@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}
}
@inproceedings{LoebSchartnerDachwaldetal.2007,
  author    = {Loeb, Horst Wolfgang and Schartner, Karl-Heinz and Dachwald, Bernd and Seboldt, Wolfgang},
  title     = {SEP-Sample return from a main belt asteroid},
  series = {30th International Electric Propulsion Conference},
  booktitle = {30th International Electric Propulsion Conference},
  pages     = {1 -- 11},
  year      = {2007},
  abstract  = {By DLR-contact, sample return missions to the large main-belt asteroid "19, Fortuna" have been studied. The mission scenario has been based on three ion thrusters of the RIT-22 model, which is presently under space qualification, and on solar arrays equipped with triple-junction GaAs solar cells. After having designed the spacecraft, the orbit-to-orbit trajectories for both, a one-way SEP mission with a chemical sample return and an all-SEP return mission, have been optimized using a combination of artificial neural networks with evolutionary algorithms. Additionally, body-to-body trajectories have been investigated within a launch period between 2012 and 2015. For orbit-to-orbit calculation, the launch masses of the hybrid mission and of the all-SEP mission resulted in 2.05 tons and 1.56 tons, respectively, including a scientific payload of 246 kg. For the related transfer durations 4.14 yrs and 4.62 yrs were obtained. Finally, a comparison between the mission scenarios based on SEP and on NEP have been carried out favouring clearly SEP.},
  language  = {en}
}