An overview of the space servicing requirements in a sustainable space age

In recent years we have witnessed a proliferation of newcomers to the space industry. Stimulated by the advancement of technology, the reduction of launch costs and an ever increasing demand for new services on Earth; private initiatives have flourished in a market typically driven by international institutions and national agencies. This explosion of new activities has disrupted a conventionally slow-evolving industry, breaking the typical market and technology barriers that in past decades had limited the space industry to a few players worldwide.
The democratization of the access to space is leading up to two different approaches that will compete in the coming years. Cheaper launch services could be seen as an opportunity to deploy more satellites with production in large batches forming constellations of potentially disposable satellites. Conversely, easier and more economic access to space could provide an incentive to finally implement on-orbit servicing as the second approach, extending satellites’ life-time and performances; beginning a new era of sustainable exploitation of resources in orbit.
Although discussed in past decades, on-orbit servicing is not yet a viable alternative that is requested on commercial missions. Excluding the missions to the International Space Station, servicing has only been a matter of a few sporadic highlights (example: replacement of Hubble optics by the Space Shuttle). Among other difficulties, orbit servicing has traditionally suffered from a chicken-egg problem: most satellites on orbit are not designed to support orbit servicing, making operations complex and with low added value to the spacecraft owner; as a result, not enough effort is put into the development of the servicer vehicles, which remain exotic and expensive adventures.
However, the evolution of technologies combined to cheaper and more flexible access to space opens up interesting opportunities to finally see on-orbit servicing deployed on a usual basis on commercial and institutional missions. In this context, MOSAR (MOdular Spacecraft Assembly and Reconfiguration) project pursues the development of key technologies to sustain future space missions by designing:
 Common robotic building blocks, improving autonomy during critical phases such as on-orbit servicing.
 Robotic manipulator to support on-orbit operations such as module assembly or replacement.
 Elaboration of a concept for modular spacecraft, proposing design standards in terms of modules shapes, functions and interfaces.
This paper describes preliminary MOSAR development and details associated requirements for on-orbit operations for a new sustainable space era.