Europa (aka Sol Vb) was a natural satellite, or moon, of Jupiter.
Europa was the smallest of the four so-called Galilean moons (the others were Callisto, Ganymede and Io) discovered by Galileo Galilei in the 17th century (and possibly independently by Simon Marius). With a diameter of 3,212.6 km, Europa is slightly smaller than Luna and the sixth-largest moon in the Sol system.
A robotic survey mission of Europa was in 2020. A year later, a crewed mission met with tragedy when the submersible Nautilus was attacked by 50-foot-long giant squid-analogues. The hull was breached, killing survey leader Heidi Rasmussen and her team. (Federation Spaceflight Chronology, vol. 2)
The first unit to carry the Penguin-class fighters, the 23rd Attack Squadron, began training flights off Europa from the carriers Barracuda and Stingray in November, 2230. (23rd-Century Carriers and Fighters)