Just figure out how much man-carrying spacecraft cost per kilogram. Then calculate the total number of kilograms of spacecraft needed for a manned trip to Mars and back. Multiply the two numbers together and add a generous buffer for overruns, operating costs, .... It comes out to a trillion dollars.
Space shuttle 83,000 kg for $2.1 billion gives about $25,000 per kilogram (empty weight).
A launch-from-low-Earth-orbit system would need to weigh at least 10,000 tonnes (empty) = 10,000,000 kg. That comes out to $250,000,000,000 ($250 billion) just for the hardware. Now add the cost of the boosters to get the personnel, equipment, supplies (food for 3 years), fuel (100,000 tonnes), etc into orbit.
The Space Shuttle: General Information
David F Mayer
Space/Science » in reply to The Luddite legions are on the march.
The one trillion dollar figure is not too hard to figure out.