The public doesn't really know. The shuttle did a handful of secret missions that could have involved satellite service.
There is also a sort of mini shuttle that has launched a number of times in the last decade called the X-37B which some have speculated might be used for servicing satellites.
It's definitely an interesting concept! The way you say the shuttle chased down satellites makes me laugh, as if the satellites were trying to escape and were zig zagging around! In reality, every mission to the ISS does the same thing as the shuttle rendezvousing with the Hubble.
I've always written "a", just because I think the other style is ugly. I have a Christmas stocking which I insisted, long ago, on having embroidered with the same style of "a".
I tried once to write "g" with loop below as commonly printed, but I couldn't make it look decent.