NASA And ESA Pick 'Eccentric' Halo Orbit For Future Gateway Outpost

Officials with NASA and the European Space Agency (ESA) have settled on which orbit will be used for the future lunar Gateway outpost, the agencies have announced. After considering different orbit options, scientists have settled on the near-rectilinear halo orbit (NRHO), which is described as an 'eccentric' route around the Moon, one that brings it close to the lunar surface at one point and far away at the other.

The Apollo mission orbited the Moon in a low lunar orbit, but the Gateway — a permanent human outpost and a new space milestone for humanity — will orbit the celestial body in an 'angelic halo' orbit, a description referencing the orbit's halo-like appearance from Earth.

When the Gateway is at the closest point of its orbit, the outpost will be only around 1,800 miles from the Moon's surface. At its farthest distance, the Gateway will be nearly 43,500 miles away. The ESA has published a simulation showing what this orbit will look like once the Gateway is in space.

This orbit will rotate with the Moon, according to the ESA, something made possible by the Moon's and Earth's gravitation forces. A single Gateway orbit will last around seven days and regularly schedule small maneuvers will ensure the outpost stays in its correct orbit over the years.

Scientists explain that this orbit is important for moving parts to the Gateway from Earth and to the lunar surface. The orbit reduces how much energy is needed to achieve these deliveries, enabling officials to leave some spacecraft parts in orbit until they're needed on the Moon's surface. Transports from the Gateway to the Moon will happen during the orbit's closest point, meaning every seven days.