Alpha Centauri Explorer II

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vidargander

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<p style="margin-top:0cm;margin-left:0cm;margin-right:0cm" class="MsoNormal"><span><font size="3"><font face="Times New Roman">I would like to pick up a previous debate that got lost in the old space forum. It started like this:</font></font></span></p><p style="margin-top:0cm;margin-left:0cm;margin-right:0cm" class="MsoNormal"><span><font face="Times New Roman" size="3">...</font></span></p><p><span style="font-size:10pt;font-family:Verdana"><em>I would like to see pictures of Alpha Centauri. A spaceship can, in theory, be sent there very soon. Close pictures from the star system will give humanity a new perspective of itself and the surroundings. It is merely a question of time before it is done. <br />An Alpha Centauri Explorer (ACE), that can weight some hundred kilos, can be lifted to Earth's orbit by a space shuttle. From there, it can start its long journey towards the star system Alpha Centauri. A stable laser beam should point at the star, as a leading thread on the way. The beam can also carry data. <br /><br />If ACE is accelerated with 10 G, it will reach the speed of light in a month. The whole journey will last 5 years according to classic physic (v=at). If Einstein's use of the Lorentz transformation is correct, and the theoretical speed limit is real, the ship can be accelerated to f.ex. 1/2 c, and the journey will last twice as long. Anyhow the speed, ACE will be a of the RT too. <br /><br />ACE can not be controlled from Earth. Its speed and distance requires pre-programmed navigation, procedures and responses to unforeseen challenges. A good share of luck will also help, for success for the first ship. <br /><br />ACE should primarily bring a relay station for laser transmission and steering for future ships, - but important as well, a satellite for scanning the star system. The transmission of pictures will take 4 years. That is a long time to wait. But then there can be a constant flow of pictures as long as the satellite lives. <br /><br />The following ships can very well be sent yearly. With the path and the target mapped, the journeys will be safer and easier. Unforeseen events with preceding satellites can be compensated and improved. In 10-20 years, the star system will be mapped like our own. <br /><br />The propulsion, that shall accelerate a month and reduce the speed just as long, should be nuclear. Such a solution is criticised. However, that seems political and irrational because space</em></span></p><p><span style="font-size:10pt;font-family:Verdana"><em>...</em></span></p><p><span><font size="3"><font face="Times New Roman">Anyone care to pick up this debate?</font></font></span><span><font face="Times New Roman" size="3">&nbsp;</font></span></p><p><span><font size="3"><font face="Times New Roman">------------------------------------------</font></font></span></p><p><span><font face="Times New Roman" size="2">Ref: &nbsp;</font><font face="Times New Roman" size="2">http://www.space.com/common/community/forums/?plckForumPage=ForumDiscussion&plckDiscussionId=Cat:c7921f8b-94ec-454a-9715-3770aac6e2caForum:bf7b9387-46b4-47ed-ad5b-34a5350b82ecDiscussion:6509aa61-cc23-4c1d-a48b-0a060504cafd&plckCurrentPage=0&sid=sitelife.space.com#none</font></span></p> <div class="Discussion_UserSignature"> </div>
 
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MeteorWayne

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I would like to pick up a previous debate that got lost in the old space forum. It started like this:...I would like to see pictures of Alpha Centauri. A spaceship can, in theory, be sent there very soon. Close pictures from the star system will give humanity a new perspective of itself and the surroundings. It is merely a question of time before it is done. An Alpha Centauri Explorer (ACE), that can weight some hundred kilos, can be lifted to Earth's orbit by a space shuttle. </DIV></p><p>Well, no it can't. The Shuttle manifest is full, there are no available slots, plus I see no way for a mission that doesn't even exist on paper to launch in 4 years.</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>From there, it can start its long journey towards the star system Alpha Centauri. A stable laser beam should point at the star, as a leading thread on the way. The beam can also carry data. </DIV></p><p>Here we run into that "soon" thing again. Where is the laser with sufficient power? Is it being designed. If the answer is no, then we are talking decades. Where is the money to design and build it?</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>If ACE is accelerated with 10 G, it will reach the speed of light in a month. The whole journey will last 5 years according to classic physic (v=at). If Einstein's use of the Lorentz transformation is correct, and the theoretical speed limit is real, the ship can be accelerated to f.ex. 1/2 c, and the journey will last twice as long. Anyhow the speed, ACE will be a of the RT too. ACE can not be controlled from Earth. Its speed and distance requires pre-programmed navigation, procedures and responses to unforeseen challenges. A good share of luck will also help, for success for the first ship. ACE should primarily bring a relay station for laser transmission and steering for future ships, - but important as well, a satellite for scanning the star system. The transmission of pictures will take 4 years. That is a long time to wait. But then there can be a constant flow of pictures as long as the satellite lives. </DIV></p><p>Whoa, hold up a minute. You want it to be a satellite? How do you propose to decelrate it from 0.5 C?</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> The following ships can very well be sent yearly. With the path and the target mapped, the journeys will be safer and easier. Unforeseen events with preceding satellites can be compensated and improved. In 10-20 years, the star system will be mapped like our own. The propulsion, that shall accelerate a month and reduce the speed just as long, should be nuclear. Such a solution is criticised. However, that seems political and irrational because space...Anyone care to pick up this debate?&nbsp;------------------------------------------Ref: &nbsp;http://www.space.com/common/community/forums/?plckForumPage=ForumDiscussion&plckDiscussionId=Cat:c7921f8b-94ec-454a-9715-3770aac6e2caForum:bf7b9387-46b4-47ed-ad5b-34a5350b82ecDiscussion:6509aa61-cc23-4c1d-a48b-0a060504cafd&plckCurrentPage=0&sid=sitelife.space.com#none <br />Posted by vidargander</DIV></p><p>Still a lot of work to be done. And the fact is there is no such money for annual launches, or even the first one for that matter. While I agree such a mission would be of great value, I don't see it happening before the end of the century.</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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qso1

