The technology for interplanetary travel is here now. Electrical propulsion will let us go from Earth to Mars in under 100 days with no "window" launch restrictions at all as to when we start. The payload is roughly 25%, from here to Mars AND RETURN- note that and return. It is so far better that chemical propulsion that there is no excuse for using rockets for any trans-lunar mission, and electrical still excels even with lunar missions.
MARS TRIP Chemical Rockets from LEO Electrical
Window once every year and a half any time
Trip time Hohman 270 day coasting 90-100 days with- worst .001g system
45-70 days with- 0.01 g system
Payload 12% one way 25% round trip
(lots of power at Mars)
Change mission You have had it IF food/air possible change
Even more to the point with easily demonstrated Nuclear power plants ( which remove un-wanted bomb grade material from Earth permanently), should allow 60 day Mars missions, and open the whole Solar system to us.
The key to Electrical propulsion is it offers a very low thrust (0.01 to 0.001 g) , BUT it thrusts all the time, day after day, building up a total velocity at half way that far exceed Solar escape velocity before we must decelerate to attain orbit at the destination. The thrust depends upon the power to weight ratio of the power supply. Existing solar cell power supplies allow 0.001 g here now, and SNAP (Small Nuclear Auxiliary Power units) which have been designed on paper should allow 0.01 g. These engines have been flown in space. This is not in the far future, it is here now.
The earth exit trajectory from LEO (Low Earth Orbit) will look line an ever expanding spiral, (very like a phonograph record groove but the grooves also get further and further apart) and must be controlled with extreme precision to be sure that they final spiral when the ship attains earth escape velocity is pointing in the right direction for the destination. This control can be done by use of higher force or lower force (feeding more or less mass into the engine exhaust). The power available is all used all the time and is a constant dependant only on the power supply available. Power, P, is Energy per time, but that also force times velocity.
P (in watts) = E/t = (F d) /t = F v
Since Power is a constant, the force can be increased by lowering the velocity of the exhaust of the engine. The ISP (force per mass) which is proportional to velocity does go down, i.e. less efficient use of the mass, but for precision control it is nearly perfect.
To reiterate THE WHOLE SOLAR SYSTEM IS OPEN TO OUR EXPLORATION NOW! All it takes is our will to do it. If we financed this with just 10% of the money spent on entertainment, that would make a healthy space program!
We as a race will either go into space or become extinct. Does this suggest perhaps our priorities are wrong?
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