Hope of exploring the universe

[questionposter]

Is it so difficult for you to comprehend a simple response?

I said that the time changes not the distance.

 

The time it takes decreases from their perspective while they still travel the same distance.

Are you still confused?

 

Edit for: Removing extra newlines.

 

Maybe what your saying is just so simple that I'm overlooking it. Are you saying traveling at light allows you to get from point A to point B faster? Or are you saying that something 80 light years away would only take 20 years to reach while traveling at the speed of light?

Edited April 21, 2012 by questionposter

[Sato]

Maybe what your saying is just so simple that I'm overlooking it. Are you saying traveling at light allows you to get from point A to point B faster? Or are you saying that something 80 light years away would only take 20 years to reach while traveling at the speed of light?

Do you have a problem distinguishing between 'year' and 'light year'? I've only mentioned the former.

[questionposter]

Do you have a problem distinguishing between 'year' and 'light year'? I've only mentioned the former.

 

You weren't being very specific either. If you said it takes 20 years to travel 80 light years, your traveling faster than light.

Because I don't see a point to saying "yeah, the speed of light is faster than what we can go now, so we'd reach places faster if we could break physics and go at the speed of light", so I assumed there would be some more in-depth meaning.

Edited April 21, 2012 by questionposter

[Sato]

You weren't being very specific either. If you said it takes 20 years to travel 80 light years, your traveling faster than light.

Because I don't see a point to saying "yeah, the speed of light is faster than what we can go now, so we'd reach places faster if we could break physics and go at the speed of light", so I assumed there would be some more in-depth meaning.

You're so difficult, it's almost overbearing..

So tell me, where do you see anything about it taking 20 years to travel 80 light years here?

 

Good job, you tried to interpret my answer. Since the time slows for the object traveling at c, they'd be experiencing maybe 20 years rather than 80 years.

[questionposter]

You're so difficult, it's almost overbearing..

So tell me, where do you see anything about it taking 20 years to travel 80 light years here?

 

 

 

I don't, your not being specific so I'm being forced to try and make sense if what your saying. If your traveling at the speed of light, time stops from your frame of reference, so you wouldn't age at all compared to the rest of the universe, I don't know what else to say.

Edited April 21, 2012 by questionposter

[hypervalent_iodine]

!

Moderator Note

Sato, give it a rest. Questionposter has been very polite and patient with you in trying to understand what you're saying and you're just being rude in return.

[Sato]

I don't, your not being specific so I'm being forced to try and make sense if what your saying. If your traveling at the speed of light, time stops relative to you, so you wouldn't age at all, I don't know what else to say.

I was being very specific, stating exactly what I wanted to communicate..

You shouldn't manipulate what people say just because you don't like how it looks.

 

[dimreepr]

As Zapatos suggested time isn’t relevant as we are very unlikely to reach anywhere significant in the lifetime of the initial travellers. That aside we already have the know how to reach a significant portion of light speed. Project Orion (http://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)) first proposed in 1946 would require a huge spaceship, for the physics to work (from memory something like 70,000 tons), so ships would have plenty of space for a good sized crew and the hydroponic farms needed.

 

 

[Purephysics]

I don't...know...if it works quite like that...Maybe I'm misunderstanding you. Are you saying traveling at light reduces the distance between two objects? I mean, you would get to a place faster, but not because the distance decreased...

Time dilation refers to the frame rate of time based on the frame of reference. If you traveled at light, then you would still travel at 186,000 miles per second, but the time of outside objects would stop flowing to you, since relative to you, you are traveling at the same speed as time and therefore see no difference in the rate of time-flow. To an outside observer, I don't remember exactly, I think they would observe that your time is stopped and therefore that you haven't aged.

 

Maybe your referring to length dilation? But I think that increases the distance, not shrinks it, otherwise you actually would be able to see things traveling faster than light.

 

Yeah you are right, the closer you get to C the slower you appear to be moving to an outside observer (oddly enough). Also if they could see your watch at 98% of C, they would swear it wasnt ticking at all. There would also be length distortion if they measured your craft from the outside, they would measure it shorter.

