Photons of light have zero rest-mass, but they do have momentum. if the area of a highly reflective (>95%) surface is sufficient, most of the photon's momentum is transfered to the sail and can produce incredible amounts of acceleration. the trick is to maximize surface area (for more propulsive thrust) and reflectivity of the sail, otherwise you wind up with too much photon absorbtion which causes the sail to heat up. the straight forward photon or Light Sail is an old concept that, while promising in the near term since the technology is fairly achievable, there are even more promising sail concepts on the drawing board, like magnetic propulsion sails and plasma sails. A really excellent far-term space sail concept is the StarWisp, which uses a very high power laser to produce thrust over interstellar distances. the StarWisp is huge, and so is the laser needed to provide power to the craft over a distance of several light years. But the concept is entirely feasible. Such a craft could reach Alpha Centauri in less than 50 years.
This is the problem with the American public. We want practical results NOW. All we seem to care about is the bottom line, with no room for creativity or imagination. Who cares if the research might be useful extremely valuable to us in years to come. Who cares if it is just really interesting for its own sake? This type of research is needed if we are ever going to explore mars or any of the other planets in our solar system. And why would we want to do that you ask? Why would we even think to spend our tax dollars on useless research into our solar system and planets and comets and asteroids? I don't know about anyone else, but that question is so meaningless to me. I have never even dreamed of NOT pursuing scientific investigation of our universe, simply to KNOW what is out there. if not for the future of exploration or space resource development then to satisfy the desire to know a little bit about where we come from and where we are going. Studying the climate and geologic history of Mars in particular could give us clues into our own future and the results of major climatic change. the desire for "practical" research is fine, but pure research is needed to make the real strides in scientific knowledge that has helped our civilization thrive and clutch its way out of the mud of ignornace that we were born into.
From what I remember, the AF had to kill the idea of launching shuttles from Vandenberg after figuring out it would be too expensive to build the facilities to launch and house the shuttles. Something like that. The idea was that shuttles launched from Vandenberg could reach polar orbit without needing as much fuel as ones launched from Cape Canaveral, but overall the shuttle is too expensive.
The name was short for Dynamic Soaring, which is a concept that dates back to Sanger's original design for a german spaceplane in WWII. Given the less than humorous attitude of the Air Force, I doubt they intended it to be funny, though looking back on it now, it kinda is.
This is the sad part about the entire Iridium fiasco. It gives a bad light to private space projects in the eyes of venture capitalists and they, sadly, are the only ones who have the money to make some of these dreams a reality. Big Government is never going to get the ball rolling in space. It is through the privatized exploitation of space and its resources that will get people interested enough to go there, build there, and live there. I am amazed too by the fact that it is the year 2000 and we are little further along in our exploration of space than we were 30 years ago! What are we waiting for? It is daunting to people like me who have grown up waiting for the day when I can take a trip to the moon and see at least a small glimpse of the future of our people. I know it will happen SOMEDAY. I just hope to God I live long enough to see it, and that I even have to say that is more than a little discouraging to those who have dreamed of it for so long.
I think that NASA does want to pursue even greater challenges with regard to space exploration. It is that the American public, and hence Congress, are too fickle and uninterested to put up the money to support it. Short of its perceived entertainment value, the majority of americans seem to have little interest in space exploration. NASA has always wanted to send people to Mars and build moon bases and the like. I know that the engineers at NASA are imaginative and can be forward thinking about the future of humans in space. The problem is that NASA is a federal agency and is thus restrained from doing anything that the U.S. government doesn't want to spend the money on, and the red tape of beaurocracy is awfully thick these days. Commercial space endeavors have great potential for opening up space to future industry, but again, the money to fund these projects has been slow in forthcoming. Why is this? It is because space is too risky and expensive for venture capitalists to fund safely. Until it can be proven that space can make a profit, and a big profit at that, the money will be in short supply. The U.S. gave up on its forward drive into the unknown after we beat the Soviets to the moon. Now, sadly, we stagnate as a space nation, sending endless shuttle missions to putter around in low earth orbit. I know that those at NASA have the same dreams that you and I have, going to Mars and finally seeing what's there, building a permanent base on the moon, and someday sending spacecraft beyond our solar system to see what's out there. However, until there is vocal public support, or someone makes a major commercial space breakthrough, I think we will continue to stagnate. I for one am glad that the Chinese have taken an interest in manned space flight, whatever their reasons.
