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1	Orbit design and estimation for surveillance missions using genetic algorithms Abdelkhalik, Osama Mohamed Omar 12 April 2006 (has links) The problem of observing a given set of Earth target sites within an assigned time frame is examined. Attention is given mainly to visiting these sites as sub-satellite nadir points. Solutions to this problem in the literature require thrusters to continuously maneuver the satellite from one site to another. A natural solution is proposed. A natural solution is a gravitational orbit that enables the spacecraft to satisfy the mission requirements without maneuvering. Optimization of a penalty function is performed to find natural solutions for satellite orbit configurations. This penalty function depends on the mission objectives. Two mission objectives are considered: maximum observation time and maximum resolution. The penalty function poses multi minima and a genetic algorithm technique is used to solve this problem. In the case that there is no one orbit satisfying the mission requirements, a multi-orbit solution is proposed. In a multi-orbit solution, the set of target sites is split into two groups. Then the developed algorithm is used to search for a natural solution for each group. The satellite has to be maneuvered between the two solution orbits. Genetic algorithms are used to find the optimal orbit transfer between the two orbits using impulsive thrusters. A new formulation for solving the orbit maneuver problem using genetic algorithms is developed. The developed formulation searches for a mini mum fuel consumption maneuver and guarantees that the satellite will be transferred exactly to the final orbit even if the solution is non-optimal. The results obtained demonstrate the feasibility of finding natural solutions for many case studies. The problem of the design of suitable satellite constellation for Earth observing applications is addressed. Two cases are considered. The first is the remote sensing missions for a particular region with high frequency and small swath width. The second is the interferometry radar Earth observation missions. In satellite constellations orbit's design, a new set of compatible orbits, called the "Two-way orbits",whose ground track path is a closed-loop trajectory that intersects itself, in some points, with tangent intersections is introduced. Conditions are derived on the orbital elements such that these Two-way Orbits exist and satellites flying in these orbits pass the tangent intersection points at the same time. Finally, the recently proposed concept of observing a space object from onboard a spacecraft using a star tracker is considered. The measurements of the star tracker provide directions to the target in space and do not provide range measurements. Estimation for the orbit of the target space object using the measurements of the star tracker is developed. An observability analysis is performed to derive conditions on the observability of the system states. The Gaussian Least Squares Differential Correction Technique is implemented. The results obtained demonstrate the feasibility of using the measurements of the star tracker to get a good estimate for the target orbit within a period of measurements ranging from about 20 percent to 50 percent of the orbital period depending on the two orbits. Orbit design Genetic Algorithms Ground Surveillance Optimization Orbit Maneuver
2	Propulsion System Development for the CanX-4 and CanX-5 Dual Nanosatellite Formation Flying Mission Risi, Benjamin 04 July 2014 (has links) The Canadian Nanosatellite Advanced Propulsion System is a liquefied cold-gas thruster system that provides propulsive capabilities to CanX-4/-5, the Canadian Advanced Nanospace eXperiment 4 and 5. With a launch date of early 2014, CanX-4/-5's primary mission objective is to demonstrate precise autonomous formation flight of nanosatellites in low Earth orbit. The high-level CanX-4/-5 mission and system architecture is described. The final design and assembly of the propulsion system is presented along with the lessons learned. A high-level test plan provides a roadmap of the testing required to qualify the propulsion system for flight. The setup and execution of these tests, as well as the analyses of the results found therein, are discussed in detail. aerospace microsatellite nanosatellite propulsion formation flying canx4 canx5 canx-4 canx-5 canx-4/-5 SFL UTIAS cold-gas thruster satellite CNAPS NANOPS nano sulfur hexafluoride SF6 vibration testing spacecraft environmental testing propulsion testing low earth orbit canx2 canx-2 station keeping orbit maneuver orbital station-keeping liquefied cold-gas propulsion micropropulsion engineering space canadian space flight laboratory canadian advanced nanospace experiment PSLV micro-propulsion thruster interferometry ground moving target indicator on-orbit servicing and inspection 0538

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Orbit design and estimation for surveillance missions using genetic algorithms

Propulsion System Development for the CanX-4 and CanX-5 Dual Nanosatellite Formation Flying Mission