 

Considering mass bends spacetime there may be some truth in the statement "traveling at 100% of C would shorten the distance between points". Since an objects mass increases with it's velocity, if a spaceship could achieve C then it would have infinite mass, and infinite mass would definitely warp or bend spacetime. Maybe we could use that as an advantage to "take the shortcut".

[Moontanman]

I'm encouraged by the very real likelihood that there are hundreds of Earth-like worlds within 30 ly of us. (By "Earth-like" I mean with an ESI greater than 0.8.) I like to imagine descendants with millennial lifespans who won't be so put off by terribly long journeys. And there are scenarios in which our descendants spread out into our little galactic neighborhood over the course of millions of years - no relativistic speeds required. Dyson, Sagan, and others have speculating about such scenarios. E.g., Gradual migration of "human" (post-human, I suppose) presence to the Kuiper belt, eventually the Oort cloud, and then seamlessly to the Oort cloud analogs of our nearest stars, and so on. Over the course of perhaps millions of years, a great interstellar diversification of life and civilization would occur. I will admit that I have my fingers crossed for something more Star-Treky.

 

 

I would like to say that this is probably the most likely scenario, while star treky stuff would be nice so far it seems unlikely but this, as described by the asinine cretin, would require no Super Science, no colonization of alien planets and some estimates say the entire galaxy could be colonized in just a few million years. A blink in the eye of cosmic time.

[hypervalent_iodine]

!

Moderator Note

I received a message from a member not long ago about my above mod note, so I just wanted to make something a little clearer to avoid confusion. I was not saying that anyone is/was right or wrong in what they are/were saying. I could have phrased this all a bit better, but my point to Sato was that his responses were a little uncalled for in their approach. It wasn't really an official warning so much as it is a reminder to keep things civil.

Sato (and everyone else), if you think someone is being obtuse or deliberately misrepresenting what you are saying, please use our report feature to inform staff and let us deal with it.

(And a thank-you to the above mentioned member for messaging me about this)

[Moontanman]

I'm encouraged by the very real likelihood that there are hundreds of Earth-like worlds within 30 ly of us. (By "Earth-like" I mean with an ESI greater than 0.8.) I like to imagine descendants with millennial lifespans who won't be so put off by terribly long journeys. And there are scenarios in which our descendants spread out into our little galactic neighborhood over the course of millions of years - no relativistic speeds required. Dyson, Sagan, and others have speculating about such scenarios. E.g., Gradual migration of "human" (post-human, I suppose) presence to the Kuiper belt, eventually the Oort cloud, and then seamlessly to the Oort cloud analogs of our nearest stars, and so on. Over the course of perhaps millions of years, a great interstellar diversification of life and civilization would occur. I will admit that I have my fingers crossed for something more Star-Treky.

 

 

I think I've figured out how we can explore space. We don't need speed, we need smarts. Here's how we do it:

 

Large floating biospheres. Fleets of them. Instead of thinking about speed. We think about survival. If we can survive in space in floating self-sufficient biospheres, we can take all the time we want in getting from star to star.

 

We build several fleets of ships. Each fleet headed by a few Battlestar Galactica sized mother ships carrying thousands of people each. Plus other smaller support craft. We build the large ships in near earth orbit, populated them with crew and provisions and test their livability and onboard life and bio-life support systems while in earth orbit. These ships will be floating self contained biospheres that orbit around stars for solar energy at just the right distance and collect sunlight through massive windows for their on board farms. Food could not only be grown on them but cloned as a second food production option to increase output. The plants on board, in turn produce oxygen for the ship's crew. These ships are designed as biospheres because their purpose is to be the home of generation after generation of crew. They are artificial Earths. A fleet of these ships not only increases our survival chances but if a ship in the fleet fails people can be shuffled onto other ships. Once we are satisfied the systems work, that the onboard bio-spheres are self supporting and humans can survive on them indefinitely, the question is, how do these ships that depend on solar energy to run their systems get to the next nearest star? The distances are too far. We'll never reach the speeds required before the ships run out of energy to power the artificial lights the Hydroponic gardens need to survive.

