Mission and System Design of a Formation-Flying Picosatellites Cluster: A Technology Demonstration Mission for Space Situational Awareness Improvement

In recent years, nano- and pico-satellite missions have risen in popularity due to the availability of affordable launches and enhanced technology to enable smaller instruments and subsystems. As space traffic increases, especially in Low Earth Orbit (LEO), the trend toward miniaturization has raised concerns in the space community. These small objects may approach the threshold of current tracking capabilities, potentially becoming space debris if they cannot be successfully identified and tracked. To pioneer space research and technology, Delft University of Technology aims to develop a mission consisting of multiple picosatellites to demonstrate the capabilities and limits of in-space and ground-based tracking means. Within this framework, the thesis focuses on the high-level mission analysis and system design of a formation-flying cluster of two PocketQubes, as part of this novel technology demonstration mission for Space Situational Awareness (SSA) improvement. Launched as a single spacecraft, once in orbit the PocketQubes will be detached in two identical and independent twin satellites. The use of Systems Tool Kit (STK) software allowed to create several scenarios, including both space and ground segments, and to build different Mission Control Sequences (MCS) for each satellite. Through the interface between STK and MATLAB environment, the sequences were used to analyse the satellite in-flight separation in terms of direction and detachment angles, the satellite undocking velocities and the consequences of drag area variations, achievable for instance by exploiting deployable solar panels. Using differential drag control led to the investigation of what occurred during the first satellite conjunctions and also affected the mission lifetime, for which at least some months of in-orbit testing had to be ensured. The simulations confirmed the mission feasibility and allowed to identify and collect high-level mission requirements. Their elicitation continued with a focus on the orbit average power, performing a power budget analysis to estimate the power available for payload functioning. Among the payloads, a Global Navigation Satellite System (GNSS) receiver will be included in each satellite equipment, thus making the satellite independent in orbital determination, and providing a way to validate its position data with respect to other tracking systems. An extensive study on the GNSS receivers was conducted to define a possible candidate among space-capable Commercial Off-the-Shelf (COTS) receivers. The mission and system requirements obtained will be used as input for detailed mission analysis, such as finding the optimum satellite control strategy in Close Proximity Operations (CPO), and for future iterations of payload design.