Orbital Maneuver

Author: Tianjiang Shuo
Website: https://cislunarspace.cn

Definition

An orbital maneuver is the process by which a spacecraft actively changes its flight orbit using rocket engine thrust or environmental forces. Unlike the passive motion of natural celestial bodies, orbital maneuvering is an active capability unique to spacecraft and serves as the fundamental means for accomplishing tasks such as orbit change, orbit transfer, and orbit adjustment.

Core Elements

Classification by Maneuver Task

Type	Description	Characteristics
Orbit change	Initial and final orbits intersect; impulse applied at the intersection point	Single large impulse with significant orbital element changes
Orbit transfer	Transfer from initial orbit to final orbit via a transfer orbit; the two orbits do not intersect	At least two impulses
Orbit adjustment	Small impulses to correct minor deviations in orbital elements	Orbit capture, orbit keeping, etc.

Classification by Thrust Duration

Type	Description
Impulsive thrust maneuver	Thrust is large enough to produce an instantaneous velocity increment; position remains unchanged while velocity jumps
Finite thrust maneuver	Thrust is limited; a finite duration is required to achieve the desired velocity increment

Impulsive Thrust Model

\Delta v = - I_{sp} g_0 \cdot \ln\left(1 - \frac{\Delta m}{m_0}\right)

where $I_{sp}$ is the engine specific impulse and $m_0$ is the total mass before the maneuver.

Finite Thrust Model

For constant thrust $F$ and specific impulse $I_{sp}$ , the thrust duration is:

\Delta t = \frac{m_0 I_{sp} g_0}{F} \left[1 - \exp\left(-\frac{\Delta v}{I_{sp} g_0}\right)\right]

The ignition time is $t_c - \Delta t/2$ and the cutoff time is $t_c + \Delta t/2$ .

Application Value

Orbital maneuvering is one of the most critical operations in space missions. Geosynchronous satellite orbit insertion, space station rendezvous and docking, interplanetary trajectory design, and satellite formation flying all depend on precise orbital maneuver planning. The impulsive thrust assumption satisfies the accuracy requirements for most preliminary maneuver orbit designs, while the finite thrust model is used for high-precision maneuver parameter calculations.

References

Zheng W, An X Y, Zhou X, He R Z. Aerospace Flight Mechanics[M]. National University of Defense Technology, 2026.
Jia P R, Chen K J, et al. Long-Range Rocket Ballistics[M]. National University of Defense Technology Press.