 

So here's my solution: We plot our route long before we leave and we send out ahead unmanned support ships, stocked with the future supplies and energy we will need. We send many of them out ahead of us but moving at a much slower speeds than we will be going so that we will eventually overtake them at calculated points along the trip. When enough of these unmanned support ships are on course toward the destination star, our biosphere ships leave for the same star, following the course of the unmanned ships. Basically, our support ships are a 19,000 year supply chain all the way to the next closest star. As our biosphere ships progress over the generations towards the destination stars, the moments we overtake and reach the support ships will be closely timed to the energy demands and supply needs of our crewed ships over the 19,000 year, multigenerational journey.

 

And that's how we do it. Ok, you may now worship me.

 

Of course, we better make sure we have a lot of vitamin D on board because we're going to be without natural sunlight for a long, long time.

 

 

 

 

 

 

Oh, I should have read the whole thread before I posted. I see I hit on the same idea.

 

 

I knew I shouldn't have used the term "Battlestar Galactica". I knew you guys would see only that. Did you even read the rest?

 

Let me ask you a question: If a biosphere is possible. And plant growth by artificial light is possible. Then why is such a concept as floating space biospheres such an impossible concept to you?

 

I really hope this place isn't competitive to the point that people just pan other people's ideas just because they are not their own. That would be really sad.

 

It's 12:12am here. Off to sleep.

 

 

A bio-sphere just seems kind of unreasonable seeing as how we can't mimic high gravity. Doing such would seem to violate physics anyway because it would increase the amount of potential energy something has without actually adding any energy, thus violating physics. But maybe there's some unexplored way yet. There's also the problem if that it takes unimaginable amounts of energy to both construct and move something that large and complex, and I doubt many people would really be on board for leaving an entire beautiful planet behind.

Before we build giant space-ships, we need some way to actually construct them.

Space ships might look good in the movies, but realistically you'd have to cram everything into a small space, because it would take so much more energy to move a space-ship that comfortable and spacious. I don't know how a bio-sphere would be hospitable.

Perhaps though, cryogenics can solve this problem if it can be perfected.

 

 

No, this has not descended into the realm of Star-Trek. It started out that way by you in your first post and we are trying to bring it back back down to earth. Lightspeed travel will never be the solution. You will never be able to supply the necessary energy.

 

 

No, he didn't read yours or mine.

 

 

Not at all. This place is usually a great place to kick ideas around as long as people are logical and ready to support any assertions they make.

 

 

 

Actually I suspect that mimicking gravity would be relatively easy. Imagine if a ship were built like a barbell. If you started the ship were rotating like a twirling baton you could make whatever 'artificial' gravity you like at either end.

 

 

Yeah I guess rotating it would help and it would add potential energy to the object, I could have swore there was a problem with it rotating though, I remember for some physics class we were exploring how interstellar travel would work, and I remember there being some drawback to using that instead of mimicking gravity...

Basically, there's drawbacks to everything, but I guess rotating it would be a good solution.

 

 

The idea of slow boats to the stars can be justified and even built with technology not very far above what we now use. The entire problem , or almost all of it, can be solved by a rotating torus. A torus made of carbon nano tubes, much like an endless suspension bridge anchored at the center, would be the ideal shape for a biosphere. Rotate it to produce artificial gravity at the rim (inside) fill it with air and rocks and life and you get a freely orbiting biosphere.

 

The problem with rotation can be at least partially solved by making it big, the inside of the rim, under the layer of rocks and soil, can be used to hide the machinery that makes it work and used as a space for storage of much need raw materials on the long jump between stars. A magnetic field can even be used as a sail to slow down and accelerate. Yes there are still technological hurdles to over come, lighting the interior seems to be a huge one for a really large torus, but none of hurdles are quite as difficult or as iffy as FTL, worm holes or folding space.

 

I'd love to see the Enterprise in orbit but it seems a less than reasonable goal at this time.

[zapatos]

So here's my solution: We plot our route long before we leave and we send out ahead unmanned support ships, stocked with the future supplies and energy we will need. We send many of them out ahead of us but moving at a much slower speeds than we will be going so that we will eventually overtake them at calculated points along the trip. When enough of these unmanned support ships are on course toward the destination star, our biosphere ships leave for the same star, following the course of the unmanned ships. Basically, our support ships are a 19,000 year supply chain all the way to the next closest star. As our biosphere ships progress over the generations towards the destination stars, the moments we overtake and reach the support ships will be closely timed to the energy demands and supply needs of our crewed ships over the 19,000 year, multigenerational journey.

