Unless something has changed, you do
not need a Detailed Surface Scanner for a First Discovered tag. There has always been a lot of confusion about that, but you only need a simple surface scan (the passive scan that starts when you approach a targeted stellar body that gives you its name). It's a
Detailed Surface Scanner, not a Detailed
Surface Scanner, and mainly increases the payout.
(See this thread for the relevant quote from Michael, I can't find the original with this handheld device:
https://forums.frontier.co.uk/showthread.php?t=108915&page=4 )
Edit: After 20+ pages of Beta 1.1 patch notes, I found it:
https://forums.frontier.co.uk/showthread.php?t=108887&page=36