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It hasn't rained in Death Valley in 200 years...It hasn't rained on Mars 200 millenia or longer. ANd wind erosion doesn't make the ground softer, it makes it harder. It picks up the lighter materials, leaving the heavier materials to get compacted down. And without water or living things to break down the rock, most of Mars will be exactly that, pure solid bedrock. The dust from the dust storms isn't going to be more than a few inches thick.
SOmehow the conversation from plasma fusion to fission. I admit I'm a little uncomfortable about the use of fission in an area where humans are present (be it on the ground or a manned space ship). Current plasma research also produces a bit of radioactivity, but at least there is no worry of an uncontrolled reaction. The Princeton Plasma Physics Laboratory, funded by the US Department of Energy, is about 10 miles from my college. Two weeks ago, the Physics Club went for a little field trip over there and got the grand tour. The current plasma research is for a D-T reaction, combining Deuterium and Tritium (hydrogen 2 and hydrogen 3 if you will). They are researching this type of fusion because it is easier then the others. Deuterium and Helium 3 is a more efficient reaction, but requires a higher heat and Helium 3 isn't all that common here on Earth. There is, however, a nearly unlimmited supply of He3 located in lunar ore. A lunar proccessing plant could provide enough fuel for plasma rockets for centuries to come.
Yes, the magsail approach has great potential for crossing vast distances in a "short" time. I don't claim to know as much as I should about this type of propulsion but this is what I do know. Depending on the configuration, the maigsail is going to produce an accelleration of about 0.1 g This gives you Earth to Mars in approximately 8 weeks.
If you want the people in the ship to live in a higher gravity field than .1 g then your goign to have to produce artifical gravity in a way other than thrust. A rotating hub format being the most favored method for this.
A lot of people seem to think of Mars as a small, distant Earth with a thin atmosphere and no biosphere. And by thinking like that, solutions are made that won't work well if at all.
When the word "dirt" or "soil" is used, it conjures images of the brown stuff underneath the grass in the back yard. But there hasn't been rainfall on Mars in a very long time. Think of how hard the ground gets on Earth when it hasn't rained in a month or so. Most of the land on Mars is going to be very hard as the wind blows the smaller stuff out and the larger stuff compacts. ANd that's where there is dirt at all. Dirt is mainly produced by numerous weathering factors, but the two biggest things needed to create dirt are living things (such as plants) and water.
Your right on the conversion; like I said, bad things happen when posting after bedtime.
As for the actual equations, I checked them 3 times. The only source of error is if I misunderstand the actual basis of nuclear propulsion. The D-He3 equation D + "3"He -> "4"He(3.7MeV) + p(14.2MeV)
It gives you 3.7 million electronVolts of energy in standard helium and 14.2 million electronVolts of energy in the form of protons. I based my equations of an example using a D-D reaction; the products were only .8 million electronVolts in He3 and a bunch of radioactive neutrons. In the example, only the He3 was utilized (thrown out the rear end of the rocket nozzle). So my numbers only involved the energy of the He4. So I don't really know if the protons can be used. If they can, the system has nearly 5 times as much energy. In that case, only 90% of the ship's mass is fuel instead of 99.6%
So the real problem isn't the efficiency of the engine, but the length of time it's being used and how hard it's worked. You've got to spit an aweful lot of little helium atoms, or helium atoms and leftover protons, to get eleven hundred tons accellerating at .4 g By the original numbers, it's ejecting nearly 5 kg of propellant per second. And 12.8 days is over a million seconds.
But I definately agree that poetic liscence can give the ship an added boost of efficiency
grrr. Never post after bedtime, it makes you look stupid. 1 million kg is 227 tons, NOT 1100 tons. So a rocket accelerating at +/- .4g for 12.8 days is going to require ~99.6% of it's take off mass to be it's Deuterium and Helium-3 fuel no matter how big it is. So now you can make the ship as big as you want, but remember 99.4% of it is going to be fuel. If you want a ship whose empty weight is 1000 tons, it's going to require 25 000 tons of fuel
Ok, it's even worse than that, I had the metric to English conversion backwards. 1 million kg IS 1100 tons, but 4430 kg of payload isn't 5 tons, its just one ton.
Hi, I just read this post and thought I'd add my 2 cents in.
If we assume that the total mass of the ship (Mo) ( = mass of fuel (Mp) + the mass of the ship & cargo (Mi)) is a nice even 1 million kg (roughly 1100 tons), then it turns out that Mp = 995570 kg and Mi = 4430 kg That's right. The ship is 99.5% fuel. And it gets worse as the ship gets heavier.
Another problem is that your 4430 kg is the weight of the ship and the cargo (i.e passengers). 4430 kg is only 4.88 tons. I hope you have a superlight material to build your ship with. For comparrison, the Space Shuttle is roughly 125 tons empty.
Sorry to paint such a grim picture for you.
ED
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