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Photons of light have zero rest-mass, but they do have momentum. if the area of a highly reflective (>95%) surface is sufficient, most of the photon's momentum is transfered to the sail and can produce incredible amounts of acceleration. the trick is to maximize surface area (for more propulsive thrust) and reflectivity of the sail, otherwise you wind up with too much photon absorbtion which causes the sail to heat up. the straight forward photon or Light Sail is an old concept that, while promising in the near term since the technology is fairly achievable, there are even more promising sail concepts on the drawing board, like magnetic propulsion sails and plasma sails. A really excellent far-term space sail concept is the StarWisp, which uses a very high power laser to produce thrust over interstellar distances. the StarWisp is huge, and so is the laser needed to provide power to the craft over a distance of several light years. But the concept is entirely feasible. Such a craft could reach Alpha Centauri in less than 50 years.
This is the problem with the American public. We want practical results NOW. All we seem to care about is the bottom line, with no room for creativity or imagination. Who cares if the research might be useful extremely valuable to us in years to come. Who cares if it is just really interesting for its own sake? This type of research is needed if we are ever going to explore mars or any of the other planets in our solar system. And why would we want to do that you ask? Why would we even think to spend our tax dollars on useless research into our solar system and planets and comets and asteroids? I don't know about anyone else, but that question is so meaningless to me. I have never even dreamed of NOT pursuing scientific investigation of our universe, simply to KNOW what is out there. if not for the future of exploration or space resource development then to satisfy the desire to know a little bit about where we come from and where we are going. Studying the climate and geologic history of Mars in particular could give us clues into our own future and the results of major climatic change. the desire for "practical" research is fine, but pure research is needed to make the real strides in scientific knowledge that has helped our civilization thrive and clutch its way out of the mud of ignornace that we were born into.
From what I remember, the AF had to kill the idea of launching shuttles from Vandenberg after figuring out it would be too expensive to build the facilities to launch and house the shuttles. Something like that. The idea was that shuttles launched from Vandenberg could reach polar orbit without needing as much fuel as ones launched from Cape Canaveral, but overall the shuttle is too expensive.
The name was short for Dynamic Soaring, which is a concept that dates back to Sanger's original design for a german spaceplane in WWII. Given the less than humorous attitude of the Air Force, I doubt they intended it to be funny, though looking back on it now, it kinda is.
This is the sad part about the entire Iridium fiasco. It gives a bad light to private space projects in the eyes of venture capitalists and they, sadly, are the only ones who have the money to make some of these dreams a reality. Big Government is never going to get the ball rolling in space. It is through the privatized exploitation of space and its resources that will get people interested enough to go there, build there, and live there. I am amazed too by the fact that it is the year 2000 and we are little further along in our exploration of space than we were 30 years ago! What are we waiting for? It is daunting to people like me who have grown up waiting for the day when I can take a trip to the moon and see at least a small glimpse of the future of our people. I know it will happen SOMEDAY. I just hope to God I live long enough to see it, and that I even have to say that is more than a little discouraging to those who have dreamed of it for so long.
I think that NASA does want to pursue even greater challenges with regard to space exploration. It is that the American public, and hence Congress, are too fickle and uninterested to put up the money to support it. Short of its perceived entertainment value, the majority of americans seem to have little interest in space exploration. NASA has always wanted to send people to Mars and build moon bases and the like. I know that the engineers at NASA are imaginative and can be forward thinking about the future of humans in space. The problem is that NASA is a federal agency and is thus restrained from doing anything that the U.S. government doesn't want to spend the money on, and the red tape of beaurocracy is awfully thick these days. Commercial space endeavors have great potential for opening up space to future industry, but again, the money to fund these projects has been slow in forthcoming. Why is this? It is because space is too risky and expensive for venture capitalists to fund safely. Until it can be proven that space can make a profit, and a big profit at that, the money will be in short supply. The U.S. gave up on its forward drive into the unknown after we beat the Soviets to the moon. Now, sadly, we stagnate as a space nation, sending endless shuttle missions to putter around in low earth orbit. I know that those at NASA have the same dreams that you and I have, going to Mars and finally seeing what's there, building a permanent base on the moon, and someday sending spacecraft beyond our solar system to see what's out there. However, until there is vocal public support, or someone makes a major commercial space breakthrough, I think we will continue to stagnate. I for one am glad that the Chinese have taken an interest in manned space flight, whatever their reasons.