in early 2030s. Just my amateurish opinin.

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1)The 1st chinese unmanned mars probe could be launched in 2013

2)Chinese Manned moon mission 2020

3)Chinese Manned mars mission early 2030s.

There will be a min energy launching windows around that time.

A martian spaceship could be module assembled in LEO using CZ--9 rockets.

The unknown is whether nuclear propulsion could be used.

I think an all chemical rocket ship is feasible but it will be big in LEO.

Could unmanned propellent plants be sent to mars to make propellent for the home trip?

^{http://en.wikipedia.org/wiki/Manned_mission_to_Mars}

" ......Windows

One of the considerations when traveling to Mars from Earth or vice versa is that the energy needed to transfer between their orbits hits a low point every 26 Earth months (2 years and 2 months).^[11] So missions are typically planned to coincide with one of these windows. In addition, the energy needed in the low-energy windows varies on roughly a 15 year cycle.^[11] The easiest windows only need half the energy of the peaks.^[12]

In the 20th century, there was a minimum in the 1969 and 1971 launch windows and another low in 1986 and 1988, then the cycle repeated.^[11]..."