There has been much talk of late as to whether it is desirable for NASA to return to Earth's Moon, or to skip it and spend the money on a manned trip to Mars.
There are several reasons for wanting to return to Luna. First is, to provide the feeling that we (The USA) Can still do it. This is a highly emotional reason, and for that, it should be suspect. Other explanations are to 'lay claim' to the moon, ahead of Chinese landings and potentially Indian ones as well. This claim would also explain an idea that NASA needs a permanent moon base (presumably, a manned one). This is a more credible reason to go to Mars, but also one which has great expense for the mere posturing in International politics and a dubious land claim. But, it is forward thinking.
Forward thinking is important. A trip that is ill-conceived and under funded will be useless in the long term. Yet, anything more than a "flags and footsteps" mission will be expensive, and without proper forethought could be a 'moondoggle' (moon + boondoggle). A moon base can function as a foothold on space, but hopefully not just for one country but for all. I will consider what the moon can offer for 'steps farther out'.
The moon has 1/6 the mass of the earth, and therefore 1/6 of the gravity and therefore requires much less energy to launch from. This could make it attractive as a 'depot' for missions to other destinations, but if that were the only purpose it were to serve, why not build a space station to use as a depot? A space station has no gravity worth speaking of, and is also free from the danger of moon-dust fouling up systems.
The moon may contain some water. However, it may be more trouble to obtain it than it is worth. It may be easier to bring water up from earth, or obtain it from free-floating places in space, such as in the tail of comets. Were it found to obtain large amounts of water that were easy to tap, then a "moon well" would be valuable indeed.
Helium 3, which is 'regular' helium plus a neutron, is more plentiful on the moon than on earth, but is still only available at ten parts per billion. It has potential use in generating power, using 'aneutronic fusion', which is a reaction producing no neutrons, and therefore no waste or reactor degradation. However, no fusion reactor has yet shown to produce more power than it consumes. Even if a practical fusion reactor is developed, fuels other than He3 may prove to be more practical. Building a moon base to provide He3 when there is no demand for it would be overly speculative, and a potential moondoggle.
The function of a moon base which is most practical is that of mining for traditional metals. The metals iron, aluminum, and titanium are present on the moon in concentrations which may make mining and processing them inexpensive, when comparing the cost of bringing these materials from Earth. Oxygen is also obtainable from lunar minerals, as is the aformentioned Helium3. In addition to refining the minerals, it may also be possible to use them in their powdered or solid form, by creating a 'lunar cement' or 'lunar concrete'. Such a concrete may be useful for ablation shields.
I believe that the priorities of NASA's lunar missions should be directed towards providing mining and manufacturing facilities once a base has been established. There should be an effort to keep the number of personnell required on the moon to a minimum. It may be more practical to launch robots to the moon with specific missions rather than set up a manned base. Research ought to be conducted towards the tradeoffs of manned versus robotic missions.
I foresee a future where the large and massive portions of spacecraft, such as the hull with radiation and ablation shields, are manufactured on the moon. Less massive and complex equipment is brought to the moon, where final assembly occurs, followed by launch. Over time, more manufacturing is transferred to Luna. Spacecraft resupply of metals, oxygen, and possibly water may be from Luna and not earth.
What Mars can provide in terms of furthering human exploration of space is less clear. Its mass is not so much less than Earth's as to make use of its water particularly attractive. It may have hydrocarbons of some value, but these might be better obtained from Titan, or other Jovian/Saturnian moons where they are far more concentrated and escape velocity is far less.
Friday, August 28, 2009
Sunday, July 12, 2009
LaGrange points: a second look
Earlier, I had mentioned that LaGrange points might be useful for interplanetary or interstellar travel. These points are useful, because very little energy is required to change trajectory within them, and that they can be orbited, in spite of having no actual mass. The problem is, this will lead to a collection of 'junk' at these points - at a real collision hazard for spacecraft travelling at high velocity relative to the LaGrange point. An example of such matter is the Trojan Asteroids at the LaGrange points of Sol-Jupiter, and speculation that another group of LaGrangian Asteroids at the Neptune-Sol LaGrange points, containing large asteroids numbering an order of magnitude large than the groups around Jupiter.
