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Abstract:
This project assessed the accuracy with which a formation of satellites, the Laser Interferometer Space Antenna (LISA), must be placed into orbit. The LISA formation will consist of three satellites orbiting the Sun, forming an equilateral triangle. The first phase dealt with the formation parameters (leg length, leg length time rate of change, interior leg angle, and formation-sun-earth angle) as a function of time. Duplication of plots contained in other papers on the topic validated the output of the analysis code. Preliminary analysis indicated the values of each parameter varied sinusoidally, and increasing the initial error conditions tended to reduce the time each parameter fell within the acceptable tolerance values. The second phase dealt with analyzing formation parameters as a function of the error size of specific initial conditions. Two of the eighteen state variables were varied simultaneously, resulting in a surface plot indicating how long a particular formation parameter was out of specification over the lifetime of the mission. The formation was most sensitive to velocity errors in the in-track direction. Furthermore, it appeared that one error can counter-act another error, agreeing with other papers on this topic. The third phase analyzed the effect of varying all eighteen variables simultaneously. A plot was created to show how the value of time out of specification for the leg length rate of change changes as the initial state variable tolerance changes. As the maximum variation in position and velocity errors increased, there was a corresponding increase in the amount of time the formation parameter was out of specification. A cross-section of the surface was created with position error range remaining constant while varying velocity error range. With an assumed maximum position error of zero, the formation tended to start going out of specification at a velocity error magnitude of 2 6 cm/sec.
| Limitations: |
 APPROVED FOR PUBLIC RELEASE |
| Pages: |
60 |
| Report Date: |
04 MAY 2007 |
| Report Number: |
A913374 |
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