In the past years, the Long-Term Storage (LTS) of the space hardware appears to be a growing topic for the European space sector. Due to longer development phase, planned or unplanned on-ground storage periods, or unforeseen events, more and more missions are launched a longer time after it was initially planed.

In Europe, several projects faced periods which can be assimilated to prolonged on-ground life, such as Atmospheric Dynamics Mission-Aeolus (ADM-Aeolus), MTG (Meteosat Third Generation), MetOp-SG (MetOp Second Generation instruments) etc. Backed by these experiences and supported by the Materials' and Processes' Technology Board (MPTB), ESA jointly with the main European space actors, including national agencies and companies are currently developing a guidelines to set recommendations and define the good practices for Long-Term Storage (LTS), focusing on all the aspects of materials and processes (M&P).

This presentation aims to introduce the topic, higlights the key challenges associated with LTS. It includes information on the aging phenomena, the accelerated aging tests, the handling and the storage conditions (environment, ground support equipment, flight hardware), the management of follower samples associated with the flight hardware or suggestions for managing risks, obsolescence, cleanliness and contamination.