Yet the LaGrange points with large bodies in them may not be as dangerous as others. Depending on the 'settlement' of the star and planetary systems, meaning, roughly, the age since a major change, minor debris may have been pulled to the surface of the more massive bodies. Since the massive bodies are more easily detected at a distance, this may mean that collission can be more easily avoided.
A useful, if ambitious, feat of celestial engineering would be to 'cleanse' LaGrange points by the use of the gravitation pull of a large spacecraft, porposeful collision with a spacecraft which is designed to withstand the collission (a slow, massive, "celestial snowplow"), or perhaps by an energetic blast of low mass (accelerated gas, perhaps - a "celestial leaf-blower"). The question remains, of where to push / pull these objects - towards a massive body in the LaGrange point, or out of the LaGrane point entirely, to be captured by the gravity of a planet or star.
I use the term 'celestial' here with some trepedation. I can't use "Solar" or "Star System" engineering, as these would seem to either apply only to the local star system, Sol, and the latter term "Star System", would seem, at first reckoning, to indicate much larger changes. Yet perhaps that is appropriate, as the system of the star and its satellites is the reason for the LaGrange points and their objects.
To conclude, the use of LaGrange points, particularly by a spacecraft at high velocity, is not to be lightly considered.
Yet the LaGrange points with large bodies in them may not be as dangerous as others. Depending on the 'settlement' of the star and planetary systems, meaning, roughly, the age since a major change, minor debris may have been pulled to the surface of the more massive bodies. Since the massive bodies are more easily detected at a distance, this may mean that collission can be more easily avoided.
A useful, if ambitious, feat of celestial engineering would be to 'cleanse' LaGrange points by the use of the gravitation pull of a large spacecraft, porposeful collision with a spacecraft which is designed to withstand the collission (a slow, massive, "celestial snowplow"), or perhaps by an energetic blast of low mass (accelerated gas, perhaps - a "celestial leaf-blower"). The question remains, of where to push / pull these objects - towards a massive body in the LaGrange point, or out of the LaGrane point entirely, to be captured by the gravity of a planet or star.
I use the term 'celestial' here with some trepedation. I can't use "Solar" or "Star System" engineering, as these would seem to either apply only to the local star system, Sol, and the latter term "Star System", would seem, at first reckoning, to indicate much larger changes. Yet perhaps that is appropriate, as the system of the star and its satellites is the reason for the LaGrange points and their objects.
To conclude, the use of LaGrange points, particularly by a spacecraft at high velocity, is not to be lightly considered.
Thursday, July 9, 2009
spacecraft in collisions with natural objects
Other than energy concerns, probably the most serious obstacle to interstellar travel, or even interplanetary travel, is the danger of collision with objects. The "Space Junk" problem with man-made rubbish in earth orbit is small in comparison with the dangers that high-speed travel brings about. For, the faster we travel, the less time we have to detect objects in a collision course and the less time we have to react to the threat.
The problem can, in part, be addressed by the same precise and accurate survey that is required by the other parts of interstellar travel and "starsystem engineering (which includes terraformation). Yet any evasion of a collision will be costly, in terms of energy.
The assumption that that an encounter with such objects is to be avoided may be overcautious. There are methods of spacecraft design which make some encounters not only less dangerous, but beneficial. Proper design can make encounters with objects too small to be detected at a distance, actually beneficial to in the propulsion of the spacecraft.
