@incollection{DachwaldUlamecBiele2013,
  author    = {Dachwald, Bernd and Ulamec, Stephan and Biele, Jens},
  title     = {Clean in situ subsurface exploration of icy environments in the solar system},
  series = {Habitability of other planets and satellites. - (Cellular origin, life in extreme habitats and astrobiology ; 28)},
  booktitle = {Habitability of other planets and satellites. - (Cellular origin, life in extreme habitats and astrobiology ; 28)},
  publisher = {Springer},
  address   = {Dordrecht},
  isbn      = {978-94-007-6545-0 (Druckausgabe)},
  pages     = {367 -- 397},
  year      = {2013},
  abstract  = {"To assess the habitability of the icy environments in the solar system, for example, on Mars, Europa, and Enceladus, the scientific analysis of material embedded in or underneath their ice layers is very important. We consider self-steering robotic ice melting probes to be the best method to cleanly access these environments, that is, in compliance with planetary protection standards. The required technologies are currently developed and tested."},
  language  = {en}
}
@article{DachwaldTuryshevDittusetal.2005,
  author    = {Dachwald, Bernd and Turyshev, Slava G. and Dittus, H. and Shao, M. [u.a.]},
  title     = {Fundamental Physics with the Laser Astrometric Test Of Relativity / S.G. Turyshev ; H. Dittus ; M. Shao ... B.Dachwald ...},
  series = {Proceedings of the 39th ESLAB Symposium "Trends in Space Science and Cosmic Vision 2020" : 19 - 21 April 2005, ESTEC, Noordwijk, the Netherlands / European Space Agency. [Comp. by: F. Favata ...] . - (ESA SP ; 588)},
  journal   = {Proceedings of the 39th ESLAB Symposium "Trends in Space Science and Cosmic Vision 2020" : 19 - 21 April 2005, ESTEC, Noordwijk, the Netherlands / European Space Agency. [Comp. by: F. Favata ...] . - (ESA SP ; 588)},
  publisher = {ESA Publ. Div.},
  address   = {Noordwijk},
  isbn      = {9290928999},
  pages     = {8 -- 11},
  year      = {2005},
  language  = {en}
}
@article{DachwaldTsinas1994,
  author    = {Dachwald, Bernd and Tsinas, L.},
  title     = {A combined neural and genetic learning algorithm / Tsinas, L. ; Dachwald, B.},
  series = {Proceedings of the First IEEE Conference on Evolutionary Computation, 1994. IEEE World Congress on Computational Intelligence.},
  journal   = {Proceedings of the First IEEE Conference on Evolutionary Computation, 1994. IEEE World Congress on Computational Intelligence.},
  address   = {Orlando, Fl},
  isbn      = {0-7803-1899-4},
  pages     = {770 -- 774},
  year      = {1994},
  language  = {en}
}
@article{DachwaldSeboldtMacdonaldetal.2005,
  author    = {Dachwald, Bernd and Seboldt, Wolfgang and Macdonald, Malcolm and Mengali, Giovanni and Quatra, Alessandro A. and McInnes, Colin R. and Rios-Reyes, Leonel and Scheerers, Daniel J. and Wie, Bong and G{\"o}rlich, Marianne and Lura, Franz and Diedrich, Benjamin and Baturkin, Volodymyr and Coverstone, Victoria L. and Leipold, Manfred and Garbe, Gregory P.},
  title     = {Potential Solar Sail Degradation Effects on Trajectory and Attitude Control},
  series = {AIAA Guidance, Navigation and Control Conference and Exhibit - AIAA Modeling and Simulation Technologies Conference and Exhibit - AIAA Atmospheric Flight Mechanics Conference and Exhibit : [San Francisco, California, 15 - 18 August 2005 ; papers]. - (AIAA meeting papers on disc ; [10.]2005,16-17)},
  journal   = {AIAA Guidance, Navigation and Control Conference and Exhibit - AIAA Modeling and Simulation Technologies Conference and Exhibit - AIAA Atmospheric Flight Mechanics Conference and Exhibit : [San Francisco, California, 15 - 18 August 2005 ; papers]. - (AIAA meeting papers on disc ; [10.]2005,16-17)},
  publisher = {American Institute of Aeronautics and Astronautics},
  address   = {Reston, Va.},
  isbn      = {1-56347-765-3},
  pages     = {2 CD-ROMs},
  year      = {2005},
  language  = {en}
}
@inproceedings{DachwaldSeboldtLoebetal.2007,
  author    = {Dachwald, Bernd and Seboldt, Wolfgang and Loeb, Horst W. and Schartner, Karl-Heinz},
  title     = {A comparison of SEP and NEP for a main belt asteroid sample return mission},
  series = {7th International Symposium on Launcher Technologies, Barcelona, Spain, 02-05 April 2007},
  booktitle = {7th International Symposium on Launcher Technologies, Barcelona, Spain, 02-05 April 2007},
  pages     = {1 -- 10},
  year      = {2007},
  abstract  = {Innovative interplanetary deep space missions, like a main belt asteroid sample return mission, require ever larger velocity increments (∆V s) and thus ever more demanding propulsion capabilities. Providing much larger exhaust velocities than chemical high-thrust systems, electric low-thrust space-propulsion systems can significantly enhance or even enable such high-energy missions. In 1995, a European-Russian Joint Study Group (JSG) presented a study report on "Advanced Interplanetary Missions Using Nuclear-Electric Propulsion" (NEP). One of the investigated reference missions was a sample return (SR) from the main belt asteroid (19) Fortuna. The envisaged nuclear power plant, Topaz-25, however, could not be realized and also the worldwide developments in space reactor hardware stalled. In this paper, we investigate, whether such a mission is also feasible using a solar electric propulsion (SEP) system and compare our SEP results to corresponding NEP results.},
  language  = {en}
}
@inproceedings{DachwaldSeboldtHaeusler2002,
  author    = {Dachwald, Bernd and Seboldt, Wolfgang and H{\"a}usler, Bernd},
  title     = {Performance requirements for near-term interplanetary solar sailcraft missions},
  series = {6th International AAAF Symposium on Space Propulsion: Propulsion for Space Transportation of the XXIst Century},
  booktitle = {6th International AAAF Symposium on Space Propulsion: Propulsion for Space Transportation of the XXIst Century},
  pages     = {9 Seiten},
  year      = {2002},
