Determination and evaluation of the orbital transition methods between two elliptical earth orbits

To transfer a satellite or a spacecraft from a low parking orbit to a geosynchronous orbit, one of the many transition methods is used. All these methods need to identify some orbital elements of the initial and final orbits as perigee and apogee distances. These methods compete to achieve the transition with minimal consumption of energy, transfer time and mass ratio consumed ), as well as highest accuracy of transition. The ten methods of transition used in this project required designing programs to perform the calculations and comparisons among them. The results showed that the evaluation must depend on the initial conditions of the initial orbit and the satellite mechanical exception as well as the target orbit. The most efficient methods of transition in terms of energy required were, sequentially, methods 10, 1, 8, 9, and 2, whereas the least efficient in terms of energy consumption, fuel and transition time were, sequentially, methods 5,6, and 7. Method 3 was the most efficient when the orbit needed to change the inclination with the transition. The first phase of multi-stage transition is the most energy consuming.

Methods of Orbit Clustering of Serviced Spacecraft

When planning orbital service operations, it is important to rationally divide a set of orbits serviced by a spacecraft into subsets (clusters) of orbits. This article proposes a technique for clustering the orbits of serviced spacecraft in the event of their servicing by a reusable service spacecraft with an electric rocket low thrust engine. The technique is based on the method of K ‑ means. As the distance between any pair of orbits of the serviced spacecraft (metrics) of the method K - means, it was proposed to use the delta-V of the orbital transition between these orbits.In this paper, a technique has been developed for clustering orbits of serviced spacecrafts. The method is based on the method K ‑ means. As a distance between any pair of orbits of the serviced spacecraft orbits (metrics) of the method K ‑ means it is proposed to use the energy metric delta - V of the interorbital transition between these orbits. Using the proposed methodology, a computer program has been developed for clustering the orbits of serviced spacecraft. The results of the test calculations showed the effectiveness of the proposed clustering technique. The technique can be applied when planning orbital service operations.

â- structure properties ofZn-Phthalocyanine organic semi-conductor

The x-ray fluorescence (XRF) of Znpc molecule with (flow of Ar) and Znpc molecule with (grow in N2) showed two peaks at (8.5and 9.5 Kv) referring to orbital transition ) K?-shell & K?-shell) respectively. The study of x-ray diffraction (XRD) where it was observed good growth of the crystal structure as a needle by the sublimation technique with a ?-phase of (monoclinic structure ) . Using Bragg equation the value of the interdistance of the crystalline plane (d-value) were calculated. We noticed good similarity with like once in the American Standards for Testing Material (ASTM) .Powder Diffraction File (PDF) Program was used to ensure the information obtained from (ASTM) . The output of (PDF) was compared with celn program, where the value of angle(2?( , crystal axis (a,b,c) and axial angles (?,?,?) were calculated. The partical grain size of H2PC was between (27-35)nm, while for ZnPC was between (17-50)nm by applying of Schreer equation. The results are in a good agreement with c-size program. The morphology was distinguished by optical microscope of (200X) magnification for a tini-fiber like a (whisker needle type) with blue color, porous nature and short term structure. The diameter of the fiber H2PC and ZnPC were (20 and 16?m) respectively.