Orbital maneuver
Published June 18th, 2008 in UncategorizedAn orbital maneuver is a change from one orbit to another, accomplished by applying thrust. In deep space it is called deep-space maneuver (DSM).
Impulsive maneuvers
An impulsive maneuver approximates a finite thrust maneuver by adding an instantaneous velocity change to an ephemeris record while maintaining the position. During the planning phase of most space missions, designers will first calculate orbital changes using impulsive maneuvers. This greatly reduces the complexity of finding the correct orbital transitions. The instantaneous changes in velocity are referred to as delta-v (<math>\Delta\mathbf{v}\,</math>), the total delta-v for all maneuvers required in the mission is called a delta-v budget. With a good approximation of the delta-v budget designers can estimate the fuel to payload requirements of the spacecraft.
Using these approximations is most useful when finite thrusts are to be executed in short bursts. Finite maneuvers like these are possible with high thrust-to-weight propulsion systems, e.g. chemical rockets. However, even for long burns, impulsive maneuver approximations remain very accurate outside the Earth’s atmosphere.
Non-impulsive maneuvers
Applying a low thrust over longer periods of time is referred to as non-impulsive maneuvers (even though any thrust can be said to produce an amount of impulse). They are less efficient as energy can be lost due to gravity drag. However those maneuvers can be the only option when efficient but low thrust-to-weight propulsion systems are used (e.g. ion engines). They are not possible for a launch.
Finite Burn Trajectories
For a few space missions, such as those including a space rendezvous, high fidelity models of the trajectories are required to meet the mission goals. Calculating a finite burn requires a detailed model of the spacecraft and its thrusters. The most important of details include: mass, center of mass, moment of inertia, thruster positions, thrust vectors, thrust curves, specific impulse, thrust centroid offsets, and fuel consumption.
See also
- Bi-elliptic transfer
- Delta-v
- Delta-v budget
- Docking maneuver
- Gravitational slingshot
- Hohmann transfer
- Low energy transfers
- Orbital inclination change
- Orbit phasing
- The Oberth effect
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