You can't just point and shoot. Do that and your spacecraft will miss Mars. So, rocket scientists use a maneuver called a Hohmann transfer orbit to send a vehicle from a small circular orbit (say, Earth's) to a larger one (Mars). The transfer orbit must be timed precisely so that when the spacecraft leaves Earth it arrives at destination orbit at the same time Mars reaches the same position. Earth and Mars only come into the right orbital alignment for a Hohmann transfer once every 26 months to allow a survivorable six-month journey with the use of available propulsion techniques. How does going back to the moon help?
Things to consider