@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} } @inproceedings{SeboldtDachwald2003, author = {Seboldt, Wolfgang and Dachwald, Bernd}, title = {Solar sails for near-term advanced scientific deep space missions}, series = {Proceedings of the 8th International Workshop on Combustion and Propulsion}, booktitle = {Proceedings of the 8th International Workshop on Combustion and Propulsion}, pages = {14 Seiten}, year = {2003}, abstract = {Solar sails are propelled in space by reflecting solar photons off large mirroring surfaces, thereby transforming the momentum of the photons into a propulsive force. This innovative concept for low-thrust space propulsion works without any propellant and thus provides a wide range of opportunities for highenergy low-cost missions. Offering an efficient way of propulsion, solar sailcraft could close a gap in transportation options for highly demanding exploration missions within our solar system and even beyond. On December 17th, 1999, a significant step was made towards the realization of this technology: a lightweight solar sail structure with an area of 20 m × 20 m was successfully deployed on ground in a large facility at the German Aerospace Center (DLR) at Cologne. The deployment from a package of 60 cm × 60 cm × 65 cm with a total mass of less than 35 kg was achieved using four extremely light-weight carbon fiber reinforced plastics (CFRP) booms with a specific mass of 100 g/m. The paper briefly reviews the basic principles of solar sails as well as the technical concept and its realization in the ground demonstration experiment, performed in close cooperation between DLR and ESA. Next possible steps are outlined. They could comprise the in-orbit demonstration of the sail deployment on the upper stage of a low-cost rocket and the verification of the propulsion concept by an autonomous and free flying solar sail in the frame of a scientific mission. It is expected that the present design could be extended to sail sizes of about (40 m)2 up to even (70 m)2 without significant mass penalty. With these areas, the maximum achievable thrust at 1 AU would range between 10 and 40 mN - comparable to some electric thrusters. Such prototype sails with a mass between 50 and 150 kg plus a micro-spacecraft of 50 to 250 kg would have a maximum acceleration in the order of 0.1 mm/s2 at 1 AU, corresponding to a maximum ∆V-capability of about 3 km/s per year. Two near/medium-term mission examples to a near-Earth asteroid (NEA) will be discussed: a rendezvous mission and a sample return mission.}, language = {en} } @inproceedings{SeboldtBlomeDachwaldetal.2004, author = {Seboldt, Wolfgang and Blome, Hans-Joachim and Dachwald, Bernd and Richter, Lutz}, title = {Proposal for an integrated European space exploration strategy}, series = {55th International Astronautical Congress of the International Astronautical Federation, the International Academy of Astronautics, and the International Institute of Space Law}, booktitle = {55th International Astronautical Congress of the International Astronautical Federation, the International Academy of Astronautics, and the International Institute of Space Law}, pages = {1 -- 10}, year = {2004}, abstract = {Recently, in his vision for space exploration, US president Bush announced to extend human presence across the solar system, starting with a human return to the Moon as early as 2015 in preparation for human exploration of Mars and other destinations. In Europe, an exploration program, termed AURORA, was established by ESA in 2001 - funded on a voluntary basis by ESA member states - with a clear focus on Mars and the ultimate goal of landing humans on Mars around 2030 in international cooperation. In 2003, a Human Spaceflight Vision Group was appointed by ESA with the task to develop a vision for the role of human spaceflight during the next quarter of the century. The resulting vision focused on a European-led lunar exploration initiative as part of a multi-decade, international effort to strengthen European identity and economy. After a review of the situation in Europe concerning space exploration, the paper outlines an approach for a consistent positioning of exploration within the existing European space programs, identifies destinations, and develops corresponding scenarios for an integrated strategy, starting with robotic missions to the Moon, Mars, and near-Earth asteroids. The interests of the European planetary in-situ science community, which recently met at DLR Cologne, are considered. Potential robotic lunar missions comprise polar landings to search for frozen volatiles and a sample return. For Mars, the implementation of a modest robotic landing mission in 2009 to demonstrate the capability for landing and prepare more ambitious and complex missions is discussed. For near-Earth asteroid exploration, a low-cost in-situ technology demonstration mission could yield important results. All proposed scenarios offer excellent science and could therefore create synergies between ESA's mandatory and optional programs in the area of planetary science and exploration. The paper intents to stimulate the European discussion on space exploration and reflects the personal view of the authors.}, language = {en} } @inproceedings{Dachwald2004, author = {Dachwald, Bernd}, title = {Solar sail performance requirements for missions to the outer solar system and beyond}, series = {55th International Astronautical Congress 2004}, booktitle = {55th International Astronautical Congress 2004}, doi = {10.2514/6.IAC-04-S.P.11}, pages = {1 -- 9}, year = {2004}, abstract = {Solar sails enable missions to the outer solar system and beyond, although the solar radiation pressure decreases with the square of solar distance. For such missions, the solar sail may gain a large amount of energy by first making one or more close approaches to the sun. Within this paper, optimal trajectories for solar sail missions to the outer planets and into near interstellar space (200 AU) are presented. Thereby, it is shown that even near/medium-term solar sails with relatively moderate performance allow reasonable transfer times to the boundaries of the solar system.