  abstract  = {Solar sailcraft provide a wide range of opportunities for high-energy low-cost missions. To date, most mission studies require a rather demanding performance that will not be realized by solar sailcraft of the first generation. However, even with solar sailcraft of moderate performance, scientifically relevant missions are feasible. This is demonstrated with a Near Earth Asteroid sample return mission and various planetary rendezvous missions.},
  language  = {en}
}
@article{DachwaldSeboldt2003,
  author    = {Dachwald, Bernd and Seboldt, Wolfgang},
  title     = {Solar sailcraft of the first generation technology development / Seboldt, Wolfgang ; Dachwald, Bernd},
  year      = {2003},
  language  = {en}
}
@article{DachwaldSeboldt2003,
  author    = {Dachwald, Bernd and Seboldt, Wolfgang},
  title     = {Solar sailcraft of the first generation mission applications to near-earth asteroids},
  year      = {2003},
  language  = {en}
}
@article{DachwaldSeboldtRichter2006,
  author    = {Dachwald, Bernd and Seboldt, W. and Richter, L.},
  title     = {Multiple rendezvous and sample return missions to near-Earth objects using solar sailcraft / Dachwald, B. ; Seboldt, W. ; Richter, L.},
  series = {Acta Astronautica. 59 (2006), H. 8-11},
  journal   = {Acta Astronautica. 59 (2006), H. 8-11},
  isbn      = {0094-5765},
  pages     = {768 -- 776},
  year      = {2006},
  language  = {en}
}
@article{DachwaldSeboldtRichter2003,
  author    = {Dachwald, Bernd and Seboldt, W. and Richter, L.},
  title     = {Multiple Rendezvous and Sample Return Missions to Near-Earth Asteroids Using Solar Sailcraft},
  series = {Proceedings of the Fifth IAA International Conference on Low Cost Planetary Missions : 24 - 26 September 2003, ESTEC, Noordwijk, the Netherlands / [comp. by R. A. Harris]},
  journal   = {Proceedings of the Fifth IAA International Conference on Low Cost Planetary Missions : 24 - 26 September 2003, ESTEC, Noordwijk, the Netherlands / [comp. by R. A. Harris]},
  publisher = {ESA},
  address   = {Noordwijk},
  isbn      = {92-9092-853-0},
  pages     = {351 -- 358},
  year      = {2003},
  language  = {en}
}
@article{DachwaldSeboldtLaemmerzahl2008,
  author    = {Dachwald, Bernd and Seboldt, W. and L{\"a}mmerzahl, W.},
  title     = {Solar Sail Propulsion: An Enabling Technology for Fundamental Physics Missions},
  series = {Lasers, Clocks and Drag Free Control : Exploration of Relativistic Gravity in Space / by Hansj{\"o}rg Dittus ..., eds. - ( Astrophysics and Space Science Library ; 349)},
  journal   = {Lasers, Clocks and Drag Free Control : Exploration of Relativistic Gravity in Space / by Hansj{\"o}rg Dittus ..., eds. - ( Astrophysics and Space Science Library ; 349)},
  publisher = {Springer},
  address   = {Berlin [u.a.]},
  isbn      = {978-3-540-34376-9},
  pages     = {379 -- 398},
  year      = {2008},
  language  = {en}
}
@article{DachwaldSeboldtLoebetal.2008,
  author    = {Dachwald, Bernd and Seboldt, W. and Loeb, H. W and Schartner, K.-H.},
  title     = {Main Belt Asteroid Sample Return Mission Using Solar Electric Propulsion},
  series = {Acta Astronautica. 63 (2008), H. 1-4},
  journal   = {Acta Astronautica. 63 (2008), H. 1-4},
  isbn      = {0094-5765},
  pages     = {91 -- 101},
  year      = {2008},
  language  = {en}
}
@article{DachwaldSeboldt2005,
  author    = {Dachwald, Bernd and Seboldt, W.},
  title     = {Multiple Near-Earth Asteroid Rendezvous and Sample Return Using First Generation Solar Sailcraft},
  series = {Acta Astronautica. 57 (2005), H. 11},
  journal   = {Acta Astronautica. 57 (2005), H. 11},
  isbn      = {0094-5765},
  pages     = {864 -- 875},
  year      = {2005},
  language  = {en}
}
@article{DachwaldSeboldt2002,
  author    = {Dachwald, Bernd and Seboldt, W.},
  title     = {Optimization of Interplanetary Rendezvous Trajectories for Solar Sailcraft Using a Neurocontroller},
  series = {A collection of technical papers / AIAA Astrodynamics Specialist Conference : Monterey, California, 5 - 8 August 2002. - Vol. 2},
  journal   = {A collection of technical papers / AIAA Astrodynamics Specialist Conference : Monterey, California, 5 - 8 August 2002. - Vol. 2},
  publisher = {American Institute of Aeronautics and Astronautics},
  address   = {Reston, Va.},
  isbn      = {1-56347-549-9},
  pages     = {1263 -- 1270},
  year      = {2002},
  language  = {en}
}
@article{DachwaldSeboldt2005,
  author    = {Dachwald, Bernd and Seboldt, W.},
  title     = {Solar Sails for Near- and Medium-Term Scientific Deep Space Missions / W. Sebolt ; B. Dachwald},
  series = {In-space propulsion : edited book of proceedings of the 10-IWCP, the 10th International Workshop on Combustion and Propulsion held in Lerici, La Spezia, Italy, 21-25 September 2003 / [ed.: Luigi T. DeLuca]},
  journal   = {In-space propulsion : edited book of proceedings of the 10-IWCP, the 10th International Workshop on Combustion and Propulsion held in Lerici, La Spezia, Italy, 21-25 September 2003 / [ed.: Luigi T. DeLuca]},
  publisher = {SP Lab, Politecnico di Milano},
  address   = {Milano},
  pages     = {getr. Z{\"a}hlung . Ill.},
  year      = {2005},
  language  = {en}
}
@article{DachwaldSeboldt2008,
  author    = {Dachwald, Bernd and Seboldt, W.},
  title     = {Solar Sails — Propellantless Propulsion for Near- and Medium-Term Deep-Space Missions / W. Seboldt ; B. Dachwald},
  series = {Advanced Propulsion Systems and Technologies, Today to 2020 / Claudio Bruno (ed.) ... - (Progress in Astronautics and Aeronautics Series ; 223)},
  journal   = {Advanced Propulsion Systems and Technologies, Today to 2020 / Claudio Bruno (ed.) ... - (Progress in Astronautics and Aeronautics Series ; 223)},
  publisher = {AIAA},
  address   = {Reston, Va.},
  isbn      = {978-1-56347-929-8},
  pages     = {460 S.},
  year      = {2008},
  language  = {en}
}
@article{DachwaldSchmidtSeboldtetal.2003,
  author    = {Dachwald, Bernd and Schmidt, Tanja D. and Seboldt, Wolfgang and Auweter-Kurtz,},
  title     = {Flight Opportunities from Mars to Earth for Piloted Missions Using Continuous Thrust Propulsion / Schmidt, Tanja D. ; Dachwald, Bernd ; Seboldt, Wolfgang ; Auweter-Kurtz, Monika},
