Re: NASA finds Masses of Water on Mars !!!!!
Posted by Southern Man on May 31, 2002 at 08:47
Re: NASA finds Masses of Water on Mars !!!!! (DA Morgan)
ď1. Who said infinitely? Who even implied it? Keep the hyperbole in check.ď
See the quotes I put around infinitely? So letís get down to basics. Just how big do you think a solar panel would have to be to electrolyze enough hydrogen and oxygen in say a month to lift a craft that will carry 2 or 3 people back to earth in say 6 months. Just to set some parameters, the Apollo 11 command module weighed 13,000 pounds and was only designed for a few days use. Now how many square meters does that panel have to be? And how much does it weigh? And how did all that panel weight get to Mars?
Iím not sure I understand your agreement. I said hydrogen was energetic enough but then, as from the very beginning, asked where are you going to get the energy to make it.
ď3. Actually it doesn't. The atmosphere on Mars is so thin it doesn't really pick up much sand. Just enough to be seen from earth.Ē
Iím not sure I totally agree (http://powerweb.grc.nasa.gov/pvsee/publications/mars/removal.html) but Iím not going to argue the point. Put the panels high enough above ground and mount them like a wind vane so when the wind blows too hard they just give and they can survive.
ď4. Making fuels from nitrogen takes more energy. Ö ď
Yes. Thatís why you get more energy release when you burn them. ADK wanted nitrogen. I think we are in agreement that nitrogen isnít a requirement. It would be nice to have but isnít needed if we can find enough energy to make pure hydrogen fuel.
You make a good point about dropping toward the sun however we donít have years to make this trip. The slower we go the more weight we need to accelerate in the form of expendables (food, water, air). More weight = more energy needed. The faster we go the more energy we need to accelerate. The minimum energy trajectory is tricky to calculate.
ď5. The only fuel we need to return from Mars is hydrogen and oxygen generated by electrolysis of water (or by some other means). Why make a problem more difficult than it need be?Ē
Why make it more complicated? Because wishful thinking doesnít always work. Sometimes you have to be realistic and understand that everything isnít possible just because you want it to be. Sometimes you have to get out a calculator and figure out that you canít get to the stars in a few hours using a rubber band powered airplane. Just finding water doesnít mean the fuel problem is solved. Water is not hydrogen/oxygen fuel. Give me a billion ton nuclear reactor here on earth and a couple of years time and I can make enough fuel to go lots of places. Limit the time to generate the fuel and the weight of the energy conversion equipment and it canít be done.