Earth Oblateness Perturbation

Author: Tianjiang Shuo

Website: https://cislunarspace.cn

Definition

Perturbation of a satellite orbit caused by the non-spherical gravitational potential of Earth, primarily the J2 term.

Application Value

Earth oblateness perturbation is one of the primary orbital perturbation sources for low Earth orbit satellites. The J2 term arises from Earth's equatorial bulge, causing the ascending node longitude and perigee argument of satellite orbits to drift. For LEO orbits, J2 perturbation causes the orbital plane to precess several degrees per day. This characteristic is exploited in designing Sun-synchronous orbits, ensuring satellites pass the equator at the same local time. In cislunar transfer trajectory design, J2 perturbation effects are relatively minor but still need consideration in long-term orbit prediction.

Related Concepts

• Orbital Perturbation
• Restricted Three-Body Problem
• Sun-synchronous Orbit
• Gravitational Constant

References

• 肖峰 - 1989 - 球面天文学与天体力学基础。