Guest
<p>I have to agree with MW on the poins he already made and would add that nuclear propulsion as we know it today is nowhere near sufficient to get a probe up to .5C. I would like to see this happen but its going to be well after I'm gone unless some miracle occurs.</p><p>One upside, you mentioned mapping the system, that we will probably have done in pretty good detail by the time an unmanned probe does reach Alpha Centauri.&nbsp;</p> <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
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DrRocket

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I would like to pick up a previous debate that got lost in the old space forum. It started like this:...I would like to see pictures of Alpha Centauri. A spaceship can, in theory, be sent there very soon. Close pictures from the star system will give humanity a new perspective of itself and the surroundings. It is merely a question of time before it is done. An Alpha Centauri Explorer (ACE), that can weight some hundred kilos, can be lifted to Earth's orbit by a space shuttle. From there, it can start its long journey towards the star system Alpha Centauri. A stable laser beam should point at the star, as a leading thread on the way. The beam can also carry data. If ACE is accelerated with 10 G, it will reach the speed of light in a month. The whole journey will last 5 years according to classic physic (v=at). If Einstein's use of the Lorentz transformation is correct, and the theoretical speed limit is real, the ship can be accelerated to f.ex. 1/2 c, and the journey will last twice as long. Anyhow the speed, ACE will be a of the RT too. ACE can not be controlled from Earth. Its speed and distance requires pre-programmed navigation, procedures and responses to unforeseen challenges. A good share of luck will also help, for success for the first ship. ACE should primarily bring a relay station for laser transmission and steering for future ships, - but important as well, a satellite for scanning the star system. The transmission of pictures will take 4 years. That is a long time to wait. But then there can be a constant flow of pictures as long as the satellite lives. The following ships can very well be sent yearly. With the path and the target mapped, the journeys will be safer and easier. Unforeseen events with preceding satellites can be compensated and improved. In 10-20 years, the star system will be mapped like our own. The propulsion, that shall accelerate a month and reduce the speed just as long, should be nuclear. Such a solution is criticised. However, that seems political and irrational because space...Anyone care to pick up this debate?&nbsp;------------------------------------------Ref: &nbsp;http://www.space.com/common/community/forums/?plckForumPage=ForumDiscussion&plckDiscussionId=Cat:c7921f8b-94ec-454a-9715-3770aac6e2caForum:bf7b9387-46b4-47ed-ad5b-34a5350b82ecDiscussion:6509aa61-cc23-4c1d-a48b-0a060504cafd&plckCurrentPage=0&sid=sitelife.space.com#none <br />Posted by vidargander</DIV></p><p>I put this together for a similar question (this one started with a 40 light-year trip, but I did talk at the end to a proxima centauri trip and the 40 light year trip is scalable by dividing everything in sight by ten) in another thread.&nbsp; But it applies here.</p><p>Right now our best&nbsp;large rockets work with an Isp of about 440 seconds.&nbsp; But let's assume that we could achieve 20,000 seconds Isp, which one might do with ion drive.&nbsp; And let's assume we have a 90% propellant mass fraction.&nbsp; Then one could achieve. 0.15% c.&nbsp; That would provide a relativistic time contraction factor of 0.99999887 for the occupants in the spacecraft.&nbsp; Not much.&nbsp; Your 40 light year trip would take 26,666.64 years in the time frame of&nbsp;the rocket and&nbsp;26,666.67years in&nbsp; the Earth's reference frame.&nbsp; At 10% c the factor is 0.99499 so&nbsp;at 10% c your 40 light year trip would take 400 years in an Earth frame of reference but only&nbsp;397.995 years in the frame of reference of the spacecraft.&nbsp; At 84% c the factor is 0.5426 so the trip would take 47.6 years in the Earth Frame and&nbsp;25.8 years in the frame of the spacecraft.&nbsp; But likely distances for an intelligent lifeform would be much larger.&nbsp; The Milky Way is about 100,000 light years in diameter.&nbsp; Even at 84% c, 1000 light years would take a long time in either frame.&nbsp; And we have absolutely no idea how to&nbsp;achieve such velocities with a macroscopic object. To achieve that speed, relative to Earth would require 7.587 x 10^16 Joules per kilogram of original mass.</p><p>BTW the nearest star, proxima centari is about 4 light years away, so with my very optimistic assumptions for ion drive Isp and mass fraction you could send a probe there in only 2666.7years Earth time.&nbsp; </p><p><br /><br />&nbsp;</p> <div class="Discussion_UserSignature"> </div>
 
