Parabolic Arc's Mission Extension Vehicle Headed for Space discusses Northrop Grumman's Mission Extension Vehicle, which is only briefly described in Wikipedia.
The article states:
A satellite launched into space can only bring so much fuel with it, and many times the fuel runs out before the satellite’s components stop functioning. This is where the MEV comes in. It is designed to locate and connect to a satellite running low on fuel, and provide the attitude control and orbit maintenance.
The MEV can dock with about 80% of satellites currently in a geostationary orbit, even if the satellite was not designed to be serviced, and can operate for about 15 years. That means the spacecraft could attach to one satellite for a few years, undock and then help out other satellites in need.
First, I wonder if "dock" is not really the right word, and perhaps it's more of a grappling effect, but hopefully not like this!
Whatever it is, I'd like to understand how it can be done to "about 80% of satellites currently in a geostationary orbit". Glue? Magic fingers? Magnets?