To back up a bit, it makes sense that the gravitational replacement be that provided by rotational inertia. This has been a well accepted concept, even in the 1969 movie '2001', and ever since it has been a prefered method of providing artificial gravity. This means that the internal 'core' of the spacecraft is not to be inhabited because it has zero gravity. Why not do away with the 'core' entirely? This would results in a conical spacecraft with a hollow interior. Yet this interior might not be useless: a replusion system could narrowly direct either around or through the spacecraft. When lightweight matter is funneled in such a way, it can perhaps be used as reaction mass. Simply speaking, the 'junk' funneling through the center of the spacecraft can be used to 'push against' an accelerated the craft, thus improving its efficiency.
In conclusion, it is a combination of early detection of large hazards, and design to death with, even take opportunity of, smaller bodies that will protect an inter (or even intra) stellar mission. Of course, super-velocity bodies will still be beyond our ability to deal with. Which is why, there maybe an advantage to a star system which has 'sweeper' high gravity bodies, such as Jupiter and Saturn provide in the solar system, to 'clean' of minor bodies (i.e. junk).
As I write this, I am watching the movie 'Contact' for the first time, on TV. I have been hesitant to watch if for so many years because I had this idea that it would be a reproduction of "E.T.". Thankfully, it was an adult movie and had much more to offer than the typical Spielburg juvenelia. Yet I still feel that any aliens will not come to us, but we will go to them. Perhaps more alarmingly, that their systems of intelligence and communication will be so different than ours, along with their biology and time scale, that we will not identify them until we are in the midst of them, and too late for either species to communicate with the other as to non-interference, never mind mutual benefit. But I believe this deserves a totally different subject heading, and I am not sure is even appropriate for this blog.
"Are we alone?" - I feel this when posting here. Who reads my posts? I can only hope that either Google or some other force can archive this for the ages, and that future generations mine my exposions for ideas and guidance.
That means that some appreciation would be most welcome. Even if you disagree with me, please let me know that my posts are being read.
The problem can, in part, be addressed by the same precise and accurate survey that is required by the other parts of interstellar travel and "starsystem engineering (which includes terraformation). Yet any evasion of a collision will be costly, in terms of energy.
The assumption that that an encounter with such objects is to be avoided may be overcautious. There are methods of spacecraft design which make some encounters not only less dangerous, but beneficial. Proper design can make encounters with objects too small to be detected at a distance, actually beneficial to in the propulsion of the spacecraft.
To back up a bit, it makes sense that the gravitational replacement be that provided by rotational inertia. This has been a well accepted concept, even in the 1969 movie '2001', and ever since it has been a prefered method of providing artificial gravity. This means that the internal 'core' of the spacecraft is not to be inhabited because it has zero gravity. Why not do away with the 'core' entirely? This would results in a conical spacecraft with a hollow interior. Yet this interior might not be useless: a replusion system could narrowly direct either around or through the spacecraft. When lightweight matter is funneled in such a way, it can perhaps be used as reaction mass. Simply speaking, the 'junk' funneling through the center of the spacecraft can be used to 'push against' an accelerated the craft, thus improving its efficiency.
In conclusion, it is a combination of early detection of large hazards, and design to death with, even take opportunity of, smaller bodies that will protect an inter (or even intra) stellar mission. Of course, super-velocity bodies will still be beyond our ability to deal with. Which is why, there maybe an advantage to a star system which has 'sweeper' high gravity bodies, such as Jupiter and Saturn provide in the solar system, to 'clean' of minor bodies (i.e. junk).
As I write this, I am watching the movie 'Contact' for the first time, on TV. I have been hesitant to watch if for so many years because I had this idea that it would be a reproduction of "E.T.". Thankfully, it was an adult movie and had much more to offer than the typical Spielburg juvenelia. Yet I still feel that any aliens will not come to us, but we will go to them. Perhaps more alarmingly, that their systems of intelligence and communication will be so different than ours, along with their biology and time scale, that we will not identify them until we are in the midst of them, and too late for either species to communicate with the other as to non-interference, never mind mutual benefit. But I believe this deserves a totally different subject heading, and I am not sure is even appropriate for this blog.