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MeteorWayne

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Posted by DrRocket</DIV></p><p>I hate to be a pragmatist, but I am a pragmatist...<img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-laughing.gif" border="0" alt="Laughing" title="Laughing" /></p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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baulten

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I have to agree with MW on the poins he already made and would add that nuclear propulsion as we know it today is nowhere near sufficient to get a probe up to .5C. I would like to see this happen but its going to be well after I'm gone unless some miracle occurs.One upside, you mentioned mapping the system, that we will probably have done in pretty good detail by the time an unmanned probe does reach Alpha Centauri.&nbsp; <br /> Posted by qso1</DIV></p><p>Well, he WAS speaking in terms of a laser sail.&nbsp; Now that'd probably more feasible for something going .5C than a nuclear propulsion system, at least in the near term.</p><p>As it is, unless we get MASSIVE funding for an Alpha Centauri mission, I can't possibly see it happening in my lifetime.&nbsp; It'd be great, but still, it's an engineering nightmare.&nbsp; Laser sails still haven't even been tested in space, let alone for an exosolar mission.&nbsp;</p><p>Edit: Oops, I fail.&nbsp; He did say Nuclear.&nbsp; Sorry, but no nuclear system, in the near term, will reach .5C.&nbsp; The most optimistic speed guestimates are around .1C with Orion-style pulse, and around .05C with fission fragment rockets.&nbsp; Fusion rockets MIGHT be able to push .2-.3C, but we can't even created a sustain fusion power plant, let alone a rocket.</p><p>The only thing that could reach .5C would be an antimatter rocket.&nbsp; If you have any prepositions for creating an antimatter rocket... well let me hear em.&nbsp;</p>
 
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qso1

Guest
<p><font color="#800080">Well, he WAS speaking in terms of a laser sail.&nbsp; Now that'd probably more feasible for something going .5C than a nuclear propulsion system, at least in the near term. As it is, unless we get MASSIVE funding for an Alpha Centauri mission, I can't possibly see it happening in my lifetime. It'd be great, but still, it's an engineering nightmare.&nbsp; Laser sails still haven't even been tested in space, let alone for an exosolar mission.&nbsp;Edit: Oops, I fail.&nbsp; He did say Nuclear.&nbsp; Sorry, but no nuclear system, in the near term, will reach .5C.&nbsp; The most optimistic speed guestimates are around .1C with Orion-style pulse, and around .05C with fission fragment rockets.&nbsp; Fusion rockets MIGHT be able to push .2-.3C, but we can't even created a sustain fusion power plant, let alone a rocket.The only thing that could reach .5C would be an antimatter rocket.&nbsp; If you have any prepositions for creating an antimatter rocket... well let me hear em. Posted by baulten</font></p><p>IIRC, a laser sail spends a lot of time accellerating slowly. It might take years to accellerate to .5C and in any case, this technology is still largely theoretical as you mentioned. The only reason I can see massive funding for an Alpha Centauri mission is if we make contact with an alien species on whatever planet they might be on orbiting Alpha "A" or "B".</p><p>All the above mentioned technologies are thought by some folks to be just a few years away. But in reality, laser sails, Bussard ramjets, Orion type nuclear pulse technologies have been on paper, in the labs for decades and have barely been developed beyond where they were decades ago.&nbsp;</p> <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
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baulten

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Nuclear Pulse really never got off the drawing board because of the obvious environmental effects on Earth and the typical societal "anti-nuclear" attitude.&nbsp; From what I heard Ramjets are not feasible because they'd generate more drag than they could produce thrust.&nbsp; Laser sails... Well, I don't really know why they haven't been tested more.&nbsp; It's too bad the Cosmos I failed to launch properly.&nbsp; I guess they're just too risky of an investment.
 