}, language = {en} } @inproceedings{Dachwald2005, author = {Dachwald, Bernd}, title = {Global optimization of low-thrust space missions using evolutionary neurocontrol}, series = {Proceedings of the international workshop on global optimization}, booktitle = {Proceedings of the international workshop on global optimization}, pages = {85 -- 90}, year = {2005}, abstract = {Low-thrust space propulsion systems enable flexible high-energy deep space missions, but the design and optimization of the interplanetary transfer trajectory is usually difficult. It involves much experience and expert knowledge because the convergence behavior of traditional local trajectory optimization methods depends strongly on an adequate initial guess. Within this extended abstract, evolutionary neurocontrol, a method that fuses artificial neural networks and evolutionary algorithms, is proposed as a smart global method for low-thrust trajectory optimization. It does not require an initial guess. The implementation of evolutionary neurocontrol is detailed and its performance is shown for an exemplary mission.}, 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} } @inproceedings{LoebSchartnerSeboldtetal.2006, author = {Loeb, Horst W. and Schartner, Karl-Heinz and Seboldt, Wolfgang and Dachwald, Bernd and Streppel, Joern and Meusemann, Hans and Sch{\"u}lke, Peter}, title = {SEP for a lander mission to the jovian moon europa}, series = {57th International Astronautical Congress}, booktitle = {57th International Astronautical Congress}, doi = {10.2514/6.IAC-06-C4.4.04}, pages = {1 -- 12}, year = {2006}, abstract = {Under DLR-contract, Giessen University and DLR Cologne are studying solar-electric propulsion missions (SEP) to the outer regions of the solar system. The most challenging reference mission concerns the transport of a 1.35-tons chemical lander spacecraft into an 80-RJ circular orbit around Jupiter, which would enable to place a 375 kg lander with 50 kg of scientific instruments on the surface of the icy moon "Europa". Thorough analyses show that the best solution in terms of SEP launch mass times thrusting time would be a two-stage EP module and a triple-junction solar array with concentrators which would be deployed step by step. Mission performance optimizations suggest to propel the spacecraft in the first EP stage by 6 gridded ion thrusters, running at 4.0 kV of beam voltage, which would save launch mass, and in the second stage by 4 thrusters with 1.25 to 1.5 kV of positive high voltage saving thrusting time. In this way, the launch mass of the spacecraft would be kept within 5.3 tons. Without a launcher's C3 and interplanetary gravity assists, Jupiter might be reached within about 4 yrs. The spiraling-down into the parking orbit would need another 1.8 yrs. This "large mission" can be scaled down to a smaller one, e.g., by halving all masses, the solar array power, and the number of thrusters. Due to their reliability, long lifetime and easy control, RIT-22 engines have been chosen for mission analysis. Based on precise tests, the thruster performance has been modeled.}, 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{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} } @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{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{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} } @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} } @inproceedings{DigelDachwaldArtmannetal.2009, author = {Digel, Ilya and Dachwald, Bernd and Artmann, Gerhard and Linder, Peter and Funke, O.}, title = {A concept of a probe for particle analysis and life detection in icy environments}, year = {2009}, abstract = {A melting probe equipped with autofluorescence-based detection system combined with a light scattering unit, and, optionally, with a microarray chip would be ideally suited to probe icy environments like Europa's ice layer as well as the polar ice layers of Earth and Mars for recent and extinct live.}, subject = {Sonde}, language = {en} } @inproceedings{GehlerOberBloebaumDachwald2009, author = {Gehler, M. and Ober-Bl{\"o}baum, S. and Dachwald, Bernd}, title = {Application of discrete mechanics and optimal control to spacecraft in non-keplerian motion around small solar system bodies}, series = {Procceedings of the 60th International Astronautical Congress}, booktitle = {Procceedings of the 60th International Astronautical Congress}, publisher = {Elsevier}, address = {Amsterdam}, isbn = {978-161567908-9}, pages = {1360 -- 1371}, year = {2009}, abstract = {Prolonged operations close to small solar system bodies require a sophisticated control logic to minimize propellant mass and maximize operational efficiency. A control logic based on Discrete Mechanics and Optimal Control (DMOC) is proposed and applied to both conventionally propelled and solar sail spacecraft operating at an arbitrarily shaped asteroid in the class of Itokawa. As an example, stand-off inertial hovering is considered, recently identified as a challenging part of the Marco Polo mission. The approach is easily extended to stand-off orbits. We show that DMOC is applicable to spacecraft control at small objects, in particular with regard to the fact that the changes in gravity are exploited by the algorithm to optimally control the spacecraft position. Furthermore, we provide some remarks on promising developments.}, language = {en} } @inproceedings{DachwaldWurm2009, author = {Dachwald, Bernd and Wurm, P.}, title = {Design concept and modeling of an advanced solar photon thruster}, series = {Advances in the Astronautical Sciences}, booktitle = {Advances in the Astronautical Sciences}, publisher = {American Astronautical Society}, address = {San Diego, Calif.}, isbn = {978-087703554-1}, issn = {00653438}, pages = {723 -- 740}, year = {2009}, abstract = {The so-called "compound solar sail", also known as "Solar Photon Thruster" (SPT), holds the potential of providing significant performance advantages over the flat solar sail. Previous SPT design concepts, however, do not consider shadowing effects and multiple reflections of highly concentrated solar radiation that would inevitably destroy the gossamer sail film. In this paper, we propose a novel advanced SPT (ASPT) design concept that does not suffer from these oversimplifications. We present the equations that describe the thrust force acting on such a sail system and compare its performance with respect to the conventional flat solar sail.}, language = {en} } @inproceedings{DachwaldWurm2009, author = {Dachwald, Bernd and Wurm, P.