Friday, November 30, 2012 4:22:04 AM
What If NASA Could Figure Out the Math of a Workable Warp Drive?
A ring-shaped warp drive device could transport a football-shape starship (center) to effective speeds faster than light. The concept was first proposed by Mexican physicist Miguel Alcubierre.
Harold White
[ http://news.discovery.com/space/warp-drive-possible-nasa-tests-100yss-120917.html ({linked in} http://investorshub.advfn.com/boards/read_msg.aspx?message_id=79664503 (and any future following})]
Alpha, Beta, and Proxima Centauri
(Wikimedia Commons)
[larger at http://cdn.theatlantic.com/static/mt/assets/science/Alpha%2C_Beta_and_Proxima_Centauri.jpg ]
A new line of research hopes to drastically reduce the amount of energy required for warping space-time, and get us to Alpha Centauri in just two weeks time.
By Rebecca J. Rosen
Nov 28 2012, 10:03 AM ET
When, a few weeks ago, astronomers announced [ http://www.theatlantic.com/technology/archive/2012/10/could-we-one-day-send-humans-to-the-newly-discovered-planet-orbiting-alpha-centauri-b/263765/ ] that an Earth-sized planet had been detected orbiting a Alpha Centauri B, a star in the closest system of stars to our own, and that this planet might, just might, mean that there is another planet, maybe another Earth-sized one, maybe, just maybe, in that magical distance from a sun that could give rise to life, and that all this was taking place right there in our galactic backyard, the next thought was inevitable: What if there is life there?
What if we, the people of the early 21st century, could be among the generation -- the first and only of all the generations ever -- that would be first to know that we were not alone?
But then there is the inevitable letdown: Even if we did find a planet in one of those nearby stars' habitable zone and even, even, if we could detect an atmosphere that could harbor life [ http://physicsworld.com/cws/article/news/2012/oct/09/the-hue-of-alien-earths ], then what? Alpha Centauri may be the closest star system to Earth, but it's still four light years away. Voyager 1, our farthest-traveled probe is moving at *38,000 miles per hour* [ http://www.jhuapl.edu/newscenter/pressreleases/2011/110615.asp ], and after 35 years, it's still in our solar system (barely [ http://www.theatlantic.com/technology/archive/2012/10/has-voyager-1-entered-interstellar-space/263706/ ]). Moving at Voyager's speed, it would take 700 *centuries* for a mission [ http://io9.com/5952827/how-will-humans-get-to-alpha-centauri ] to reach Alpha Centauri. With speeds like that, we stand to become the first generation to know life is out there, and to not be able to know much more than that. The prospect is maddening.
Of course, our only hope would be to travel at much, much greater speeds. As MIT astronomer Sara Seager explained here at The Atlantic to Ross Andersen [ http://www.theatlantic.com/technology/archive/2012/10/could-we-one-day-send-humans-to-the-newly-discovered-planet-orbiting-alpha-centauri-b/263765/ ]:
There are a lot of people who think we have the capabilities to get to a tenth of the speed of light. People are using that number as a benchmark of what they think is attainable, whether it's with a solar sail or nuclear pulse propulsion. If we could achieve that speed, then we could get to Alpha Centauri in just over 40 years.
Whenever I give a talk to a public audience I explain the hazards of living on a spacecraft for 40 years, the fact that life could be extremely tedious, and could possibly even include some kind of induced hibernation. But then I always ask if anyone in the audience would volunteer for a 40+ year journey, and every single time I get a show of hands. And then I say "oh I forgot to mention, it's a one way trip," and even then I get the same show of hands. This tells me that our drive to explore is so great that if and when engineers succeed at traveling at least 10 percent of the speed of light, there will be people willing to make the journey. It's just a matter of time.
So, one-tenth the speed of light and we could be there in 40 years. That's not half bad. As Seager notes, many people would be willing to give up Earth and make that assuredly miserable journey for the privilege of being the first humans to explore another solar system. But still: 40 years, it's no cakewalk.
