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Multi-objective hybrid optimal control for multiple-flyby interplanetary mission design using chemical propulsion
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Vavrina, Matthew A. Englander, Jacob A. |
| Copyright Year | 2015 |
| Description | Preliminary design of highâthrust interplanetary missions is a highly complex process. The mission designer must choose discrete parameters such as the number of flybys and the bodies at which those flybys are performed. For some missions, such as surveys of small bodies, the mission designer also contributes to target selection. In addition, realâvalued decision variables, such as launch epoch, flight times, maneuver and flyby epochs, and flyby altitudes must be chosen. There are often many thousands of possible trajectories to be evaluated. The customer who commissions a trajectory design is not usually interested in a point solution, but rather the exploration of the trade space of trajectories between several different objective functions. This can be a very expensive process in terms of the number of human analyst hours required. An automated approach is therefore very desirable. This work presents such an approach by posing the impulsive mission design problem as a multiâobjective hybrid optimal control problem. The method is demonstrated on several realâworld problems. Two assumptions are frequently made to simplify the modeling of an interplanetary highâthrust trajectory during the preliminary design phase. The first assumption is that because the available thrust is high, any maneuvers performed by the spacecraft can be modeled as discrete changes in velocity. This assumption removes the need to integrate the equations of motion governing the motion of a spacecraft under thrust and allows the change in velocity to be modeled as an impulse and the expenditure of propellant to be modeled using the timeâindependent solution to Tsiolkovsky's rocket equation [1]. The second assumption is that the spacecraft moves primarily under the influence of the central body, i.e. the sun, and all other perturbing forces may be neglected in preliminary design. The path of the spacecraft may then be modeled as a series of conic sections. When a spacecraft performs a close approach to a planet, the central body switches from the sun to that planet and the trajectory is modeled as a hyperbola with respect to the planet. This is known as the method of patched conics. The impulsive and patchedâconic assumptions significantly simplify the preliminary design problem. |
| File Size | 254808 |
| Page Count | 5 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20150011450 |
| Archival Resource Key | ark:/13960/t24b8327k |
| Language | English |
| Publisher Date | 2015-08-09 |
| Access Restriction | Open |
| Subject Keyword | Optimization Trajactory Design Interplanetary Trajectories Propellants Optimal Control Flyby Missions Mission Planning Trajectories Space Exploration Equations of Motion Design Analysis Spacecraft Motion Chemical Propulsion Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
