Constitution-A

Known in official literature as the Achernar subclass after the first vessel built to these specifications, this was the previous generation of Capital ship in Federation service. Only one ship of this class, the USS Cheron, still served at the dawn of the 24th century; Cheron was mothballed along with the Constitution-B class in 2324, though with greater care taken to adhere to proper storage specs than her sisters saw.

As losses among the Constitution-class explorers rose in the late 2260s, and the threat of Romulan attack increased even as the Klingons remained a credible threat despite the Treaty of Organia, Starfleet found that the 2240s-vintage Constitution-class was starting to show its age. Design work on the much larger Excelsiors began around this time, but it was clear that such a radical departure from existing naval engineering could not bear fruit for fifteen to twenty years. As a stopgap measure, it was proposed to develop a follow-on class of more advanced explorers, but the large number of one-megaton berths constructed to service the Constitutions would not support a significantly larger vessel. As such, it was decided to focus on refit of the existing explorer fleet in lieu of designing a follow-on class.

Thus, the Constitution-A refit program sought to modernize the 2240s-vintage Constitution class with 2260s-era technology. Refit work began in the early 2270s and continued until all Constitutions had been refitted. Modifications were extensive, including a semi-modern vertical warp core, expanded torpedo tubes designed to accommodate the much more advanced and capable torpedo designs of the 2270s, and substantially upgraded duotronic computer systems and interfaces.

The Constitution-As remained Starfleet's primary capital ship up through the signing of the Khitomer Accords in 2293, after which the bulk of the class was mothballed on the order of the president as part of the general stand-down and demobilization of Starfleet after the Accords and the Cartwright Conspiracy. Admiral Rogers aborted the scrapping of many of the ships, though this proved to do little good, as the hulls were already unserviceable as of the day he took office.

Parts of several Constitution-As were salvaged for construction of the Constitution-B "rebuild" series around 2308-11, mostly including warp nacelles and interior fittings.