Dedicated military naval design has led to a convergence around a few fairly standard classes of ship for battleships. Frigates, on the other hand, represent a different tradition, where multi-purpose, flexible, and frequently independent operation are more important than focused, streamline designs.
Where there is relatively little differentiation between the various types of destroyers and even dreadnoughts, there is a massive amount of differentiation in frigate design.
The Calypso class represents an older, multi-purpose frigate design that remains very common due to its broad adaptability, being used as short-range patrols boats, cheap small transports of goods and people, courier vessels, smuggling, and independent mining and salvage operators.
Congruent with this custom, the Calypso class frigate is named after the nymph whose unrequited love (though, it should be noted, not unrequited lust) for Odysseus led to the Greek hero being trapped on her island for several years, until the goddess Athena asks Zeus to order Calypso to free Odysseus to complete his long journey homeward.
Featuring two independently controlled paired engines that are capable of independent 360 degree rotation in addition to a primary rear engine, it typically flies with the paired engines rotated towards the rear, an arrangement which shifts to a perpendicular configuration at the final stage of landing or the initial stage of take-off. In addition to the paired engines for a total of four exothermic engines, the primary rear engine is comprised of six additional engines.
The primary benefit of this approach is that it allows for a considerably easier process of loading and unloading cargo, particularly in environments without sophisticated, or even any, port facilities. The Calypso is rated to comfortably land on any planetary body sporting a gravity of equal to or less than 0.135g, and with difficulty is able to manage this with gravities up to 0.166g. It is able to land on even an undeveloped asteroid, load or unload crew, then launch again with no interruption of service.
Unlike the larger research vessels and military dreadnoughts, the Calypso does not feature any rotational elements, meaning that its crew operates in zero g when not under direct power. Further, due to the ship's orientation and reliance on hydrocarbon sources for fuel, engine burns are generally limited in scope, with the great majority of time being spent coasting.
Typically, the rear third of the Calypso is used for engines and fuel, the middle third for cargo, and the front third for crew quarters. In its most common configuration the Calypso has a crew of two to five, although it is not uncommon for the cargo compartment to sport as many as a dozen cryosleep tubes, though these would normally be used for passenger use rather than crew use.
The Calypso is usually armed with a single HED Lance battery intended as much for mining purposes as any kind of last-ditch defense against piracy, although it has certainly seen use in that regard. A basic, very limited AMG is rated against standard amounts of cosmic radiation, but is insufficiently powerful to provide a significant defense against opposing particle weaponry.
While not efficient for large-scale transport of cargo, personnel, and not ideal for sustained combat operations, the frigate in general, and the Calypso class in particular, represents a cheap, quickly built, easy to operate, and flexible ship useful for innumerable functions. Unlike the more specialized battleship classes, frigates are relatively easy to construct, and continue to be built in many shipyards throughout the solar system, even out as far as the Kuiper Belt.