I've been thinking about the unmanned support ships and have gone back and forth between 'what a good idea' and 'not necessary'. I think I've settled on 'not necessary'.

 

Why not just bring the support ships with you? Energy requirements shouldn't change significantly, and it leaves you the option to change your plans later if during that 19,000 years something unexpected happens. Should also help with your disaster recovery planning.

[Sato]

The idea of slow boats to the stars can be justified and even built with technology not very far above what we now use. The entire problem , or almost all of it, can be solved by a rotating torus. A torus made of carbon nano tubes, much like an endless suspension bridge anchored at the center, would be the ideal shape for a biosphere. Rotate it to produce artificial gravity at the rim (inside) fill it with air and rocks and life and you get a freely orbiting biosphere.

 

The problem with rotation can be at least partially solved by making it big, the inside of the rim, under the layer of rocks and soil, can be used to hide the machinery that makes it work and used as a space for storage of much need raw materials on the long jump between stars. A magnetic field can even be used as a sail to slow down and accelerate. Yes there are still technological hurdles to over come, lighting the interior seems to be a huge one for a really large torus, but none of hurdles are quite as difficult or as iffy as FTL, worm holes or folding space.

 

I'd love to see the Enterprise in orbit but it seems a less than reasonable goal at this time.

This seems somewhat plausible but where would they build it? How would they keep the plants from dying out after draining the soil of nutrients, or some other method? Nonetheless, this is a very cool idea and I hope for it to be constructed one day.

As Zapatos suggested time isn't relevant as we are very unlikely to reach anywhere significant in the lifetime of the initial travellers. That aside we already have the know how to reach a significant portion of light speed. Project Orion (http://en.wikipedia....lear_propulsion)) first proposed in 1946 would require a huge spaceship, for the physics to work (from memory something like 70,000 tons), so ships would have plenty of space for a good sized crew and the hydroponic farms needed.

The life time of the initial travelers shouldn't be too significant of an obstacle in that situation; read all of the above posts.

 

 

 

[the asinine cretin]

I've not caught up on the recent posts in this thread but I just wanted to make a quick comment.

This seems somewhat plausible but where would they build it? How would they keep the plants from dying out after draining the soil of nutrients, or some other method? Nonetheless, this is a very cool idea and I hope for it to be constructed one day.

I imagine something like an artificial biosphere with feedbacks and such. This is possible to a large extent with current science and technology. So long as the system is as closed as possible (e.g., don't discard human excrement) you wouldn't need much in the way of inputs. The system could provide many benefits beyond food production as well.

 

P.S. For examples go here: Wikipedia: Closed ecological system, and for more info consider the "See also" section of that page.

Edited April 21, 2012 by the asinine cretin

[md65536]

Good job, you tried to interpret my answer. Since the time slows for the object traveling at c, they'd be experiencing maybe 20 years rather than 80 years.

Assuming you meant "near c"...

 

In a case like this, with gamma = 4.0, they'd be travelling faster than 0.968c.

In the 80 years it might pass on Earth, they'd travel over 77 light years.

 

If you could travel that fast, you could travel to a destination 77 light years away from Earth in only 20 years local time. The Earth would age 80 years. This doesn't violate special relativity, questionposter, because your travel distance would be length-contracted to 19.4 light years, and you'd remain sub-luminal with a speed of .968c.

[dimreepr]

As Zapatos suggested time isn't relevant as we are very unlikely to reach anywhere significant in the lifetime of the initial travellers.

 

The life time of the initial travelers shouldn't be too significant of an obstacle in that situation; read all of the above posts.

 

 

 

 

I think you should read my sentence more carefully

[Moontanman]

This seems somewhat plausible but where would they build it? How would they keep the plants from dying out after draining the soil of nutrients, or some other method? Nonetheless, this is a very cool idea and I hope for it to be constructed one day.

 

Nutrients would be recycled just like they are on earth. The biggest obstacle I can see is lighting the interior, over large periods of time mass would be lost to space so it would have to be replaced but this could be slowed to time frames of hundreds of thousands of years if you were careful and the habitat was large.