That's why a new number, care of NASA physicist Harold White, is so stunning: Two weeks. Two weeks to Alpha Centauri, he told io9, if only we can travel by warping space-time.
Of course, of course, easier said than done, but White thinks it's possible, and he and a team at NASA are at the very early stages of making it so. io9's George Dvorsky explains [ http://io9.com/5963263/how-nasa-will-build-its-very-first-warp-drive ]:
The idea came to White while he was considering a rather remarkable equation formulated by physicist Miguel Alcubierre. In his 1994 paper titled, "The Warp Drive: Hyper-Fast Travel Within General Relativity," Alcubierre suggested a mechanism by which space-time could be "warped" both in front of and behind a spacecraft.
Michio Kaku dubbed Alcubierre's notion a "passport to the universe." It takes advantage of a quirk in the cosmological code that allows for the expansion and contraction of space-time, and could allow for hyper-fast travel between interstellar destinations. Essentially, the empty space behind a starship would be made to expand rapidly, pushing the craft in a forward direction -- passengers would perceive it as movement despite the complete lack of acceleration. ...
In terms of the engine's mechanics, a spheroid object would be placed between two regions of space-time (one expanding and one contracting). A "warp bubble" would then be generated that moves space-time around the object, effectively repositioning it -- the end result being faster-than-light travel without the spheroid (or spacecraft) having to move with respect to its local frame of reference.
And that's not even the hard part: Ever since this idea was floated, the catch has been the absolutely enormous amount of energy such an event would require. As White explains, "Space-time is really stiff, so to create the expansion and contraction effect in a useful manner in order for us to reach interstellar destinations in reasonable time periods would require a lot of energy." When he says a lot, he doesn't mean a couple of nuclear-power plants' worth; he means energy equal to the mass-energy of Jupiter, the biggest planet in our solar system. So that's not going to work.
But, as Dvorsky explains, White has recently come up with a new design for a warp drive, one that, theoretically, would require way, way less energy. "I suddenly realized," he told Dvorsky, "that if you made the thickness of the negative vacuum energy ring larger -- like shifting from a belt shape to a donut shape -- and oscillate the warp bubble, you can greatly reduce the energy required -- perhaps making the idea plausible." White believes that with his new design, warp drive could be achieved with the power of a mass that is even smaller than Voyager 1's. I'm not going to pretend that I have the faintest clue how this would work or how NASA would conceivably build such a thing, but the idea that physicists at NASA are even toying with it gives me hope that interstellar travel could one day be possible, even if this isn't how it is ultimately accomplished.
White emphasizes that all of this is *extremely* preliminary, just theoretical math and some very small-scale lab experiments. Additionally, other scientists have raised concerns that warp drive could be potentially very dangerous [ http://www.universetoday.com/93882/warp-drives-may-come-with-a-killer-downside/ ], potentially destroying the destination in its path. But, still, it's an exciting reminder that the parameters we accept today may some day melt away.
Copyright © 2012 by The Atlantic Monthly Group
http://www.theatlantic.com/technology/archive/2012/11/what-if-nasa-could-figure-out-the-math-of-a-workable-warp-drive/265655/ [with comments]
===
Nuclear and Stirling engines spur space exploration
LANL's new reactor concept
(Image: LANL)
A team of researchers from NASA and Los Alamos National Laboratory have demonstrated a new reactor concept that combines a Stirling engine with modern heat pipe cooling technology to provide a power source for future space missions.
27 November 2012
The design is a remarkably simple combination of old and modern technology that is flexible, lightweight and does not require complex controls. According to the developers it could be used on exploration missions to supplement existing Pu-238 power systems, and therefore help preserve stocks of the valuable radioisotope, which is currently in short supply.
A full-scale reactor would consists of just six sections: a 23 kg enriched uranium core, a core reflector, a single control rod fully capable of turning the reactor on and off, radiation shielding and eight heat pipes connected to eight Stirling engines that would generate electricity. The entire unit would be compact and passively safe - relying on principles of nuclear physics to adjust reactivity and power output rather than any additional equipment.
