TY - JOUR A1 - Campen, R. A1 - Kowalski, Julia A1 - Lyons, W.B. A1 - Tulaczyk, S. A1 - Dachwald, Bernd A1 - Pettit, E. A1 - Welch, K. A. A1 - Mikucki, J.A. T1 - Microbial diversity of an Antarctic subglacial community and high‐resolution replicate sampling inform hydrological connectivity in a polar desert JF - Environmental Microbiology Y1 - 2019 U6 - http://dx.doi.org/10.1111/1462-2920.14607 SN - 1462-2920 IS - accepted article PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Dachwald, Bernd A1 - Seboldt, W. A1 - Loeb, H. W A1 - Schartner, K.-H. T1 - Main Belt Asteroid Sample Return Mission Using Solar Electric Propulsion JF - Acta Astronautica. 63 (2008), H. 1-4 Y1 - 2008 SN - 0094-5765 N1 - International Astronautical Federation Congress <58, 2007, Hyderabad> ; International Astronautical Congress <58, 2007, Hyderabad> ; IAC-07-A3.5.07 SP - 91 EP - 101 ER - TY - JOUR A1 - Dachwald, Bernd T1 - Low-Thrust Trajectory Optimization and Interplanetary Mission Analysis Using Evolutionary Neurocontrol JF - Deutscher Luft- und Raumfahrtkongress 2004 : Dresden, 20. bis 23. September 2004, Motto: Luft- und Raumfahrt - Brücke für eine wissensbasierte Gesellschaft / Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V. (DGLR). [Red.: Peter Brandt (verantwortlich)]. - Bd. 2. - (Jahrbuch ... der Deutschen Gesellschaft für Luft- und Raumfahrt) Y1 - 2004 N1 - Deutscher Luft- und Raumfahrt-Kongress <2004, Dresden> ; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth ; DGLR-2004-116 SP - 917 EP - 926 CY - Bonn ER - TY - CHAP A1 - Dachwald, Bernd T1 - Low-Thrust Mission Analysis and Global Trajectory Optimization Using Evolutionary Neurocontrol: New Results T2 - European Workshop on Space Mission Analysis ESA/ESOC, Darmstadt, Germany 10 { 12 Dec 2007 N2 - 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 Y1 - 2007 ER - TY - JOUR A1 - Dachwald, Bernd A1 - Carnelli, I. A1 - Vasile, M. T1 - Low-Thrust Gravity Assist Trajectory Optimization Using Evolutionary Neurocontrollers / I. Carnelli ; B. Dachwald ; M. Vasile ... JF - 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) Y1 - 2006 SN - 0-87703-527-X N1 - Astrodynamics Conference <2005, South Lake Tahoe, Calif.> ; American Astronautical Society ; Number: AAS-05-374 SP - 1911 EP - 1928 PB - Univelt CY - San Diego, Calif. ER - TY - CHAP A1 - Dachwald, Bernd ED - Knopf, George K. ED - Otani, Yukitoshi T1 - Light propulsion systems for spacecraft T2 - Optical nano and micro actuator technology Y1 - 2017 SN - 9781315217628 (eBook) SP - 577 EP - 598 PB - CRC Press CY - Boca Raton ER - TY - CHAP A1 - Seefeldt, Patric A1 - Bauer, Waldemar A1 - Dachwald, Bernd A1 - Grundmann, Jan Thimo A1 - Straubel, Marco A1 - Sznajder, Maciej A1 - Tóth, Norbert A1 - Zander, Martin E. T1 - Large lightweight deployable structures for planetary defence: solar sail propulsion, solar concentrator payloads, large-scale photovoltaic power T2 - 4th IAA Planetary Defense Conference - PDC 2015, 13-17 April 2015, Frascati, Roma, Italy Y1 - 2015 N1 - IAA-PDC-15-P-20 ER - TY - JOUR A1 - Dachwald, Bernd A1 - Ulamec, Stephan A1 - Postberg, Frank A1 - Sohl, Frank A1 - Vera, Jean-Pierre de A1 - Christoph, Waldmann A1 - Lorenz, Ralph D. A1 - Hellard, Hugo A1 - Biele, Jens A1 - Rettberg, Petra T1 - Key technologies and instrumentation for subsurface exploration of ocean worlds JF - Space Science Reviews N2 - In this chapter, the key technologies and the instrumentation required for the subsurface exploration of ocean worlds are discussed. The focus is laid on Jupiter’s moon Europa and Saturn’s moon Enceladus because they have the highest potential for such missions in the near future. The exploration of their oceans requires landing on the surface, penetrating the thick ice shell with an ice-penetrating probe, and probably diving with an underwater vehicle through dozens of