Question

How long will it take a manned mission to reach Mars?

Answer 1

Approximately 150 to 300 days. if we choose proper launch window.

Explanation:

Earth goes round the sun in 365.24 days and mars in 687 days.
So both planets comes near only once i n 2 years. So if we choose the proper launch window for mars journey ti will take about 150 to 300 days. with present day rockets..