}, title = {Mission analysis for an advanced solar photon thruster}, series = {60th International Astronautical Congress 2009, IAC 2009}, volume = {Vol. 8}, booktitle = {60th International Astronautical Congress 2009, IAC 2009}, publisher = {Elsevier}, address = {Amsterdam}, isbn = {978-161567908-9}, pages = {6838 -- 6851}, year = {2009}, abstract = {The so-called "compound solar sail", also known as "Solar Photon Thruster" (SPT), is a solar sail design concept, for which the two basic functions of the solar sail, namely light collection and thrust direction, are uncoupled. In this paper, we introduce a novel SPT concept, termed the Advanced Solar Photon Thruster (ASPT). This model does not suffer from the simplified assumptions that have been made for the analysis of compound solar sails in previous studies. We present the equations that describe the force, which acts on the ASPT. After a detailed design analysis, the performance of the ASPT with respect to the conventional flat solar sail (FSS) is investigated for three interplanetary mission scenarios: An Earth-Venus rendezvous, where the solar sail has to spiral towards the Sun, an Earth-Mars rendezvous, where the solar sail has to spiral away from the Sun, and an Earth-NEA rendezvous (to near-Earth asteroid 1996FG3), where a large orbital eccentricity change is required. The investigated solar sails have realistic near-term characteristic accelerations between 0.1 and 0.2mm/s2. Our results show that a SPT is not superior to the flat solar sail unless very idealistic assumptions are made.}, language = {en} } @inproceedings{SchartnerLoebDachwaldetal.2009, author = {Schartner, Karl-Heinz and Loeb, H. W. and Dachwald, Bernd and Ohndorf, Andreas}, title = {Perspectives of electric propulsion for outer planetary and deep space missions}, series = {European Planetary Science Congress 2009}, booktitle = {European Planetary Science Congress 2009}, pages = {416 -- 416}, year = {2009}, abstract = {Solar-electric propulsion (SEP) is superior with respect to payload capacity, flight time and flexible launch window to the conventional interplanetary transfer method using chemical propulsion combined with gravity assists. This fact results from the large exhaust velocities of electric low-thrust propulsion and is favourable also for missions to the giant planets, Kuiper-belt objects and even for a heliopause probe (IHP) as shown in three studies by the authors funded by DLR. They dealt with a lander for Europa and a sample return mission from a mainbelt asteroid [1], with the TANDEM mission [2]; the third recent one investigates electric propulsion for the transfer to the edge of the solar system. All studies are based on triple-junction solar arrays, on rf-ion thrusters of the qualified RIT-22 type and they use the intelligent trajectory optimization program InTrance [3].}, 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} } @inproceedings{DigelLeimenaDachwaldetal.2010, author = {Digel, Ilya and Leimena, W. and Dachwald, Bernd and Linder, Peter and Porst, Dariusz and Kayser, Peter and Funke, O. and Temiz Artmann, Ayseg{\"u}l and Artmann, Gerhard}, title = {In-situ biological decontamination of an ice melting probe : [abstract]}, year = {2010}, abstract = {The objective of our study was to investigate the efficacy of different in-situ decontamination protocols in the conditions of thermo-mechanical ice-melting.}, subject = {Sonde}, language = {en} } @inproceedings{BorggraefeDachwald2010, author = {Borggr{\"a}fe, Andreas and Dachwald, Bernd}, title = {Mission performance evaluation for solar sails using a refined SRP force model with variable optical coefficients}, series = {2nd International Symposium on Solar Sailing}, booktitle = {2nd International Symposium on Solar Sailing}, pages = {1 -- 6}, year = {2010}, abstract = {Solar sails provide ignificant advantages over other low-thrust propulsion systems because they produce thrust by the momentum exchange from solar radiation pressure (SRP) and thus do not consume any propellant.The force exerted on a very thin sail foil basically depends on the light incidence angle. Several analytical SRP force models that describe the SRP force acting on the sail have been established since the 1970s. All the widely used models use constant optical force coefficients of the reflecting sail material. In 2006,MENGALI et al. proposed a refined SRP force model that takes into account the dependancy of the force coefficients on the light incident angle,the sail's distance from the sun (and thus the sail emperature) and the surface roughness of the sail material [1]. In this paper, the refined SRP force model is compared to the previous ones in order to identify the potential impact of the new model on the predicted capabilities of solar sails in performing low-cost interplanetary space missions. All force models have been implemented within InTrance, a global low-thrust trajectory optimization software utilizing evolutionary neurocontrol [2]. Two interplanetary rendezvous missions, to Mercury and the near-Earth asteroid 1996FG3, are investigated. Two solar sail performances in terms of characteristic acceleration are examined for both scenarios, 0.2 mm/s2 and 0.5 mm/s2, termed "low" and "medium" sail performance. In case of the refined SRP model, three different values of surface roughness are chosen, h = 0 nm, 10 nm and 25 nm. The results show that the refined SRP force model yields shorter transfer times than the standard model.}, language = {en} } @inproceedings{DachwaldXuFeldmannetal.2011, author = {Dachwald, Bernd and Xu, Changsheng and Feldmann, Marco and Plescher, Engelbert and Digel, Ilya and Artmann, Gerhard}, title = {Development and testing of a subsurface probe for detection of life in deep ice : [abstract]}, year = {2011}, abstract = {We present the novel concept of a combined drilling and melting probe for subsurface ice research. This probe, named "IceMole", is currently developed, built, and tested at the FH Aachen University of Applied Sciences' Astronautical Laboratory. Here, we describe its first prototype design and report the results of its field tests on the Swiss Morteratsch glacier. Although the IceMole design is currently adapted to terrestrial glaciers and ice shields, it may later be modified for the subsurface in-situ investigation of extraterrestrial ice, e.g., on Mars, Europa, and Enceladus. If life exists on those bodies, it may be present in the ice (as life can also be found in the deep ice of Earth).