  The latest high-performance telescopes for deep space observation employ very
large primary mirrors that are made of smaller segments, like the JWST which
employs monolithic beryllium hexagonal segments. A very promising development
stage of these systems is to make them active and to operate on their
reflective surfaces to change their shape and compensate for aberrations as
well as to perform a very precise alignment. This is possible by employing a
reference body that stores actuators to modify the shape of the shell, like in
the SPLATT project where voice coil actuators are used. However, the lack of
physical contact between the main body and shell places, along with the many
advantages related to the physical decoupling of the two bodies, some concerns
related to the retaining of the shell under all the possible acceleration
conditions affecting the system during the mission lifetime. This paper aims to
study the acceleration environment affecting the spacecraft during its lifetime
and to use it as a baseline for operational requirements of a retaining system
for the shells. Any solution is selected in this paper to leave complete
freedom for the development of a constraining system, just some are
qualitatively discussed.
