@article{PeloniDachwaldCeriotti2017, author = {Peloni, Alessandro and Dachwald, Bernd and Ceriotti, Matteo}, title = {Multiple near-earth asteroid rendezvous mission: Solar-sailing options}, series = {Advances in Space Research}, journal = {Advances in Space Research}, number = {In Press, Corrected Proof}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0273-1177}, doi = {10.1016/j.asr.2017.10.017}, year = {2017}, language = {en} } @article{DachwaldSeboldt2005, author = {Dachwald, Bernd and Seboldt, W.}, title = {Multiple Near-Earth Asteroid Rendezvous and Sample Return Using First Generation Solar Sailcraft}, series = {Acta Astronautica. 57 (2005), H. 11}, journal = {Acta Astronautica. 57 (2005), H. 11}, isbn = {0094-5765}, pages = {864 -- 875}, year = {2005}, language = {en} } @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{GrundmannBorellaCeriottietal.2021, author = {Grundmann, Jan Thimo and Borella, Laura and Ceriotti, Matteo and Chand, Suditi and Cordero, Federico and Dachwald, Bernd and Fexer, Sebastian and Grimm, Christian D. and Hendrikse, Jeffrey and Herč{\´i}k, David and Herique, Alain and Hillebrandt, Martin and Ho, Tra-Mi and Kesseler, Lars and Laabs, Martin and Lange, Caroline and Lange, Michael and Lichtenheldt, Roy and McInnes, Colin R. and Moore, Iain and Peloni, Alessandro and Plettenmeier, Dirk and Quantius, Dominik and Seefeldt, Patric and Venditti, Flaviane c. F. and Vergaaij, Merel and Viavattene, Giulia and Virkki, Anne K. and Zander, Martin}, title = {More bucks for the bang: new space solutions, impact tourism and one unique science \& engineering opportunity at T-6 months and counting}, series = {7th IAA Planetary Defense Conference}, booktitle = {7th IAA Planetary Defense Conference}, year = {2021}, abstract = {For now, the Planetary Defense Conference Exercise 2021's incoming fictitious(!), asteroid, 2021 PDC, seems headed for impact on October 20th, 2021, exactly 6 months after its discovery. Today (April 26th, 2021), the impact probability is 5\%, in a steep rise from 1 in 2500 upon discovery six days ago. We all know how these things end. Or do we? Unless somebody kicked off another headline-grabbing media scare or wants to keep civil defense very idle very soon, chances are that it will hit (note: this is an exercise!). Taking stock, it is barely 6 months to impact, a steadily rising likelihood that it will actually happen, and a huge uncertainty of possible impact energies: First estimates range from 1.2 MtTNT to 13 GtTNT, and this is not even the worst-worst case: a 700 m diameter massive NiFe asteroid (covered by a thin veneer of Ryugu-black rubble to match size and brightness), would come in at 70 GtTNT. In down to Earth terms, this could be all between smashing fireworks over some remote area of the globe and a 7.5 km crater downtown somewhere. Considering the deliberate and sedate ways of development of interplanetary missions it seems we can only stand and stare until we know well enough where to tell people to pack up all that can be moved at all and save themselves. But then, it could just as well be a smaller bright rock. The best estimate is 120 m diameter from optical observation alone, by 13\% standard albedo. NASA's upcoming DART mission to binary asteroid (65803) Didymos is designed to hit such a small target, its moonlet Dimorphos. The Deep Impact mission's impactor in 2005 successfully guided itself to the brightest spot on comet 9P/Tempel 1, a relatively small feature on the 6 km nucleus. And 'space' has changed: By the end of this decade, one satellite communication network plans to have launched over 11000 satellites at a pace of 60 per launch every other week. This level of series production is comparable in numbers to the most prolific commercial airliners. Launch vehicle production has not simply increased correspondingly - they can be reused, although in a trade for performance. Optical and radio astronomy as well as planetary radar have made great strides in the past decade, and so has the design and production capability for everyday 'high-tech' products. 60 years ago, spaceflight was invented from scratch within two years, and there are recent examples of fast-paced space projects as well as a drive towards 'responsive space'. It seems it is not quite yet time to abandon all hope. We present what could be done and what is too close to call once thinking is shoved out of the box by a clear and present danger, to show where a little more preparedness or routine would come in handy - or become decisive. And if we fail, let's stand and stare safely and well instrumented anywhere on Earth together in the greatest adventure of science.}, 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{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} } @article{MaiwaldDachwald2010, author = {Maiwald, Volker and Dachwald, Bernd}, title = {Mission Design for a Multiple-Rendezvous Mission to Jupiter's Trojans}, pages = {3}, year = {2010}, 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} } @article{DachwaldWurm2011, author = {Dachwald, Bernd and Wurm, Patrick}, title = {Mission analysis and performance comparison for an Advanced Solar Photon Thruster}, series = {Advances in Space Research}, volume = {48}, journal = {Advances in Space Research}, number = {11}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0273-1177}, pages = {1858 -- 1868}, year = {2011}, 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} }