Heh, you know that's my problem, I can't start out a story and imagine a character from nothing, I usually start with one idea and then it kind of fizzes away beacause I don't a want "simple" story, but this sounds like good. So good job so far for a days work.
my main problem with this is that he still looks like a regular punk, opposed to what a space punk could look completely different. Think outside of the box!
Yeah, kind of the same feeling. Plus even as a regular "punk", he looks "un-punkish", since he is in waste disposal, I guess his looks/clothes aren't that formal, so you might add on pockets like on millitary stlye pants. Maybe a chain hanging from the belt. Make the boots darker but with steel toes, think military boots.
Leave the tattoo on, it adds to the character.
Might consider going cyberpunk with him. Perhaps change that hair to something more extreme, posibly more addapted to life on a star ship (depending on if it's like an Enterprise big thing or like most waste disposal ships with a crowded space for the crew). Small hallways would make it difficult to pass through quickly. Maybe something similar to Chris Tuckers hairdo from Fifth element, maybe add some neon lights into it as details. Hightech protective/radiation sensory goggles as well perhaps, hanging around his neck, Riddick stlye...detail in general.
Also as a punk, you might design a radiation or protection suit but then cut it out a bit, show some wear and tear on it (but that also depends on the technology in you story). Perhaps wearing some hightech rubber gloves but rolled up sleeves - which would make it kind a low protetction, but he doesn't care, he's punk.
In any case you might add a vest (like the pilots in fighter planes use), but the shirt underneath with torn out sleeves (so on his upper arm he has a strap for like a cigarette box but instead has futuristic (neon color) drug vials. In any case something to spruce up the silhouette and add character to your character.