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qso1

Guest
<p><font color="#800080">Nuclear Pulse really never got off the drawing board because of the obvious environmental effects on Earth and the typical societal "anti-nuclear" attitude.&nbsp; From what I heard Ramjets are not feasible because they'd generate more drag than they could produce thrust.&nbsp; Laser sails... Well, I don't really know why they haven't been tested more.&nbsp; It's too bad the Cosmos I failed to launch properly.&nbsp; I guess they're just too risky of an investment. Posted by baulten</font></p><p>Nuclear pulse was canned because of conflict with the atmospheric test ban treaty which prevented nuclear explosions endoatmospherically. And as you mentioned, there were prevailing anti nuclear attitudes. This is what eventually lead to the test ban treaty.</p><p>I recall hearing something to that effect on ramjets. But that was largely a paper study. The ram scoop was to be roughly the diameter of earth or maybe slightly larger. This to scoop out enough hydrogen floating around in space to power the ramjet.</p><p>I'm of the opinion were probably going to have to wait for the development of some new technology to really nail any sort of interstellar travel.&nbsp;</p> <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
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vidargander

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<p><br /><br /><span><font size="3"><font face="Times New Roman">That ACE debate was initiated 3 year ago. It turned out to be rather intense and I learned a lot. </font></font></span><span><font size="3"><font face="Times New Roman">This time I will be more humble to science and less enthusiastic about fiction. </font></font></span></p><p><span><font size="3"><font face="Times New Roman">However, still I can&rsquo;t abandon the wish to see the exploration of another star system, like Alpha Centauri.</font></font></span><span><font face="Times New Roman" size="3">&nbsp;</font></span><span><font size="3"><font face="Times New Roman">I think there are three major obstacles, and they are all in our heads:</font></font></span> </p><ul style="margin-top:0cm"><li class="MsoNormal" style="margin-top:0cm;margin-left:0cm;margin-right:0cm;tab-stops:list36.0pt"><span><font size="3"><font face="Times New Roman">Nukes in space are banned by the UN. We won&rsquo;t get far with such a legal barrier.</font></font></span></li><li class="MsoNormal" style="margin-top:0cm;margin-left:0cm;margin-right:0cm;tab-stops:list36.0pt"><span><font size="3"><font face="Times New Roman">The misinterpretation of the theory of relativity makes us believe light speed is impossible.</font></font></span></li><li class="MsoNormal" style="margin-top:0cm;margin-left:0cm;margin-right:0cm;tab-stops:list36.0pt"><span><font size="3"><font face="Times New Roman">Alternative propulsion, like a nuclear/electromagnetically is needed. I think it possible.</font></font></span></li></ul><p><span><font size="3"><font face="Times New Roman">&hellip; and I don&rsquo;t think any ACEs will be manned. ACEs will be small probes with communication facilities.</font></font></span><span><font face="Times New Roman" size="3">&nbsp;</font></span></p><p><span><font size="3"><font face="Times New Roman">I truly believe humanity will manage explore Alpha Centauri sometime. It&rsquo;s simply a matter of time. All we have to do is to figure out how.</font></font></span></p> <div class="Discussion_UserSignature"> </div>
 
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MeteorWayne

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>The misinterpretation of the theory of relativity makes us believe light speed is impossible.Posted by vidargander</DIV><br /><br />And you have some verifiable theory that shows Einstein was wrong about that?</p><p>The fact is, that as we understand it now, it requires an infinite amount of energy to accelerate a mass to the speed of light. Remember, this is scince, not science fiction where warp speed and wormholes exist.</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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DrRocket

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>...lThe misinterpretation of the theory of relativity makes us believe light speed is impossible.Alternative propulsion, like a nuclear/electromagnetically is needed. I think it possible.&hellip;...<br />Posted by vidargander</DIV></p><p>I can assure you that this is not a misinterpretation.&nbsp; Any superluminal travel will have to entail a wholesale revision of general relativity and not simply a re-interpretation.&nbsp; Perhaps a theory of quantum gravity would shed some light, but that does not seem to be something that we will see in the near term, although it is a very active area of research.</p><p>Nuclear propulsion is not likely to provide and Isp as high, let alone higher, than what I assumed you might get from an ion drive.</p><p>What do you mean by electromagnetic propulsion ?&nbsp; Light sails ?&nbsp;&nbsp;How to you propose to use light to travel faster than light ?&nbsp; </p> <div class="Discussion_UserSignature"> </div>
 
