This is one of those difficult topics that isn't strictly science fact, nor is it completely science fiction, so I am hoping this posting is not going to be thought of as inappropriate by this group. Assuming it isn't, here goes. Suppose that through a long number of decades of on-orbit engineering in a future era, humanity has managed to patch together an interstellar ark of the sort of dimensions and mass I have outlined in my new sci-fi concept. Now, suppose this object is orbiting above the Earth at around 28,000 miles (just past the Geostationary satellite belt) and it grosses a final mass of some 1.8 x 10^14 kg (circa 10% of Deimos - the smaller moon of Mars). Now, since no science authority has yet modelled such a large-scale interstellar vehicle, I'm wondering if the timescales and the dynamical sequences for departure from our solar system that I'm visualising - or hypothesising - sound "about right"?! I don't have answers for the total amount of energy that's going to be required nor the precise kind of propulsion or specific impulse of the engines to hand, but I still want to project some kind of a realistic timescale in order to get this craft booted out of our solar system... on its way to Alpha Centauri. I have managed to patch together an article here that I think (and hope) looks right:- http://www.astroscience.org/abdul-ahad/firstarktoalphacentauri/escape-sequence.htm... Now, I want some views from experts here if they see any major flaws or have a violent disagreement with my projections. Thanks for any serious thoughts. Please Register or Log in to view the hidden image! AA
So it will take 50,000 years to get to Alpha Centauri, according to your website? That's an awful long time. Will there be live people on it? How will they feed themselves? What will their source of energy be? In general my main objections to interstellar travel are: 1. It takes too long and requires too much energy. 2. Breathable gases will escape through pores in the hull long before reaching the destination. This can only be slowed down by minimizing the surface area of the hull. 3. Most activities on board will generate heat that must be dissipated by increasing the surface area of the hull. 4. Objections #2 and #3 compete with each other in the design of the interstellar vessel, making objection #1 so much more poignant. In fact, the very idea of interstellar travel defeats itself on these bases.
Hi, dubble A Instirute, I am not responding to your questions, but I am just trying to help you with my own thinkings. In think 50,000 years is way to long. That is aproximinately as long as humanity exists, although in the current form of our race. According to Einstein you cannot travel faster then 300,000 km par second, but as far as I know, there is no phisical law that says that you cannot make the time go faster. The only problem is that I still need to find out how to do so. Then there is another problem, caused bye the retardation. If you speed up or slow down to fast then you will be crushed down or blowed up, that much that you won't survive it. Maybe the following is a solution, but I don't know If I am correct with this. If you are seated in some kind of suit, that fits vacuum, and the suit is connected to the walls or the floor of the ark, in that way that the suits is one body with the ark. Because the suit is vacuum, the suit is also one body with your own body. In order to breath there is a small room, full of oxygene whych is connected with tour mound. the walls of this rooms are made of a material strong enough for the high pressure caused by the retardation. can someone tell my thinkings are helpfull and correct?
Not much encouragement there AA. You mention the ark is about 10% the size of Deimos. Why so small? Why not set up inside one of the minor planets, say Ceres. Use its ejected mass to accelerate you to 2% or 3% of c. That will reduce the time to Alpha Centauri to a few centuries. Anything longer than that and the ship society will fall to pieces.
You're absolutely right Dragonrider, 50,000 years is way to long for the so-called ark to travel to Alpha centauri. I think 400 or 500 years would do nicely for such a journey. Besides, where are you going to store all that canned salmon at for a 50,000 year space journey? Please Register or Log in to view the hidden image!
Novacane, I know another way to have a meal into the ark, this is stead of storing canned salmon. You need to invent a biosystem with it's own atmospehre inside the ark, that has the ability to preserve its maintenance. You can use this to do agriculture activiteis and to hunt animals or go fishing. You need some kind of replacement for the sun and the water must be able to evaporate, so the atmosphere of the biosystem can produce rain of its own. This system of course has to be locked down from the ecospace. Extually there are lot of scientist who try to make such a biosystem. Ther are to main probelems: 1 after a while the plants and the animals die. 2 They don't succeed in making a system that has it's own atmosphere to preduce rain. For the sun you can use a huge lamp. If it's to cold you can use the heat of the engine of the ark to warm up the biosystem. Of course you first need to cool this heath because if you don't the whole system will be scorched.