"Are we alone?" - I feel this when posting here. Who reads my posts? I can only hope that either Google or some other force can archive this for the ages, and that future generations mine my exposions for ideas and guidance.
That means that some appreciation would be most welcome. Even if you disagree with me, please let me know that my posts are being read.
Tuesday, July 7, 2009
Doing useful work when slowing at star arrival
In my previous post, I had mentioned the possibility of using a sort of 'reverse gravity assist', where a man-made object (a spacecraft) would purposely change the orbit of another object. I had suggested this as a way of flushing space junk from Earth's orbit. Lying awake last night, I thought about how approximately half of the energy expended in interstellar travel would be to slow down upon approach to the destination star system. Then it occured to me: If we are using the energy of our star system (Sol) to accelerate, then we can pump energy into the destination star system upon arrival, to slow down. Better yet, we can change the arrival system to our benefit (with limits, of course). For instance, it is postulated that comets are balls of ice from the very edge of our solar system, some of which have obtain an orbit which brings them close enough to the sun to melt, thus their distinctive appearance. This theory also says that there are other 'snowballs' at the outer solar system that do not have these orbits, and remain hidden from us (for now). Theories of planetary formation have said that the earth is too close to the Sun for water to have formed as the planet formed. If this is so, the water must have arrived after planetary formation - most likely from a collision with a comet. I think that such a collision would be so energetic as to possible cause the earth to crumble, and much rocky matter and cometary water be thrown off. I think what is more likely is that a comet had a trajectory that took it near enough to Earth so that Earth's gravity was able to strip off some of its liquid and gaseous water. Perhaps this was a periodic even, leading to repeated addition of water to earth, or perhaps it was a very massive comet and one such event was all that was needed. Or, perhaps the comet became trapped in the Earth's orbit, and it rained for a thousand years. Whichever actually happened, it is possible that we can perturb a comet in the destination system to contribute water to a dry, rocky planet much like the same mass as earth.
There are, of course, some limitations and pitfalls to such a plan. The first is that we must, before arrival, have a precise and accurate map of the star system and the composition of its massive bodies. The velocity at which we enter this system will be high, and therefore any collision could be catastrophic. We need to be able to sense even pebbles from a distance, or be able to correct course very quickly, or both. Another limitation is that decelerating in this manner may take much more time than the traditional interstellar, fueled deceleration, especially if we want to make the best use of it. Furthermore, the calculations involved in order to best chart the spacecraft's course are computationally expensive. But of the last limitation, that is the one I have the least concern about, as we humans seem to be able to build very fast computers. It is the sensors we need, and it is the map-building and then careful course plotting that will be time consuming.
As I type this, I wonder if we could not attempt to 'throw a snowball' at Mars. That planet will need enough mass to be able to keep its water, so it may have to be a very big snowball.
There are, of course, some limitations and pitfalls to such a plan. The first is that we must, before arrival, have a precise and accurate map of the star system and the composition of its massive bodies. The velocity at which we enter this system will be high, and therefore any collision could be catastrophic. We need to be able to sense even pebbles from a distance, or be able to correct course very quickly, or both. Another limitation is that decelerating in this manner may take much more time than the traditional interstellar, fueled deceleration, especially if we want to make the best use of it. Furthermore, the calculations involved in order to best chart the spacecraft's course are computationally expensive. But of the last limitation, that is the one I have the least concern about, as we humans seem to be able to build very fast computers. It is the sensors we need, and it is the map-building and then careful course plotting that will be time consuming.
As I type this, I wonder if we could not attempt to 'throw a snowball' at Mars. That planet will need enough mass to be able to keep its water, so it may have to be a very big snowball.
Monday, July 6, 2009
Gravity and rotational Intertia assisted travel
There are methods to reduce the amount of energy used to travel in space by taking advantage of the gravity and rotational inertia of massive bodies. To use these methods, a celestial navigator must know much about the mass and velocity of these large objects, such as planets as moons, and even stars.
