The correct industry name for an orbiting ‘Space Tug’ and its functionality is for In-Orbit Servicing (IoS) of existing satellites. They can also be called ‘Mission Extension Vehicles’, and quite a few technology companies are building suitable spacecraft capable of rescuing and servicing orbiting satellites.
With a typical satellite costing around $300 million to build, launch (and insure) it makes perfect sense to consider the huge potential savings available from using something that is already orbiting.
A report from Northern Sky Research (NSR) says – in theory – IoS presents diverse opportunities, from extending satellite life and transporting it to the correct orbit in the near term, to repairs and potentially even for in-orbit assembly in the longer term.
But IoS also comes with its own basket of challenges. “The lack of a strong business case, mostly due to significant initial investment required, is one of the most acknowledged factors to have attributed to the demise of IoS efforts historically. While its full potential is yet to be realised, the persistent attempts to make IoS a reality against significant financial risks involved, makes for a compelling discussion.”
NSR says that the most tangible benefit – to a satellite operator – is to use a Space Tug or Mission Extension Vehicle as a form of deferring capital expenditure on a new satellite to replace one with a problem.
There are a few well-established manufacturers of Space Tugs, including Orbital-ATK which is due to fly its first mission in 2019 and initially to extend the life of Intelsat 901. Orbital has two such Tugs in manufacture (MEV-1 and 2).
SES has ordered its own Space Tug from MDA-Space Systems/Loral which it wants to be in operation by 2021.
Airbus also has a Tug in development, which it says can refuel, repair and re-locate a satellite that’s drifted and also help clean up space of debris.