 

John Varley wrote a science fiction book with the premise of a huge rotating torus found in orbit of Saturn, it was 1300 kilometers in diameter, and was a an artificial life form engineered to spread it's creators to the stars. The torus would release small eggs from it's rim that had velocity enough to escape the solar system and find small moons or Kuiper belt type objects around other stars to use to grow on and become another torus. The eggs held the genetic information to built the torus and the life forms that lived inside. The books are named Titan, Wizard, and Demon... It was fiction but it was also quite eye opening...

[Sato]

I think you should read my sentence more carefully

 

I did, and made an opposing reply.

Still, I see how it was a bit vague so I'll restate:

There's a fair chance that the initial travelers would reach their destinations due to their traveling at (close to) c and aging maybe 1/4th of the rate at Earth so, time is indeed relevant.

[questionposter]

Assuming you meant "near c"...

 

In a case like this, with gamma = 4.0, they'd be travelling faster than 0.968c.

In the 80 years it might pass on Earth, they'd travel over 77 light years.

 

If you could travel that fast, you could travel to a destination 77 light years away from Earth in only 20 years local time. The Earth would age 80 years. This doesn't violate special relativity, questionposter, because your travel distance would be length-contracted to 19.4 light years, and you'd remain sub-luminal with a speed of .968c.

 

I think that makes more sense, because "at c", time stops and there wouldn't be this issue, and I was thrown off the the word "experience", but it makes more sense to say for the person traveling near C that they only experience 20 years of "local time" or time on Earth when traveling "near c".

 

 

Nutrients would be recycled just like they are on earth. The biggest obstacle I can see is lighting the interior, over large periods of time mass would be lost to space so it would have to be replaced but this could be slowed to time frames of hundreds of thousands of years if you were careful and the habitat was large.

 

John Varley wrote a science fiction book with the premise of a huge rotating torus found in orbit of Saturn, it was 1300 kilometers in diameter, and was a an artificial life form engineered to spread it's creators to the stars. The torus would release small eggs from it's rim that had velocity enough to escape the solar system and find small moons or Kuiper belt type objects around other stars to use to grow on and become another torus. The eggs held the genetic information to built the torus and the life forms that lived inside. The books are named Titan, Wizard, and Demon... It was fiction but it was also quite eye opening...

 

Biosphere's are actually probably probable, because even if you have limited nutrients in the soil, if you have the energy to remake the compounds, then it's fine, I just don't know how we will get both the energy to create and propel such a large object and to sustain it for that long.

Edited April 21, 2012 by questionposter

[Sato]

Nutrients would be recycled just like they are on earth. The biggest obstacle I can see is lighting the interior, over large periods of time mass would be lost to space so it would have to be replaced but this could be slowed to time frames of hundreds of thousands of years if you were careful and the habitat was large.

 

John Varley wrote a science fiction book with the premise of a huge rotating torus found in orbit of Saturn, it was 1300 kilometers in diameter, and was a an artificial life form engineered to spread it's creators to the stars. The torus would release small eggs from it's rim that had velocity enough to escape the solar system and find small moons or Kuiper belt type objects around other stars to use to grow on and become another torus. The eggs held the genetic information to built the torus and the life forms that lived inside. The books are named Titan, Wizard, and Demon... It was fiction but it was also quite eye opening...

Ah, then I'm having a misconception of the environment on board. You're saying full-blow forest like areas, including rain and different animals? And I think the idea in the book is a bit drastic, but who knows.

[the asinine cretin]

We'll need these incredible velocities because of the distances involved (it would take us something near to 20 years just to reach pluto).

When New Horizons reaches Pluto only about nine years will have passed since its launch. The speed of New Horizons is about 58,536 km/h. The current speed record, Helios 2, has a speed of 252,800 km/h. (I have some understanding of the difficulties involved in space launch, and the specific requirements of manned launch, but all I'm saying is that it need not take twenty years.) Even with current propulsion technology, using gravity assists, I suspect we could develop a launch system and design a manned mission that could reach the Pluto-Charon system in considerably less than 20 years, if we really wanted to (leaving aside every other problem involved in such a mission, as well as economics).

 

And what about more or less plausible near-future tech? I've only glanced at the report (I plan on reading it soon), but I imagine something like the "Discovery II" concept could reach Pluto in under a year. The purported Jupiter in four months is pretty darn good. (Yes, I realize the much greater distance of Pluto but I'm guessing it would be under acceleration for a longer period.)