}, subject = {Eisschicht}, language = {en} } @inproceedings{DachwaldXuFeldmannetal.2011, author = {Dachwald, Bernd and Xu, Changsheng and Feldmann, Marco and Plescher, Engelbert}, title = {IceMole : Development of a novel subsurface ice probe and testing of the first prototype on the Morteratsch Glacier}, series = {EGU General Assembly 2011 Vienna | Austria | 03 - 08 April 2011}, booktitle = {EGU General Assembly 2011 Vienna | Austria | 03 - 08 April 2011}, year = {2011}, abstract = {We present the novel concept of a combined drilling and melting probe for subsurface ice research. This probe, named "IceMole", is currently developed, built, and tested at the FH Aachen University of Applied Sciences' Astronautical Laboratory. Here, we describe its first prototype design and report the results of its field tests on the Swiss Morteratsch glacier. Although the IceMole design is currently adapted to terrestrial glaciers and ice shields, it may later be modified for the subsurface in-situ investigation of extraterrestrial ice, e.g., on Mars, Europa, and Enceladus. If life exists on those bodies, it may be present in the ice (as life can also be found in the deep ice of Earth).}, language = {en} } @inproceedings{LoebSchartnerDachwaldetal.2011, author = {Loeb, Horst W. and Schartner, Karl-Heinz and Dachwald, Bernd and Ohndorf, Andreas and Seboldt, Wolfgang}, title = {An Interstellar - Heliopause mission using a combination of solar/radioisotope electric propulsion}, series = {Presented at the 32nd International Electric Propulsion Conference}, booktitle = {Presented at the 32nd International Electric Propulsion Conference}, pages = {1 -- 7}, year = {2011}, abstract = {There is common agreement within the scientific community that in order to understand our local galactic environment it will be necessary to send a spacecraft into the region beyond the solar wind termination shock. Considering distances of 200 AU for a new mission, one needs a spacecraft travelling at a speed of close to 10 AU/yr in order to keep the mission duration in the range of less than 25 yrs, a transfer time postulated by ESA.Two propulsion options for the mission have been proposed and discussed so far: the solar sail propulsion and the ballistic/radioisotope electric propulsion. As a further alternative, we here investigate a combination of solar-electric propulsion and radioisotope-electric propulsion. The solar-electric propulsion stage consists of six 22 cm diameter "RIT-22"ion thrusters working with a high specific impulse of 7377 s corresponding to a positive grid voltage of 5 kV. Solar power of 53 kW BOM is provided by a light-weight solar array. The REP-stage consists of four space-proven 10 cm diameter "RIT-10" ion thrusters that will be operating one after the other for 9 yrs in total. Four advanced radioisotope generators provide 648 W at BOM. The scientific instrument package is oriented at earlier studies. For its mass and electric power requirement 35 kg and 35 W are assessed, respectively. Optimized trajectory calculations, treated in a separate contribution, are based on our "InTrance" method.The program yields a burn out of the REP stage in a distance of 79.6 AU for a usage of 154 kg of Xe propellant. With a C3 = 45,1 (km/s)2 a heliocentric probe velocity of 10 AU/yr is reached at this distance, provided a close Jupiter gravity assist adds a velocity increment of 2.7 AU/yr. A transfer time of 23.8 yrs results for this scenario requiring about 450 kg Xe for the SEP stage, jettisoned at 3 AU. We interpret the SEP/REP propulsion as a competing alternative to solar sail and ballistic/REP propulsion. Omiting a Jupiter fly-by even allows more launch flexibility, leaving the mission duration in the range of the ESA specification.}, 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{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} } @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} } @inproceedings{KonstantinidisDachwaldOhndorfetal.2013, author = {Konstantinidis, K. and Dachwald, Bernd and Ohndorf, A. and Dykta, P. and Voigt, K. and F{\"o}rstner, R.}, title = {Enceladus explorer (ENEX): A lander mission to probe subglacial water pockets on Saturn's moon enceladus for life}, series = {64th International Astronautical Congress 2013 (IAC 2013) : Beijing, China, 23 - 27 September 2013. (Proceedings of the International Astronautical Congress, IAC ; 2)}, booktitle = {64th International Astronautical Congress 2013 (IAC 2013) : Beijing, China, 23 - 27 September 2013. (Proceedings of the International Astronautical Congress, IAC ; 2)}, publisher = {Curran}, address = {Red Hook, NY}, organization = {International Astronautical Congress <64, 2013, Beijing>}, isbn = {978-1-62993-909-4}, pages = {1340 -- 1350}, year = {2013}, language = {en} } @inproceedings{DupratDachwaldHilchenbachetal.2013, author = {Duprat, J. and Dachwald, Bernd and Hilchenbach, M. and Engrand, Cecile and Espe, C. and Feldmann, M. and Francke, G. and G{\"o}r{\"o}g, Mark and L{\"u}sing, N. and Langenhorst, Falko}, title = {The MARVIN project: a micrometeorite harvester in Antarctic snow}, series = {44th Lunar and Planetary Science Conference}, booktitle = {44th Lunar and Planetary Science Conference}, year = {2013}, abstract = {MARVIN is an automated drilling and melting probe dedicated to collect pristine interplanetary dust particles (micrometeorites) from central Antarctica snow.}, language = {en} } @inproceedings{PeloniCeriottiDachwald2015, author = {Peloni, Alessandro and Ceriotti, Matteo and Dachwald, Bernd}, title = {Solar-Sailing Trajectory Design for Close-up NEA Observations Mission}, series = {4th IAA Planetary Defense Conference - PDC 2015, 13-17 April 2015, Frascati, Roma, Italy}, booktitle = {4th IAA Planetary Defense Conference - PDC 2015, 13-17 April 2015, Frascati, Roma, Italy}, pages = {21 S.}, year = {2015}, language = {de} } @inproceedings{GrundmannBauerBieleetal.2015, author = {Grundmann, Jan Thimo and Bauer, Waldemar and Biele, Jens and Cordero, Frederico and Dachwald, Bernd and Koncz, Alexander and Krause, Christian and Mikschl, Tobias and Montenegro, Sergio and Quantius, Dominik and Ruffer, Michael and Sasaki, Kaname and Schmitz, Nicole and Seefeldt, Patric and T{\´o}th, Norbert and Wejmo, Elisabet}, title = {From Sail to Soil - Getting Sailcraft Out of the Harbour on a Visit to One of Earth's Nearest Neighbours}, series = {4th IAA Planetary Denfense Conference - PDC 2015, 13-17 April 2015, Frascati, Roma, Italy}, booktitle = {4th IAA Planetary Denfense Conference - PDC 2015, 13-17 April 2015, Frascati, Roma, Italy}, pages = {20 S.