@article{Dachwald2005, author = {Dachwald, Bernd}, title = {Optimization of very-low-thrust trajectories using evolutionary neurocontrol}, series = {Acta Astronautica}, volume = {57}, journal = {Acta Astronautica}, number = {2-8}, publisher = {Elsevier}, address = {Amsterdam [u.a.]}, isbn = {1879-2030}, pages = {175 -- 185}, year = {2005}, abstract = {Searching optimal interplanetary trajectories for low-thrust spacecraft is usually a difficult and time-consuming task that involves much experience and expert knowledge in astrodynamics and optimal control theory. This is because the convergence behavior of traditional local optimizers, which are based on numerical optimal control methods, depends on an adequate initial guess, which is often hard to find, especially for very-low-thrust trajectories that necessitate many revolutions around the sun. The obtained solutions are typically close to the initial guess that is rarely close to the (unknown) global optimum. Within this paper, trajectory optimization problems are attacked from the perspective of artificial intelligence and machine learning. Inspired by natural archetypes, a smart global method for low-thrust trajectory optimization is proposed that fuses artificial neural networks and evolutionary algorithms into so-called evolutionary neurocontrollers. This novel method runs without an initial guess and does not require the attendance of an expert in astrodynamics and optimal control theory. This paper details how evolutionary neurocontrol works and how it could be implemented. The performance of the method is assessed for three different interplanetary missions with a thrust to mass ratio <0.15mN/kg (solar sail and nuclear electric).}, language = {en} } @inproceedings{SpurmannOhndorfDachwaldetal.2009, author = {Spurmann, J{\"o}rn and Ohndorf, Andreas and Dachwald, Bernd and Seboldt, Wolfgang and L{\"o}b, Horst and Schartner, Karl-Heinz}, title = {Interplanetary trajectory optimization for a sep mission to Saturn}, series = {60th International Astronautical Congress 2009}, booktitle = {60th International Astronautical Congress 2009}, isbn = {9781615679089}, pages = {5234 -- 5248}, year = {2009}, abstract = {The recently proposed NASA and ESA missions to Saturn and Jupiter pose difficult tasks to mission designers because chemical propulsion scenarios are not capable of transferring heavy spacecraft into the outer solar system without the use of gravity assists. Thus our developed mission scenario based on the joint NASA/ESA Titan Saturn System Mission baselines solar electric propulsion to improve mission flexibility and transfer time. For the calculation of near-globally optimal low-thrust trajectories, we have used a method called Evolutionary Neurocontrol, which is implemented in the low-thrust trajectory optimization software InTrance. The studied solar electric propulsion scenario covers trajectory optimization of the interplanetary transfer including variations of the spacecraft's thrust level, the thrust unit's specific impulse and the solar power generator power level. Additionally developed software extensions enabled trajectory optimization with launcher-provided hyperbolic excess energy, a complex solar power generator model and a variable specific impulse ion engine model. For the investigated mission scenario, Evolutionary Neurocontrol yields good optimization results, which also hold valid for the more elaborate spacecraft models. Compared to Cassini/Huygens, the best found solutions have faster transfer times and a higher mission flexibility in general.}, 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} } @incollection{MacdonaldMcGrathAppourchauxetal.2014, author = {Macdonald, Malcolm and McGrath, C. and Appourchaux, T. and Dachwald, Bernd and Finsterle, W. and Gizon, L. and Liewer, P. C. and McInnes, Colin R. and Mengali, G. and Seboldt, Wolfgang and Sekii, T. and Solanki, S. K. and Velli, M. and Wimmer-Schweingruber, R. F. and Spietz, Peter and Reinhard, Ruedeger}, title = {Gossamer roadmap technology reference study for a solar polar mission}, series = {Advances in solar sailing}, booktitle = {Advances in solar sailing}, editor = {Macdonald, Malcolm}, publisher = {Springer}, address = {Berlin, Heidelberg}, isbn = {978-3-642-34906-5}, doi = {10.1007/978-3-642-34907-2_17}, pages = {243 -- 257}, year = {2014}, abstract = {A technology reference study for a solar polar mission is presented. The study uses novel analytical methods to quantify the mission design space including the required sail performance to achieve a given solar polar observation angle within a given timeframe and thus to derive mass allocations for the remaining spacecraft sub-systems, that is excluding the solar sail sub-system. A parametric, bottom-up, system mass budget analysis is then used to establish the required sail technology to deliver a range of science payloads, and to establish where such payloads can be delivered to within a given timeframe. It is found that a solar polar mission requires a solar sail of side-length 100-125 m to deliver a 'sufficient value' minimum science payload, and that a 2.5 μm sail film substrate is typically required, however the design is much less sensitive to the boom specific mass.