The Moon, located approximately 386,000 kilometers from Earth, is preparing to receive its first space port, the Gateway. Engineers have developed a set of flight guidelines and orbital navigation rules to allow diverse spacecraft to operate safely in one of the most complex environments for human exploration.

The American Space Agency (NASA) is preparing to establish the pioneering space port in lunar orbit. To this end, experts develop a system dedicated to traffic control, aiming to ensure the safe and effective movement of all spacecraft involved.

It is estimated that, over the next two decades, NASA’s Gateway project will consolidate itself as the first permanent lunar spaceport. Its role will be to support missions involving manned Orion capsules, lunar landing modules, cargo transport ships and astronauts traveling between the Earth, the Moon and deep space.

Unlike land airports, the Gateway will not have physical infrastructure such as runways or boarding gates. The spacecraft will instead navigate a complex invisible network, directly influenced by the gravity of the Earth, Moon and surrounding space, with trajectories calculated by rigorous mathematical rules.

Managing this flow of vehicles will require a specific type of traffic control, adapted for the orbital environment.

Teams of engineers from Texas A&M University, NASA’s Johnson Space Center, and Purdue University developed algorithms and operational strategies. The objective is to manage spacecraft waiting in the vicinity of the Gateway and coordinate multiple vehicles that share the same orbital environment.

The researchers provided mathematical guidelines and navigation rules that aim to ensure safety and predictability in the movement of various ships in this challenging space region.

Developing navigation around the Moon

The studies included thousands of computer simulations. These tests analyzed the safe positioning of spacecraft around NASA’s Gateway space station, seeking a balance between precise navigation, fuel efficiency and the complexities of future lunar missions.

The findings of this research, published in the journal Acta Astronautica, explore the optimization of propellant consumption in conjunction with operational demands. The main focus is to minimize the likelihood of collisions between ships in space.

Dr. Diane Davis, associate professor of space engineering at the Texas A&M University College of Engineering and one of the study’s authors, said that “the future of lunar exploration depends as much on traffic management as it does on rocket science.”

Gateway Orbit: a challenge for vehicle flow

The realization of a continuous human presence in the vicinity of the Moon is not just about reaching the location. It will be essential that spacecraft have an infrastructure that guarantees occupation and movement in the same gravitational environment without causing mutual interference.

The Gateway and the vehicles that visit it operate in a specific environment, concentrated in a nearly rectilinear halo orbit, known as NRHO.

Davis explained that “Gateway’s NRHO orbit is a highly elongated, quasi-stable orbit around the Moon that provides an uninterrupted line of sight for communications with Earth and requires little propellant to maintain.”

Even with the advantages, the Gateway and ships in its proximity will be subject to variable gravitational forces. These forces are exerted by both the Earth and the Moon, influencing the path in the elongated orbit.

The adopted trajectory differs from any orbit previously used by crewed spacecraft. The Gateway approaches within 1,600 kilometers of the lunar north pole, and then moves away almost 64,000 kilometers, passing beyond the south pole.

At a distance of approximately 386,000 kilometers from Earth, the Moon is preparing to house the Gateway, the first spaceport of its kind. To achieve this, engineers developed a detailed flight manual and orbital “rules of navigation.” The goal is to allow multiple spacecraft to safely share this environment, considered one of the most difficult for human exploration.

Maintaining a single station on its trajectory can be done with periodic activations of the thrusters. However, the complexity increases considerably when a manned Orion capsule, an unmanned cargo ship and a large lunar lander need to approach, dock, depart or simply wait in the same area.

Davis warned that “collisions and serious damage can occur. To ensure crew safety and mission success, effective traffic management at NRHO is crucial.”

Extended stay ensures safe separation of spacecraft

The fundamental conception of this space traffic system revolves around the idea of ​​remaining in orbit. This concept involves maintaining a spacecraft in a controlled manner in a defined orbit or trajectory while awaiting permission to proceed.

“Remaining in orbit in space means maintaining a spacecraft relative to a specific orbit or trajectory without executing an immediate maneuver,” Davis said.

The basic premise is similar to air traffic control at airports. In it, aircraft wait at boarding gates, stop on taxiways or perform holding patterns before receiving authorization to proceed.

In the space context, ships approaching the Gateway may face similar delays. A vehicle may have to wait for hours, days, or even weeks until a docking port is free or another mission is completed.

The main distinction lies in the absence of a fixed surface, causing all vehicles to remain in constant motion.

Davis explained: “Every spacecraft is constantly moving. It’s like finding the sweet spot: keeping the vehicles ‘parked’ far enough apart to ensure safety, but close enough to their destination so that resources are used efficiently.”

Identifying this balance point was one of the primary objectives of the research.

Conceptual illustration of future space exploration showcases the work of Texas A&M University. From exploring new worlds to creating technologies for life beyond Earth, the institution’s space engineers address the challenges of the new era. Research spans space robotics, long-duration missions and lunar technology, turning ambitious visions into reality.

Through thousands of computer simulations, engineers tested methods for keeping spacecraft adequately separated in the vicinity of the Gateway. These tests considered realistic navigation errors, imperfect thruster performance, and small perturbations expected on future Artemis missions.

Simulation results indicated that modest adjustments to position-holding maneuvers could bring the spacecraft closer to their planned trajectories. This would require only small modifications in propellant expenditure.

Davis explained that “greater positional accuracy means mission planners can better predict where each spacecraft will be, conserving valuable fuel.”

Knowing the exact position of each vehicle simplifies the coordination of docking schedules and the planning of rendezvous operations. Furthermore, it reduces risks for both manned and robotic missions.

“Every maneuver has a cost,” Davis said. She added that, “just like air traffic control on Earth, spacecraft need predictable positions and trajectories to safely coordinate their movements.”

Increasing predictability would also simplify the complex sequence of spacecraft arrivals and departures at the Gateway.

New space formation could optimize lunar flow

Instead of visiting ships waiting independently, the researchers propose that the spacecraft maintain calculated positions, either ahead or behind the Gateway, until they are cleared to dock or depart. This organization is described as a “string of pearls” formation.

Davis explained that “just as pearls organize themselves into a necklace, spacecraft would position themselves naturally along the lunar orbit and in relation to the Gateway.” She added that “keeping the patrol vehicle in relation to the Gateway allows for closer formation and reduces the risk of vehicles coming dangerously close to each other.”

While the change may seem subtle, it has the potential to establish a crucial framework for managing increasingly intricate operations around the Moon.

Davis described the initiative: “It’s the beginning of a new kind of traffic control. An exciting frontier in infrastructure planning for an entire transportation system.”

For Doctor Davis, orbital traffic planning has its roots in years of dedication to mission design and the field of astrodynamics.

Before joining the Texas A&M University Aerospace Department in 2026, the specialist dedicated more than ten years to NASA’s Johnson Space Center. There, she served as principal engineer and mission project leader for the Gateway.

In her current role as associate professor, Davis researches cislunar astrodynamics and space traffic management. It also prepares students for the increasing complexities of lunar missions that will follow continued human presence around the Moon.

“Nothing excites me more than training and developing future engineers and scientists,” Davis said. She emphasized that “it is an incredible opportunity because they will be the ones planning lunar missions and managing space traffic for humanity beyond Earth.”

If trips to the Moon become common, maintaining a safe flow of traffic will depend on elements that go beyond rockets and spacecraft. It will be essential to have the mathematical rules that define who waits, who moves and how the vehicles remain safely separated, almost 386,000 kilometers away from Earth.