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  • 1.
    Bazzocchi, Michael C. F.
    et al.
    University of Toronto, Institute for Aerospace Studies.
    De Decker, Nathan
    University of Liège.
    Emami, Reza
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Application of pseudo-equinoctial shaping to Near-Earth asteroid orbital transfer2017Ingår i: IEEE Aerospace Conference Proceedings, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, artikel-id 7943777Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper determines the near-optimal transfer trajectory of a Near-Earth Asteroid (NEA) to an orbit in the Earth-Moon system through the use of an ion beam redirection method. The ion beam method is a hovering approach to asteroid redirection. The method operates through the use of two diametrically opposed thrusters. The redirection mission targets Arjuna-type asteroids, and uses a sample asteroid, 2013 RZ53, to demonstrate the applicability of the pseudo-equinoctial shaping to asteroid orbital transfer. The asteroid transfer from its initial orbit about the Sun to its final orbit in the Earth-Moon system is divided into two phases using a patched conics approximation. The first phase includes the transfer of the asteroid from its initial orbit to an optimized rendezvous point with Earth. The second phase begins as soon as the asteroid arrives within the Earth's sphere of influence and ends with the transfer of the asteroid into a stable orbit about Earth and Moon. The pseudo-equinoctial shaping approach is employed during each phase, and determines the near-optimal solution for the lowest combined delta-v required to complete the orbital transfer. The pseudo-equinoctial method is a shape-based approach to trajectory design which assumes the trajectory transfer can be modelled as a variation of a conic arc. The transfer considers the eccentricity, inclination, and semi-major axis, as well as optimizes several free parameters, such as the thrust, the start of transfer and the rendezvous point with Earth. The optimization is completed using a genetic algorithm, and the results of the optimization are presented in terms of time of flight, thrust, number of revolutions, and delta-v. Lastly, the results are detailed and the feasibility of a redirection mission for an Arjuna-type asteroid is discussed.

  • 2.
    Bazzocchi, Michael C. F.
    et al.
    University of Toronto, Canada.
    Emami, M. Reza
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik. University of Toronto, Canada.
    A Systematic Assessment of Asteroid Redirection Methods for Resource Exploitation2015Konferensbidrag (Refereegranskat)
  • 3.
    Bazzocchi, Michael C. F.
    et al.
    Institute for Aerospace Studies, University of Toronto, Canada.
    Emami, M. Reza
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik. Institute for Aerospace Studies, University of Toronto, Canada.
    An Assessment of Multiple Spacecraft Formation for Asteroid Redirection2016Ingår i: Transactions of the Japan Society for Aeronautical and Space Sciences, Aerospace Technology Japan, E-ISSN 1884-0485, Vol. 14, nr ists30, s. Pk_137-Pk_146Artikel i tidskrift (Refereegranskat)
  • 4.
    Bazzocchi, Michael C. F.
    et al.
    Institute for Aerospace Studies, University of Toronto.
    Emami, M. Reza
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik. Institute for Aerospace Studies, University of Toronto.
    Asteroid Redirection Mission Evaluation Using Multiple Landers2018Ingår i: The Journal of the astronautical sciences, ISSN 0021-9142, Vol. 65, nr 2, s. 183-204Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, a low-thrust tugboat redirection method is assessed using multiple spacecraft for a target range of small near-Earth asteroids. The benefits of a landed configuration of tugboat spacecraft in formation are examined for the redirection of a near-Earth asteroid. The tugboat method uses a gimballed thruster with a highly collimated ion beam to generate a thrust on the asteroid. The target asteroid range focuses on near-Earth asteroids smaller than 150 m in diameter, and carbonaceous (C-type) asteroids, due to the volatiles available for in-situ utilization. The assessment focuses primarily on the three key parameters, i.e., the asteroid mass redirected, the timeframe for redirection, and the overall system cost. An evaluation methodology for each parameter is discussed in detail, and the parameters are employed to determine the expected return and feasibility of the redirection mission. The number of spacecraft employed is optimized along with the electrical power needed for each spacecraft to ensure the highest possible return on investment. A discussion of the optimization results and the benefits of spacecraft formation for the tugboat method are presented.

