Plenary Lecture
Comparison Between Different Approaches to Interplanetary Mission Design
Professor Giancarlo Genta
Co-author P. Federica Maffione
Department of Mechanical and Aerospace Engineering
Politecnico di Torino
Italy
E-mail: giancarlo.genta@polito.it
Abstract: When designing an interplanetary mission, one of the basic design choices are related with the start and arrival dates and the trajectory. The computation of the trajectory can be performed at different accuracy levels, from studying a simple two-body problem to taking into account the presence of the various bodies of the solar system, and other effects like the pressure of the solar radiation on the spacecraft. The simplified approach allows to study a large number of design alternatives, although in an approximate way, while high accuracy solutions allow to refine the final design choices. A large difference exists between the case of impulsive propulsion and (that of) low, continuous thrust. In the first case the usual approach for the simplified solution is the so called ‘patched conics approach’, in which the shape of the relevant arcs of trajectory is known (it is either an ellipse, a parabola or an hyperbola) and thus the problem can be solved (it is possible to deal with arcs of trajectory which are known) in closed form. Therefore, it is possible to summarize the main design characteristics of the various trajectories in a synthesis diagram usually referred to as a pork-chop plot. In the case of low thrust, on the contrary, the trajectory cannot be obtained in closed form and must be computed together with the thrust profile, usually resorting to optimization techniques of either the direct or the indirect type. Also in this case, it is possible to summarize the characteristics of the possible trajectories in a few synthesis diagrams, useful to take the relevant design choices. The authors prepared a general purpose design code for interplanetary missions, allowing to deal with both impulsive propulsion (using the patched conics approach) and low continuous thrust, based on the two-body problem. In the latter case, indirect methods were chosen . The present paper shows a comparison between different approaches and methods, to evaluate the reliability and accuracy of the proposed code in different applications, and finally shows how it is possible to go beyond the simplified two-body approach, once that the basic parameters of the mission have been stated and a refinement of the chosen solution is required.
Brief Biography of the Speaker: Giancarlo Genta got a degree in Aeronautical Engineering in 1971 and one in Aerospace Engineering in 1972 at the Politecnico di Torino. He then became assistant professor and then full professor of Machine Design at the same University. He taught courses in Astronautical Propulsion, Motor Vehicle Mechanics, Design of Aircraft Engines and Dynamic Design of Machines. From 1989 to 1995 he was head of the Department of Mechanics at Politecnico di Torino. From 1998 to 2015 he coordinated the PhD course in Mechatronics at the PhD School of Politecnico di Torino and is now responsible for the courses in Automotive Engineering. Since 1999 he is a member of the Academy of Sciences of Torino and since 2006 he is a member (corresponding member since 2001) of the International Academy of Astronautics. In 2013 he received the International Yangel Medal for Outstanding Contributions to the development of space sciences and technologies and, in the same year, received the Engineering Science Award for outstanding achievement in engineering science of the International Academy of Astronautics. He performed research, mainly in the field of machine design, in particular dealing with static and dynamic structural analysis.He was one of the promoters of the Interdepartmental Laboratory of Mechatronics which works in the areas of magnetic bearings (active, passive, and superconducting) and mobile robots. Since 1996 he deals with space systems and space robotics. Since 2012 he heads the IAA Study Group on Human Mars Exploration (SG 3.16, and then SG 3.27). He is a member of the Advisory Board of the Starshot Project. He is the author of over 350 scientific papers covering various sectors of mechanical design, published in scientific journals or presented at conferences, and of 4 patents. He is the author of 24 books, including textbooks, research monographies and popular science books. He is also the author of two science fiction novels, published in Italian and English www.giancarlogenta.it