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| 2. |
- Bazzocchi, Michael C. F., et al.
(författare)
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A Systematic Assessment of Asteroid Redirection Methods for Resource Exploitation
- 2015
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Konferensbidrag (refereegranskat)abstract
- This paper provides a systematic comparison of the primary asteroid redirection techniques from the perspective of resource exploitation. The goal is to examine the methods for the redirection of a near-Earth asteroid to a stable and easily accessible orbit in the Earth-moon system in order to exploit asteroid resources. The context of resource exploitation provides clear constraints on the asteroid redirection mission, and a systematic comparison can be established within this scope. This work describes each redirection method, and considers the major criteria for mission design. Moreover, a Monte Carlo analysis is performed to assess some attributes concerning the uncertainty intrinsic to asteroid redirection missions. The attributes for each redirection method are then aggregated using a multi-criteria decision making approach. Lastly, the results of the aggregation are presented and discussed.
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| 3. |
- Bazzocchi, Michael C. F., et al.
(författare)
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An Assessment of Multiple Spacecraft Formation for Asteroid Redirection
- 2016
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Ingår i: Transactions of the Japan Society for Aeronautical and Space Sciences, Aerospace Technology Japan. - Tokyo : Japan Society for Aeronautical and Space Sciences. - 1884-0485. ; 14:ists30, s. Pk_137-Pk_146
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Tidskriftsartikel (refereegranskat)
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| 4. |
- Bazzocchi, Michael C. F., et al.
(författare)
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Application of asteroid redirection methods to orbital debris removal
- 2016
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Ingår i: 2016 IEEE Aerospace Conference. - Piscataway, NJ : IEEE Communications Society. - 9781467376761
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Konferensbidrag (refereegranskat)abstract
- 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
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| 5. |
- Bazzocchi, Michael C. F., et al.
(författare)
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Application of pseudo-equinoctial shaping to Near-Earth asteroid orbital transfer
- 2017
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Ingår i: IEEE Aerospace Conference Proceedings. - Piscataway, NJ : Institute of Electrical and Electronics Engineers (IEEE). - 9781509016136
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 6. |
- Bazzocchi, Michael C. F., et al.
(författare)
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Asteroid detumbling for redirection missions
- 2018
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Ingår i: 2018 IEEE Aerospace Conference. - : IEEE Computer Society. - 9781538620144
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Konferensbidrag (refereegranskat)abstract
- In order to accomplish most asteroid redirection missions, rotational control of the asteroid body is required. Small near-Earth asteroids tend to exhibit a significant range of rotational and tumbling properties. This work provides an analysis of asteroid detumbling using a formation of spacecraft. Through an orbiter and three landed thruster spacecraft, a low-thrust detumbling maneuver is performed on two illustrative asteroids. The asteroid scenarios are designed such that they reflect the characteristics of possible redirection scenarios. In particular the geometries, densities, angular velocities, and masses of the asteroids are adjusted according to available asteroid data to provide two unique redirection scenarios. The asteroid and spacecraft specifications are outlined, as well as the formulations for the detumbling maneuver. The results of the maneuver are discussed along with the key detumbling parameters and timeframe required.
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| 7. |
- Bazzocchi, Michael C. F., et al.
(författare)
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Asteroid Redirection Mission Evaluation Using Multiple Landers
- 2018
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Ingår i: The Journal of the astronautical sciences. - : Springer. - 0021-9142 .- 2195-0571. ; 65:2, s. 183-204
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 8. |
- Bazzocchi, Michael C.F., et al.
(författare)
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Comparative analysis of redirection methods for asteroid resource exploitation
- 2016
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Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765 .- 1879-2030. ; 120, s. 1-19
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 9. |
- Bazzocchi, Michael C. F., et al.
(författare)
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Concurrent Redirection and Attitude Control of an Asteroid
- 2019
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Ingår i: 2019 IEEE Aerospace Conference. - : IEEE.
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Konferensbidrag (refereegranskat)abstract
- This paper demonstrates the applicability of two low-thrust spacecraft for the task of concurrently redirecting an asteroid and controlling its attitude. Through the use of available observational data, a synthetic near-Earth asteroid, with suitable characteristics for a resource utilization mission, is designed. The asteroid is given an initial orientation and angular velocity, such that it is in a tumbling state. The two spacecraft are attached to the asteroid surface, and employ low-thrust ion thrusters for the attitude control and redirection of the asteroid. The spacecraft first detumble the asteroid body using their torque-inducing thrusters, and then re-orient the asteroid such that the redirection thrusters are aligned with the redirection thrust vector. The spacecraft then ensure the asteroid's orientation is aligned with the redirection thrust vector throughout the entire trajectory transfer maneuver, while ensuring the angular velocity remains bounded around zero. The trajectory design is a low-thrust maneuver, based on Gauss' variational equations, which redirects the asteroid from its orbit about the Sun to rendezvous with Earth. A linear control law is employed for both the detumbling and redirection maneuver with attitude control. The overall performance of the system and the applicability of the approach are discussed.
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| 10. |
- Bazzocchi, Michael C. F., et al.
(författare)
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Formation of Multiple Landers for Asteroid Detumbling
- 2018
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Ingår i: Advances in Space Research. - : Elsevier. - 0273-1177 .- 1879-1948. ; 62:3, s. 732-744
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Tidskriftsartikel (refereegranskat)abstract
- This work develops a method for ascertaining the landing locations and thruster orientations of a formation of multiple spacecraft on an irregular asteroid for discrete time optimal detumbling control, as a prerequisite to asteroid redirection. Asteroid geometries are known to be extremely irregular, especially for small asteroids, which are the typical targets for redirection missions. The method entails the modelling of asteroids as convex polyhedra with triangular facets, and computing the mass and inertial properties through the divergence theorem and Green’s theorem. Given the asteroid geometry, mass, and inertial properties, the feasible lander locations and thruster orientations are determined. The model ensures full attitude control of the asteroid, using multiple spacecraft with fixed-orientation, low-thrust modules, through measures imposed on the location and orientation of each thruster. A linear control scheme is employed to assess the time and fuel requirements of the asteroid detumbling maneuver, given feasible spacecraft formation configurations and thruster orientations. The method then assesses the detumbling time performance of each formation configuration to determine the discrete optimal landed formation configuration for a given asteroid. Simulations are performed to demonstrate the method using an irregular asteroid with characteristics derived from available asteroid data. Extensions of the method are further discussed in light of the results.
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