In that year, the starship USS Enterprise encountered a vessel from Sigma Draconis VI which utilized ion propulsion. The crew eventually discovered that the technology had been developed in the distant past, and that its users could only operate it for short periods of time while under the influence of the Teacher. (TOS: "Spock's Brain")
Star Trek Timeline [INTERACTIVE]
Do you like this video?
For the sub-light drive, please see ion drive.