A path around the L1 or L2 Lagrangian points of a two-body system. Lissajous orbits are utilized by certain spacecraft that are required to be in a stable position relative to the Earth and Sun while making long-term observations. In a Lissajous orbit the spacecraft follows a natural (but complex) motion that requires the minimum amount of energy for station-keeping, unlike a halo orbit, in which the craft follows a simple circular or elliptical path. Spacecraft that use a Lissajous orbit around the Sun-Earth L2 point are the Herschel Space Observatory and Planck. The James Webb Space Telescope will also be placed in a Lissajous orbit at the same location. Such orbits are named after the French mathematician Jules Antoine Lissajous (1822–80), who studied the types of curves followed by an object in such a position.
Subjects: Astronomy and Astrophysics.