efficient 'splosion there could possibly be. Yet, producing enough would be a huge undertaking and it's likely to be impossible using current tech. Containing it is a problem as well despite popularized accounts of magnetic bottles being horded by terrorist organizations. In short, it's the most expensive man made material on the face of the planet... not exactly something people would like to dump out the back of a rocket...

Beamed propulsion...Beamed propulsion seems to be the best interstellar travel technique presently available, since it uses known physics and known technology that is being developed for other purposes, and would be considerably cheaper than nuclear pulse propulsion

My, what big lasers you gots!

A laser capable of doing that would be pretty big and eat up a large amount of power. In fact, it would be best based on the Moon or in orbit so it wouldn't have to deal with Earth's pesky atmosphere. That also brings into play the fact that even though there's not a lot out there in the depths of space between star systems, there is still something. Light can be refracted, scattered, reflected, etc... Some of the power would be lost to that. In short, it'd have to be a big mohawkin' lazor!

The advantage is that what is needed is constant acceleration. So, a laser could provide that if it was tracked well and did not deteriorate too much over the vast distances... oh, and if it was powerful enough..

[youtube]http://www.youtube.com/watch?v=fyuNidSrVik[/youtube]

 

[ZenGalacticore]

If we could attain 1% the speed of light--which would be an astonishing achievement and milestone-- it would still take us 400 years to get to Alpha Centauri. (1,186 miles per/second.)

Probably in much less than 100 years, we'll know which nearby systems are worth going to, ie, systems with living planets or promising ones. But, even knowing which ones to go to, I doubt we'll be able to get there in any reasonable amount of time, or at all. (Within 100 years, that is.)

I agree. Unless there is some kind of hitherto-unknown method of circumventing the speed of light, it's doubtful that we will have the technology or economic resources to send a manned mission to even the nearest star within the next couple of hundred years. And then there's always that problem: once interstellar travel is barely possible, do you send a mission right away, or do you wait for the technology to improve? It doesn't make much sense to send a slow manned mission that takes 100 years to get to Alpha Centauri, if a couple of decades worth of development will get you a ship that will get you there in 50 or 25 years.

Yes sir! That's always been the factual conundrum. (There's that word again, conundrum.)

Gerard Oneil mentioned it back in the late 1970's. Suppose we can do something so miraculous as achieving 1% c. Then what do we do? Wait until we can achieve 2%, or, 10% speed-of-light?

Let's say we wait until we can do 10% c. We launch our majestic starships, with their intrepid crews. All crewmembers are "perfect" physical and mental specimens. Exemplars of humanity! They, and their non-relativistic starship race at one tenth the speed of light towards 55-Cancri system, some 36 light-years away.


Now, going 10% the speed of light, there will be no significant time dilation. IOWs, the time it takes the travelers to get to their destination, won't be that far off the time perceived by those (all of us) left behind on the Earth. So, it will take our pioneers, traveling at 10% c., 360 years to reach 55-Cancri, 36 light-years distant. (Of course, the time duration onboard the ship will be less than what we observe. But not substantially.)

And then, back on Earth, some jackwad loveable son-of-a-beautiful woman (or ugly woman, but hey, it's all relative) figures out how to propel a craft at 86.4% the speed of light! And so, we can now build ships that can get to 55-Cancri in about 50 years, earthtime. By the "time" the original explorers who set out for 55 Cancri get there, the "later" designed starships will have already colonized the system, and would have been there already for over 300 years.

(Or, something like that...)

 

[eburacum45]

Beamed propulsion...Beamed propulsion seems to be the best interstellar travel technique presently available, since it uses known physics and known technology that is being developed for other purposes, and would be considerably cheaper than nuclear pulse propulsion

A laser capable of doing that would be pretty big and eat up a large amount of power. In fact, it would be best based on the Moon or in orbit so it wouldn't have to deal with Earth's pesky atmosphere. That also brings into play the fact that even though there's not a lot out there in the depths of space between star systems, there is still something. Light can be refracted, scattered, reflected, etc... Some of the power would be lost to that. In short, it'd have to be a big mohawkin' lazor!

The advantage is that what is needed is constant acceleration. So, a laser could provide that if it was tracked well and did not deteriorate too much over the vast distances... oh, and if it was powerful enough.

Beamed Propulsion has one big advantage over the other methods; the energy is transferred straight to the ship, rather than having to accelerate a giant mass of fuel and propellant as well. But light doesn't carry much momentum, which is why I'm very impressed with Jordin Kare's Sailbeam concept
http://www.space.com/businesstechnology ... 211-1.html

but from a Sci-Fi point of view, it's a little difficult to write interesting stories about a spaceship propelled by laser-driven tinfoil...

