Near-rectilinear halo orbit


A near-rectilinear halo orbit is a type of halo orbit that is currently planned in cislunar space, but as of mid-2020, has not been used on any spacecraft. One planned instance of a NRHO is a Moon-centric orbit that will serve as a staging area for future lunar missions. However, an NRHO need not be involved with the Earth-Moon system, and the orbit could be used in a variety of other contexts around other bodies in the Solar System and beyond.
NHRO orbits are one theoretical solution to the classic three-body problem in gravitational mechanics.

Planned NRHO usage

By 2018, NASA had begun considering use of a near-rectilinear halo orbit for a future lunar mission,
and by 2020, an NRHO is the planned orbit for the NASA Lunar Gateway, to be orbiting Earth-Moon in circa 2024. The Gateway orbit is planned to be a highly-elliptical seven-day near-rectilinear halo orbit around the Moon, which would bring the small space station within of the lunar north pole at closest approach and as far away as over the lunar south pole.
, the company Advanced Space was building a 12-unit cubesat to fly on a Gateway precursor mission for NASA. Named CAPSTONE, the spacecraft is expected to be the first spacecraft to operate in a NRHO lunar orbit. The mission objective is to test and verify the calculated orbital stability planned later for the Lunar Gateway space station, and the spacecraft will fly the identical orbital parameters planned later for Gateway. It will also test a navigation system that will measure spacecraft position relative to NASA's Lunar Reconnaissance Orbiter, without relying on ground stations.