The first of these is called 'gravity assist' or 'gravitational slingshot'. This utilises a close approach to a massive body to change the spacecraft's trajectory relative to the massive object, which can be seen as an acceleration from the point of reference of other celestial bodies. The energy imparted to the spacecraft is subtracted from the linear momentum of the massive body, but the difference in mass between the two makes such loss negligible. Though, it may be worthy of note that this effect might be used to dispose of space junk, by a flyby of a spaceship to impart velocity at an appropriate angle to nudge the junk to fall into the atmosphere and burn up.
The second method is to use the LaGrange points, at which trajectories can be changed with little or no expenditure of energy. These points in space are caused by the orbit of one massive body relative to another, and can be expressed as the 'three body problem', with, for instance, the Sun, Earth, and Spacecraft representing the three bodies. These points have the peculiar property in that an object can orbit them, in spite of their being no object at the center and therefore no gravity. There are an infinite number of paths leading away from a LaGrange point, so a celestial navigator merely needs to pick one by leaving on a particular trajectory.
The Interplanetary Transport Network (ITN) utilizes a path through various LaGrange points in a system of massive bodies, such as a star system. The various courses are calculated ahead of time, by knowledge of system's bodies, their courses, and masses. The ITN is calculated for the solar system. However, the lowest energy course between to places is most likely not the most direct one, so the "(almost) free rides" on the ITN are slow. It reminds me much of taking a city bus system, and having to transfer buses many times. A direct route would be more like a helicopter from point A to B, and takes much more energy but can be completed much more quickly.
So, that's all well and fine for travel within the solar system. We can ship freight (ala "Surface mail") for little energy expense, but when you need to get their in a hurry, you need a more or less direct route (ala 2nd day air, or overnight) and have to expend a lot more energy.
What about Interstellar Travel? Well, we can certainly change direction from different points in the solar system, but when what we want is so far away, why not just launch directly from Earth (or some other leaving point) in that direction? I suppose we can hope to get to the outer edge of the solar system, where the sun's gravity is less and therefore less energy is needed to overcome it. And what about Gravity Assist? According to Wikipedia, the Gravity Assist as described here is only useful for travel with the sun as a reference point, and not travel outside the solar system. Though, and object coming from elsewhere in the universe, could use the energy of the sun's orbit around the Milky Way as an energy source, but that the means to do this are beyond our current level of technology. Of this, I am not sure. Of either the conclusion that Gravity Assist cannot help us in interstellar travel, or that use of the gravity of the orbit of the Sun around the Milky Way is beyond our means. For me, it means that I have to understand more of celestial mechanics in order to either believe what I've been told, or to disprove it or to find a loophole.
Even if the limitations of the gravity assist as currently understood by celestial navigators is true, there is still that possibility of 'swinging by' other star systems on a journey, we just need to figure out how.
The first of these is called 'gravity assist' or 'gravitational slingshot'. This utilises a close approach to a massive body to change the spacecraft's trajectory relative to the massive object, which can be seen as an acceleration from the point of reference of other celestial bodies. The energy imparted to the spacecraft is subtracted from the linear momentum of the massive body, but the difference in mass between the two makes such loss negligible. Though, it may be worthy of note that this effect might be used to dispose of space junk, by a flyby of a spaceship to impart velocity at an appropriate angle to nudge the junk to fall into the atmosphere and burn up.
The second method is to use the LaGrange points, at which trajectories can be changed with little or no expenditure of energy. These points in space are caused by the orbit of one massive body relative to another, and can be expressed as the 'three body problem', with, for instance, the Sun, Earth, and Spacecraft representing the three bodies. These points have the peculiar property in that an object can orbit them, in spite of their being no object at the center and therefore no gravity. There are an infinite number of paths leading away from a LaGrange point, so a celestial navigator merely needs to pick one by leaving on a particular trajectory.