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baulten

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Nuclear Pulse really never got off the drawing board because of the obvious environmental effects on Earth and the typical societal "anti-nuclear" attitude.&nbsp; From what I heard Ramjets are not feasible because they'd generate more drag than they could produce thrust.&nbsp; Laser sails... Well, I don't really know why they haven't been tested more.&nbsp; It's too bad the Cosmos I failed to launch properly.&nbsp; I guess they're just too risky of an investment. Posted by baultenNuclear pulse was canned because of conflict with the atmospheric test ban treaty which prevented nuclear explosions endoatmospherically. And as you mentioned, there were prevailing anti nuclear attitudes. This is what eventually lead to the test ban treaty.I recall hearing something to that effect on ramjets. But that was largely a paper study. The ram scoop was to be roughly the diameter of earth or maybe slightly larger. This to scoop out enough hydrogen floating around in space to power the ramjet.I'm of the opinion were probably going to have to wait for the development of some new technology to really nail any sort of interstellar travel.&nbsp; <br /> Posted by qso1</DIV></p><p>Er yes, sorry, I know it conflicted with the Partial Test Ban Treaty.&nbsp; I thought it was sort of on the downfall before that, though, because of the anti-nuclear sentaments of society.&nbsp; Maybe I was mistaken.</p><p>On the note of ISPs equal or higher than ion thrusters, aren't several proposed fusion designs capable of reaching higher ISPs, at least on paper?</p><p>Antimatter will be what ultimately gets us to&nbsp; other star systems.&nbsp; Of course, I could see a mission to Alpha Centauri using the Project Longshot design if we made some discovery of life or intelligence.&nbsp; Guess it would depend on the situation. </p>
 
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MeteorWayne

Guest
Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Er yes, sorry, I know it conflicted with the Partial Test Ban Treaty.&nbsp; I thought it was sort of on the downfall before that, though, because of the anti-nuclear sentaments of society.&nbsp; Maybe I was mistaken.On the note of ISPs equal or higher than ion thrusters, aren't several proposed fusion designs capable of reaching higher ISPs, at least on paper?Antimatter will be what ultimately gets us to&nbsp; other star systems.&nbsp; Of course, I could see a mission to Alpha Centauri using the Project Longshot design if we made some discovery of life or intelligence.&nbsp; Guess it would depend on the situation. <br />Posted by baulten</DIV><br /><br />Antimatter still suffers from the same extended timeframe. We haven't even solved the long term storage problem, and how much antimatter have we created in our accelerators in human history? A gram? I doubt it's even that much (though don't know for sure) so to consider that as an energy source for a mission in any of our lifetimes is completely unrealistic, Star Trek notwithstanding. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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baulten

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Antimatter still suffers from the same extended timeframe. We haven't even solved the long term storage problem, and how much antimatter have we created in our accelerators in human history? A gram? I doubt it's even that much (though don't know for sure) so to consider that as an energy source for a mission in any of our lifetimes is completely unrealistic, Star Trek notwithstanding. <br /> Posted by MeteorWayne</DIV><br />Antimatter is something we know exists, and know we can manipulate.&nbsp; Not that it's not difficult and probably going to be very difficult to produce/handle for a long time, but we know it's there.&nbsp; I never said in our lifetimes.&nbsp; Eventually, since it has the highest energy density of any fuel we currently know of, it'll probably fuel a mission to another star, barring humanity destroying itself.&nbsp; Right now, of course, it is completely unrealistic to try to build any kind of mission around it until we can better produce and store it.</p><p>As to the amount, I think we've produced a few hundred nanograms?&nbsp; Not sure. </p>
 
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vidargander

Guest
Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>And you have some verifiable theory that shows Einstein was wrong about that?The fact is, that as we understand it now, it requires an infinite amount of energy to accelerate a mass to the speed of light. Remember, this is scince, not science fiction where warp speed and wormholes exist. <br />Posted by MeteorWayne</DIV><br /><br /><p style="margin-top:0cm;margin-left:0cm;margin-right:0cm" class="MsoNormal"><span><font face="Times New Roman"><font size="2">My critique of the common misinterpretation of the relative theory does not indicate that Einstein was wrong. The relative theory explains the distortion the observer sence, not what rally happens to the traveller. </font></font></span></p><p style="margin-top:0cm;margin-left:0cm;margin-right:0cm" class="MsoNormal"><span><font face="Times New Roman"><font size="2">It&rsquo;s like the Doppler effect for sound transformed to light. We all know that a passing car sounds like having a higher frequent sound when approaching than when passed. The observer&rsquo;s distorted sensation hasn&rsquo;t changed the reality. The happy traveller hasn&rsquo;t suffered any change. Knowing that when a supersonic jet plane pass an observer in a thundering blast, - it didn&rsquo;t blow the pilot up or alter him or the plane in any way.</font></font></span></p><p><span><font face="Times New Roman"></font></span>&nbsp;<span><font face="Times New Roman"><font size="2">Likewise, even though there&rsquo;s some Doppler-like formulas for light as for sound, it doesn&rsquo;t change any space-traveler&rsquo;s reality. Just as an observer can&rsquo;t hear a supersonic plane before it has passed, an observer can&rsquo;t see a superluminal plane before it has passed. An observer can&rsquo;t see a superluminal ship approaching, because it is faster than its light. When it passes, the observer will see a flash, like the supersonic observer will hear a crash. However, the spacetraveler hasn&rsquo;t suffered any distortions and can well travel pass the speed of light in good health.</font></font></span><span><font face="Times New Roman" size="2">&nbsp;</font></span></p><p><span><font face="Times New Roman"><font size="2">I must admit that I previously argued Einstein was wrong. Now I think the interpretations were wrong. Anyway, there is no scientific reason to believe that superluminal impossible, just as we have proved that supersonic speed is.</font></font></span></p> <div class="Discussion_UserSignature"> </div>
 