  • 5.
    Bazzocchi, Michael C. F.
    et al.
    Institute for Aerospace Studies, University of Toronto.
    Emami, Reza
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Application of asteroid redirection methods to orbital debris removal2016Ingår i: 2016 IEEE Aerospace Conference: AERO 2016, Big Sky, United States, 5 - 12 March 2016, Piscataway, NJ: IEEE Communications Society, 2016, artikel-id 7500750Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper discusses the applicability of some of the asteroid redirection methods, prominently studied in the literature, to orbital debris removal. The tasks of asteroid redirection and orbital debris removal share the common goal of controlled redirection of an uncooperative target. Three asteroid redirection methods are systematically compared and analyzed to assess their viability for an orbital debris reentry mission, i.e., ion beam shepherd, laser sublimation, and tugboat. These methods are investigated in terms of the characteristics of the orbital debris population and based on the major criteria for mission design of controlled reentry of uncooperative objects. In addition, the uncertainty intrinsic to the orbital debris population is quantified through the use of a Monte Carlo simulation, which provides insight into the robustness of the methods for various ranges of orbital debris. The Analytical Hierarchy Process will be employed to assess the viability of each method in a logically consistent fashion, namely, through aggregation of the relative preference (of each method) and relative importance (of each criterion). The advantages and drawbacks of each redirection method are discussed in light of the assessment results for orbital debris reentry

  • 6.
    Bazzocchi, Michael C. F.
    et al.
    Institute for Aerospace Studies, University of Toronto.
    Emami, Reza
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik. Institute for Aerospace Studies, University of Toronto.
    Low-thrust orbit transfer of Arjuna-type asteroids2016Ingår i: AIAA/AAS Astrodynamics Specialist Conference, 2016, American Institute of Aeronautics and Astronautics, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper investigates the accessible low-thrust transfer trajectories for a near-Earth asteroid transfer mission. The target asteroids considered are Arjuna type asteroids, which are characterized by their Earth-like orbital paths including low-eccentricity and low-inclination. The asteroid range is characterized by specific semi-major axes and transfer angles to provide an overall assessment of the potential Arjuna transfer domain. A single hovering ion beam spacecraft is employed for the task of asteroid redirection. The method utilizes a continuous thrust over the duration of the transfer maneuver to redirect the asteroid to an Earth bound orbit. The transfer model employs a minimized form of Gauss's variational equations to determine the available trajectories for asteroid redirection. The transfer model employs, in addition to the aforementioned orbital equations, spacecraft thruster and sizing metrics, as well as mission cost analysis formulae. The system parameters and orbital transfer paths are assessed with regards to key mission parameters, namely, timeframe for redirection, number of orbital revolutions, system mass, propellant mass, thrust, power, system cost, and financial return rate

  • 7.
    Bazzocchi, Michael C. F.
    et al.
    University of Toronto, Toronto, ON, Canada; Institute for Aerospace Studies, 4925 Dufferin Street, Canada.
    Emami, Reza
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik. University of Toronto, Toronto, ON, Canada; Institute for Aerospace Studies, 4925 Dufferin Street, Canada.
    Study of Arjuna-Type Asteroids for Low-Thrust Orbital Transfer2018Ingår i: Journal of Spacecraft and Rockets, ISSN 0022-4650, E-ISSN 1533-6794, Vol. 55, nr 1, s. 37-48Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper investigates the accessible low-thrust transfer trajectories for a near-Earth asteroid transfer mission. The target asteroids considered are Arjuna-type asteroids, which are characterized by their Earth-like orbital paths including low eccentricity and low inclination. The asteroid range is characterized by a specific range of semimajor axes and transfer angles to provide an overall assessment of the potential Arjuna transfer domain. A single hovering ion beam spacecraft is employed for the task of asteroid redirection. The method uses a continuous thrust over the duration of the transfer maneuver to redirect the asteroid to an Earth-bound orbit. The transfer model employs a minimized form of Gauss's variational equations to determine the available trajectories for asteroid redirection. The transfer model employs, in addition to the aforementioned orbital equations, spacecraft thruster and sizing metrics as well as mission cost analysis formulae. The system parameters and orbital transfer paths are assessed with regard to key mission parameters, namely, time frame for redirection, number of orbital revolutions, system mass, propellant mass, thrust, power, system cost, and financial return rate