  publisher = {-},
  pages     = {1 -- 9},
  year      = {2003},
  language  = {en}
}
@incollection{DachwaldOhndorf2019,
  author    = {Dachwald, Bernd and Ohndorf, Andreas},
  title     = {Global optimization of continuous-thrust trajectories using evolutionary neurocontrol},
  series = {Modeling and Optimization in Space Engineering},
  booktitle = {Modeling and Optimization in Space Engineering},
  publisher = {Springer},
  address   = {Cham},
  isbn      = {978-3-030-10501-3},
  doi       = {10.1007/978-3-030-10501-3_2},
  pages     = {33 -- 57},
  year      = {2019},
  abstract  = {Searching optimal continuous-thrust trajectories is usually a difficult and time-consuming task. The solution quality of traditional optimal-control methods depends strongly on an adequate initial guess because the solution is typically close to the initial guess, which may be far from the (unknown) global optimum. Evolutionary neurocontrol attacks continuous-thrust optimization problems from the perspective of artificial intelligence and machine learning, combining artificial neural networks and evolutionary algorithms. This chapter describes the method and shows some example results for single- and multi-phase continuous-thrust trajectory optimization problems to assess its performance. Evolutionary neurocontrol can explore the trajectory search space more exhaustively than a human expert can do with traditional optimal-control methods. Especially for difficult problems, it usually finds solutions that are closer to the global optimum. Another fundamental advantage is that continuous-thrust trajectories can be optimized without an initial guess and without expert supervision.},
  language  = {en}
}
@article{DachwaldOhndorfWie2006,
  author    = {Dachwald, Bernd and Ohndorf, A. and Wie, Bong},
  title     = {Solar Sail Trajectory Optimization for the Solar Polar Imager (SPI) Mission},
  series = {AIAA Guidance, Navigation, and Control Conference \& Exhibit - AIAA Atmospheric Flight Mechanics Conference \& Exhibit - AIAA Modeling and Simulation Technologies Conference \& Exhibit - AIAA/AAS Astrodynamics Specialist Conference \& Exhibit : [21 - 24 August 2006, Keystone, Colorado ; papers]. - (AIAA meeting papers on disc ; [11.]2006,19-20 )},
  journal   = {AIAA Guidance, Navigation, and Control Conference \& Exhibit - AIAA Atmospheric Flight Mechanics Conference \& Exhibit - AIAA Modeling and Simulation Technologies Conference \& Exhibit - AIAA/AAS Astrodynamics Specialist Conference \& Exhibit : [21 - 24 August 2006, Keystone, Colorado ; papers]. - (AIAA meeting papers on disc ; [11.]2006,19-20 )},
  publisher = {American Institute of Aeronautics and Astronautics},
  address   = {Reston, Va.},
  isbn      = {1-56347-802-1},
  pages     = {2 CD-ROMs.},
  year      = {2006},
  language  = {en}
}
@article{DachwaldOhndorfGill2009,
  author    = {Dachwald, Bernd and Ohndorf, A. and Gill, E.},
  title     = {Optimization of low-thrust Earth-Moon transfers using evolutionary neurocontrol / Ohndorf, A. ; Dachwald, B. ; Gill, E.},
  series = {IEEE Congress on Evolutionary Computation, 2009. CEC '09.},
  journal   = {IEEE Congress on Evolutionary Computation, 2009. CEC '09.},
  isbn      = {978-1-4244-2958-5},
  pages     = {358 -- 364},
  year      = {2009},
  language  = {en}
}
@article{DachwaldOhndorf2007,
  author    = {Dachwald, Bernd and Ohndorf, A.},
  title     = {1st ACT Global Trajectory Optimisation Competition : Results found at DLR},
  series = {Acta Astronautica. 61 (2007), H. 9},
  journal   = {Acta Astronautica. 61 (2007), H. 9},
  isbn      = {0094-5765},
  pages     = {742 -- 752},
  year      = {2007},
  language  = {en}
}
@article{DachwaldMikuckiTulaczyketal.2014,
  author    = {Dachwald, Bernd and Mikucki, Jill and Tulaczyk, Slawek and Digel, Ilya and Espe, Clemens and Feldmann, Marco and Francke, Gero and Kowalski, Julia and Xu, Changsheng},
  title     = {IceMole : A maneuverable probe for clean in situ analysis and sampling of subsurface ice and subglacial aquatic ecosystems},
  series = {Annals of Glaciology},
  volume    = {55},
  journal   = {Annals of Glaciology},
  number    = {65},
  publisher = {Cambridge University Press},
  address   = {Cambridge},
  issn      = {1727-5644},
  doi       = {10.3189/2014AoG65A004},
  pages     = {14 -- 22},
  year      = {2014},
  abstract  = {There is significant interest in sampling subglacial environments for geobiological studies, but they are difficult to access. Existing ice-drilling technologies make it cumbersome to maintain microbiologically clean access for sample acquisition and environmental stewardship of potentially fragile subglacial aquatic ecosystems. The IceMole is a maneuverable subsurface ice probe for clean in situ analysis and sampling of glacial ice and subglacial materials. The design is based on the novel concept of combining melting and mechanical propulsion. It can change melting direction by differential heating of the melting head and optional side-wall heaters. The first two prototypes were successfully tested between 2010 and 2012 on glaciers in Switzerland and Iceland. They demonstrated downward, horizontal and upward melting, as well as curve driving and dirt layer penetration. A more advanced probe is currently under development as part of the Enceladus Explorer (EnEx) project. It offers systems for obstacle avoidance, target detection, and navigation in ice. For the EnEx-IceMole, we will pay particular attention to clean protocols for the sampling of subglacial materials for biogeochemical analysis. We plan to use this probe for clean access into a unique subglacial aquatic environment at Blood Falls, Antarctica, with return of a subglacial brine sample.},
  language  = {en}
}
@inproceedings{DachwaldMikuckiTulaczyketal.2012,
  author    = {Dachwald, Bernd and Mikucki, Jill A. and Tulaczyk, Slawek and Digel, Ilya and Feldmann, Marco and Espe, Clemens and Plescher, Engelbert and Xu, Changsheng},