Hi Dragonrider, Actually, a lot of what you say is really the core theme of my first book in the series, which is out now (see links below). I have a thriving and vibrant community living inside the ark, who are utilising a closed ecological life support system ('CELSS') as I originally outlined on this page: http://www.astroscience.org/abdul-ahad/firstarktoalphacentauri/FAQ.htm If you are not able to read my book, here is an "exclusive" sneak preview of some scenes from my novel: http://www.astroscience.org/abdul-ahad/firstarktoalphacentauri/chapter3.htm I do have high hopes for this to become a movie in the future... Please Register or Log in to view the hidden image! (Still hoping.) AA
Sorry to be so negative, but none of your three sequences as diagrammed make any sense. 1. To go from a circular to highly elliptical orbit, you'd only be accellerating for one or two segments each orbit. Why? Whatever type of space drive you use, it should be able to accellerate steadily... unless your ship has to be resupplied with fuel periodically. If it's as massive as you say, that's entirely possible, but then how do you resupply it when leaving the solar system? 2. If it takes so long to go from near-earth solar orbit to a more distant orbit, then you should be using the gas giants, particularly Jupiter, for a slingshot "gravity assist" to speed things up. 3. No-- this is entirely wrong! You don't aim straight at your destination the entire trip; that's highly wasteful of time and energy. You aim directly at the place your destination star/planet will be when you get there. The path from the solar system to the destination star should be a straight line. Where did the ship come from? If it's a hollowed out asteroid, it would be much more cost-effective to ferry the passengers and cargo out to the asteroid belt and put them on the ark there, than to move the entire ark into and then out of Earth orbit. Are you thinking of actually building the thing from scratch by ferrying mass up from the earth's surface? Again, why? It would be much more cost-effective to hollow out an existing asteroid, or at worst use a linear accellerator to throw stuff up from the surface of an airless world such as one of the moons of Saturn, or at the very worst from Luna (Earth's moon). And there's absolutely no way to estimate how long the trip will take until you can tell us what kind of spacedrive they're using, and how powerful the thrust is. The formula for accelleration is very simple, once you have that, and you don't even need to use math: just google on "acceleration calculator" and find a website that will do it for you. If you're using a very low-thrust system like an ion drive, it will take a very long time. If you're using a moderate-thrust system like a Project Orion drive (see the Wikipedia article if you aren't familiar with that) it will take a moderately long time. If you're using a very advanced drive such as antimatter or a "reactionless" drive (a science fictional concept impossible according to modern physics) it will take a relatively short time. Again I hate to be so negative, but you don't appear to have the knowledge necessary to believably construct such a tale. In fact, you seem to think it's an original idea. Apparently you haven't read any stories of multi-generation ships, such as Robert Heinlein's Orphans of the Sky or Non-Stop by Brian W. Aldiss or Spacebred Generations by Clifford D. Simak. Oh dear, I was afraid you had used a vanity press like PublishAmerica to get your book printed, and indeed I see I was right-- it's PublishAmerica. They are not a "publisher", but merely a printer-- despite their lying claims. Info here: http://www.freewebs.com/truthaboutpa/faqs.htm Forum for PublishAmerica victims here: http://www.absolutewrite.com/forums/showthread.php?t=26537
The inside of my ark's body is going to be rocky (asteroidal material) brought in via lunar slingshot, which is then overlaid on the outside with a metallic alloy transported up from Earth. The latter comprises a small fraction of its total mass, however, and is a tough synthetic designed to withstand three things: (1) the rapid spin rate of the cylinder to generate 1-g of Earth gravity all the way round on the inside, (2) the ability to withstand high speed travel through strong gravity fields of Jupiter and Saturn (to pick up escape velocity needed to get booted out of our Solar System) and (3) to deflect any interstellar debris encountered in the Oort cloud. Incidentally, that is why I made the front a 'bullet' shape, as the optimum design for a projectile moving through a non-vacuum medium. The rock part of the ark could be constructed by impacting a large asteroid onto the far side of the Moon and taking the resulting debris thrown off, as I illustrated a couple of years ago on this article: http://www.astroscience.org/abdul-ahad/earth-ring.htm As regards corrections to the trajectory, I started a short discussion on google groups here: http://groups.google.com/group/uk.s...68230040f447e?lnk=raot&hl=en#3a468230040f447e Well, the propulsion remains open still, though I expect it will be nuclear fission for the 5 giant engines (each one is of roughly a kilometer in diameter!), utilising Project Orion type of heavy blasting to make First Ark to Alpha Centauri move forward like a super-heavy elephant Please Register or Log in to view the hidden image! Incidentally, the 50,000 year voyage duration is what I like to call a "least-cost versus most-safe optimisation". If the ark moves much slower and it takes any longer than this timescale, you can see that Alpha Centauri will soon start to drift out of range, and the vehicle will be playing 'catch up' with its destination. If it speeds much faster, and aims to reach Alpha Centauri in say just 5,000 or 10,000 years from now, then the craft will need a lot more propulsive energy on the way out of our Solar System, suffer major impacts from any Oort cloud bodies encountered en-route and also need excessive delta-v at the other end in order to slow right down and successfully rendezvous with New Earth. Thanks for your input. AA
and then; Er, do you see the problem with this? You have a large spinning object, and then try and steer it using nukes, so the entire outside of your craft will need to be nuke proof, not just one small shielded area! How is that going to work?
