Analysis of requirements and propellant management strategies for a lunar nano drone

In recent years, there has been a significant surge in lunar exploration efforts, driven by initiatives like NASA's Artemis program and ESA's Terrae Novae exploration program. One notable accomplishment is India's Chandrayaan-3 mission, which successfully executed a soft landing on the lunar surface, distinguishing it from recent missions like Russia's Luna-25, HAKUTO-R M1 by the Japanese company ispace, and Israeli SpaceIL's Beresheet. Additionally, upcoming lunar expeditions involve private companies like Intuitive Machines and Astrobotic, operating as part of the NASA Commercial Lunar Payload Services (CLPS) program. This program coordinates multiple precursor robotic missions aimed at investigating and characterizing promising lunar sites and testing in-situ resource utilization (ISRU) technologies. Of particular interest are lunar lava tubes, potentially valuable for human habitat creation, and the polar regions, especially the permanently shadowed regions (PSRs), which show potential for ISRU. These scientifically and economically significant sites require further exploration beyond orbital measurements, which often offer limited spatial resolution. Such data are crucial for mission planning and site prioritization, directing costly missions toward the most promising locations. The exploration of lunar pits is a compelling case study, as reliance solely on orbital measurements has proven inadequate for assessing whether these pits offer access to lunar lava tubes. To address this need, the concept of LuNaDrone was conceived in 2020, designed as a low-cost precursor mission involving a small flying spacecraft for initial reconnaissance. While LuNaDrone's primary purpose is lunar pit exploration, it also presents a viable alternative for traditional rover missions in various locations, such as PSRs. This thesis first dealt with the review of mission requirements, with a particular focus on those that must be met to be compliant with the potential launchers and landers that will transport LuNaDrone to the lunar surface. One of the goals of this activity was to determine the certifications and tests that LuNaDrone will need to carry out to meet the requirements. The next phase involved a review of the propulsion system architecture in preparation for the next activity, which was the preliminary design of the propellant management device (PMD). These devices allow the control and regulation of propellant flow in microgravity conditions when weightlessness and adverse accelerations don’t allow a clear separation between the liquid and gas phases within the propellant tank. In the case of LuNaDrone, given the high propellant mass to wet mass ratio, the use of these devices is critical to ensure proper management of propellant sloshing. This study led to a trade-off analysis, which involved the use of Analytical Hierarchy Process (AHP) to identify the most suitable device for the mission. The last phase involved the preliminary design of the PMD and the study of different configurations of the propellant tank, with the goal of identifying the best possible solution for the drone.