  title     = {IceMole - a maneuverable probe for clean in-situ analysis and sampling of subsurface ice and subglacial aquatic ecosystems : extended abstract / SCAR Open Science Conference 2012, Session 29: Advancing Clean Technologies for Exploration of Glacial Aquatic Ecosystems},
  year      = {2012},
  abstract  = {The "IceMole" is a novel maneuverable subsurface ice probe for clean in-situ analysis and sampling of subsurface ice and subglacial water/brine. It is developed and build at FH Aachen University of Applied Sciences' Astronautical Laboratory. A first prototype was successfully tested on the Swiss Morteratsch glacier in 2010. Clean sampling is achieved with a hollow ice screw (as it is used in mountaineering) at the tip of the probe. Maneuverability is achieved with a differentially heated melting head. Funded by the German Space Agency (DLR), a consortium led by FH Aachen currently develops a much more advanced IceMole probe, which includes a sophisticated system for obstacle avoidance, target detection, and navigation in the ice. We intend to use this probe for taking clean samples of subglacial brine at the Blood Falls (McMurdo Dry Valleys, East Antarctica) for chemical and microbiological analysis. In our conference contribution, we 1) describe the IceMole design, 2) report the results of the field tests of the first prototype on the Morteratsch glacier, 3) discuss the probe's potential for the clean in-situ analysis and sampling of subsurface ice and subglacial liquids, and 4) outline the way ahead in the development of this technology.},
  subject      = {Eisschicht},
  language  = {en}
}
@article{DachwaldMengaliQuartaetal.2007,
  author    = {Dachwald, Bernd and Mengali, Giovanni and Quarta, Alessandro A. and Circi, Christian},
  title     = {Refined Solar Sail Force Model with Mission Application / Giovanni Mengali ; Alessandro A. Quarta , Christian Circi ; Bernd Dachwald},
  series = {Journal of Guidance, Control, and Dynamics. 30 (2007), H. 2},
  journal   = {Journal of Guidance, Control, and Dynamics. 30 (2007), H. 2},
  isbn      = {0162-3192},
  pages     = {512 -- 520},
  year      = {2007},
  language  = {en}
}
@inproceedings{DachwaldMengaliQuartaetal.2007,
  author    = {Dachwald, Bernd and Mengali, Giovanni and Quarta, Alessandro A and Macdonald, Malcolm and McInnes, Colin R},
  title     = {Optical solar sail degradation modelling},
  series = {1st International Symposium on Solar Sailing},
  booktitle = {1st International Symposium on Solar Sailing},
  pages     = {1 -- 27},
  year      = {2007},
  abstract  = {We propose a simple parametric OSSD model that describes the variation of the sail film's optical coefficients with time, depending on the sail film's environmental history, i.e., the radiation dose. The primary intention of our model is not to describe the exact behavior of specific film-coating combinations in the real space environment, but to provide a more general parametric framework for describing the general optical degradation behavior of solar sails.},
  language  = {en}
}
@article{DachwaldMengaliQuartaetal.2006,
  author    = {Dachwald, Bernd and Mengali, Giovanni and Quarta, Alessandrao A. and Macdonald, Malcolm},
  title     = {Parametric Model and Optimal Control of Solar Sails with Optical Degradation},
  series = {Journal of guidance, control, and dynamics. 29 (2006), H. 5},
  journal   = {Journal of guidance, control, and dynamics. 29 (2006), H. 5},
  isbn      = {0162-3192},
  pages     = {1170 -- 1178},
  year      = {2006},
  language  = {en}
}
@article{DachwaldMcDonaldMcInnesetal.2007,
  author    = {Dachwald, Bernd and McDonald, Malcolm and McInnes, Colin R. and Mengali, Giovanni},
  title     = {Impact of Optical Degradation on Solar Sail Mission Performance},
  series = {Journal of Spacecraft and Rockets. 44 (2007), H. 4},
  journal   = {Journal of Spacecraft and Rockets. 44 (2007), H. 4},
  isbn      = {0022-4650},
  pages     = {740 -- 749},
  year      = {2007},
  language  = {en}
}
@article{DachwaldMacDonaldMcInnes2007,
  author    = {Dachwald, Bernd and MacDonald, Malcolm and McInnes, Colin R.},
  title     = {Heliocentric Solar Sail Orbit Transfers with Locally Optimal Control Laws / Malcolm Macdonald ; Colin McInnes ; Bernd Dachwald},
  series = {Journal of Spacecraft and Rockets. 44 (2007), H. 1},
  journal   = {Journal of Spacecraft and Rockets. 44 (2007), H. 1},
  isbn      = {0022-4650},
  pages     = {273 -- 276},
  year      = {2007},
  language  = {en}
}
@article{DachwaldLeipoldFichtner2003,
  author    = {Dachwald, Bernd and Leipold, M. and Fichtner, H.},
  title     = {Heliopause Explorer - A Sailcraft Mission to the Outer Boundaries of the Solar System / M. Leipold ; H. Fichtner ; B. Heber ... B. Dachwald ...},
  series = {Proceedings of the Fifth IAA International Conference on Low Cost Planetary Missions : 24 - 26 September 2003, ESTEC, Noordwijk, the Netherlands / [comp. by R. A. Harris]},
  journal   = {Proceedings of the Fifth IAA International Conference on Low Cost Planetary Missions : 24 - 26 September 2003, ESTEC, Noordwijk, the Netherlands / [comp. by R. A. Harris]},
  publisher = {ESA},
  address   = {Noordwijk},
  isbn      = {92-9092-853-0},
  pages     = {367 -- 375},
  year      = {2003},
  language  = {en}
}
@article{DachwaldKahleWie2006,
  author    = {Dachwald, Bernd and Kahle, Ralph and Wie, Bong},
  title     = {Solar Sailing Kinetic Energy Impactor (KEI) Mission Design Tradeoffs for Impacting and Deflecting Asteroid 99942 Apophis},
  series = {AIAA Guidance, Navigation, and Control Conference \& Exhibit - AIAA Atmospheric Flight Mechanics Conference \& Exhibit - AIAA Modeling and Simulation Technologies Conference \& Exhibit - AIAA/AAS Astrodynamics Specialist Conference \& Exhibit : [21 - 24 August 2006, Keystone, Colorado ; papers]. - (AIAA meeting papers on disc ; [11.]2006,19-20 )},
  journal   = {AIAA Guidance, Navigation, and Control Conference \& Exhibit - AIAA Atmospheric Flight Mechanics Conference \& Exhibit - AIAA Modeling and Simulation Technologies Conference \& Exhibit - AIAA/AAS Astrodynamics Specialist Conference \& Exhibit : [21 - 24 August 2006, Keystone, Colorado ; papers]. - (AIAA meeting papers on disc ; [11.]2006,19-20 )},
