For what it's worth:
In Star Trek: Online,
the Luna-class (and its derivatives) is classified as a recoinnassance science vessel, or RSV. It is a designated science vessel and a bit less combat-oriented than the deep space science vessels (DSSV).
-class itself is not yet in STO but its 'design family' belongs to the heavy cruiser category and includes the following classes: Stargazer, Dakota
However, The Needs of the Many depicted the USS Stargazer-A
(prototype of the Stargazer
-class) at the forefront of exploration: first contact with the Lorians (possible descendants of the Xindi-Avians), re-contact with the Metron Consortium and, in-game, the first contact with the Xaraxian Congress is mentioned occuring early in the 25th century.
In short, whether you consider a ship a 'science vessel' depends how much weight you put on the initial classification vs. the actual mission profile.
BTW, people keep mentioning Spot as a 'she'. Remember: it was a 'he' in The Persistence of Memory