 

NASA Report: Realizing "2001: A Space Odyssey": Piloted Spherical Torus Nuclear Fusion Propulsion (PDF)

 

I'd be curious to know the theoretical limit on the specific impulse of fusion propulsion. I imagine the possibilities for interplanetary travel are very good even being pretty conservative about future propulsion.

 

And what about somewhat possible far-future tech? I think that under 0.01g constant acceleration you could reach Pluto-Charon (at perihelion) in about four months. Let's pretend that we'll have ships capable of 0.1g constant acceleration in the not-too-distant future. If you spend half your trip accelerating and the other half decelerating I think you could reach Pluto in a few weeks. This all assumes that the code I just threw together is correct. lol. Either way, I think it is safe to say that with the 0.1g ship interplanetary travel would be easy - at least as far as time is concerned - and going from planet to planet would take days, not months or years.

 

Throw in suspended animation tech (which is very plausible) and interstellar travel in our neighborhood might be doable. I would still imagine a gradual radiation from nearest stars to nearest stars. And as I said before, there are probably hundreds of Earth-like worlds within 30 ly (meaning ESI > 0.8). While a breathable atmosphere is super unlikely, I think that planets with comfortable atmospheric pressure and large regions of habitable temperatures are out there. Now that I think about it, that movie Avatar was pretty good in these respects. Also, there is reason to think that Earth-like moons are considerably more common than Earth-like planets. Oh, and even if we don't find a perfect Earth-analog nearby (major problem being the requirement of a specific geochemical-biological-ecological history) I think we'll surely find candidates for terraforming that are highly superior to any worlds in our solar system. In the more ideal circumstances terraforming may simply be a matter of establishing the biome and waiting for time to take its course (with tuning and pruning to finagle the desired result). The other side of the coin is that our descendants will be much more plastic than we are - in the sense that it might be much easier for them to adapt to the environment than to adapt the environment to their needs. The obvious tools are genetic engineering, bionic implants, and all that good stuff. Spinning off of a post I made in a different thread, maybe the inhabitants of planet such-and-such will have colonies of nanites in their lungs and skin that harvest normally unavailable oxygen from compounds in the environment; or whatever. This would follow the general pattern of our expansion on this planet to different environments via the progressive augmentation of technology.

 

In the gradual expansion scenario (see my post on page 1) Earth-like worlds aren't as relevant since most people - or whatever they are - will live in non-planetary habitats. There may be an overwhelming majority of comet dwellers vs. planet dwellers. A recent paper suggests that rogue planets are far more abundant than star-bound planets; perhaps by several orders of magnitude. The distribution of civilization may be first among the comets, rogue planets, planetary systems (including moons) bound to red dwarfs, and maybe brown dwarfs, and finally planets/moons around FGK-type stars. Being from an Earth-like planet orbiting a G-type star would be an oddity indeed.

Edited April 21, 2012 by the asinine cretin

[Moontanman]

Biosphere's are actually probably probable, because even if you have limited nutrients in the soil, if you have the energy to remake the compounds, then it's fine, I just don't know how we will get both the energy to create and propel such a large object and to sustain it for that long.

 

A biosphere recycles nutrients using various natural chemical processes, the energy to create an object like this could come from solar or nuclear power. The materials it would be made of are already in space, the Lagrange points of Jupiter contain enough material to make millions of torus habitats. As I said the main problem I can see is how to provide enough light in the interior to allow significant photosynthesis.

 

Ah, then I'm having a misconception of the environment on board. You're saying full-blow forest like areas, including rain and different animals? And I think the idea in the book is a bit drastic, but who knows.

 

Yes, a full blown biosphere but in the book the torus was in of it's self a living creature, it absorbed the energy of light and other particle energies that exist around Saturn to power it's biosphere. it was at best a fanciful rendition of what i am talking about. but there is no reason why a large enough torus couldn't be a reasonably stable environment. It wouldn't be entirely self contained and would require inputs of both mass and energy but that is not beyond possible technologies.

