No astronaut is not a collective noun since it is not referring to a group of people

He became an astronaut in October 1963.
October 1963, part of the "New 14", or third group of astronauts.

Astronaut Wives Club - 2014 1-4 was released on:

USA: 2014

Astronaut - 2006 was released on:

USA: 4 November 2006 (Underground Vegas Film)

FLATS had nothing to do with what the women wore. It stood for First Lady Astronaut Trainees. The FLATs were a group of women who applied for astronaut training during the days of the Mercury space program. None of them were ever selected.