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vidargander

Guest
Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>What do you mean by electromagnetic propulsion ?&nbsp; Light sails ?&nbsp;&nbsp;How to you propose to use light to travel faster than light ?&nbsp; <br />Posted by DrRocket</DIV><br /><br /><span><font face="Times New Roman"><font size="2">I definitely do not think of light sails to do interstellar travelling. That is impossible.</font></font></span><span><font face="Times New Roman" size="2">&nbsp;</font></span> <p style="margin:0cm0cm0pt" class="MsoNormal"><span><font face="Times New Roman"><font size="2">Nukes are the only way. Funny that nukes are banned in a highly radioactive space. It doesn&rsquo;t make any sense after the cold war fears.</font></font></span></p><span><font face="Times New Roman" size="2">&nbsp;</font></span><span><font size="3"><font face="Times New Roman"><font size="2">I think that it is very possible to make pulsating electromagnetic propulsion. There are some scientific mental barriers stuck in ancient physical laws though. Anyway, it&rsquo;s as simple as hammering on the front of a vessel, - it will eventually move forward, - no matter what physical laws says.</font> </font></font></span> <div class="Discussion_UserSignature"> </div>
 
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qso1

Guest
<p><font color="#800080">Er yes, sorry, I know it conflicted with the Partial Test Ban Treaty.&nbsp; I thought it was sort of on the downfall before that, though, because of the anti-nuclear sentaments of society Maybe I was mistaken</font><font color="#800080">.</font></p><p>No need to apologize because essentially, you were right. I just didn't know if you knew the test ban was the instrument used to put the nails in Orions coffin. Even here when you mentioned the anti nuclear sentiments being sort of a downfall before the test ban. Exactly right, there were protests that eventually filtered up the line and resulted in the test ban.&nbsp;</p><p><font color="#800080">On the note of ISPs equal or higher than ion thrusters, aren't several proposed fusion designs capable of reaching higher ISPs, at least on paper?Antimatter will be what ultimately gets us to&nbsp; other star systems.</font></p><p>I think you mentioned fusion being able to get up to velocities approaching .2c which IIRC, is the upper limit for fusion technology we think we might be able to do. Problem is, as someone else mentioned...we have yet to sustain nuclear fusion for earthly power production.&nbsp;</p><p><font color="#800080">Of course, I could see a mission to Alpha Centauri using the Project Longshot design if we made some discovery of life or intelligence.&nbsp; Guess it would depend on the situation. Posted by baulten</font></p><p>Project Longshot? Got any links to that one. I don't think I've ever heard of it...how'd I miss that one?</p><p>I agree that its going to take discovery of at least an earthlike world at a minimum to begin to see development of the necessary technologies, whatever they turn out to be. Also, in maybe 50 years, the private sector could transform the whole economic equation of space travel which would in turn make interstellar travel much easier relatively speaking.&nbsp;</p> <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
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qso1

