Optimal trajectory planning for multiple asteroid tour mission by means of an incremental bio-inspired tree search algorithm

In this paper, a combinatorial optimisation algorithm inspired by the Physarum Polycephalum mould is presented and applied to the optimal trajectory planning of a multiple asteroid tour mission. The Automatic Incremental Decision Making And Planning (AIDMAP) algorithm is capable of solving complex discrete decision making problems with the use of the growth and exploration of the decision network. The stochastic AIDMAP algorithm has been tested on two discrete astrodynamic decision making problems of increased complexity and compared in terms of accuracy and computational cost to its deterministic counterpart. The results obtained for a mission to the Atira asteroids and to the Main Asteroid Belt show that this non-deterministic algorithm is a good alternative to the use of traditional deterministic combinatorial solvers, as the computational cost scales better with the complexity of the problem

GTOC 9 : Results from University of Strathclyde (team Strath++)

The design and planning of space trajectories is a challenging problem in mission analysis. In the last years global optimisation techniques have proven to be a valuable tool for automating the design process that otherwise would mostly rely on engineers’ expertise. The paper presents the optimisation approach and problem formulation proposed by the team Strathclyde++ to address the problem of the 9th edition of the Global Trajectory Optimisation Competition. While the solution approach is introduced for the design of a set of multiple debris removal missions, the solution idea can be generalised to a wider set of trajectory design problems that have a similar structure

Development of an Improved Spherical Shaping Method for High-Inclination Trajectories

Over the past years, numerous missions for spacecraft with low-thrust propulsion have been planned to include large orbital plane changes. In order efficiently generate and evaluate orbits for such missions, use can be made of the spherical shaping method proposed by Novak. When inclinations larger than 15 degrees are present however, the error in the ΔV found by this method increases significantly. It was found that the spherical shaping method’s applicability and accuracy at high orbital inclinations can be improved through the development of a more accurate elevation shaping function. The purpose of this MSc thesis was therefore to do research on the development and implementation of such a function.Using a number of test cases, three potential methods to obtaining a more accurate elevation shaping function were evaluated. These methods included the usage of spherical triangles, Fourier series and an alternative function that was obtained during the development. By evaluating the ability of various functions to describe the unperturbed and perturbed orbits included in the test cases, a new elevation shaping function was found. This shaping function was based on the aforementioned alternative function obtained during the development.The accuracy of the new elevation shaping function was tested using a number of cases. It was observed that the new elevation shaping function significantly increased the spherical shaping method’s accuracy at high orbital inclinations; at an inclination of 20 degrees, the error in the ΔV found was decreased to less than 1 percent. However, this error did increase as the inclination became larger.The spherical shaping method was furthermore applied together with the new elevation shaping function to the design of two missions. These missions included rendezvous trajectories to the dwarf planet Makemake and to the comet 2003 EH1. It was found that the new elevation shaping function enabled the spherical shaping method to produce smooth trajectories with attainable ΔVs to both targets, even though the inclination of 2003 EH1 is approximately 70 degrees. Aerospace Engineerin

S-TrackS: A Secure Snapshot-Based Solution for Positioning and Timing

With the large-scale usage of satellite navigation, spoofing and jamming are considerable threats to civilian society. Recent developments, such as Galileo’s Open Service Navigation Message Authentication and GPS’s Chimera, mitigate these risks. However, they provide authentication of the navigation message or ranging code, but not a true position in the case of interference. In critical applications, a protected navigation service is desired, such as Galileo’s Public Regulated Service (PRS). PRS provides an access-controlled navigation service for authorized governmental users, with fully encrypted ranging codes and data channels, providing users with higher robustness against interference. The main challenge of implementing PRS on a large scale is the need to protect the cryptographic material that is required to access the PRS signals inside the receiver. For many applications, a stand-alone receiver solution is unnecessary. These applications could use a remote server for PRS. In this methodology, the end-user device has only a radio frequency front-end which sends short samples to a secure server. The (classified) signal processing is then carried out on this secure server, removing the need for the user device to protect cryptographic material. Besides decreasing the device’s security requirements and power consumption, it also allows to utilize the advantages of PRS in applications that would otherwise not be able to use PRS. In this approach the PRS usage authorization would only be required for the server operations, and not for the end-user devices. It furthermore allows for using additional processing power for unaided PRS acquisition in case of interference. Within the Netherlands, a remote server solution is developed by CGI: S-TrackS, making PRS accessible. In this paper, the application of PRS and architecture for various use cases is presented. It is shown that PRS usage based on a remote server is feasible and can increase the robustness for governmental applications