SC-4
From Memory Alpha, the free Star Trek reference
SC-4 was the designation of a shuttlecraft assigned to a future Starfleet Command.
As part of Admiral Kathryn Janeway's plan to alter the timeline, and bring USS Voyager back to Earth twenty years early, it was equipped with a chrono deflector, stolen from Korath.
The shuttlecraft traveled back to 2378, and was used by Janeway to infiltrate the Unicomplex and deliver a neurolytic pathogen into the Borg Collective. (VOY: "Endgame")
In 2404 of an alternate timeline, this shuttlecraft was Admiral Janeway's personal vessel. The shuttle had been equipped with a stealth generator, ablative generator-deployed hull armor, transphasic torpedoes, and a neural interface and synaptic transceiver system.
 Ablative armor active |
 Shuttle cockpit |
