Children's sci-fi from 1980's: Boy travels the stars

I'm trying to remember the name of a children's/YA science fiction book from the late 70's/early 80's. The main character was a boy (named William, maybe?), and he lived on a space station that was shaped like a barbell, and at some point he has a quest that sends him out into the stars. There he "meets" constellations such as Cygnus and Orion. He has a sword, and I remember a terrific battle at the ends where he is falling among rocks... I also believe the title had the word "Wanderer" or "Traveler", and cover illustrations showed the boy with curly hair... and that's about it. :(

Any suggestions or hints? Thank you!

>1 JDiver:: Watchers of Space by Etchemendy?

It doesn't have "wanderer" or "traveller" in it but, otherwise, is very close to your description.

ETA: here's a cover, if that helps

Brilliant, thank you so much! I think the printing I recalled had a different cover, but it's most likely the same book - 25 year old mystery solved!

Here's another cover, although it's kinda blurry.


Also, there's a sequel The Crystal City.