in the future

[MBA_UIU]

Okay here is the problem from a strictly business point of view. First there is the cost of building such a way station. How many trips would a shuttle (which is already outdated) need to bring enough material into orbit to build such a station? Once built how many trips would it take to bring up the required fuel and supplies? How much energy is being used? Let’s say the shuttle would need to make 10 trips for each trip that goes to the moon. IIRC half the fuel you need to lift off is used to lift the remaining second half of fuel which will power your remaining flight. Without making a number of calculations on efficiency it would appear that you would use less fuel and encounter less cost by just building a bigger rocket. <br /><br />BTW objects in LEO are still within 98% of Earth’s gravity well which would mean that launching anything from them would still need a large amount of fuel for escape. <br /> <div class="Discussion_UserSignature"> <p><strong><font color="#0000ff"><br /><br /> <br /><img id="268587ce-7170-4b41-a87b-8cd443f9351a" src="http://sitelife.space.com/ver1.0/Content/images/store/6/8/268587ce-7170-4b41-a87b-8cd443f9351a.Large.jpg" alt="blog post photo" /><br /></font></strong></p> </div>

 

[frodo1008]

Good post! As I said I don't think the problem of being able to land a lifting body type craft is that great. I am certain that an aircraft/spacecraft type of designer as clever as Rutan will find a way.<br /><br />Also, I indeed do think that someone will also find a way to a far better TPS system. And for its own purposes (an extremely rapid responce type of craft) the Air Force is going to fund the research. And as the military space budget is actually far larger than NASA's. I think they will find the answers that people such as Rutan will then be able to use for civilian uses!<br /><br />So, there really is some hope here!<br /><br />In the meantime NASA can finish the ISS the way it should be, and then lead the way back to the moon and on to Mars! <br /><br />As I have said in other posts we need to be positive on both the efforts of the likes of Rutan AND NASA!

 

[frodo1008]

The important change that is needed to go on to the moon from LEO does NOT depend on the amount of gravity here anyway. For instance, looking up the velocities of Apollo 8 on google I found that the orbital velocity was 7,600 meters per second, and the velocity used to escape to the moon was 11,800 meters per second. This represents an increase in velocity of 3,200 meters per second. So the anology of the actual force of gravity really doesn't apply here.<br /><br />However, what I was proposing would be to use a type of continous thrust, small thrust type of engine, such as some form of electric propulsion. Even with a small thrust you have a continuing change in velocity as you don't have an appreciable friction with the Earth's atmosphere. It would take longer, but it would take far less fuel. Heck, if you could supply the electrical energy from large solar arrays, then it would take zero fuel weight. And once the arrays were brought up no additional surface to LEO flights would be necessary! <br /><br />However, I would be willing to admit that such a system quite probably would not be in place until quite some time after NASA's current moon program had already gone back to the moon. But for true efficient travel between here and the moon this would be the best possible system! It would also suffice for transportation between space stations in a High Earth Orbit, Goecynchronous Orbit, L1 station, and finally a moon orbiting station! <br /><br />Eventually, to have a true cis-lunar industrial commerce system going this would be the type of transportation system that would be needed. It WILL happen (and even be highly profitable to those countries and companies involved), the only question is how long in the future? <br /><br />I would say the it would be quite possible to have such a system in place by the time that most people estimate the first manned mission to Mars of about 2030. <br /><br />Much of the material need for such an infrastruture does NOT eve

 

[MBA_UIU]

First of all our present knowledge in ION thrust drives would not be powerful enough to keep you in LEO orbit. Secondly, even with the best solar energy sails that could made they would be so massive that their weight would be far greater then using a liquid fuel source. I highly doubt that any ION engine could be made that would provide enough thrust to make using that system, even 30 years in the future, particle. And finally you must remember that ION drives still use fuel!! This means that, just like their liquid driven cousins, ION ships would still need to carry a fuel supply. Think about how massive the size of this craft would be. That alone makes it impractical for this application. <div class="Discussion_UserSignature"> <p><strong><font color="#0000ff"><br /><br /> <br /><img id="268587ce-7170-4b41-a87b-8cd443f9351a" src="http://sitelife.space.com/ver1.0/Content/images/store/6/8/268587ce-7170-4b41-a87b-8cd443f9351a.Large.jpg" alt="blog post photo" /><br /></font></strong></p> </div>

 

[frodo1008]

There have been vehicles powered by electric propulsion from earth orbit, but I would admit that they are far too small for manned trips to the moon. However, there are ways and means to improve the thrust, such as the Vasimir project, which some far thinking people are exploring. <br /><br />Also, I know that it has political baggage, but using nuclear propulsion in space itself is going to happen, and quite probably in the same time frame.<br /><br />My major point is that I actually agree with you if you are talking about purely chemical propulsion, and bringing up such propellents form the Earth itself. Bringing up enough such fuel would be prohibitive. However, if there really is a considerable quantity of water ice in the deep craters of the moon's poles, then it becomes feasable to generate rocket fuel on the moon itself, and it is far cheaper and easier (1/6 th Earth's gravith, and no atmosphere) to ship such fuel to an orbit around the moon, and then use this fuel for such a system.<br /><br />My major point is that there are solutions to this problem. True, some of them may require some thinking out of the box, but it is certainly easier than "space elevators", which I don't discount either. <br /><br />If we are going to go back to the moon to truly exploit its resources instead of just plant flags, then we are going to have to find something easier (and therefore far cheaper) than just using bigger rockets!<br /><br />

 

[pathfinder_01]

“First of all our present knowledge in ION thrust drives would not be powerful enough to keep you in LEO orbit. Secondly, even with the best solar energy sails that could made they would be so massive that their weight would be far greater then using a liquid fuel source. I highly doubt that any ION engine could be made that would provide enough thrust to make using that system, even 30 years in the future, particle. And finally you must remember that ION drives still use fuel!! This means that, just like their liquid driven cousins, ION ships would still need to carry a fuel supply. Think about how massive the size of this craft would be. That alone makes it impractical for this application.?”<br /><br />That depends, electric propulsion is far more fuel efficient than chemical propulsion. You still need fuel but a lot less of it. This can translate into cost savings, for instance the Smart 1 probe hitched a ride on a rocket that carried another satellite into orbit. It did take a year for the craft to go from earth orbit to lunar orbit, but still it used a smaller rocket to get to the moon. <br /><br /><br />Now for a manned trip to the moon ION is probably not the way to go. The long trip combined would require more supplies and would subject the crew to more radiation from cosmic rays. Plasma or Nuclear thermal maybe, but more than likely a chemical rocket would be best for such a short trip. <br /><br /><br />For an unmanned cargo ship it could work quite well. <br /><br />On a longer trip an electrically powered craft could possibly achieve a higher speed than a chemically powered one and get there in less time. An electrically powered probe could go to the outer planets without the need for fly bys. <br /><br />The only hitch is that an electrically powered craft would need to start breaking about halfway to the destination. For a trip to mars it would be about even, with the chemical rocket. It would possibly be cheaper and it would likely have greater margins. . A