Being modular with an intended capacity of 500 We, it would be straightforward to add units as required and future scaled-up designs could even be used for both surface and space propulsion. The simplicity of the design makes it easy to assemble and should make it comparatively easy to license.
The Demonstration Using Flattop Fission (DUFF) experiment was carried out at the Nevada National Security Site’s Device Assembly Facility. The scaled-down prototype - dubbed KRUSTY (Kilowatt Reactor Using Stirling TechnologY) -produced only 24 We, but confirmed the basic principle of the design. "The nuclear characteristics and thermal power level of the experiment are remarkably similar to our space reactor flight concept," noted Los Alamos engineer David Poston. "The biggest difference between DUFF and a possible flight system is that the Stirling input temperature would need to be hotter to attain the required efficiency and power output needed for space missions."
DUFF is noteworthy in being the first demonstration of a new space reactor system to take place in the USA since 1965. Its designers hope that it will open up "new frontiers" for space exploration and research. The demonstration arguably also holds lessons for the verification and testing of new nuclear power reactors. "Perhaps one of the more important aspects of this experiment is that it was taken from concept to completion in 6 months for less than a million dollars," said Los Alamos engineer David Dixon. "We wanted to show that with a tightly-knit and focused team, it is possible to successfully perform practical reactor testing."
*
Technology old and new
The Stirling engine was originally designed in the 19th century but only now with improved efficiency is it finding small niche applications. It is a simple closed loop design which contains a cylinder of pressurized gas that expands as it heats up and contracts as it does work. This can be used to generate electricity on a small scale, although it is not suitable for power stations. Requiring neither pumps or fans, heat pipes are a form of passive cooling technology now commonly included in laptops and other electronics. They consist of a sealed tube containing an internal liquid which circulates to transport heat. They were invented in Los Alamos in 1963.
*
Researched and written by World Nuclear News
©2012 World Nuclear Association
http://www.world-nuclear-news.org/C-Nuclear_and_Stirling_engines_spur_space_exploration_271112a.html
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A ring-shaped warp drive device could transport a football-shape starship (center) to effective speeds faster than light. The concept was first proposed by Mexican physicist Miguel Alcubierre.
Harold White
[ http://news.discovery.com/space/warp-drive-possible-nasa-tests-100yss-120917.html ({linked in} http://investorshub.advfn.com/boards/read_msg.aspx?message_id=79664503 (and any future following})]
Alpha, Beta, and Proxima Centauri
(Wikimedia Commons)
[larger at http://cdn.theatlantic.com/static/mt/assets/science/Alpha%2C_Beta_and_Proxima_Centauri.jpg ]
A new line of research hopes to drastically reduce the amount of energy required for warping space-time, and get us to Alpha Centauri in just two weeks time.
By Rebecca J. Rosen
Nov 28 2012, 10:03 AM ET
When, a few weeks ago, astronomers announced [ http://www.theatlantic.com/technology/archive/2012/10/could-we-one-day-send-humans-to-the-newly-discovered-planet-orbiting-alpha-centauri-b/263765/ ] that an Earth-sized planet had been detected orbiting a Alpha Centauri B, a star in the closest system of stars to our own, and that this planet might, just might, mean that there is another planet, maybe another Earth-sized one, maybe, just maybe, in that magical distance from a sun that could give rise to life, and that all this was taking place right there in our galactic backyard, the next thought was inevitable: What if there is life there?
What if we, the people of the early 21st century, could be among the generation -- the first and only of all the generations ever -- that would be first to know that we were not alone?