}, year = {2015}, 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{PeloniCeriottiDachwald2015, author = {Peloni, A. and Ceriotti, M. and Dachwald, Bernd}, title = {Preliminary trajectory design of a multiple NEO rendezvous mission through solar sailing}, series = {Proceedings of the International Astronautical Congress, IAC, Vol. 8, 2014}, booktitle = {Proceedings of the International Astronautical Congress, IAC, Vol. 8, 2014}, publisher = {Curran}, address = {Red Hook, NY}, isbn = {978-1-63439-986-9}, pages = {5352 -- 5366}, year = {2015}, language = {en} } @inproceedings{KonstantinidisKowalskiMartinezetal.2015, author = {Konstantinidis, K. and Kowalski, Julia and Martinez, C. F. and Dachwald, Bernd and Ewerhart, D. and F{\"o}rstner, R.}, title = {Some necessary technologies for in-situ astrobiology on enceladus}, series = {Proceedings of the International Astronautical Congress}, booktitle = {Proceedings of the International Astronautical Congress}, isbn = {978-151081893-4}, pages = {1354 -- 1372}, year = {2015}, language = {en} } @inproceedings{GrundmannLangeDachwaldetal.2015, author = {Grundmann, Jan Thimo and Lange, Caroline and Dachwald, Bernd and Grimm, Christian and Koch, Aaron and Ulamec, Stephan}, title = {Small Spacecraft in Planetary Defence Related Applications-Capabilities, Constraints, Challenges}, series = {IEEE Aerospace Conference}, booktitle = {IEEE Aerospace Conference}, pages = {1 -- 18}, year = {2015}, abstract = {In this paper we present an overview of the characteristics and peculiarities of small spacecraft missions related to planetary defence applications. We provide a brief overview of small spacecraft missions to small solar system bodies. On this background we present recent missions and selected projects and related studies at the German Aerospace Center, DLR, that contribute to planetary defence related activities. These range from Earth orbit technology demonstrators to active science missions in interplanetary space. We provide a summary of experience from recently flown missions with DLR participation as well as a number of studies. These include PHILAE, the lander recently arrived on comet 67P/Churyumov-Gerasimenko aboard ESA's ROSETTA comet rendezvous mission, and the Mobile Asteroid Surface Scout, MASCOT, now underway to near-Earth asteroid (162173) 1999 JU3 aboard the Japanese sample-return probe HAYABUSA-2. We introduce the differences between the conventional methods employed in the design, integration and testing of large spacecraft and the new approaches developed by small spacecraft projects. We expect that the practical experience that can be gained from projects on extremely compressed timelines or with high-intensity operation phases on a newly explored small solar system body can contribute significantly to the study, preparation and realization of future planetary defence related missions. One is AIDA (Asteroid Impact \& Deflection Assessment), a joint effort of ESA,JHU/APL, NASA, OCA and DLR, combining JHU/APL's DART (Double Asteroid Redirection Test) and ESA's AIM (Asteroid Impact Monitor) spacecraft in a mission towards near-Eath binary asteroid (65803) Didymos.}, language = {en} } @inproceedings{PirovanoSeefeldtDachwaldetal.2015, author = {Pirovano, Laura and Seefeldt, Patric and Dachwald, Bernd and Noomen, Ron}, title = {Attitude and orbital modeling of an uncontrolled solar-sail experiment in low-Earth orbit}, series = {25th International Symposium on Space Flight Dynamics ISSFD}, booktitle = {25th International Symposium on Space Flight Dynamics ISSFD}, pages = {1 -- 15}, year = {2015}, abstract = {Gossamer-1 is the first project of the three-step Gossamer roadmap, the purpose of which is to develop, prove and demonstrate that solar-sail technology is a safe and reliable propulsion technique for long-lasting and high-energy missions. This paper firstly presents the structural analysis performed on the sail to understand its elastic behavior. The results are then used in attitude and orbital simulations. The model considers the main forces and torques that a satellite experiences in low-Earth orbit coupled with the sail deformation. Doing the simulations for varying initial conditions in attitude and rotation rate, the results show initial states to avoid and maximum rotation rates reached for correct and faulty deployment of the sail. Lastly comparisons with the classic flat sail model are carried out to test the hypothesis that the elastic behavior does play a role in the attitude and orbital behavior of the sail}, language = {en} } @inproceedings{SeefeldtBauerDachwaldetal.2015, author = {Seefeldt, Patric and Bauer, Waldemar and Dachwald, Bernd and Grundmann, Jan Thimo and Straubel, Marco and Sznajder, Maciej and T{\´o}th, Norbert and Zander, Martin E.}, title = {Large lightweight deployable structures for planetary defence: solar sail propulsion, solar concentrator payloads, large-scale photovoltaic power}, series = {4th IAA Planetary Defense Conference - PDC 2015, 13-17 April 2015, Frascati, Roma, Italy}, booktitle = {4th IAA Planetary Defense Conference - PDC 2015, 13-17 April 2015, Frascati, Roma, Italy}, pages = {24}, year = {2015}, language = {en} } @inproceedings{GrundmannBieleDachwaldetal.2016, author = {Grundmann, Jan Thimo and Biele, Jens and Dachwald, Bernd and Grimm, Christian and Lange, Caroline and Ulamec, Stephan}, title = {Small spacecraft for small solar system body science, planetary defence and applications}, series = {IEEE Aerospace Conference 2016}, booktitle = {IEEE Aerospace Conference 2016}, pages = {1 -- 20}, year = {2016}, abstract = {Following the recent successful landings and occasional re-awakenings of PHILAE, the lander carried aboard ROSETTA to comet 67P/Churyumov-Gerasimenko, and the launch of the Mobile Asteroid Surface Scout, MASCOT, aboard the HAYABUSA2 space probe to asteroid (162173) Ryugu we present an overview of the characteristics and peculiarities of small spacecraft missions to small solar system bodies (SSSB). Their main purpose is planetary science which is transitioning from a 'pure' science of observation of the distant to one also supporting in-situ applications relevant for life on Earth. Here we focus on missions at the interface of SSSB science and planetary defence applications. We provide a brief overview of small spacecraft SSSB missions and on this background present recent missions, projects and related studies at the German Aerospace Center, DLR, that contribute to the worldwide planetary defence community. These range from Earth orbit technology demonstrators to active science missions in interplanetary space. We provide a summary of experience from recently flown missions with DLR participation as well as a number of studies. These include PHILAE, the lander of ESA's ROSETTA comet rendezvous mission now on the surface of comet 67P/Churyumov-Gerasimenko, and the Mobile Asteroid