Duration: 12 months
Space debris are a major threat to current and future space missions, especially in LEO, where orbits are overcrowded. The issue has become a priority for the space sector, and ESA is promoting the Zero Debris Approach, which aims to stop the generation of debris in valuable orbits by 2030. In LEO, this means de-orbiting satellites at the end-of-life. There are two main strategies : either a controlled re-entry that targets a specific uninhabited area, or an uncontrolled re-entry, with minimum fragments that re-enter the atmosphere. Uncontrolled re-entry is often preferred by industry as it is much less constraining than controlled re-entry for AOCS, propulsion or structure subsystems. It implies to design the satellite so the casualty risk does not exceed 1 in 1000 for all possible re-entry trajectories. A clear ESA roadmap is defined to improve platform demisability, and promising technologies are being developed. However, optical payloads often represent a significant part of the fragments surviving the re-entry, as some components have very high fusion temperatures (ceramics benches, titanium frames, etc.). Since the few studies on payload demisability in 2017, including a contribution of Thales Alenia Space, the subject has not really been addressed. Recent technological developments open up new perspectives and potential solutions to this problem of optical payload re-entry. An interesting idea consists in improving the telescope demisability by replacing non demisable materials with other materials. This leads to a degradation of the telescope thermo-mechanical behaviour, limiting the Line-of-Sight (LOS) stability and Wave front Error (WFE) performance. The study proposes the application of well mastered line of sight stabilization techniques (opto-mechanical or digital) and active optics to compensate most of the resulting optical aberrations (focus, LOS, astigmatism, etc.), with the objective to recover the target optical performance.