  publisher = {American Institute of Aeronautics and Astronautics},
  address   = {Reston, Va.},
  isbn      = {1-56347-802-1},
  pages     = {1 -- 20},
  year      = {2006},
  language  = {en}
}
@inproceedings{DachwaldKahleWie2006,
  author    = {Dachwald, Bernd and Kahle, Ralph and Wie, Bong},
  title     = {Solar sail Kinetic Energy Impactor (KEI) mission design tradeoffs for impacting and deflecting asteroid 99942 Apophis},
  series = {AIAA/AAS Astrodynamics Specialist Conference and Exhibit},
  booktitle = {AIAA/AAS Astrodynamics Specialist Conference and Exhibit},
  doi       = {10.2514/6.2006-6178},
  pages     = {1 -- 20},
  year      = {2006},
  abstract  = {Near-Earth asteroid 99942 Apophis provides a typical example for the evolution of asteroid orbits that lead to Earth-impacts after a close Earth-encounter that results in a resonant return. Apophis will have a close Earth-encounter in 2029 with potential very close subsequent Earth-encounters (or even an impact) in 2036 or later, depending on whether it passes through one of several so-called gravitational keyholes during its 2029-encounter. Several pre-2029-deflection scenarios to prevent Apophis from doing this have been investigated so far. Because the keyholes are less than 1 km in size, a pre-2029 kinetic impact is clearly the best option because it requires only a small change in Apophis' orbit to nudge it out of a keyhole. A single solar sail Kinetic Energy Impactor (KEI) spacecraft that impacts Apophis from a retrograde trajectory with a very high relative velocity (75-80 km/s) during one of its perihelion passages at about 0.75 AU would be a feasible option to do this. The spacecraft consists of a 160 m x 160 m, 168 kg solar sail assembly and a 150 kg impactor. Although conventional spacecraft can also achieve the required minimum deflection of 1 km for this approx. 320 m-sized object from a prograde trajectory, our solar sail KEI concept also allows the deflection of larger objects. In this paper, we also show that, even after Apophis has flown through one of the gravitational keyholes in 2029, solar sail Kinetic Energy Impactor (KEI) spacecraft are still a feasible option to prevent Apophis from impacting the Earth, but many KEIs would be required for consecutive impacts to increase the total Earth-miss distance to a safe value. In this paper, we elaborate potential pre- and post-2029 KEI impact scenarios for a launch in 2020, and investigate tradeoffs between different mission parameters.},
  language  = {en}
}
@inproceedings{DachwaldKahleWie2007,
  author    = {Dachwald, Bernd and Kahle, Ralph and Wie, Bong},
  title     = {Head-on impact deflection of NEAs: a case study for 99942 Apophis},
  series = {Planetary Defense Conference 2007},
  booktitle = {Planetary Defense Conference 2007},
  pages     = {1 -- 12},
  year      = {2007},
  abstract  = {Near-Earth asteroid (NEA) 99942 Apophis provides a typical example for the evolution of asteroid orbits that lead to Earth-impacts after a close Earth-encounter that results in a resonant return. Apophis will have a close Earth-encounter in 2029 with potential very close subsequent Earth-encounters (or even an impact) in 2036 or later, depending on whether it passes through one of several less than 1 km-sized gravitational keyholes during its 2029-encounter. A pre-2029 kinetic impact is a very favorable option to nudge the asteroid out of a keyhole. The highest impact velocity and thus deflection can be achieved from a trajectory that is retrograde to Apophis orbit. With a chemical or electric propulsion system, however, many gravity assists and thus a long time is required to achieve this. We show in this paper that the solar sail might be the better propulsion system for such a mission: a solar sail Kinetic Energy Impactor (KEI) spacecraft could impact Apophis from a retrograde trajectory with a very high relative velocity (75-80 km/s) during one of its perihelion passages. The spacecraft consists of a 160 m × 160 m, 168 kg solar sail assembly and a 150 kg impactor. Although conventional spacecraft can also achieve the required minimum deflection of 1 km for this approx. 320 m-sized object from a prograde trajectory, our solar sail KEI concept also allows the deflection of larger objects. For a launch in 2020, we also show that, even after Apophis has flown through one of the gravitational keyholes in 2029, the solar sail KEI concept is still feasible to prevent Apophis from impacting the Earth, but many KEIs would be required for consecutive impacts to increase the total Earth-miss distance to a safe value},
  language  = {en}
}
@inproceedings{DachwaldFeldmannEspeetal.2012,
  author    = {Dachwald, Bernd and Feldmann, Marco and Espe, Clemens and Plescher, Engelbert and Konstantinidis, K. and Forstner, R.},
  title     = {Enceladus explorer - A maneuverable subsurface probe for autonomous navigation through deep ice},
  series = {63rd International Astronautical Congress 2012, IAC 2012; Naples; Italy; 1 October 2012 through 5 October 2012. (Proceedings of the International Astronautical Congress, IAC ; 3)},
  booktitle = {63rd International Astronautical Congress 2012, IAC 2012; Naples; Italy; 1 October 2012 through 5 October 2012. (Proceedings of the International Astronautical Congress, IAC ; 3)},
  publisher = {Curran},
  address   = {Red Hook, NY},
  organization    = {International Astronautical Congress <63, 2012, Napoli>},
  isbn      = {978-1-62276-979-7},
  pages     = {1756 -- 1766},
  year      = {2012},
  language  = {en}
}
@article{DachwaldCarnelliVasile2009,
  author    = {Dachwald, Bernd and Carnelli, Ian and Vasile, Massimiliano},
  title     = {Evolutionary Neurocontrol: A Novel Method for Low-Thrust Gravity-Assist Trajectory Optimization / Carnelli, Ian ; Dachwald, Bernd ; Vasile, Massimiliano},
  series = {Journal of guidance control and dynamics. 32 (2009), H. 2},