If the Ark spins along the axis of motion, the thrust will be along that axis and the spin would not affect the movement in the direction of thrust, However a slightly off-centre thrust would cause the Ark to precess like a gyroscope. Much better to start the spin later in the mission, after the thrust is finished. I think you have a misconception about the Oort Cloud, however. The objects in the Cloud are very thinly spread- your ship is unlikely to hit anything significant, even if you travel a hundred times faster. Large objects in the Oort cloud are much further apart than objects in the Asteroid belt- and they are so far apart you can rarely see from one object to another. Oort cloud objects are several AU apart from each other. Place a fairly thick ice shield at the front end and your ship will be able to withstand impacts with dust grains at 0.01 light speed.
Possibly, but we cannot be certain of that by any means. Besides, I just didn't want to take that kind of risk. The maiden voyage of the Titanic sailing from England to New England... then hitting an iceberg in the North Atlantic ... what an astonishing earthly parallel Please Register or Log in to view the hidden image! The Centauri Princess could hit an iceberg in the Oort cloud going from Earth to New Earth - I dread the thought! To accelerate a craft of this size to 0.01c calls for steep, steep engineering requirements, which even gravity slingshots from the largest gas giants in our solar system will not achieve, no matter how optimistic the calculations. Besides, even at 0.01c, it would still take 17 consecutive generations or 430 years to reach Alpha Centauri. I have argued this in my original article on this back in August 2004: "With the vast immensity of interstellar oceans separating us from the stars, even with the most optimistic, *theoretical* fractions of light speed mission concepts, few envision a journey where the person departing from Earth will be the one who gets to enjoy the end goals of the mission. Almost invariably, it will be your children who benefit from any hardships you encounter along the voyage. With my "generation" starship concept, I question the wisdom that if you are not going to be the one to see the light of day on the other end of the interstellar tunnel, then provided conditions onboard the starship are nice and comfortable, does it really matter whether its the generation after you... or the [2,000th] generation after you that eventually gets greeted by New Earth?! " From: http://www.astroscience.org/abdul-ahad/firstarktoalphacentauri/interstellar-propulsion.htm AA
Well, yes it does; to maintain a 'comfortable' environment inside a sealed environment takes energy, and a lot of it. To recycle wastes into food, dirty water into clean, and CO2 into oxygenn willtake a ceratin minimum amount of energy per person each day. If you delay the arrival of the ship by tens of thousands of years you increase the amount of energy that you require by an enormous amount. I suspect that a CELSS will be subject to diminishing returns as well, so that wihthout the import of new mayerial it will become harder to maintain a closed system, and increasing amounts of energy will be required over time. Better to use that energy to accelerate the ship in the first place so you get there faster. Safety is not a great consideration; you are not likely to hit anything.
I mean to say you won't hit anything that ten metres of reinforced ice shielding can't take care of; here is the preferred material, a World War II ice composite called Pykrete http://en.wikipedia.org/wiki/Pycrete
The colonization of the stars will need to follow a 3 major steps... 1) the easy access and use of the asteriod belt near mars orbit.... 2) the collecting, and cutting and stacking of asteriods of varied quality and size for the purposes of resourses, shielding and fuel and making up the body of the interstellar ships themselves. the means of propulsion will be most probubly, nuclear rockets... using gases developed from the mass of large ice chunks and heavy elements collected from the same asteriod belt,, before the trip. in this way, using full on nuclear power, and ionizing and projecting matter on a large scale rapidly our ships.. could easily reach other stars using fuel that could easily be packed on board. and is essentially... free.. in the asteriod belt. other than nuclear rockets, at top speed, an electrical system can take over using ion acceloration to bring our trip to nearer light speed.... and of course we could then slow down by this same process.. facing reverse. 3) it would require that we develop a CONFORTABLE DAY TO DAY RUGGED survivable space culture... living and working daily in space, where by in all probability, colonization of other stars once we arive there, is likely to begin with the various moons, and sub planets, since 'oxygen/ water earths'.... maynot be common place. in my mind... i would say our species was succeeding well.. if we had developed colonises on the moons of non-earthlike worlds. moons, are better than nothing... and we can build more collony ships from there. -MT
hi, If the Ark spins along the axis of motion, the thrust will be along that axis and the spin would not affect the movement in the direction of thrust, However a slightly off-centre thrust would cause the Ark to precess like a gyroscope. Much better to start the spin later in the mission, after the thrust is finished. staffingpower.com sentersoftech.