Guest
<p><font color="#800080">That ACE debate was initiated 3 year ago. It turned out to be rather intense and I learned a lot. This time I will be more humble to science and less enthusiastic about fiction. However, still I can&rsquo;t abandon the wish to see the exploration of another star system, like Alpha Centauri.&nbsp;I think there are three major obstacles, and they are all in our heads: Nukes in space are banned by the UN. We won&rsquo;t get far with such a legal barrier.The misinterpretation of the theory of relativity makes us believe light speed is impossible.Alternative propulsion, like a nuclear/electromagnetically is needed. I think it possible.&hellip; and I don&rsquo;t think any ACEs will be manned. ACEs will be small probes with communication facilities.&nbsp;I truly believe humanity will manage explore Alpha Centauri sometime. It&rsquo;s simply a matter of time. All we have to do is to figure out how. Posted by vidargander</font></p><p>Actually, I would say continue to be just as enthusiastic as you were before you got the dose of scientific reality as it is known today. And that is precisely because scientific reality as we know it today might well change tomorrow should some new discovery happen.</p><p>There is no reason to abandon your wish. I'd say many of us here at SDC would like to see the same thing. The trick is knowing what scientific reality as we know it today...is capable of and either debate proposals on how to get around it or simply imagine we have gotten around it.</p><p>Just imagine if the internet existed in 1865 and people had just gotten their hands on that hot new book by Jules Verne called "From The Earth To The Moon". Imagine the scientific reviewers of the day. Criticizing the cannon shot method in which case they'd be right. Criticizing the choice of Florida as a launch site in which case they'd be wrong.</p><p>And keeping in mind this is a mental excercise but the reason I hypothesized the criticism of Florida is that Florida was a very different place in 1865. But the similarities of today were apparent as well and anyone contemplating a launch site then would probably pick Florida only as a last resort...Mosquitos, swamps, heat and humidity, hurricanes.</p><p>Propulsion? Jules Verne didn't envision rocketry for spaceflight because cannons seemed to make more sense. Cannons in effect, were the Orion pulse or other nuclear propulsion state of the art concepts of their day just as Bussard ramjets, light sails, nuclear fusion are todays concepts.</p><p>But its quite possible non of todays concepts will be adapted or more likely they will appear with ideas incorporated into them that are not yet even concieved today.&nbsp;</p><p>To address a couple other comments you made. AFAIK, nuclear weapons in space are banned by the U.N. (Per the 1967 treaty) not nuclear propulsion systems. If and hopefully when the day comes when nuclear propulsion is ready for space travel, any future ban that might result from continued anti nuclear concerns would probably have language written into it that would make exceptions to ccertain beneficial uses for nuclear power or propulsion.</p><p>I pretty much accept the state of scientific knowledge as it is today recognizing that the people who have advanced science do not include me. My hats are off to them even when it produces pesky limitations at times. I recognize also that I may disagree with some of the science but would never expect people to buy my ideas so to speak without the supporting data.</p><p>Still, I wrote a graphic novel about a human mission to Alpha Centauri which departs earth in 2156. A GN that tries where possible to maintain as much scientific reality as possible. Chosen propulsion...something that would be loosely interpreted as antigravity propulsion and something that I couldn't present for actual scientific analysis and expect to have someone actually tell me that it would work.</p><p>I know that number 1, I'm nowhere near being a rocket designer...can barely spell the word. But I accept that knowing I can at least have some fun writing graphic novels. I did adhere to the current known limitations on SOL by keeping the mission at .75C since it is the first mission and many follow on missions would be at .75C as well.</p><p>But if I do another story set in say 2525 (In the year 2525), I would probably have superluminal speed craft portrayed just to show humanity had eventually conquered the SOL barrier. Or if I chose to assume the SOL barrier is unbreakable, colony class starships that do not plan on ever returning to earth.</p><p>The most important thing is to keep right on being the enthusiast. The space travel we have seen so far began with enthusiastic dreamers who put their words and ideas into action. Robert Goddard, Konstantin Tsiolkovsky to name just two. It just seems to be the case that engineers and scientists are limited in vision by the state of what they know at a given time while the sci fi writers and dreamers are limited in the ability to actually pull off many of the ideas they adhere to.</p><p>Thats why we can exchange the combined ideas of writer and scientist alike that will hopefully one day lead to the stars. Like you said at the end of your well thought out comment..."All we have to do is figure out how".&nbsp;</p> <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
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baulten

Guest
<p>"Project Longshot? Got any links to that one. I don't think I've ever heard of it...how'd I miss that one?"</p><p>It was a study by the U.S. Naval Academy that essentially built on the idea of Project Daedalus, but it was designed to orbit Alpha Centauri A after a 100 year journey.</p><p>http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19890007533_1989007533.pdf</p><p>On the topic of the Partial Ban Test Treaty, it bans nuclear explosions in space.&nbsp; I'm pretty sure there is another treaty that bans the stationing of nuclear weapons in space (such as an orbital nuclear platform).&nbsp; Nothing bans nuclear reactions such a would be used in "confined" nuclear propulsion systems (salt water, gas core, etc.).&nbsp; They'd have to go take care of the Sun if that were the case, and all the stars! :p&nbsp;</p><p>"<span><font size="3"><font face="Times New Roman"><font size="2">Anyway, it&rsquo;s as simple as hammering on the front of a vessel, - it will eventually move forward, - no matter what physical laws says."</font></font></font></span></p><p>No, that would not work.&nbsp; Everytime you swung your arm back the ship would move back.&nbsp; Conservation of momentum is a well-proven law.&nbsp; I suggest you wiki "Reactionless propulsion" to find an explanation of why "hammering on the front of the vessel" wouldn't work.&nbsp;</p>
 
