New Mars Forums

Agreed. IMO anything that can't lift at least 2000 kg is pretty much useless. Sounds like a bad investment when you consider the cost of superconducting track and the tiny payload. My guess is that these would have to be type I superconductors because of the high magnetic fields and currents, which require very expensive cyrocoolers.

Well, because of the shock angle and lack of concave undersurfaces, I'd say that it's not supposed to be a wave rider, plus the fact that on JP's website there are pictures (in the videos) that look like traditional wave riders, suggesting that they have not come up with an amazing new way to build wave riders. The problem with the engine in my mind is that unless they can figure out a way to accelerate all the air that passes over the craft, the are going to push the little bit of air they do have very quickly, and no matter what the method used is, that is going to be energy intensive. Not to say it can't ever work, they probably have a few tricks up their sleeve. I think something similar, using thin plastic mirrors instead of solar panels would work better, (thin large mirrors are defiantly my pet favorites no matter where they're used ) if some sort of rarified gas scramjet could be designed that used concentrated light instead of fuel as a heat source.

The shuttle technology will be reused, only not the orbiter. The tanks and solidfule boosters will make up part of the CEV system along with new and 60's tech.

I fail to see how aristotle's few innitial assumtions that were wrong, makes our innitial assumptions about the accuracy and presision of pellets, laser pulse power and accuracy, fluxuations in the earth gravity field, the destructive shock waves in a vaporised pellet and so on wrong. Another problem with a solar sail is that since they are so thin and dellecate, unless your suborbiter is the same size as the sail you will only get a little bit of momentum exchange, most of the sial will rip off and go past the suborbiter.

Have a spat if you like but leave Aristotle out of it. Without his philosophy western civilization would be very different. While logic cannot explain the universe, it is necessary for everyday life and the scientific method, and therefore going into space , which depends on scientific research, needs logic and Aristotle.

Thanks, so instead of a cowl on it's scram jet it uses the boundary layer. Sounds cool, too bad it's inefficient. He said that all the first scram jets were like that, I wonder if they are easier to design or something? Seems all you'd need are fuel injectors and maybe a flame holder. Do you know what the geometry of the thing is?

I agree, it is not really practical, however, I think the concept of intersteller travel with pellets was that the pellets are shot in a strait line one after another very quickly, another aspect we haven't discussed, and the starship catches up with each pellets and then with an onbord powersorce and probably some kind of magnet pushes the pellet backward, thus gaining momentum. So it's different from the earth to LEO version. Sort of line a liner electric motor, with pellets instead of a track.

I have no personal intrest in traveling at reletevistic velocities, holding out for FTL  , so I leave you on your own to figure out the magsail. One thing that does intrest me about them is that once I read an article somewhere that claimed besides their thurst they provided excellent radiation shielding. Wish I remembered where that was...

I'd like to point out, if belatedly, that the Soyuz has been upgraded many many times since the russians first laid down the plans and is the cheapest maned spacecraft plus being on of the most reliable. Upgrades are not evil, if done well they can be very helpful in extending the usefulness of spacecraft over it's lifetime.

Please keep reading on page nine, the rocket moves in a long arc around the balloon/station. To heat the hydrogen coal dust is mixed with it so it will absorb the sunlight very well, it is inside an fussed quartz regenerative cooled nozzle. At 30 km up there are no winds, it is perfectly calm. The aiming is a problem, but I think it can be solved by putting the balloons on the ground or lower and using a smaller secondary mirror for aiming. It may not work, but requires less costly infrastructure than the moon pellets idea. What it really comes down to on each others designs is how accurately your mirror/rail-gun can be aimed. While 1400 km is a long distance, it is no where near the distance between the earth and the moon. To hit a meter sized target my mirror must be accurate to 0.040926 degrees in the x and y axis. Hard, but not undo-able. The distance from the moon to the earth is 360,000 to 405, 000 km. There is the first problem that must be dealt with by careful timing as being off by 45 000 km could leave the pellets in a drastically different orbit, or miss orbit all together by hitting the earth or flying past it. Secondly, the since the distance is so small if you want to be accurate to one meter (having the pellets spread out over thousands of square meters is not going to be good no mater how much your sub orbiter can adjust), you need to have a rail-gun accurate to 1.592x10^-4 degrees, and be able to accelerate your pellets to 2800 m/s. I can't think off any way you are going to be able to get that kind of accuracy. if one end of the rail-gun assuming 500 meter length is off just 0.2 millimetres you will miss the target, if the pellet has no other forces to disturb it like a slightly less polished rail on one side that but the time it reached earth would have been amplified into a huge difference, or some other slight change. Then there is the laser that is supposed to explode these pellets at just the right time which is going to add a good bit of cost and complexity. Just because theoretically we can determine the path of a particle because of the laws of physics doesn't mean that we can be perfectly accurate because our machines all involve a certain level of ambiguity. I don't see how this is going to save money without some changes.

I know infrastructure can reduce costs, but disposible pellets with extremely acuret GPS recivers and thrusters sound like a waste to me. Either you are going to have to build a huge mass driver on the moon with real human workers, plus import a hefty nuculer reactor or solar power plant, plus import all the electronics and thrusters for each individual pellet, I'm not sure you'd come out ahead unitl you had an automated factory for the chips and thrusters and an automated minning base to get the raw materials, since you can only use each pellet once.  You are probably right that it can't compete with other interorbital methods like solar/nuculer thermal. The best use for suborbital flights is to make a bundle from tourism and use that money to get to orbit.

That sounds VERY expensive, and therese pellets are being shot from the moon? That's a lot of infrastructure and will need quite the industrial base on the moon. I don't think this is any where near a short term option, though I really like the concept of the rocket in reverse. I'd use it for interplanetary missions first though, were it's easier to aim. The craft uses some external power source to acellerate the pellets/gas like nucelar electric and external MHD thrusters?