A: There is no ‘best’ way to reach the Moon because space travel is always a matter of time, fuel, and payload mass. If a mission carries a human crew, mission designers will prioritize speed to reduce astronauts’ exposure to space radiation, at the expense of burning more fuel.

In contrast, a robotic cargo mission might take a longer, more circuitous route to save fuel and carry more mass. Missions have different goals and budgets, so the ‘best route’ depends on what the spacecraft is carrying and how quickly it needs to travel.

A recent study by researchers from Brazil, France and Portugal, published in Astrodynamics, has reported a new ‘best’ route while minimizing fuel use. Using a mathematical tool called functional connection theory (TFC), they used the L1 Lagrangian point – a strategic point located between the Earth and the Moon – as the midpoint of the route.

They then designed a trajectory where a spacecraft would fly by the Moon to reach an orbit around the L1 point, before ultimately landing on the Moon’s surface. To move the spacecraft, the team took advantage of invariant manifolds, which are like natural gravitational currents in space. Using TFC, the team was able to evaluate millions of possible paths to find the most efficient path.

According to the team’s results, the new route could reduce fuel use by at least 58. 8 m/s compared to previous options.

On the other hand, it takes about 32 days to reach the Moon.