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DrRocket

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>"Project Longshot? Got any links to that one. I don't think I've ever heard of it...how'd I miss that one?"It was a study by the U.S. Naval Academy that essentially built on the idea of Project Daedalus, but it was designed to orbit Alpha Centauri A after a 100 year journey.http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19890007533_1989007533.pdfOn the topic of the Partial Ban Test Treaty, it bans nuclear explosions in space.&nbsp; I'm pretty sure there is another treaty that bans the stationing of nuclear weapons in space (such as an orbital nuclear platform).&nbsp; Nothing bans nuclear reactions such a would be used in "confined" nuclear propulsion systems (salt water, gas core, etc.).&nbsp; They'd have to go take care of the Sun if that were the case, and all the stars! :p&nbsp;"Anyway, it&rsquo;s as simple as hammering on the front of a vessel, - it will eventually move forward, - no matter what physical laws says."No, that would not work.&nbsp; Everytime you swung your arm back the ship would move back.&nbsp; Conservation of momentum is a well-proven law.&nbsp; I suggest you wiki "Reactionless propulsion" to find an explanation of why "hammering on the front of the vessel" wouldn't work.&nbsp; <br />Posted by baulten</DIV></p><p>That Naval Academy study strikes me as a very nice and instructive classroom excercise, in which the cadets showed a lot of imagination and applied a bit of engineering.&nbsp; However, it is not a serious attempt to design a mission to Alpha Centari.&nbsp; There are way too many enabling assumptions, not the least of which is a sustainable 1,000,000 sec Isp propulsion system using micro thermonuclear explosions.</p> <div class="Discussion_UserSignature"> </div>
 
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dryson

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> <em><font size="2">A stable laser beam should point at the star, as a leading thread on the way. The beam can also carry data. </font></em><br /></DIV></p><p><font size="3">Wouldn't the laser photons be bent by various gravitiational considerations thus, sending the ship in a completely different direction? The same would happen with the data. A laser designator would be perfect for solar sytem use, but outside of a solar system, the effect&nbsp;would be like throwing a boomerrang into the sky wondering where it will end up at.</font></p><p><font size="3">What about using ION engines in stages. An example would be having an engine suite of 8 engines. The first two fire reaching maxium velocity, then the next two would fire until all eight were firing. Would this&nbsp;double the total velocity by four or would the&nbsp;velocity still only equal two ION engines?</font></p><p><br /></p>
 
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vidargander

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Everytime you swung your arm back the ship would move back.&nbsp; Conservation of momentum is a well-proven law.&nbsp; I suggest you wiki "Reactionless propulsion" to find an explanation of why "hammering on the front of the vessel" wouldn't work.&nbsp; <br />Posted by baulten</DIV></p><p><span><font face="Times New Roman"><font size="2">A cart will move forward if you sit on it and hit it hard on the back. </font></font></span><span><font face="Times New Roman"><font size="2">That&rsquo;s a fact that can be proved. </font></font></span><span><font face="Times New Roman"><font size="2">That fact&nbsp;can be used for propulsion.</font></font></span><span><font face="Times New Roman" size="2">&nbsp;</font></span></p><p><span><font face="Times New Roman"><font size="2">I suggest that an interior generator, making electromagnetic pulses directed to a magnetic front (of the same polarity) will make a vessel move forwards. A thousand pulses per second will provide a steady forward motion.</font></font></span> </p><p style="margin-top:0cm;margin-left:0cm;margin-right:0cm" class="MsoNormal"><span><font face="Times New Roman" size="2">That should be possible to test on a ship.</font></span></p> <div class="Discussion_UserSignature"> </div>
 
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qso1

Guest
Thanks for the Project Longshot link baulten. Guess they knew how daunting this task is considering the name. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
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baulten

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>A cart will move forward if you sit on it and hit it hard on the back. That&rsquo;s a fact that can be proved. That fact&nbsp;can be used for propulsion.&nbsp;I suggest that an interior generator, making electromagnetic pulses directed to a magnetic front (of the same polarity) will make a vessel move forwards. A thousand pulses per second will provide a steady forward motion. That should be possible to test on a ship. <br /> Posted by vidargander</DIV></p><p>This works on Earth because gravity causes us to press against the ground.&nbsp; So when you throw hard enough forward, the whole thing slides.&nbsp; It can't slide back when you recoil slower because of friction.&nbsp; In space there is virtually no friction, so every time you swung back, the entire, ship would move back a little.</p><p>In your "electromagnetic pulse" idea, it wouldn't work because the pulses woudl be reflected, then hit the rear of the ship and the ship would move back.&nbsp; Unless the back was open, but if it was, then you'd have the same effect if you just turned the generator around and fired the pulses out the rear.&nbsp; It'd be really low thrust because photons have 0 rest mass.&nbsp; I'm not sure how you'd calculate it.<br /><br />http://en.wikipedia.org/wiki/Reactionless_drive explains it better than I can.</p>
 
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