Escape timelines for my interstellar ark

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voyager12

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This is one of those difficult topics that isn't strictly science fact, <br />nor is it completely science fiction, so I am hoping this posting is <br />not going to be thought of as inappropriate by this group. Assuming it <br />isn't, here goes. Suppose that through a long number of decades of <br />on-orbit engineering in a future era, humanity has managed to patch <br />together an interstellar ark of the sort of dimensions and mass I have <br />outlined in my sci-fi concept 'First Ark to Alpha Centauri'. <br /><br />Now, suppose this object is orbiting above the Earth at around 28,000 <br />miles (just past the Geostationary satellite belt) and it grosses a <br />final mass of some 1.8 x 10^14 kg (circa 10% of Deimos - the smaller <br />moon of Mars). Now, since no science authority has yet modelled such a <br />large-scale interstellar vehicle, I'm wondering if the timescales and <br />the dynamical sequences for departure from our solar system that I'm <br />visualising - or hypothesising - sound "about right"?! <br /><br />I don't have answers for the total amount of energy that's going to be <br />required nor the precise kind of propulsion or specific impulse of the <br />engines to hand, but I still want to project some kind of a realistic <br />timescale in order to get this craft booted out of our solar system... <br />on its way to Alpha Centauri. I have managed to patch together an <br />article here that I think (and hope) looks right:- <br /><br />http://www.astroscience.org/abdul-ahad/firstarktoalphacentauri/escape-sequence.htm<br /><br />Now, I want some views from experts here if they see any major flaws or <br />have a violent disagreement with my projections. Thanks for any serious <br />thoughts. <br /><br />AA
 
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ve7rkt

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Just as you've broken down the escape sequence, you're going to have to break down the capture sequence at Alpha Centauri...
 
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nexium

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Assuming the space elevator www.liftport.com is successful, we can be delivering a million tons to 26,000 kilometers altitude anually beginning about 2030 at a cost of 0.4 trillion dollars per year (2006 USA dollars)<br />At this rate it will take 180,000 years to deliver that much mass to 26,000 kilometers altitude. With a large human presence in space and other breakthoughs besides the space elevator, a lower cost and shorter time may be practical, but my guess is you need to think about 1000 times less mass. Neil
 
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strandedonearth

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Hmmm, and how much mass would be available from NEA or lunar sources? It might be easier to capture one or more NEA's into an Earth or L-point orbit than to loft it from Earth. <br /><br />I gather that much of the outfitting of the Ark would be done while the orbit is being expanded. I didn't see a mention of the propulsion system, would that be an ion drive or some sort of mass driver?
 
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vogon13

Guest
Might want to look at Orion for this.<br /><br />25 million tons delivered to any nearby star.<br /><br />Possibility of .03 to maybe .08C velocity.<br /><br />'Off the shelf propulsion' hardware.<br /><br /><br />I realize 25 million tons isn't any where close to 10% the mass of Deimos, but 25 million tons would get you a viable colony at the destination, and what more do you need than that?<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
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nexium

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Perhaps you could increase Orion's mass 40 times to one billion tons. Orion might still have enough delta V to get from 26,000 miles circular orbit of Earth to a sling shot manuver of Earth, or the Sun or Jupiter, whichever takes the least delta V. Additional sling shot manuvers = gravity assist manuvers, might get the speed up to a billion miles per year = 2.7 million miles per day = 114,080 miles per hour. At this speed, it will take 25,620 years to reach Alpha Centarii. Scarsely anything they brought on the arc will be funtional after that long and many systems will have to be retrofited thousands of times during this long a period. If the ark has the facilities to build a super conducting magnetic sail a few years before reaching Centarii A, it may be possible to slow to air breaking speed at the new planet. After 1000 generations the occupants of the arc will probably lack the technical know how to build the mag sail or much of the other technology needed to colonize the planet. What incentave will the ancestors of the arriving pioneers have to learn, and teach their children skills that they cannot practice on the arc?<br />I suspect Orion at 25 million tons cannot average 0.03 c even if it begins the journey from Pluto's orbit. Neil
 
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vogon13

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.03C is an estimate generated in the 1960s by the design team at General Atomics. I don't feel this figure is in dispute.<br /><br />Advances in bomb design in the 40+ years since then, advances in materials and advanced staging concepts give resonable confidence to the upper figure.<br /><br />I would rather you look at launching 40 consecutive Orion vehicles to 40 different destinations in under 1000 years, rather than an all or nothing behemoth in one shot to one destination.<br /><br />I still don't understand why you need to take more than the equivalent of 1 viable colony.<br /><br />If 25 million tons isn't enough, send 2. The second one can take a shopping mall and the Great Pyramid of Cheops.<br /><br />And some aircraft carriers.<br /><br />And the Empire State Building.<br /><br />And the Golden Gate Bridge.<br /><br />And the Eiffel Tower.<br /><br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
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qso1

Guest
If you were dealing with a Mars mission some two to three decades out, I'd say you would have a lot to research to ensure science fact within your science fiction. But since your dealing with a century or more out, and an interstellar destination. Whos to say what will be employed. All the ideas presented here are valid ones. Best advice I can think of is look at all the suggestions then see what you can come up with to ensure you put your signature so to speak on your work. I say this because I too, have written books or more accurately, illustrated or graphic novels dealing with both near term and long term human space exploration.<br /><br />BTW, like the website. <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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spayss

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''Off the shelf propulsion' hardware. '<br /><br />What shelf where?<br /><br />
 
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vogon13

Guest
Nukes!<br /><br />Think there are 40-50 thousand lying around.<br /><br />Nice start on a little Orion demo project.<br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
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vogon13

Guest
<font color="black">.</font> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
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spacefire

Guest
after you build all the SS Modules, SS Structural, SS Life Support, SS Fuel Cells and SS Propulsion you can launch in one turn...soon after the Global Warming meltdown will occur and jungles will sprout all around your cities. By that time I just build lots of nukes and drop them on whatever cities my competitors have left. <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>
 
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vogon13

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I am still a little unsure why we are talking about sending something so big.<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
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tap_sa

Guest
The French refused to give Eiffel Tower. We'll be taking Mount Rushmore instead.
 
