Do astronauts get co-authorship for experiments they conduct in space? Astronauts aboard the ISS help perform plenty of experiments during their flight. Do they get listed as co-authors for the research they help conduct?
Here is a page collecting research performed on the ISS, with citations to published papers.  And here is a list of ISS crew.  The first few papers I checked from the 2015-16 report didn't have any crew members among their authors.

This seems reasonable to me.  Normally authorship is based on making an intellectual contribution to the project: designing experiments, analyzing data, and so on.  I wouldn't particularly expect the astronauts to be involved that way - I'd assume they are mainly just carrying out the procedures designed by other researchers.  It's an important role, obviously, but it's not what authorship is intended to recognize.