Increasingly demanding space-based applications require a large primary mirror diameter, on which the optical instrument resolution depends. However, the mass and volume of a monolithic primary mirror would dramatically increase along with its size, which, in addition to cost and technical issues, is also limited by the available volumen in the launch vehicle fairing. Thus, to reach large primary mirror diameters, the development of an instrument that will include a deployable, segmented primary mirror and an active correction loop to optimise its optical performance will be of utmost interest. Such technologies will allow us to address highly demanding space-based applications such as high-contrast imaging for Earth-like exoplanets, or high-resolution Earth observation from geostationary orbit.

This study aimed at defining a technological roadmap of such an active optics correction loop, which would include sensing devices and active correction components. This technological roadmap has been supported by the design of two active correction loops implemented in two preliminary instrument designs dedicated to two different missions:

• A science mission case, the goal of which is the imaging and characterisation of Earth-like exoplanets

• An high-resolution Earth observation mission, from geostationary orbit

For both cases, the active optics loop design was performed through trade-off analysis of correction strategies and technologies, based on the requested performances evaluation at system level. Such an evaluation allowed us to identify the active optics correction chain technical challenges and led to a development roadmap