The Interplanetary Transport Network (ITN) utilizes a path through various LaGrange points in a system of massive bodies, such as a star system. The various courses are calculated ahead of time, by knowledge of system's bodies, their courses, and masses. The ITN is calculated for the solar system. However, the lowest energy course between to places is most likely not the most direct one, so the "(almost) free rides" on the ITN are slow. It reminds me much of taking a city bus system, and having to transfer buses many times. A direct route would be more like a helicopter from point A to B, and takes much more energy but can be completed much more quickly.
So, that's all well and fine for travel within the solar system. We can ship freight (ala "Surface mail") for little energy expense, but when you need to get their in a hurry, you need a more or less direct route (ala 2nd day air, or overnight) and have to expend a lot more energy.
What about Interstellar Travel? Well, we can certainly change direction from different points in the solar system, but when what we want is so far away, why not just launch directly from Earth (or some other leaving point) in that direction? I suppose we can hope to get to the outer edge of the solar system, where the sun's gravity is less and therefore less energy is needed to overcome it. And what about Gravity Assist? According to Wikipedia, the Gravity Assist as described here is only useful for travel with the sun as a reference point, and not travel outside the solar system. Though, and object coming from elsewhere in the universe, could use the energy of the sun's orbit around the Milky Way as an energy source, but that the means to do this are beyond our current level of technology. Of this, I am not sure. Of either the conclusion that Gravity Assist cannot help us in interstellar travel, or that use of the gravity of the orbit of the Sun around the Milky Way is beyond our means. For me, it means that I have to understand more of celestial mechanics in order to either believe what I've been told, or to disprove it or to find a loophole.
Even if the limitations of the gravity assist as currently understood by celestial navigators is true, there is still that possibility of 'swinging by' other star systems on a journey, we just need to figure out how.
Friday, July 3, 2009
Sublight Interstellar travel
Speculation of scientific and technological progress which will enable Interstellar travel, and fiction based upon this.
Ever since childhood, I've been interested in space travel. From Star Trek to Star Wars to Asimov to StarGate, it's seemed so fascinating...yet so frustratingly out of reach. We just don't have any warp drive or wormholes. So, I've thought, like many, that we just ought to posit travel at some fraction of the speed of light. This, of course, requires many years for a voyage to even our closest neighbors. There's been suggestions of suspended animation, but while there is more hope that this can be achieved than Faster-Than-Light travel, it is still a long way from being practical. I believe that we'll have generation ships - living communities, living for generations on the journey. In order for there to be a high likelihood of success, we can't limit our travelers to just a few dozen people. We'd need hundreds, in order to make a viable community. And while there's an amount of readjustment that can be made in the expectations of personal space and privacy, there is good reason to assume that we're going to need a lot of room. Our travelers will increase their numbers along the journey. We can try to enforce some responsibility in reproduction rates, but at least replacement numbers plus some fraction will be required, and children are not born in fractions.
We are not just transporting humans and machinery, but also life of other forms, in order to both maintain the nutritional needs of the community during the voyage but also to spread the wide variety of terran life into new places. We are the ultimate seed carriers. Our ships will be Noah's ark, in a fasion. We will need tools to expand and terraform the worlds we find. In summary, our ships will be HUGE. Millions of tons. That requires an enormous amount of energy. Certainly, we can save energy by not attempting to travel at 1G acceleration, but propulsion is key.
