The next big leap in institutional and commercial space exploration is inextricably linked to the human desire both to reach Moon and Mars and to establish there a permanently inhabited colony. In the last decades, this has been one of the major, more demanding challenges for industry and agencies, since this imposes a creative re-thinking of previous missions approaches.

Earth dependency has always represented the bottle-neck for freely conceiving a human outpost on the Moon and Mars. It is widely recognized that a key enabler to any sustainable presence in space is the ability to manufacture necessary structures and spare parts in-situ and on-demand by recycling and re-using the available resources. This will reduce cost, volume, and up-mass constraints, being also in line with the ESA space debris mitigation policy towards environmentally sustainable space activities.

In this frame, the scope of this paper is to present the concepts investigated during the ESA-funded HARMONISE study concerning both in-situ materials recycling and partial or complete re-use of end-of-life hardware to serve different purposes during Moon/Mars exploration missions.

The investigation approach was threefold: recycling of polyethylene Ziplock® bags into 3D-printable filament, melting and casting of scrap aluminium for tools fabrication, and partial re-utilisation of rack blind panels for habitat furniture design. For each of these strategies, a dedicated demonstrator has been designed, manufactured and tested w.r.t. pre-defined success criteria, to fulfil functional requirements for both Earth and lunar/martian scenarios. Moreover, a dedicated study has been performed to re-use components of a lander propulsion system (residual propellant and modular elements).

The HARMONISE study will contribute to ushering a new, more sustainable space exploration era, supporting an emerging circular economy through in-orbit servicing and off-Earth manufacturing by 2050.