Well, solving the problems in sending a man to Mars is a Herculean task. But it is simply not impossible.
Rather than launching the entire spacecraft, it can be sent up in form of different modules using conventional launch systems. These modules can then be assembled in space, similar to the way the space stations are set up. This would save us the problems of launching the entire payload at one go, as it would consume huge amount of fuel. For example, we would not have to build a new launch vehicle capable of carrying such a heavy load.
Use of new technologies of propulsion, like ion propulsion, nuclear propulsion, antimatter propulsion and so on (see different propulsion technologies) can reduce the time of flight and consume lesser fuel.
Heavy shielding of the spaceship and optimizing the spacesuits could reduce the effect of cosmic radiation on humans.
As for the resources, once on Mars, man can ‘harvest Mars' and get almost anything he needs for survival.
Yes! He can even get the fuel for return journey to earth. Let us see how.
As compared to earth, Mars has a meager atmosphere. It has 95% carbon dioxide. Though this carbon dioxide is not useful directly, we can use it to produce a variety of useful materials.
Martian rocks and soil contain a lot many useful elements like magnesium, hydrogen, oxygen, water. We only need a solvent to get them out. When carbon dioxide is compressed to a pressure of 73 atmospheres and heated to 31.1 degrees Celsius, it becomes a supercritical fluid--and a marvelous solvent.
Supercritical carbon dioxide molecules flow into solid matter. They surround atoms and pull them away.
Supercritical fluid can dissolve magnesium. Magnesium ignites easily and can be used to fuel rockets.
Another method suggests the use of magnesium as a material for many parts of the lander, like wheels, arm etc. at the end of the mission we can use the magnesium as fuel for return to earth.
Water, Oxygen and other gases
Supercritical CO2 can also be used to generate water. The hydrogen in the rocks reacts with supercritical carbon dioxide forming water and leaves carbon behind in the rocks. Once water is produced, water can be split into hydrogen for fuel, and oxygen for breathing or as an oxidizer for some sort of engine.
Other gases can also be produced in similar manner.
One source of water can also be the polar ice caps in Mars.
Also hydrogen peroxide, found in Martian atmosphere, is believed to be a potential chemical that can satisfy our needs on Mars.
One cubic meter of hydrogen peroxide (1.47 tonnes at 0 degrees centigrade) yields
once all this is done it is easy to build up an on-site greenhouse to grow vegetation.
Thus, given time, we can overcome.