I am going to throw a concept on the table, that no doubt will get me some flack. And that is that the fuel should be antimatter. I reason this because it is the most compact energy source possible. Sure, we only have been able to 'manufacture' the smallest amounts of it, and we will need several orders of magnitude more of it, in order to achieve acceleration of one or two million tons. And yes, I realize that our current technology to create antimatters is dreadfully inefficient. But consider, that it may not be the ultimate efficiency that counts, when we have a relatively close energy source which provides more than we can hope to use, and that is our sun, Sol. If we design some antimatter factories that can operate in a tight orbit of the Sun, we can reap the immense power that the sun provides, much better than we get so far away from it. With the power that the first of these factories provide, we have the energy to create many more...hundreds of factories, thousands of factories, from which anitmatter is regularly harvestedand kept, a safe distance from Earth and other important and vulnerable objects. Of course, our interstellar spacecraft will have lots of antimatter inconviently close to them, so the missions will be very dangerous. We can do our best to minimize these risks, but there will no doubt be accidents which will totally destroy the craft and all life aboard.
I present these arguments as I design a solid background for a novel, or several, that I am writing. I want to make the level of technology and society in this beginning era of interstellar colonization believable, with as firm a basis in science as we know it and technology as we predict it. I intend to present a society that reflects human nature as we know it, with its beauty and ugliness together. I'll tell you more, later, on how I am engineering this novel. But for now, I'd like to hear responses that intelligently address what I have proposed. With numbers and logic, if you can.
Ever since childhood, I've been interested in space travel. From Star Trek to Star Wars to Asimov to StarGate, it's seemed so fascinating...yet so frustratingly out of reach. We just don't have any warp drive or wormholes. So, I've thought, like many, that we just ought to posit travel at some fraction of the speed of light. This, of course, requires many years for a voyage to even our closest neighbors. There's been suggestions of suspended animation, but while there is more hope that this can be achieved than Faster-Than-Light travel, it is still a long way from being practical. I believe that we'll have generation ships - living communities, living for generations on the journey. In order for there to be a high likelihood of success, we can't limit our travelers to just a few dozen people. We'd need hundreds, in order to make a viable community. And while there's an amount of readjustment that can be made in the expectations of personal space and privacy, there is good reason to assume that we're going to need a lot of room. Our travelers will increase their numbers along the journey. We can try to enforce some responsibility in reproduction rates, but at least replacement numbers plus some fraction will be required, and children are not born in fractions.
We are not just transporting humans and machinery, but also life of other forms, in order to both maintain the nutritional needs of the community during the voyage but also to spread the wide variety of terran life into new places. We are the ultimate seed carriers. Our ships will be Noah's ark, in a fasion. We will need tools to expand and terraform the worlds we find. In summary, our ships will be HUGE. Millions of tons. That requires an enormous amount of energy. Certainly, we can save energy by not attempting to travel at 1G acceleration, but propulsion is key.
I am going to throw a concept on the table, that no doubt will get me some flack. And that is that the fuel should be antimatter. I reason this because it is the most compact energy source possible. Sure, we only have been able to 'manufacture' the smallest amounts of it, and we will need several orders of magnitude more of it, in order to achieve acceleration of one or two million tons. And yes, I realize that our current technology to create antimatters is dreadfully inefficient. But consider, that it may not be the ultimate efficiency that counts, when we have a relatively close energy source which provides more than we can hope to use, and that is our sun, Sol. If we design some antimatter factories that can operate in a tight orbit of the Sun, we can reap the immense power that the sun provides, much better than we get so far away from it. With the power that the first of these factories provide, we have the energy to create many more...hundreds of factories, thousands of factories, from which anitmatter is regularly harvestedand kept, a safe distance from Earth and other important and vulnerable objects. Of course, our interstellar spacecraft will have lots of antimatter inconviently close to them, so the missions will be very dangerous. We can do our best to minimize these risks, but there will no doubt be accidents which will totally destroy the craft and all life aboard.
I present these arguments as I design a solid background for a novel, or several, that I am writing. I want to make the level of technology and society in this beginning era of interstellar colonization believable, with as firm a basis in science as we know it and technology as we predict it. I intend to present a society that reflects human nature as we know it, with its beauty and ugliness together. I'll tell you more, later, on how I am engineering this novel. But for now, I'd like to hear responses that intelligently address what I have proposed. With numbers and logic, if you can.
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