The USS Cosmos (NX-80819) was a Cosmos-class Starfleet prototype starship that was schedule for construction in late 2382. (Star Trek: Pioneer: "For Bette or Worse") In 2380, Admiral John Hayes was aboard the USS Guanine, the sister-ship of the USS Cosmos, when there was a malfunction during the ship's Quantum slipstream drive testing trials. Commander Taylor Ferguson, the ship's executive officer, Admiral Hayes, and the entire engineering crew died in the explosion. ("The Teacher")