 

[eburacum45]

Yes sir! That's always been the factual conundrum. (There's that word again, conundrum.)
Gerard Oneil mentioned it back in the late 1970's. Suppose we can do something so miraculous as achieving 1% c. Then what do we do? Wait until we can achieve 2%, or, 10% speed-of-light?
Let's say we wait until we can do 10% c. We launch our majestic starships, with their intrepid crews. All crewmembers are "perfect" physical and mental specimens. Exemplars of humanity! They, and their non-relativistic starship race at one tenth the speed of light towards 55-Cancri system, some 36 light-years away.
Now, going 10% the speed of light, there will be no significant time dilation. IOWs, the time it takes the travelers to get to their destination, won't be that far off the time perceived by those (all of us) left behind on the Earth. So, it will take our pioneers, traveling at 10% c., 360 years to reach 55-Cancri, 36 light-years distant. (Of course, the time duration onboard the ship will be less than what we observe. But not substantially.)
And then, back on Earth, some jackwad loveable son-of-a-beautiful woman (or ugly woman, but hey, it's all relative) figures out how to propel a craft at 86.4% the speed of light! And so, we can now build ships that can get to 55-Cancri in about 50 years, earthtime. By the "time" the original explorers who set out for 55 Cancri get there, the "later" designed starships will have already colonized the system, and would have been there already for over 300 years.

(Or, something like that...)

Here's a little story I wrote a few years ago which mentions that problem...

http://www.voicesoa.net/deceleration-phase/

 

[a_lost_packet_]

...but from a Sci-Fi point of view, it's a little difficult to write interesting stories about a spaceship propelled by laser-driven tinfoil...

Well, it'd be pretty exciting, wouldn't it. Think of all the opportunities for drama!

"Commander, more dust spotted directly ahead!"
"Take Evasive action!"
"Commander, more dust spotted directly ahead!"
"Take Evasive action!"
"Commander, more dust spotted directly ahead!"
"Take Evasive action!"
"Commander, more dust spotted directly ahead!"
"Take Evasive action!"
"Commander, more dust spotted directly ahead!"
"Take Evasive action!"
"Commander, more dust spotted directly ahead!"
"DANGIT! Turn this Kleenex Box around! I'm going back to punch those engineers in the face!"

 

[StarRider1701]

Yes sir! That's always been the factual conundrum. (There's that word again, conundrum.)

Now, going 10% the speed of light, there will be no significant time dilation. IOWs, the time it takes the travelers to get to their destination, won't be that far off the time perceived by those (all of us) left behind on the Earth. So, it will take our pioneers, traveling at 10% c., 360 years to reach 55-Cancri, 36 light-years distant. (Of course, the time duration onboard the ship will be less than what we observe. But not substantially.)

And then, back on Earth, some jackwad loveable son-of-a-beautiful woman (or ugly woman, but hey, it's all relative) figures out how to propel a craft at 86.4% the speed of light! And so, we can now build ships that can get to 55-Cancri in about 50 years, earthtime. By the "time" the original explorers who set out for 55 Cancri get there, the "later" designed starships will have already colonized the system, and would have been there already for over 300 years.

Ok, technology always keeps improving. What's your point, Zen? In the future of space travel there will always be the question of - "do we go now or wait for 10 or 50 or 100 more years until technology gets better?" And just as that question will always be there, the answer will always be "GO" for the people who spent thier money and thier time investing in the ship and learning how to fly her.

 

[orionrider]

Our nearest star is Alpha Centauri

It is not. Proxima Centauri is the closest at 4.2LY.

If we sent a probe to Proxima or Alpha Centauri, we could not receive its transmissions, it's much too far.
So what would be the point?

 

[Mee_n_Mac]

Our nearest star is Alpha Centauri

It is not. Proxima Centauri is the closest at 4.2LY.

If we sent a probe to Proxima or Alpha Centauri, we could not receive its transmissions, it's much too far.
So what would be the point?

I'd think be that time we'd have built bigger dish(es) and more powerful transmitters. Or be using lasers.

 

[crazyeddie]

Our nearest star is Alpha Centauri

It is not. Proxima Centauri is the closest at 4.2LY.

If we sent a probe to Proxima or Alpha Centauri, we could not receive its transmissions, it's much too far.
So what would be the point?

Proxima Centauri is currently the closest star, true, but it is thought to be the third component of the Alpha Centauri system, orbiting the other two stars in a period of 500,000 years. "Data from the Hipparcos satellite, combined with ground-based observations, is consistent with the hypothesis that the three stars are truly a bound system", according to Wikipedia. I know it's quibbling, but unless further data disproves the conclusion that Proxima Centauri is orbiting Alpha Centauri A and B, it's is acceptable to generalize and refer to Alpha Centauri as "our nearest star", because it includes the red dwarf as part of a trinary system.

Why do you say we could not receive a transmission from a probe at that distance? If it's transmitter were powerful enough, our largest radio telescopes could certainly pick up a signal.