  journal   = {Journal of guidance control and dynamics. 32 (2009), H. 2},
  publisher = {AIAA},
  address   = {Reston, Va.},
  isbn      = {0731-5090},
  pages     = {616 -- 625},
  year      = {2009},
  language  = {en}
}
@article{DachwaldCarnelliVasile2006,
  author    = {Dachwald, Bernd and Carnelli, I. and Vasile, M.},
  title     = {Low-Thrust Gravity Assist Trajectory Optimization Using Evolutionary Neurocontrollers / I. Carnelli ; B. Dachwald ; M. Vasile ...},
  series = {Astrodynamics 2005 : proceedings of the AAS/AIAA astrodynamics conference held August 7 - 11, 2005, South Lake Tahoe, California / ed. by Bobby G. Williams. - Pt. 3. - (Advances in the astronautical sciences ; 123,3)},
  journal   = {Astrodynamics 2005 : proceedings of the AAS/AIAA astrodynamics conference held August 7 - 11, 2005, South Lake Tahoe, California / ed. by Bobby G. Williams. - Pt. 3. - (Advances in the astronautical sciences ; 123,3)},
  publisher = {Univelt},
  address   = {San Diego, Calif.},
  isbn      = {0-87703-527-X},
  pages     = {1911 -- 1928},
  year      = {2006},
  language  = {en}
}
@article{DachwaldCarnelliVasile2007,
  author    = {Dachwald, Bernd and Carnelli, I. and Vasile, M.},
  title     = {Optimizing low-thrust gravity assist interplanetary trajectories using evolutionary neurocontrollers / I. Carnelli ; B. Dachwald ; M. Vasile},
  series = {IEEE Congress on Evolutionary Computation, 2007 : CEC 2007 ; 25 - 28 September 2007, Singapore},
  journal   = {IEEE Congress on Evolutionary Computation, 2007 : CEC 2007 ; 25 - 28 September 2007, Singapore},
  publisher = {IEEE Service Center},
  address   = {Piscataway, NJ},
  isbn      = {978-1-424-41339-3},
  pages     = {965 -- 972},
  year      = {2007},
  language  = {en}
}
@article{DachwaldCarnelliVasile2006,
  author    = {Dachwald, Bernd and Carnelli, I. and Vasile, M.},
  title     = {Evolutionary Neurocontrol as a Novel Method for Low-Thrust Gravity Assist Trajectory Optimization / I. Carnelli ; B. Dachwald ; M. Vasile},
  series = {Proceedings of the Twenty-Fifth International Symposium on Space Technology and Science (Selected papers) : Kanazawa, [June 4 through June 11, 2006, at Kanazawa-shi Kanko Kaikan in Kanazawa city] / [Japan Society for Aeronautical and Space Sciences. Kohtaro Matsumoto [ed.-in-chief]},
  journal   = {Proceedings of the Twenty-Fifth International Symposium on Space Technology and Science (Selected papers) : Kanazawa, [June 4 through June 11, 2006, at Kanazawa-shi Kanko Kaikan in Kanazawa city] / [Japan Society for Aeronautical and Space Sciences. Kohtaro Matsumoto [ed.-in-chief]},
  publisher = {JSASS},
  address   = {Tokyo},
  isbn      = {4-99005-002-9},
  pages     = {569 -- 574},
  year      = {2006},
  language  = {en}
}
@incollection{DachwaldBoehnhardtBrojetal.2014,
  author    = {Dachwald, Bernd and Boehnhardt, Herrmann and Broj, Ulrich and Geppert, Ulrich R. M. E. and Grundmann, Jan-Thimo and Seboldt, Wolfgang and Seefeldt, Patric and Spietz, Peter and Johnson, Les and K{\"u}hrt, Ekkehard and Mottola, Stefano and Macdonald, Malcolm and McInnes, Colin R. and Vasile, Massimiliano and Reinhard, Ruedeger},
  title     = {Gossamer roadmap technology reference study for a multiple NEO Rendezvous Mission},
  series = {Advances in solar sailing},
  booktitle = {Advances in solar sailing},
  publisher = {Springer},
  address   = {Berlin [u.a.]},
  isbn      = {978-3-642-34906-5 (Print) ; 978-3-642-34907-2 (E-Book)},
  pages     = {211 -- 226},
  year      = {2014},
  abstract  = {A technology reference study for a multiple near-Earth object (NEO) rendezvous mission with solar sailcraft is currently carried out by the authors of this paper. The investigated mission builds on previous concepts, but adopts a strong micro-spacecraft philosophy based on the DLR/ESA Gossamer technology. The main scientific objective of the mission is to explore the diversity of NEOs. After direct interplanetary insertion, the solar sailcraft should—within less than 10 years—rendezvous three NEOs that are not only scientifically interesting, but also from the point of human spaceight and planetary defense. In this paper, the objectives of the study are outlined and a preliminary potential mission profile is presented.},
  language  = {en}
}
@article{DachwaldBaturkinCoverstoneetal.2006,
  author    = {Dachwald, Bernd and Baturkin, Volodymyr and Coverstone, Victoria L. and Dietrich, Benjamin and Garbe, Gregory P. and G{\"o}rlich, Marianne and Leipold, Manfred and Lura, Franz and Macdonald, Malcolm and McInnes, Colin R. and Mengali, Giovanni and Quatra, Alessandro A. and Rios-Reyes, Leonel and Scheeres, Daniel J. and Seboldt, Wolfgang and Wie, Bong},
  title     = {Potential Effects of Optical Solar Sail Degradation on Interplanetary Trajectory Design},
  series = {Astrodynamics 2005 : proceedings of the AAS/AIAA astrodynamics conference held August 7 - 11, 2005, South Lake Tahoe, California / ed. by Bobby G. Williams. - Pt. 3. - (Advances in the astronautical sciences ; 123,3)},
  journal   = {Astrodynamics 2005 : proceedings of the AAS/AIAA astrodynamics conference held August 7 - 11, 2005, South Lake Tahoe, California / ed. by Bobby G. Williams. - Pt. 3. - (Advances in the astronautical sciences ; 123,3)},
  publisher = {Univelt},
  address   = {San Diego, Calif.},
  isbn      = {0-87703-527-X},
  pages     = {2569 -- 2592},
  year      = {2006},
  language  = {en}
}
@inproceedings{DachwaldBaturkinCoverstoneetal.2005,
  author    = {Dachwald, Bernd and Baturkin, Volodymyr and Coverstone, Victoria and Diedrich, Ben and Garbe, Gregory and G{\"o}rlich, Marianne and Leipold, Manfred and Lura, Franz and Macdonald, Malcolm and McInnes, Colin and Mengali, Giovanni and Quarta, Alessandro and Rios-Reyes, Leonel and Scheeres, Daniel J. and Seboldt, Wolfgang and Wie, Bong},
  title     = {Potential effects of optical solar sail degredation on trajectory design},
  series = {AAS/AIAA Astrodynamics Specialist},
  booktitle = {AAS/AIAA Astrodynamics Specialist},