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revolutionary

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If you think your colonists can survive the breakup of the crew following the captain's death ... if they manage that they'll have to survive the psi attacks from Planet's fungal neural network until Transcedence is completed. <br /><br />
 
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baktothemoon

Guest
Too bad they don't have space weapons in Civ, that would be sweet.
 
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voyager12

Guest
A lot of this is covered in my first book that's currently on release at the moment. To make the interior as "earth-like" and "homely" as possible, it is necesary to keep the curving landscape not too vertigouous for the community living inside... hence the bigger size. Add to this the need for cloud formation and natural rainfall, four seasons, fruiting and flowering cycle for plants and vegetaion,... size matters. The thing to remember is that this is not for 50 years or a 100 years or even 1,000 years. This is for near eternity and boredom, rebellion, factionalisation and other mental aggression issues with traditional closed-environment generation ships need to be overcome with a spacious, "beautiful" and idyllic environment that will soothe the mind <img src="/images/icons/smile.gif" /><br /><br />As to the fuel requirements and if the idea sounds "plausible", there is a parallel discussion here:<br /><br />http://groups.google.com/group/uk.sci.astronomy/browse_frm/thread/6f6570c2b06edf21/3a468230040f447e?hl=en#3a468230040f447e<br /><br />Hope this helps. But the bottom line is, yes this is a work of fiction!<br /><br />AA
 
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jhoblik

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For that long journey we really need a lot of resources. <br />My suggestion is to pick asteroid with best composition and shape. We will need lot of water(ice) and building material iron, etc. <br />Shape has to be close to cylinder shape. Create inside asteroid space in shape of cylinder, that will be airtight.<br />Rotation of asteroid give us necessary gravity.<br />We have to deliver just material that will be not available a necessary for journey, like plutonium for nuclear plants etc..<br />
 
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voyager12

Guest
Alpha Centauri is a really special case for a first interstellar destination for humans, for quite a few reasons. Firstly, the two primary stars are very 'sun-like' compared to the next nearest major systems, like Sirius and Procyon which are also much further out than Alpha Centauri. Secondly, there is a possibility of Oort clouds existing between it and the Sun that could act as a reservoir for mining water/ice from the surfaces of comets along the voyage.<br /><br />I have gone into some prior research into the hypothetical possibilities on that on these two pages:<br /><br />http://www.astroscience.org/abdul-ahad/firstarktoalphacentauri/interstellar-propulsion.htm<br /><br />http://www.astroscience.org/abdul-ahad/firstarktoalphacentauri.htm<br /><br />Notice that I rejected the asteroid interior idea for my ark on the grounds that finding such a body of the right size/shape/composition etc. would be immensely difficult. Even if one were to be found, to accelerate such a gigantic vehicle up to the necessary speeds could call for close gravity-assisted fly by's of planets within our solar system. Further, to generate artificial gravity to 1g of Earth's gravity equivalent inside the biosphere floor, requires a 6-mile wide cylinder to ratate at 500 miles/hour. An asteroid could easily shred itself to pieces under those circumstances, especially as its mass distribution would be unevenly spread throughout the body.<br /><br />In the end, I settled for a synthetic/asteroidal construction, which is described fully in my novel. Incidentally, also, the 50,000 year timespan is an *optimum* on speed vs energy vs a moving destination target.<br /><br />If the ship moves much faster than the 60,000 mile/hour nominal, then it is going to be that much more difficult to mine come
 
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nacnud

Guest
I like the design of the ark but why build it in Earth space? Send something like Daedalus with a load of Von Neumann probes and construct your ark at the other end as an O'Neill habitat. Once all is set up either send a small number of humans on a faster ship or make the humans in situ.<br /><br />Use the realities of the physical world to your advantage, physical objects are hard to move but information is easy. Where possible move only bits. I think this would be an interesting take on the problem of the relatively slow speed of light and therefore spacecraft. You can always make it interesting by having to move some human knowledge the traditional way, inside someone’s head. Sometimes there is no substitute for experience.<br />
 
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barrykirk

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Kind of reminds me of the original series Star Trek episode, "For the Earth is Hollow and I have touched the Sky"
 
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spayss

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Why is this ship going to Alpha Centauri? What does it do once it arrives in orbit around the star?
 
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nexium

Guest
We did not think multi sun systems had planets, but computer modeling shows that there may be planets. If Centarii A is unsuitable as a habitat/colony; Centarii B and Proxima are reasonably close. Almost as attractive options are 6 to 60 light years away or more. Sirus likely produces lots more deadly radiation in the habitable zone.<br />A solar system wide extintion event is possible, but The Centarri system is far enough away to offer some hope that it would be the home of the only living humans. Neil
 
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