}, 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} } @inproceedings{OhndorfDachwaldSeboldtetal.2011, author = {Ohndorf, Andreas and Dachwald, Bernd and Seboldt, Wolfgang and Schartner, Karl-Heinz}, title = {Flight times to the heliopause using a combination of solar and radioisotope electric propulsion}, series = {32nd International Electric Propulsion Conference}, booktitle = {32nd International Electric Propulsion Conference}, pages = {1 -- 12}, year = {2011}, abstract = {We investigate the interplanetary flight of a low-thrust space probe to the heliopause,located at a distance of about 200 AU from the Sun. Our goal was to reach this distance within the 25 years postulated by ESA for such a mission (which is less ambitious than the 15-year goal set by NASA). Contrary to solar sail concepts and combinations of allistic and electrically propelled flight legs, we have investigated whether the set flight time limit could also be kept with a combination of solar-electric propulsion and a second, RTG-powered upper stage. The used ion engine type was the RIT-22 for the first stage and the RIT-10 for the second stage. Trajectory optimization was carried out with the low-thrust optimization program InTrance, which implements the method of Evolutionary Neurocontrol,using Artificial Neural Networks for spacecraft steering and Evolutionary Algorithms to optimize the Neural Networks' parameter set. Based on a parameter space study, in which the number of thrust units, the unit's specific impulse, and the relative size of the solar power generator were varied, we have chosen one configuration as reference. The transfer time of this reference configuration was 29.6 years and the fastest one, which is technically more challenging, still required 28.3 years. As all flight times of this parameter study were longer than 25 years, we further shortened the transfer time by applying a launcher-provided hyperbolic excess energy up to 49 km2/s2. The resulting minimal flight time for the reference configuration was then 27.8 years. The following, more precise optimization to a launch with the European Ariane 5 ECA rocket reduced the transfer time to 27.5 years. This is the fastest mission design of our study that is flexible enough to allow a launch every year. The inclusion of a fly-by at Jupiter finally resulted in a flight time of 23.8 years,which is below the set transfer-time limit. However, compared to the 27.5-year transfer,this mission design has a significantly reduced launch window and mission flexibility if the escape direction is restricted to the heliosphere's "nose".}, language = {en} } @inproceedings{PirovanoSeefeldtDachwaldetal.2015, author = {Pirovano, Laura and Seefeldt, Patric and Dachwald, Bernd and Noomen, Ron}, title = {Attitude and Orbital Dynamics Modeling for an Uncontrolled Solar-Sail Experiment in Low-Earth Orbit}, series = {25th International Symposium on Spaceflight Dynamics, 2015, Munich, Germany}, booktitle = {25th International Symposium on Spaceflight Dynamics, 2015, Munich, Germany}, pages = {15 S.}, year = {2015}, language = {en} } @inproceedings{JeanPierrePBaqueBillietal.2018, author = {Jean-Pierre P., de Vera and Baque, Mickael and Billi, Daniela and B{\"o}ttger, Ute and Bulat, Sergey and Czupalla, Markus and Dachwald, Bernd and de la Torre, Rosa and Elsaesser, Andreas and Foucher, Fr{\´e}d{\´e}ric and Korsitzky, Hartmut and Kozyrovska, Natalia and L{\"a}ufer, Andreas and Moeller, Ralf and Olsson-Francis, Karen and Onofri, Silvano and Sommer, Stefan and Wagner, Dirk and Westall, Frances}, title = {The search for life on Mars and in the Solar System - strategies, logistics and infrastructures}, series = {69th International Astronautical Congress (IAC)}, booktitle = {69th International Astronautical Congress (IAC)}, pages = {1 -- 8}, year = {2018}, abstract = {The question "Are we alone in the Universe?" is perhaps the most fundamental one that affects mankind. How can we address the search for life in our Solar System? Mars, Enceladus and Europa are the focus of the search for life outside the terrestrial biosphere. While it is more likely to find remnants of life (fossils of extinct life) on Mars because of its past short time window of the surface habitability, it is probably more likely to find traces of extant life on the icy moons and ocean worlds of Jupiter and Saturn. Nevertheless, even on Mars there could still be a chance to find extant life in niches near to the surface or in just discovered subglacial lakes beneath the South Pole ice cap. Here, the different approaches for the detection of traces of life in the form of biosignatures including pre-biotic molecules will be presented. We will outline the required infrastructure for this enterprise and give examples of future mission concepts to investigate the presence of life on other planets and moons. Finally, we will provide suggestions on methods, techniques, operations and strategies for preparation and realization of future life detection missions.}, language = {en} } @article{DachwaldWi2007, author = {Dachwald, Bernd and Wi, Bong}, title = {Solar Sail Kinetic Energy Impactor Trajectory Optimization for an Asteroid-Deflection Mission}, series = {Journal of Spacecraft and Rockets. 44 (2007), H. 4}, journal = {Journal of Spacecraft and Rockets. 44 (2007), H. 4}, isbn = {0022-4650}, pages = {755 -- 764}, year = {2007}, 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} }