But then there is the inevitable letdown: Even if we did find a planet in one of those nearby stars' habitable zone and even, even, if we could detect an atmosphere that could harbor life [ http://physicsworld.com/cws/article/news/2012/oct/09/the-hue-of-alien-earths ], then what? Alpha Centauri may be the closest star system to Earth, but it's still four light years away. Voyager 1, our farthest-traveled probe is moving at *38,000 miles per hour* [ http://www.jhuapl.edu/newscenter/pressreleases/2011/110615.asp ], and after 35 years, it's still in our solar system (barely [ http://www.theatlantic.com/technology/archive/2012/10/has-voyager-1-entered-interstellar-space/263706/ ]). Moving at Voyager's speed, it would take 700 *centuries* for a mission [ http://io9.com/5952827/how-will-humans-get-to-alpha-centauri ] to reach Alpha Centauri. With speeds like that, we stand to become the first generation to know life is out there, and to not be able to know much more than that. The prospect is maddening.
Of course, our only hope would be to travel at much, much greater speeds. As MIT astronomer Sara Seager explained here at The Atlantic to Ross Andersen [ http://www.theatlantic.com/technology/archive/2012/10/could-we-one-day-send-humans-to-the-newly-discovered-planet-orbiting-alpha-centauri-b/263765/ ]:
There are a lot of people who think we have the capabilities to get to a tenth of the speed of light. People are using that number as a benchmark of what they think is attainable, whether it's with a solar sail or nuclear pulse propulsion. If we could achieve that speed, then we could get to Alpha Centauri in just over 40 years.
Whenever I give a talk to a public audience I explain the hazards of living on a spacecraft for 40 years, the fact that life could be extremely tedious, and could possibly even include some kind of induced hibernation. But then I always ask if anyone in the audience would volunteer for a 40+ year journey, and every single time I get a show of hands. And then I say "oh I forgot to mention, it's a one way trip," and even then I get the same show of hands. This tells me that our drive to explore is so great that if and when engineers succeed at traveling at least 10 percent of the speed of light, there will be people willing to make the journey. It's just a matter of time.
So, one-tenth the speed of light and we could be there in 40 years. That's not half bad. As Seager notes, many people would be willing to give up Earth and make that assuredly miserable journey for the privilege of being the first humans to explore another solar system. But still: 40 years, it's no cakewalk.
That's why a new number, care of NASA physicist Harold White, is so stunning: Two weeks. Two weeks to Alpha Centauri, he told io9, if only we can travel by warping space-time.
Of course, of course, easier said than done, but White thinks it's possible, and he and a team at NASA are at the very early stages of making it so. io9's George Dvorsky explains [ http://io9.com/5963263/how-nasa-will-build-its-very-first-warp-drive ]:
The idea came to White while he was considering a rather remarkable equation formulated by physicist Miguel Alcubierre. In his 1994 paper titled, "The Warp Drive: Hyper-Fast Travel Within General Relativity," Alcubierre suggested a mechanism by which space-time could be "warped" both in front of and behind a spacecraft.
Michio Kaku dubbed Alcubierre's notion a "passport to the universe." It takes advantage of a quirk in the cosmological code that allows for the expansion and contraction of space-time, and could allow for hyper-fast travel between interstellar destinations. Essentially, the empty space behind a starship would be made to expand rapidly, pushing the craft in a forward direction -- passengers would perceive it as movement despite the complete lack of acceleration. ...
In terms of the engine's mechanics, a spheroid object would be placed between two regions of space-time (one expanding and one contracting). A "warp bubble" would then be generated that moves space-time around the object, effectively repositioning it -- the end result being faster-than-light travel without the spheroid (or spacecraft) having to move with respect to its local frame of reference.
And that's not even the hard part: Ever since this idea was floated, the catch has been the absolutely enormous amount of energy such an event would require. As White explains, "Space-time is really stiff, so to create the expansion and contraction effect in a useful manner in order for us to reach interstellar destinations in reasonable time periods would require a lot of energy." When he says a lot, he doesn't mean a couple of nuclear-power plants' worth; he means energy equal to the mass-energy of Jupiter, the biggest planet in our solar system. So that's not going to work.