  pages     = {1 -- 23},
  year      = {2005},
  abstract  = {The optical properties of the thin metalized polymer films that are projected for solar sails are assumed to be affected by the erosive effects of the space environment. Their degradation behavior in the real space environment, however, is to a considerable degree indefinite, because initial ground test results are controversial and relevant inspace tests have not been made so far. The standard optical solar sail models that are currently used for trajectory design do not take optical degradation into account, hence its potential effects on trajectory design have not been investigated so far. Nevertheless, optical degradation is important for high-fidelity solar sail mission design, because it decreases both the magnitude of the solar radiation pressure force acting on the sail and also the sail control authority. Therefore, we propose a simple parametric optical solar sail degradation model that describes the variation of the sail film's optical coefficients with time, depending on the sail film's environmental history, i.e., the radiation dose. The primary intention of our model is not to describe the exact behavior of specific film-coating combinations in the real space environment, but to provide a more general parametric framework for describing the general optical degradation behavior of solar sails. Using our model, the effects of different optical degradation behaviors on trajectory design are investigated for various exemplary missions.},
  language  = {en}
}
@article{DachwaldBallUlamecetal.2009,
  author    = {Dachwald, Bernd and Ball, Andrew J. and Ulamec, Stephan and Price, Michael E.},
  title     = {A small mission for in situ exploration of a primitive binary near-Earth asteroid / Ball, Andrew J. ; Ulamec, Stephan ; Dachwald, Bernd ; Price, Michael E. ; [u.a.]},
  series = {Advances in Space Research. 43 (2009), H. 2},
  journal   = {Advances in Space Research. 43 (2009), H. 2},
  publisher = {Elsevier},
  address   = {Amsterdam},
  isbn      = {0273-1177},
  pages     = {317 -- 324},
  year      = {2009},
  language  = {en}
}
@article{Dachwald2005,
  author    = {Dachwald, Bernd},
  title     = {Optimization of very-low-thrust trajectories using evolutionary neurocontrol},
  series = {Acta Astronautica. 57 (2005), H. 2-8},
  journal   = {Acta Astronautica. 57 (2005), H. 2-8},
  isbn      = {0094-5765},
  pages     = {175 -- 185},
  year      = {2005},
  language  = {en}
}
@article{Dachwald2004,
  author    = {Dachwald, Bernd},
  title     = {Minimum Transfer Times for Nonperfectly Reflecting Solar Sailcraft},
  series = {Journal of Spacecraft and Rockets. 41 (2004), H. 4},
  journal   = {Journal of Spacecraft and Rockets. 41 (2004), H. 4},
  isbn      = {0022-4650},
  pages     = {693 -- 695},
  year      = {2004},
  language  = {en}
}
@article{Dachwald2005,
  author    = {Dachwald, Bernd},
  title     = {Optimal Solar Sail Trajectories for Missions to the Outer Solar System},
  series = {Journal of guidance, control, and dynamics. 28 (2005), H. 6},
  journal   = {Journal of guidance, control, and dynamics. 28 (2005), H. 6},
  isbn      = {0162-3192},
  pages     = {1187 -- 1193},
  year      = {2005},
  language  = {en}
}
@article{Dachwald2004,
  author    = {Dachwald, Bernd},
  title     = {Optimization of Interplanetary Solar Sailcraft Trajectories Using Evolutionary Neurocontrol},
  series = {Journal of guidance, control, and dynamics. 27 (2004), H. 1},
  journal   = {Journal of guidance, control, and dynamics. 27 (2004), H. 1},
  isbn      = {0162-3192},
  pages     = {66 -- 72},
  year      = {2004},
  language  = {en}
}
@article{Dachwald2004,
  author    = {Dachwald, Bernd},
  title     = {Interplanetary Mission Analysis for Non-Perfectly Reflecting Solar Sailcraft Using Evolutionary Neurocontrol},
  series = {Astrodynamics 2003 : proceedings of the AAS/AIAA Astrodynamics Conference held August 3 - 7, 2003, Big Sky, Montana / ed. by Jean de Lafontaine. - Pt. 2. - (Advances in the astronautical sciences ; 116,2)},
  journal   = {Astrodynamics 2003 : proceedings of the AAS/AIAA Astrodynamics Conference held August 3 - 7, 2003, Big Sky, Montana / ed. by Jean de Lafontaine. - Pt. 2. - (Advances in the astronautical sciences ; 116,2)},
  publisher = {Univelt},
  address   = {San Diego, Calif.},
  isbn      = {0-87703-509-1},
  pages     = {1247 -- 1262},
  year      = {2004},
  language  = {en}
}
@article{Dachwald2004,
  author    = {Dachwald, Bernd},
  title     = {Low-Thrust Trajectory Optimization and Interplanetary Mission Analysis Using Evolutionary Neurocontrol},
  series = {Deutscher Luft- und Raumfahrtkongress 2004 : Dresden, 20. bis 23. September 2004, Motto: Luft- und Raumfahrt - Br{\"u}cke f{\"u}r eine wissensbasierte Gesellschaft / Deutsche Gesellschaft f{\"u}r Luft- und Raumfahrt - Lilienthal-Oberth e.V. (DGLR). [Red.: Peter Brandt (verantwortlich)]. - Bd. 2. - (Jahrbuch ... der Deutschen Gesellschaft f{\"u}r Luft- und Raumfahrt)},
  journal   = {Deutscher Luft- und Raumfahrtkongress 2004 : Dresden, 20. bis 23. September 2004, Motto: Luft- und Raumfahrt - Br{\"u}cke f{\"u}r eine wissensbasierte Gesellschaft / Deutsche Gesellschaft f{\"u}r Luft- und Raumfahrt - Lilienthal-Oberth e.V. (DGLR). [Red.: Peter Brandt (verantwortlich)]. - Bd. 2. - (Jahrbuch ... der Deutschen Gesellschaft f{\"u}r Luft- und Raumfahrt)},
  address   = {Bonn},
  pages     = {917 -- 926},
  year      = {2004},
  language  = {en}
}
@article{Dachwald2004,
  author    = {Dachwald, Bernd},
  title     = {Evolutionary Neurocontrol: A Smart Method for Global Optimization of Low-Thrust Trajectories},
  series = {22nd AIAA Applied Aerodynamics Conference and Exhibit - AIAA/AAS Astrodynamics Specialist Conference and Exhibit - AIAA Guidance, Navigation, and Control Conference and Exhibit - AIAA Modeling and Simulation Technologies Conference and Exhibit - AIAA Atmospheric Flight Mechanics Conference and Exhibit : 16 - 19 August 2004, Providence, Rhode Island / American Institute of Aeronautics and Astronautics. - (AIAA meeting papers on disc ; 2004,14-15)},
