If your digital copies or vintage DVDs lack captions, several dedicated communities provide fan-made and official subtitle files (usually in .srt format):
If you own the series on physical media, official subtitles are usually built right into the discs: space 1999 subtitles
If you want, I can:
Ensure your subtitle file is labeled for the "Restored" or "Remastered" versions if you are watching a high-definition copy, as these often have different intro sequences that can throw off timing. The Global Legacy of Space: 1999 If your digital copies or vintage DVDs lack