Star Trek: Every Auxiliary Craft Explained

In the two-part Voyager episode Future's End, we learned that a Starfleet timeship from the 29th century, the Aeon, had crash landed in 1960s America and accidentally kickstarted a revolution in computer technology. Henry Starling found the vessel and reverse engineered it's tech to create Chronowerx Industries. Later, Starling nearly accidentally destroyed the entire solar system with a temporal explosion by trying to use the Aeon to travel to the 29th century to steal more tech. Clearly, these small ships can be pretty dangerous in the wrong hands.

The Aeon was a small, one-person Model HB-88 timeship used by the Federation's Temporal Integrity Commission in the 29th century. This organisation was tasked with policing incursions and anomalies in the timeline.

The USS Relativity (a Wells-class vessel) was a futuristic, time-travelling starship used by these agents, and the Aeon seemed to be a form of support craft for it, or similar larger timeships, though it is possible that the Aeon was advanced enough to function autonomously for long periods.