Graphical solution for space applications

Abstract

Graphical solution for space applications is aimed at determining for spacecraft operation planning. The software basically gives the ground-trace and visibility pattern over the selected ground station. Ground-trace of a spacecraft is a path trace by the pierce point of a ray dropped from a given spacecraft in such a direction that it intersects normally the surface of the planet about which motion occurs. In the generation of the ground-trace the user is requested to give the starting time and closing time of the satellite to generate ground-trace. To generate the latitude and longitude values of the visibility circle the user has to get the name of station to which he requires the visibility circle data file. The ground-trace data file and visibility circle data file are separately generated and these data files are used for graphical solution. The eccentric anomaly is chosen as the independent variable in order to avoid the iterative solution of Kepler's equation each time a ground point is desired. In this paper the analysis is developed about the adopted elements and their relation to the central planet about which the satellite moves; it is formulated for elliptic motion by using heliocentric-elliptic coordinate system, geocentric-equatorial coordinate system and perifocal coordinate system. Mercatro projection is employed to make world map on which ail spirals of constants compass heading appear as straight lines. Software consists of two-versions: a) the solution with Mercator projection and b) the solution without Mercator projection. The graphical solution provides a visual aid for comprehensive planning of certain critical operations. Ground station setting of this comes as a visual tool. It gives the graphical display about ground trace and visibility pattern over the selected ground station. It will be extensively used during planning phase of various missions, includes the geosynchronous transfer orbit and all types of low Earth orbits, and it is user friendly.