The journey to Mars is a complex and challenging mission. The first step is meticulous planning that begins here on Earth, long before any spacecraft leaves the ground. Engineers, scientists and astronauts spend years calculating every detail of the journey, from fuel to the best time to launch. Because Mars and Earth orbit the Sun at different speeds, launch windows occur every 26 months, when Mars and Earth are closest to each other. A small margin of error can cause the mission to fail or result in dangerous deviations.
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