Every two years or so, Mars and Earth reach their closest point, called “opposition”, when Mars can be as close as 55,000,000 km from Earth. How long does it take to get to Mars? You can’t point directly at Mars and start firing your rockets, because by the time you got there, Mars would have already moved. How to Get to Mars with the Least Amount of Fuel:The primary concern of engineers is how to get a spacecraft to Mars, on the least amount of fuel. Eventually that orbit will intersect the orbit of Mars – at the exact moment that Mars is there too.