On Mon, 13 Aug 2012 09:07:30 -0700 (PDT), "Ramon F. Herrera"
wrote:


I read somewhere that a manned trip to Mars would take years. The
"Curiosity" probe, however, took only 8 months.

The manned flight duration is for the round trip. Curiosity won't be
coming home!

The outbound flight will be about the same (using conventional
propulsion) whether it is manned or unmanned (eight to ten months,
depending on variations in the Earth/Mars distance with each close
approach... 2003 was particularly close.)

The return flight will take about twice as long, if they leave within
a month or so of landing on Mars. Beyond 30 days or so on Mars, Earth
is no longer in position to return quickly, and the crew has to wait
another two years before returning. Flying a course that swings by
Venus first will cut some of the return time, but we're still talking
about years total flight time.

Brian