  journal   = {22nd AIAA Applied Aerodynamics Conference and Exhibit - AIAA/AAS Astrodynamics Specialist Conference and Exhibit - AIAA Guidance, Navigation, and Control Conference and Exhibit - AIAA Modeling and Simulation Technologies Conference and Exhibit - AIAA Atmospheric Flight Mechanics Conference and Exhibit : 16 - 19 August 2004, Providence, Rhode Island / American Institute of Aeronautics and Astronautics. - (AIAA meeting papers on disc ; 2004,14-15)},
  publisher = {American Inst. of Aeronautics and Astronautics},
  address   = {Reston, Va.},
  pages     = {2 CD-ROMs},
  year      = {2004},
  language  = {en}
}
@article{Dachwald2004,
  author    = {Dachwald, Bernd},
  title     = {Optimal Solar Sail Trajectories for Missions to the Outer Solar System},
  series = {22nd AIAA Applied Aerodynamics Conference and Exhibit - AIAA/AAS Astrodynamics Specialist Conference and Exhibit - AIAA Guidance, Navigation, and Control Conference and Exhibit - AIAA Modeling and Simulation Technologies Conference and Exhibit - AIAA Atmospheric Flight Mechanics Conference and Exhibit : 16 - 19 August 2004, Providence, Rhode Island / American Institute of Aeronautics and Astronautics. - (AIAA meeting papers on disc ; 2004,14-15)},
  journal   = {22nd AIAA Applied Aerodynamics Conference and Exhibit - AIAA/AAS Astrodynamics Specialist Conference and Exhibit - AIAA Guidance, Navigation, and Control Conference and Exhibit - AIAA Modeling and Simulation Technologies Conference and Exhibit - AIAA Atmospheric Flight Mechanics Conference and Exhibit : 16 - 19 August 2004, Providence, Rhode Island / American Institute of Aeronautics and Astronautics. - (AIAA meeting papers on disc ; 2004,14-15)},
  publisher = {American Inst. of Aeronautics and Astronautics},
  address   = {Reston, Va.},
  pages     = {2 CD-ROMs},
  year      = {2004},
  language  = {en}
}
@inproceedings{Dachwald2007,
  author    = {Dachwald, Bernd},
  title     = {Low-Thrust Mission Analysis and Global Trajectory Optimization Using Evolutionary Neurocontrol: New Results},
  series = {European Workshop on Space Mission Analysis ESA/ESOC, Darmstadt, Germany 10 { 12 Dec 2007},
  booktitle = {European Workshop on Space Mission Analysis ESA/ESOC, Darmstadt, Germany 10 { 12 Dec 2007},
  year      = {2007},
  abstract  = {Interplanetary trajectories for low-thrust spacecraft are often characterized by multiple revolutions around the sun. Unfortunately, the convergence of traditional trajectory optimizers that are based on numerical optimal control methods depends strongly on an adequate initial guess for the control function (if a direct method is used) or for the starting values of the adjoint vector (if an indirect method is used). Especially when many revolutions around the sun are re- quired, trajectory optimization becomes a very difficult and time-consuming task that involves a lot of experience and expert knowledge in astrodynamics and optimal control theory, because an adequate initial guess is extremely hard to find. Evolutionary neurocontrol (ENC) was proposed as a smart method for low-thrust trajectory optimization that fuses artificial neural networks and evolutionary algorithms to so-called evolutionary neurocontrollers (ENCs) [1]. Inspired by natural archetypes, ENC attacks the trajectoryoptimization problem from the perspective of artificial intelligence and machine learning, a perspective that is quite different from that of optimal control theory. Within the context of ENC, a trajectory is regarded as the result of a spacecraft steering strategy that maps permanently the actual spacecraft state and the actual target state onto the actual spacecraft control vector. This way, the problem of searching the optimal spacecraft trajectory is equivalent to the problem of searching (or "learning") the optimal spacecraft steering strategy. An artificial neural network is used to implement such a spacecraft steering strategy. It can be regarded as a parameterized function (the network function) that is defined by the internal network parameters. Therefore, each distinct set of network parameters defines a different network function and thus a different steering strategy. The problem of searching the optimal steering strategy is now equivalent to the problem of searching the optimal set of network parameters. Evolutionary algorithms that work on a population of (artificial) chromosomes are used to find the optimal network parameters, because the parameters can be easily mapped onto a chromosome. The trajectory optimization problem is solved when the optimal chromosome is found. A comparison of solar sail trajectories that have been published by others [2, 3, 4, 5] with ENC-trajectories has shown that ENCs can be successfully applied for near-globally optimal spacecraft control [1, 6] and that they are able to find trajectories that are closer to the (unknown) global optimum, because they explore the trajectory search space more exhaustively than a human expert can do. The obtained trajectories are fairly accurate with respect to the terminal constraint. If a more accurate trajectory is required, the ENC-solution can be used as an initial guess for a local trajectory optimization method. Using ENC, low-thrust trajectories can be optimized without an initial guess and without expert attendance. Here, new results for nuclear electric spacecraft and for solar sail spacecraft are presented and it will be shown that ENCs find very good trajectories even for very difficult problems. Trajectory optimization results are presented for 1. NASA's Solar Polar Imager Mission, a mission to attain a highly inclined close solar orbit with a solar sail [7] 2. a mission to de ect asteroid Apophis with a solar sail from a retrograde orbit with a very-high velocity impact [8, 9] 3. JPL's \2nd Global Trajectory Optimization Competition", a grand tour to visit four asteroids from different classes with a NEP spacecraft},
  language  = {en}
}