[questionposter]

A biosphere recycles nutrients using various natural chemical processes, the energy to create an object like this could come from solar or nuclear power. The materials it would be made of are already in space, the Lagrange points of Jupiter contain enough material to make millions of torus habitats. As I said the main problem I can see is how to provide enough light in the interior to allow significant photosynthesis.

 

What about artificial light converted from nuclear reactions?

Edited April 21, 2012 by questionposter

[the asinine cretin]

I think LED lighting in the wavelengths actually used by a given crop, which varies with its stage of development, would be the ideal assuming only current tech. Example:

You wouldn't be wasting such a big chunk of your energy on photons that the plant doesn't need. Also a good system wouldn't run them beyond the optimal time requirements for each crop. I know that a lot of this research has already been done and is even implemented by commercial hydroponics operations and NASA experiments. I'm quite sure that adequate power systems could be designed. I don't know much about spacecraft power generators but as one example I seem to recall the Soviets putting a spy satellite in orbit back in the '80s that had a radioisotope thermoelectric generator that could generate 6 kilowatts of electricity for a number of years. I'm guessing you could power a lot of LEDs on 6 kilowatts and I also suppose that we could do much better than an '80s era Soviet contraption if we really wanted to.

 

Some of my previous post assumed the existence of fusion reactors. That could surely solve the power problem for a hydroponics bay.

 

P.S. I remember a Google Tech Talk, or some such thing, in which a fellow explained how the world's nuclear weapons stockpiles could be dismantled and used to create electrical generators for spacecraft. I quite like that idea.

 

 

P.P.S. If the light requirement were costly the on-board diet could be engineered such that these food sources are minimized. Fungi are excellent and can be processed in a variety of ways. I know of a commercial meat substitute made from mycoprotein cultured in fermentation vats. Even less appetizing, but perhaps worthwhile, would be in virto meat, which I believe is cultured from animal stem cells. I don't know what the input requirements are like though and it may not be worth it. Fortunately there are many other possibilities for spaceborne food production. If it were more pertinent to this thread I'd further indulge myself on the topic.

 

 

Edited to add:

 

Here is a talk related to some of the above, although not the talk I was thinking of.

 

 

 

There are many more interesting talks related to this on the Google Tech Talks youtube channel.

 

 

One last thing.

 

 

 

 

"The size and age of the Cosmos are beyond ordinary human understanding. Lost somewhere between immensity and eternity is our tiny planetary home. In a cosmic perspective, most human concerns seem insignificant, even petty. And yet our species is young and curious and brave and shows much promise. In the last few millennia we have made the most astonishing and unexpected discoveries about the Cosmos and our place within it, explorations that are exhilarating to consider. They remind us that humans have evolved to wonder, that understanding is a joy, that knowledge is prerequisite to survival. I believe our future depends powerfully on how well we understand this Cosmos in which we float like a mote of dust in the morning sky."

 

"We embarked on our journey to the stars with a question first framed in the childhood of our species and in each generation asked anew with undiminished wonder: What are the stars? Exploration is in our nature. We began as wanderers, and we are wanderers still. We have lingered long enough on the shores of the cosmic ocean. We are ready at last to set sail for the stars."

 

"The choice is with us still, but the civilization now in jeopardy is all humanity. As the ancient myth makers knew, we are children equally of the earth and the sky. In our tenure on this planet we've accumulated dangerous evolutionary baggage — propensities for aggression and ritual, submission to leaders, hostility to outsiders — all of which puts our survival in some doubt. But we've also acquired compassion for others, love for our children and desire to learn from history and experience, and a great soaring passionate intelligence — the clear tools for our continued survival and prosperity. Which aspects of our nature will prevail is uncertain, particularly when our visions and prospects are bound to one small part of the small planet Earth. But up there in the immensity of the Cosmos, an inescapable perspective awaits us. There are not yet any obvious signs of extraterrestrial intelligence and this makes us wonder whether civilizations like ours always rush implacably, headlong, toward self-destruction. National boundaries are not evident when we view the Earth from space. Fanatical ethnic or religious or national chauvinisms are a little difficult to maintain when we see our planet as a fragile blue crescent fading to become an inconspicuous point of light against the bastion and citadel of the stars. Travel is broadening."

 

- Carl Sagan, Cosmos

 

 

 

Edited April 22, 2012 by the asinine cretin