Surface Scout, MASCOT, now in cruise to the ~1 km diameter C-type near-Earth asteroid (162173) Ryugu aboard the Japanese sample-return probe HAYABUSA2. We introduce the differences between the conventional methods employed in the design, integration and testing of large spacecraft and the new approaches developed by small spacecraft projects. We expect that the practical experience that can be gained from projects on extremely compressed timelines or with high-intensity operation phases on a newly explored small solar system body can contribute significantly to the study, preparation and realization of future planetary defence related missions. One is AIDA (Asteroid Impact \& Deflection Assessment), a joint effort of ESA, JHU/APL, NASA, OCA and DLR, combining JHU/APL's DART (Double Asteroid Redirection Test) and ESA's AIM (Asteroid Impact Monitor) spacecraft in a mission towards near-Earth binary asteroid system (65803) Didymos. DLR is currently applying MASCOT heritage and lessons learned to the design of MASCOT2, a lander for the AIM mission to support a bistatic low frequency radar experiment with PHILAE/ROSETTA CONSERT heritage to explore the inner structure of Didymoon which is the designated impact target for DART.}, language = {en} } @inproceedings{HallmannHeideckerSchlottereretal.2016, author = {Hallmann, Marcus and Heidecker, Ansgar and Schlotterer, Markus and Dachwald, Bernd}, title = {GTOC8: results and methods of team 15 DLR}, series = {26th AAS/AIAA Space Flight Mechanics Meeting, Napa, CA}, booktitle = {26th AAS/AIAA Space Flight Mechanics Meeting, Napa, CA}, year = {2016}, abstract = {This paper describes the results and methods used during the 8th Global Trajectory Optimization Competition (GTOC) of the DLR team. Trajectory optimization is crucial for most of the space missions and usually can be formulated as a global optimization problem. A lot of research has been done to different type of mission problems. The most demanding ones are low thrust transfers with e.g. gravity assist sequences. In that case the optimal control problem is combined with an integer problem. In most of the GTOCs we apply a filtering of the problem based on domain knowledge.}, language = {en} } @inproceedings{GrundmannMessBieleetal.2017, author = {Grundmann, Jan Thimo and Meß, Jan-Gerd and Biele, Jens and Seefeldt, Patric and Dachwald, Bernd and Spietz, Peter and Grimm, Christian D. and Spr{\"o}witz, Tom and Lange, Caroline and Ulamec, Stephan}, title = {Small spacecraft in small solar system body applications}, series = {IEEE Aerospace Conference 2017, Big Sky, Montana, USA}, booktitle = {IEEE Aerospace Conference 2017, Big Sky, Montana, USA}, organization = {IEEE Aerospace Conference}, isbn = {978-1-5090-1613-6}, doi = {10.1109/AERO.2017.7943626}, pages = {1 -- 20}, year = {2017}, language = {en} } @inproceedings{CarzanaDachwaldNoomen2017, author = {Carzana, Livio and Dachwald, Bernd and Noomen, Ron}, title = {Model and trajectory optimization for an ideal laser-enhanced solar sail}, series = {68th International Astronautical Congress}, booktitle = {68th International Astronautical Congress}, year = {2017}, abstract = {A laser-enhanced solar sail is a solar sail that is not solely propelled by solar radiation but additionally by a laser beam that illuminates the sail. This way, the propulsive acceleration of the sail results from the combined action of the solar and the laser radiation pressure onto the sail. The potential source of the laser beam is a laser satellite that coverts solar power (in the inner solar system) or nuclear power (in the outer solar system) into laser power. Such a laser satellite (or many of them) can orbit anywhere in the solar system and its optimal orbit (or their optimal orbits) for a given mission is a subject for future research. This contribution provides the model for an ideal laser-enhanced solar sail and investigates how a laser can enhance the thrusting capability of such a sail. The term "ideal" means that the solar sail is assumed to be perfectly reflecting and that the laser beam is assumed to have a constant areal power density over the whole sail area. Since a laser beam has a limited divergence, it can provide radiation pressure at much larger solar distances and increase the radiation pressure force into the desired direction. Therefore, laser-enhanced solar sails may make missions feasible, that would otherwise have prohibitively long flight times, e.g. rendezvous missions in the outer solar system. This contribution will also analyze exemplary mission scenarios and present optimial trajectories without laying too much emphasis on the design and operations of the laser satellites. If the mission studies conclude that laser-enhanced solar sails would have advantages with respect to "traditional" solar sails, a detailed study of the laser satellites and the whole system architecture would be the second next step}, language = {en} } @inproceedings{PeloniDachwaldCeriotti2017, author = {Peloni, Alessandro and Dachwald, Bernd and Ceriotti, Matteo}, title = {Multiple NEA rendezvous mission: Solar sailing options}, series = {Fourth International Symposium on Solar Sailing}, booktitle = {Fourth International Symposium on Solar Sailing}, pages = {1 -- 11}, year = {2017}, abstract = {The scientific interest in near-Earth asteroids (NEAs) and the classification of some of those as potentially hazardous asteroid for the Earth stipulated the interest in NEA exploration. Close-up observations of these objects will increase drastically our knowledge about the overall NEA population. For this reason, a multiple NEA rendezvous mission through solar sailing is investigated, taking advantage of the propellantless nature of this groundbreaking propulsion technology. Considering a spacecraft based on the DLR/ESA Gossamer technology, this work focuses on the search of possible sequences of NEA encounters. The effectiveness of this approach is demonstrated through a number of fully-optimized trajectories. The results show that it is possible to visit five NEAs within 10 years with near-term solar-sail technology. Moreover, a study on a reduced NEA database demonstrates the reliability of the approach used, showing that 58\% of the sequences found with an approximated trajectory model can be converted into real solar-sail trajectories. Lastly, this second study shows the effectiveness of the proposed automatic optimization algorithm, which is able to find solutions for a large number of mission scenarios without any input required from the user.