As humanity looks to expand its presence on and around the Moon, researchers have worked hard to fine-tune small details that could make or break a lunar mission. A team claims to have mathematically mapped out the most fuel-efficient route yet to the Moon.
According to a recent Astrodynamics article, the new route reduces fuel consumption costs by 58.80 meters per second (m/s) compared to known calculations. For the analysis, the team used functional connection theory, a mathematical framework that solves constrained optimization problems without requiring costly computer simulations of spaceflight. The team behind the new study simulated 30 million different routes, comparing its calculations with hundreds of thousands of previous simulations from other groups.
“When it comes to space travel, every meter per second equals massive fuel consumption,” Allan Kardec de Almeida Júnior, lead author of the study and a researcher at the University of Coimbra in Portugal, said in a statement.
Roam the skies
Needless to say, sending a spacecraft to the Moon isn’t as simple as asking Google Maps for the shortest route from your location to the nearest metro station. According to NASA, planning a spacecraft’s flight path carefully considers many factors, such as designing the trajectory, reconstructing the orbit, tracking the spacecraft’s position and speed, predicting its future trajectory, and the tools navigators use to control the spacecraft once it is in space.
As a result, the latest study is not a complete solution to all spaceflight planning requirements, but it offers a good starting point. The team began by plotting a two-part trajectory from Earth’s orbit to the Moon. First, the spacecraft leaves Earth and enters the Moon’s orbit around the Lagrange point L1, where the gravitational attraction of the two bodies cancels. This allows the spacecraft to drift naturally along a “variable trajectory,” a “natural trajectory” leading toward the L1 orbit while saving fuel, the researchers explained.
Counter-current solutions
The team’s simulations showed that the most economical route contradicted existing models of the most efficient route. Current models assume that it is better to enter the variable through a branch closer to Earth, but the new simulations suggest the opposite: that it was better to enter through a route closer to the Moon.
In fact, this route reduces the chances of communication interruptions, said Vitor Martins de Oliveira, co-author of the study and postdoctoral researcher at the University of Coimbra. “The Artemis 2 mission, for example, lost communication with Earth for a while because it was directly behind the Moon,” he added. “The orbit we are proposing is a solution that maintains uninterrupted communication.”
Still work to do
Again, planning a real mission would require more complex procedures. To be clear, the researchers are not claiming that their model can decide everything on its own. On the one hand, the simulations only took into account the gravity of the Moon and the Earth, not of other celestial bodies. The proposed route is also not necessarily the cheapest, although it is the most cost-effective.
That said, the team remains confident that this method could be leveraged by mission planners to run a large number of simulations to get an idea of what the best trajectory might be. Of course, each trajectory should be tailored to the details of that particular launch.
“For example, if we simulate the mission launch date as December 23, we will obtain results valid only for a mission launched on that date,” Almeida said. At the same time, this also means that the method is quite flexible; it’s “something that could be adopted more widely in the future,” he added.
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