kilometers of water to the ocean floor, to have the chance to find life, if it exists. Technologically, such missions are extremely challenging. The required key technologies include power generation, communications, pressure resistance, radiation hardness, corrosion protection, navigation, miniaturization, autonomy, and sterilization and cleaning. Simpler mission concepts involve impactors and penetrators or – in the case of Enceladus – plume-fly-through missions. Y1 - 2020 U6 - http://dx.doi.org/10.1007/s11214-020-00707-5 SN - 1572-9672 N1 - Corresponding author: Bernd Dachwald VL - 216 IS - Art. 83 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Hein, Andreas M. A1 - Eubanks, T. Marshall A1 - Lingam, Manasvi A1 - Hibberd, Adam A1 - Fries, Dan A1 - Schneider, Jean A1 - Kervella, Pierre A1 - Kennedy, Robert A1 - Perakis, Nikolaos A1 - Dachwald, Bernd T1 - Interstellar now! Missions to explore nearby interstellar objects JF - Advances in Space Research N2 - The recently discovered first hyperbolic objects passing through the Solar System, 1I/’Oumuamua and 2I/Borisov, have raised the question about near term missions to Interstellar Objects. In situ spacecraft exploration of these objects will allow the direct determination of both their structure and their chemical and isotopic composition, enabling an entirely new way of studying small bodies from outside our solar system. In this paper, we map various Interstellar Object classes to mission types, demonstrating that missions to a range of Interstellar Object classes are feasible, using existing or near-term technology. We describe flyby, rendezvous and sample return missions to interstellar objects, showing various ways to explore these bodies characterizing their surface, dynamics, structure and composition. Their direct exploration will constrain their formation and history, situating them within the dynamical and chemical evolution of the Galaxy. These mission types also provide the opportunity to explore solar system bodies and perform measurements in the far outer solar system. KW - Interstellar objects KW - Trajectories KW - Missions Y1 - 2022 U6 - http://dx.doi.org/10.1016/j.asr.2021.06.052 SN - 0273-1177 VL - 69 IS - 1 SP - 402 EP - 414 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Hein, Andreas M. A1 - Eubanks, T. Marshall A1 - Hibberd, Adam A1 - Fries, Dan A1 - Schneider, Jean A1 - Lingam, Manasvi A1 - Kennedy, Robert A1 - Perakis, Nikolaos A1 - Dachwald, Bernd A1 - Kervella, Pierre T1 - Interstellar Now! Missions to and sample returns from nearby interstellar objects N2 - The recently discovered first high velocity hyperbolic objects passing through the Solar System, 1I/'Oumuamua and 2I/Borisov, have raised the question about near term missions to Interstellar Objects. In situ spacecraft exploration of these objects will allow the direct determination of both their structure and their chemical and isotopic composition, enabling an entirely new way of studying small bodies from outside our solar system. In this paper, we map various Interstellar Object classes to mission types, demonstrating that missions to a range of Interstellar Object classes are feasible, using existing or near-term technology. We describe flyby, rendezvous and sample return missions to interstellar objects, showing various ways to explore these bodies characterizing their surface, dynamics, structure and composition. Interstellar objects likely formed very far from the solar system in both time and space; their direct exploration will constrain their formation and history, situating them within the dynamical and chemical evolution of the Galaxy. These mission types also provide the opportunity to explore solar system bodies and perform measurements in the far outer solar system. Y1 - 2020 SP - 1 EP - 8 PB - Elsevier CY - Amsterdam ER -