CubeSat Mission Concept for Environmental Analysis in Low Earth Orbit

To ensure future space development and sustainable orbital exploitation, it is essential to improve the knowledge of the space environment and of the phenomena that could influence spacecraft's operations. Space debris could pose a threat to space operations, and a collision with such an object could degrade the mission performance. Space debris' environment knowledge is mainly based on ground radar observations, that allow to precisely identify objects of at least 5-10 cm in diameter in Low Earth Orbit. For smaller debris only statistical models on their concentration are available, but these models are affected by uncertainties, due to the scarce amount of data and the difficulty to model and predict space debris evolution. Moreover, the atmospheric models' uncertainties highly affect the end-of-life trajectory changing the ground footprint and the casualty risk. This work addresses the emerging need to characterise the sub-millimetre scale debris environment of the Low Earth Orbit region and to improve models' accuracy during the atmospheric re-entry event of space objects. In this work, a preliminary mission study is proposed to design a 12- unit CubeSat equipped with an array of payloads, selected to characterise the sub-millimetre debris particles and the upper atmosphere temperature and pressure, as well as aerodynamic and thermal loads on the spacecraft. Initially, a parametric orbit selection for the mission is presented. The key parameters were identified as the number of submillimetre scale debris' impacts on a sensitive surface of the payload, the residence time of the spacecraft in the upper atmosphere, in particular the region below 200 km altitude, and the compliance with the decay time regulations. A trade-off analysis of possible payload technologies for in-situ detection of sub-millimetre scale debris is presented, starting from state-of-the-art devices. Moreover, the possibility to retrieve re-entry data below 200 km altitude poses a constraint to the residence time below 200 km to be able to collect enough data. Finally, a preliminary design of the CubeSat main subsystems is presented, for an initial definition of mission budgets. This work aims at proposing a feasibility study for a CubeSat mission concept for more sustainable use of space, focusing on space debris and atmospheric modelling.