But, as Dvorsky explains, White has recently come up with a new design for a warp drive, one that, theoretically, would require way, way less energy. "I suddenly realized," he told Dvorsky, "that if you made the thickness of the negative vacuum energy ring larger -- like shifting from a belt shape to a donut shape -- and oscillate the warp bubble, you can greatly reduce the energy required -- perhaps making the idea plausible." White believes that with his new design, warp drive could be achieved with the power of a mass that is even smaller than Voyager 1's. I'm not going to pretend that I have the faintest clue how this would work or how NASA would conceivably build such a thing, but the idea that physicists at NASA are even toying with it gives me hope that interstellar travel could one day be possible, even if this isn't how it is ultimately accomplished.
White emphasizes that all of this is *extremely* preliminary, just theoretical math and some very small-scale lab experiments. Additionally, other scientists have raised concerns that warp drive could be potentially very dangerous [ http://www.universetoday.com/93882/warp-drives-may-come-with-a-killer-downside/ ], potentially destroying the destination in its path. But, still, it's an exciting reminder that the parameters we accept today may some day melt away.
Copyright © 2012 by The Atlantic Monthly Group
http://www.theatlantic.com/technology/archive/2012/11/what-if-nasa-could-figure-out-the-math-of-a-workable-warp-drive/265655/ [with comments]
===
Nuclear and Stirling engines spur space exploration
LANL's new reactor concept
(Image: LANL)
A team of researchers from NASA and Los Alamos National Laboratory have demonstrated a new reactor concept that combines a Stirling engine with modern heat pipe cooling technology to provide a power source for future space missions.
27 November 2012
The design is a remarkably simple combination of old and modern technology that is flexible, lightweight and does not require complex controls. According to the developers it could be used on exploration missions to supplement existing Pu-238 power systems, and therefore help preserve stocks of the valuable radioisotope, which is currently in short supply.
A full-scale reactor would consists of just six sections: a 23 kg enriched uranium core, a core reflector, a single control rod fully capable of turning the reactor on and off, radiation shielding and eight heat pipes connected to eight Stirling engines that would generate electricity. The entire unit would be compact and passively safe - relying on principles of nuclear physics to adjust reactivity and power output rather than any additional equipment.
Being modular with an intended capacity of 500 We, it would be straightforward to add units as required and future scaled-up designs could even be used for both surface and space propulsion. The simplicity of the design makes it easy to assemble and should make it comparatively easy to license.
The Demonstration Using Flattop Fission (DUFF) experiment was carried out at the Nevada National Security Site’s Device Assembly Facility. The scaled-down prototype - dubbed KRUSTY (Kilowatt Reactor Using Stirling TechnologY) -produced only 24 We, but confirmed the basic principle of the design. "The nuclear characteristics and thermal power level of the experiment are remarkably similar to our space reactor flight concept," noted Los Alamos engineer David Poston. "The biggest difference between DUFF and a possible flight system is that the Stirling input temperature would need to be hotter to attain the required efficiency and power output needed for space missions."
DUFF is noteworthy in being the first demonstration of a new space reactor system to take place in the USA since 1965. Its designers hope that it will open up "new frontiers" for space exploration and research. The demonstration arguably also holds lessons for the verification and testing of new nuclear power reactors. "Perhaps one of the more important aspects of this experiment is that it was taken from concept to completion in 6 months for less than a million dollars," said Los Alamos engineer David Dixon. "We wanted to show that with a tightly-knit and focused team, it is possible to successfully perform practical reactor testing."
*
Technology old and new
The Stirling engine was originally designed in the 19th century but only now with improved efficiency is it finding small niche applications. It is a simple closed loop design which contains a cylinder of pressurized gas that expands as it heats up and contracts as it does work. This can be used to generate electricity on a small scale, although it is not suitable for power stations. Requiring neither pumps or fans, heat pipes are a form of passive cooling technology now commonly included in laptops and other electronics. They consist of a sealed tube containing an internal liquid which circulates to transport heat. They were invented in Los Alamos in 1963.
*
Researched and written by World Nuclear News
©2012 World Nuclear Association
http://www.world-nuclear-news.org/C-Nuclear_and_Stirling_engines_spur_space_exploration_271112a.html
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from John Philpot Curran, Speech
upon the Right of Election, 1790
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