}, language = {en} } @inproceedings{GrundmannBieleDachwaldetal.2017, author = {Grundmann, Jan Thimo and Biele, Jens and Dachwald, Bernd and Grimm, Christian D. and Lange, Caroline and Ulamec, Stephan and Ziach, Christian and Spr{\"o}witz, Tom and Ruffer, Michael and Seefeldt, Patric and Spietz, Peter and Toth, Norbert and Mimasu, Yuya and Rittweger, Andreas and Bibring, Jean-Pierre and Braukhane, Andy and Boden, Ralf Christian and Dumont, Etienne and Jahnke, Stephan Siegfried and Jetzschmann, Michael and Kr{\"u}ger, Hans and Lange, Michael and Gomez, Antonio Martelo and Massonett, Didier and Okada, Tatsuaki and Sagliano, Marco and Sasaki, Kaname and Schr{\"o}der, Silvio and Sippel, Martin and Skoczylas, Thomas and Wejmo, Elisabet}, title = {Small landers and separable sub-spacecraft for near-term solar sails}, series = {The Fourth International Symposium on Solar Sailing 2017}, booktitle = {The Fourth International Symposium on Solar Sailing 2017}, pages = {1 -- 10}, year = {2017}, abstract = {Following the successful PHILAE landing with ESA's ROSETTA probe and the launch of the MINERVA rovers and the Mobile Asteroid Surface Scout, MASCOT, aboard the JAXA space probe, HAYABUSA2, to asteroid (162173) Ryugu, small landers have found increasing interest. Integrated at the instrument level in their mothership they support small solar system body studies. With efficient capabilities, resource-friendly design and inherent robustness they are an attractive exploration mission element. We discuss advantages and constraints of small sub-spacecraft, focusing on emerging areas of activity such as asteroid diversity studies, planetary defence, and asteroid mining, on the background of our projects PHILAE, MASCOT, MASCOT2, the JAXA-DLR Solar Power Sail Lander Design Study, and others. The GOSSAMER-1 solar sail deployment concept also involves independent separable sub-spacecraft operating synchronized to deploy the sail. Small spacecraft require big changes in the way we do things and occasionally a little more effort than would be anticipated based on a traditional large spacecraft approach. In a Constraints-Driven Engineering environment we apply Concurrent Design and Engineering (CD/CE), Concurrent Assembly, Integration and Verification (CAIV) and Model-Based Systems Engineering (MBSE). Near-term solar sails will likely be small spacecraft which we expect to harmonize well with nano-scale separable instrument payload packages.}, language = {en} } @inproceedings{GrundmannBodenCeriottietal.2017, author = {Grundmann, Jan Thimo and Boden, Ralf and Ceriotti, Matteo and Dachwald, Bernd and Dumont, Etienne and Grimm, Christian D. and Lange, Caroline and Lichtenheldt, Roy and Pelivan, Ivanka and Peloni, Alessandro and Riemann, Johannes and Spr{\"o}witz, Tom and Tardivel, Simon}, title = {Soil to sail-asteroid landers on near-term sailcraft as an evolution of the GOSSAMER small spacecraft solar sail concept for in-situ characterization}, series = {5th IAA Planetary Defense Conference}, booktitle = {5th IAA Planetary Defense Conference}, pages = {30 Seiten}, year = {2017}, language = {en} } @inproceedings{Dachwald2017, author = {Dachwald, Bernd}, title = {Radiation pressure force model for an ideal laser-enhanced solar sail}, series = {4th International Symposium on Solar Sailing}, booktitle = {4th International Symposium on Solar Sailing}, pages = {1 -- 5}, year = {2017}, abstract = {The concept of a laser-enhanced solar sail is introduced and the radiation pressure force model for an ideal laser-enhanced solar sail is derived. A laser-enhanced solar sail is a "traditional" solar sail that is, however, not solely propelled by solar radiation, but additionally by a laser beam that illuminates the sail. The additional laser radiation pressure increases the sail's propulsive force and can give, depending on the location of the laser source, more control authority over the direction of the solar sail's propulsive force vector. This way, laser-enhanced solar sails may augment already existing solar sail mission concepts and make novel mission concepts feasible.}, language = {en} } @inproceedings{BaaderReiswichBartschetal.2018, author = {Baader, Fabian and Reiswich, M. and Bartsch, M. and Keller, D. and Tiede, E. and Keck, G. and Demircian, A. and Friedrich, M. and Dachwald, Bernd and Sch{\"u}ller, K. and Lehmann, R. and Chojetzki, R. and Durand, C. and Rapp, L. and Kowalski, Julia and F{\"o}rstner, R.}, title = {VIPER - Student research on extraterrestrical ice penetration technology}, series = {Proceedings of the 2nd Symposium on Space Educational Activities}, booktitle = {Proceedings of the 2nd Symposium on Space Educational Activities}, pages = {1 -- 6}, year = {2018}, abstract = {Recent analysis of scientific data from Cassini and earth-based observations gave evidence for a global ocean under a surrounding solid ice shell on Saturn's moon Enceladus. Images of Enceladus' South Pole showed several fissures in the ice shell with plumes constantly exhausting frozen water particles, building up the E-Ring, one of the outer rings of Saturn. In this southern region of Enceladus, the ice shell is considered to be as thin as 2 km, about an order of magnitude thinner than on the rest of the moon. Under the ice shell, there is a global ocean consisting of liquid water. Scientists are discussing different approaches the possibilities of taking samples of water, i.e. by melting through the ice using a melting probe. FH Aachen UAS developed a prototype of maneuverable melting probe which can navigate through the ice that has already been tested successfully in a terrestrial environment. This means no atmosphere and or ambient pressure, low ice temperatures of around 100 to 150K (near the South Pole) and a very low gravity of 0,114 m/s^2 or 1100 μg. Two of these influencing measures are about to be investigated at FH Aachen UAS in 2017, low ice temperature and low ambient pressure below the triple point of water. Low gravity cannot be easily simulated inside a large experiment chamber, though. Numerical simulations of the melting process at RWTH Aachen however are showing a gravity dependence of melting behavior. Considering this aspect, VIPER provides a link between large-scale experimental simulations at FH Aachen UAS and numerical simulations at RWTH Aachen. To analyze the melting process, about 90 seconds of experiment time in reduced gravity and low ambient pressure is provided by the REXUS rocket. In this time frame, the melting speed and contact force between ice and probes are measured, as well as heating power and a two-dimensional array of ice temperatures. Additionally, visual and infrared cameras are used to observe the melting process.