Space Infrastructure Servicing

Space Infrastructure Servicing (SIS) is a spacecraft being developed by Canadian aerospace firm MacDonald, Dettwiler and Associates to operate as a small-scale in-space refueling depot for communication satellites in geosynchronous orbit. Intelsat is a requirements and funding partner for the initial demonstration satellite which, as of March 2011^[update], was planned to be launched in approximately 2015. MDA put the launch plans on hold in November 2011 pending finding a second launch partner, beyond Intelsat. Such a customer was not found, and Intelsat dropped out of the collaboration in January 2012. In February 2012, MDA indicated that it was waiting on a possible DARPA contract before shelving the project. In February 2017, DARPA selected MDA's Palo Alto, California company, SSL, as their commercial partner for the Agency’s Robotic Servicing of Geosynchronous Satellites (RSGS) program.

MDA Corporation announced in early 2010 that a small-scale geosynchronous-orbit refueling project was under development. The design point was to be a single spacecraft that would refuel other spacecraft in orbit as a satellite-servicing demonstration. The 2010 announcement indicated that MDA had already signed an option agreement "with an unidentified satellite fleet operator that has agreed to provide an aging telecommunications spacecraft for a refueling operation as the inaugural customer." Missions contemplated included not only satellite refueling but also space debris mitigation by including the vehicle capability to "push dead satellites into graveyard orbits."

The early technical design point included a fuel-depot vehicle that would maneuver to an operational communications satellite, dock at the target satellite’s apogee-kick motor, remove a small part of the target spacecraft’s thermal protection blanket, connect to a fuel-pressure line and deliver the propellant. In 2010, it was estimated that "the docking maneuver would take the communications satellite out of service for about 20 minutes."

...
Wikipedia