I know this would be trivial or redundant on a site centered around space exploration, but I believe iss should have what it stands for as a tag synonym international-space-station.
Most people visiting this site are probably familiar with the iss, but I think it would be good to have for the odd visitor that isn't used to the acronym, yet seeks or wants to make a question about it.
In general, I think it would be good to have the full name as a synonym to the acronyms, since the excerpt is not searched when typing in the tags bar of a question.
For example environmental-control-and-life-support-system as a synonym to eclss