Etienne Dumont

Design of a Modular Transportation System for Future Lunar Robotic Missions

A new transportation system for future lunar robotic missions should be designed in the frame of the ROBEX project. This system should be able to adapt to different types of payload and different landing sites. First, three different missions during which a LOFAR (low frequency array), a habitat and an ISRU (in-situ resource utilization) plant should be installed and put into operations robotically on the surface of the Moon are defined. The emphasis has been put on the characteristics which have an influence on the design of the transportation system: the payload mass, the dimensions and when required the frequency of the missions. It is followed by the preliminary design of a reusable lunar resupply vehicle. This vehicle is the first element of the modular transportation system under study. As a first step the results of the trajectory analyses and structure pre-sizing, are presented, for this vehicle which should fly at least twice a year from the Moon surface to a low lunar orbit and back.

Launch Vehicle Design applying Concurrent Engineering

Developing space launch vehicles (SLVs) is a complex and multidisciplinary task and hence their early design process is an obvious candidate to be performed applying the collaborative and highly iterative approach of Concurrent Engineering (CE). This methodology generally aims at reducing time, cost and inconsistencies already during the first project phases. It has been proven that working together with all relevant technical and programmatic disciplines simultaneously is an efficient means of converging effectively on a space system design. This includes the presence of the customer as well as the use of a common data model, a dedicated infrastructure and a guided process. During several studies at the DLR Concurrent Engineering Facility (CEF) it has been identified that in contrast to Phase-A satellite design activities, the classical, internal CE approach could not be directly applied for upper stage and more generally launch vehicle development. This mainly refers to the set of technical domains (e.g. power, structure), the use of data-/design models, the process-related communication flow as well as session scheduling. Of course, there are general differences such as margin philosophies and staging between SLV and space segment design. However, the CE process, which benefits from rapid feasibility-, cost- and performance analyses during the advanced development phases, requires additional and important modifications in order to provide the expected results to the customer in time. During the study preparation phase for instance, sensitivity analyses and iterations of the structural index (SI) are crucial for a successful CE activity. This is because characteristics such as the SI are very important for technical matters (e.g. staging) and also influence the administrative preparation which has to ensure a well-balanced allocation of resources during the CE study phase. The examples described in the present work are mainly related to upper stage design studies in which the lower stages have been considered with a given structure and performance. This has been the most recurring case in the DLR CEF, as for the ‘Kickstage‘-study and the VEGA new upper stage studies called ‘VENUS-II’. This paper shall increase awareness by highlighting major differences and special characteristics with respect to launch vehicle- compared to other space system CE studies. Based on our experiences, it provides lessons learnt and recommendations of how to adapt certain CE elements for responding to various launcher and upper stage study objectives. Additionally, it identifies gaps which currently exist in the range of required tools, such as dedicated integrated design models for launch vehicles including their parameter hierarchy.