  • 8.
    Bazzocchi, Michael C.F.
    et al.
    Institute for Aerospace Studies, University of Toronto.
    Emami, Reza
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Comparative analysis of redirection methods for asteroid resource exploitation2016Ingår i: Acta Astronautica, ISSN 0094-5765, E-ISSN 1879-2030, Vol. 120, s. 1-19Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An in-depth analysis and systematic comparison of asteroid redirection methods is performed within a resource exploitation framework using different assessment mechanisms. Through this framework, mission objectives and constraints are specified for the redirection of an asteroid from a near-Earth orbit to a stable orbit in the Earth-Moon system. The paper provides a detailed investigation of five redirection methods, i.e., ion beam, tugboat, gravity tractor, laser sublimation, and mass ejector, with respect to their capabilities for a redirection mission. A set of mission level criteria are utilized to assess the performance of each redirection method, and the means of assigning attributes to each criterion is discussed in detail. In addition, the uncertainty in physical characteristics of the asteroid population is quantified through the use of Monte Carlo analysis. The Monte Carlo simulation provides insight into the performance robustness of the redirection methods with respect to the targeted asteroid range. Lastly, the attributes for each redirection method are aggregated using three different multicriteria assessment approaches, i.e., the analytical hierarchy process, a utility-based approach, and a fuzzy aggregation mechanism. The results of each assessment approach as well as recommendations for further studies are discussed in detail.

  • 9.
    Emami, Reza
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik. Institute for Aerospace Studies, University of Toronto, Toronto, Canada.
    Bazzocchi, Michael C. F.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Hakima, Houman
    Institute for Aerospace Studies, University of Toronto, Toronto, Canada.
    Engineering design pedagogy: a performance analysis2019Ingår i: International journal of technology and design education, ISSN 0957-7572, E-ISSN 1573-1804Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cornerstone design courses have become a major part of engineering curricula, where students with different personality types and learning styles work together to design, develop, build, and demonstrate the functionality of a prototype within the duration of a term. This study analyzes student and team performance against gender, personality types, and learning styles in a second-year engineering design course. Further, the correlations between several assessment mechanisms are studied, and the effects of three different instructional design approaches on students’ performance are explored. Data have been collected on student performance and psychometrics, including marks, gender, personality type, and learning style from 2001 to 2018. To identify students’ personality types and learning styles, Myers–Briggs Type Indicators (MBTI) and Neil Fleming’s Learning VARK tests were administered. To evaluate students’ performance in the course, a number of assessment mechanisms have been defined. Several statistical methods are used to analyze data, and to determine correlation between datasets. Over nearly two decades of marks, gender, MBTI, and VARK data for 2637 students are presented for an engineering design course. The results demonstrated that there was no significant difference in performance across most assessments based on gender or gender distribution on a team. A better performance was observed from VK bimodal and quadmodal learning styles in most assessment mechanisms. Further, certain MBTI groups, namely, judging types outperformed their peers in engineering design assessments, with interesting interplay between MBTI dimensions for specific assessments and team dynamics. Traditional assessment mechanisms, such as engineering notebook and design proposals, are shown to be good predictors of student success. Lastly, scaffolded design activities and front-loading of lecture content were shown to be beneficial for student learning. There is negligible performance difference between female and male students in the engineering design course. Students whose preferred learning styles align with the assessment themes showed better performance in the course. The outcomes of this paper can be readily applied by instructors for design of assessment mechanisms, course materials, team formation, and instructional design.

  • 10.
    Hakima, Houman
    et al.
    Institute for Aerospace Studies, University of Toronto .
    Bazzocchi, Michael C. F.
    Institute for Aerospace Studies, University of Toronto.
    Emami, Reza
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik. Institute for Aerospace Studies, University of Toronto.
    A Deorbiter CubeSat for Active Orbital Debris Removal2018Ingår i: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 61, nr 9, s. 2377-2392Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper introduces a mission concept for active removal of orbital debris based on the utilization of the CubeSat form factor. The CubeSat is deployed from a carrier spacecraft, known as a mothership, and is equipped with orbital and attitude control actuators to attach to the target debris, stabilize its attitude, and subsequently move the debris to a lower orbit where atmospheric drag is high enough for the bodies to burn up. The mass and orbit altitude of debris objects that are within the realms of the CubeSat’s propulsion capabilities are identified. The attitude control schemes for the detumbling and deorbiting phases of the mission are specified. The objective of the deorbiting maneuver is to decrease the semi-major axis of the debris orbit, at the fastest rate, from its initial value to a final value of about 6,471 km (i.e., 100 km above Earth considering a circular orbit) via a continuous low-thrust orbital transfer. Two case studies are investigated to verify the performance of the deorbiter CubeSat during the detumbling and deorbiting phases of the mission. The baseline target debris used in the study are the decommissioned KOMPSAT-1 satellite and the Pegasus rocket body. The results show that the deorbiting times for the target debris are reduced significantly, from several decades to one or two years.

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