(covers information from several alternate timelines)
The 1990s decade covers the period from 1990-1999.
The 1990s were described by Spock as a "strange, violent time" in the history of Earth. Along with bacteriological warfare experiments, genetic engineering spawns the Augments. (TOS: "Space Seed", "The Omega Glory") After the dissolution of the Soviet Union and the end of the Earth Cold War, the Human "supermen" seize control of large portions of the planet. The devastating Eugenics Wars among those leaders find them defeated and exiled.
In the fields of science, cryonics becomes popular on Earth and cryonics satellites are launched. Khan Noonien Singh and his followers are exiled in a sleeper ship. Human scientists discover evidence of past life on Mars and NASA launches the Sojourner, the first vehicle to roam the planet.
- During the 1990s, Earth conducts several bacteriological warfare experiments. According to Dr. McCoy, one of their noted experiments produced an infection which resembles those found on the USS Enterprise crewmembers who visited Omega IV. (TOS: "The Omega Glory")