}, language = {en} } @inproceedings{GrundmannBauerBorchersetal.2018, author = {Grundmann, Jan Thimo and Bauer, Waldemar and Borchers, Kai and Dumont, Etienne and Grimm, Christian D. and Ho, Tra-Mi and Jahnke, Rico and Lange, Caroline and Maiwald, Volker and Mikulz, Eugen and Quantius, Dominik and Reershemius, Siebo and Renger, Thomas and Riemann, Johannes and Sasaki, Kaname and Seefeldt, Patric and Spietz, Peter and Spr{\"o}witz, Tom and Toth, Norbert and Wejmo, Elisabet and Biele, Jens and Krause, Christian and Cerotti, Matteo and Peloni, Alessandro and Dachwald, Bernd}, title = {Small Spacecraft Solar Sailing for Small Solar System Body Multiple Rendezvous and Landing}, series = {2018 IEEE Aerospace Conference : 3-10 March 2018}, booktitle = {2018 IEEE Aerospace Conference : 3-10 March 2018}, isbn = {978-1-5386-2014-4}, pages = {20 Seiten}, year = {2018}, language = {en} } @inproceedings{WaldmannVeraDachwaldetal.2018, author = {Waldmann, Christoph and Vera, Jean-Pierre de and Dachwald, Bernd and Strasdeit, Henry and Sohl, Frank and Hanff, Hendrik and Kowalski, Julia and Heinen, Dirk and Macht, Sabine and Bestmann, Ulf and Meckel, Sebastian and Hildebrandt, Marc and Funke, Oliver and Gehrt, Jan-J{\"o}ran}, title = {Search for life in ice-covered oceans and lakes beyond Earth}, series = {2018 IEEE/OES Autonomous Underwater Vehicle Workshop, Proceedings November 2018, Article number 8729761}, booktitle = {2018 IEEE/OES Autonomous Underwater Vehicle Workshop, Proceedings November 2018, Article number 8729761}, doi = {10.1109/AUV.2018.8729761}, year = {2018}, abstract = {The quest for life on other planets is closely connected with the search for water in liquid state. Recent discoveries of deep oceans on icy moons like Europa and Enceladus have spurred an intensive discussion about how these waters can be accessed. The challenge of this endeavor lies in the unforeseeable requirements on instrumental characteristics both with respect to the scientific and technical methods. The TRIPLE/nanoAUV initiative is aiming at developing a mission concept for exploring exo-oceans and demonstrating the achievements in an earth-analogue context, exploring the ocean under the ice shield of Antarctica and lakes like Dome-C on the Antarctic continent.}, language = {en} } @inproceedings{GrundmannBauerBieleetal.2018, author = {Grundmann, Jan Thimo and Bauer, Waldemar and Biele, Jens and Boden, Ralf and Ceriotti, Matteo and Cordero, Federico and Dachwald, Bernd and Dumont, Etienne and Grimm, Christian D. and Herč{\´i}k, David and Ho, Tra-Mi and Jahnke, Rico and Koch, Aaron D and Koncz, Alexander and Krause, Christian and Lange, Caroline and Lichtenheldt, Roy and Maiwald, Volker and Mikschl, Tobias and Mikulz, Eugen and Montenegro, Sergio and Pelivan, Ivanka and Peloni, Alessandro and Quantius, Dominik and Reershemius, Siebo and Renger, Thomas and Riemann, Johannes and Ruffer, Michael and Sasaki, Kaname and Schmitz, Nicole and Seboldt, Wolfgang and Seefeldt, Patric and Spietz, Peter and Spr{\"o}witz, Tom and Sznajder, Maciej and Tardivel, Simon and T{\´o}th, Norbert and Wejmo, Elisabet and Wolff, Friederike and Ziach, Christian}, title = {Small spacecraft based multiple near-earth asteroid rendezvous and landing with near-term solar sails and 'Now-Term 'technologies}, series = {69 th International Astronautical Congress (IAC)}, booktitle = {69 th International Astronautical Congress (IAC)}, pages = {1 -- 18}, year = {2018}, abstract = {Physical interaction with small solar system bodies (SSSB) is the next step in planetary science, planetary in-situ resource utilization (ISRU), and planetary defense (PD). It requires a broader understanding of the surface properties of the target objects, with particular interest focused on those near Earth. Knowledge of composition, multi-scale surface structure, thermal response, and interior structure is required to design, validate and operate missions addressing these three fields. The current level of understanding is occasionally simplified into the phrase, "If you've seen one asteroid, you've seen one asteroid", meaning that the in-situ characterization of SSSBs has yet to cross the threshold towards a robust and stable scheme of classification. This would enable generic features in spacecraft design, particularly for ISRU and science missions. Currently, it is necessary to characterize any potential target object sufficiently by a dedicated pre-cursor mission to design the mission which then interacts with the object in a complex fashion. To open up strategic approaches, much broader in-depth characterization of potential target objects would be highly desirable. In SSSB science missions, MASCOT-like nano-landers and instrument carriers which integrate at the instrument level to their mothership have met interest. By its size, MASCOT is compatible with small interplanetary missions. The DLR-ESTEC Gossamer Roadmap Science Working Groups' studies identified Multiple Near-Earth asteroid (NEA) Rendezvous (MNR) as one of the space science missions only feasible with solar sail propulsion. The Solar Polar Orbiter (SPO) study showed the ability to access any inclination, theDisplaced-L1 (DL1) mission operates close to Earth, where objects of interest to PD and for ISRU reside. Other studies outline the unique capability of solar sails to provide access to all SSSB, at least within the orbit of Jupiter, and significant progress has been made to explore the performance envelope of near-term solar sails for MNR. However, it is difficult for sailcraft to interact physically with a SSSB. We expand and extend the philosophy of the recently qualified DLR Gossamer solar sail deployment technology using efficient multiple sub-spacecraft integration to also include landers for one-way in-situ investigations and sample-return missions by synergetic integration and operation of sail and lander. The MASCOT design concept and its characteristic features have created an ideal counterpart for thisand has already been adapted to the needs of the AIM spacecraft, former part of the NASA-ESA AIDA missionDesigning the 69th International Astronautical Congress (IAC), Bremen, Germany, 1-5 October 2018. IAC-18-F1.2.3 Page 2 of 17 combined spacecraft for piggy-back launch accommodation enables low-cost massively parallel access to the NEA population.}, 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} }