Project Indigo was UNIT's first experimental teleportation device developed in 2009. It was reverse-engineered from Sontaran technology which was left behind following their failed invasion of Earth in that year.
The first person to (successfully) field-test the prototype was Martha Jones during the Dalek invasion later in 2009. Prior to this, Jack Harkness warned Martha against using it given its experimental nature. As the device teleported her to her mother's house, "the place [she] most wanted to be", it suggested the integration of a neural interface device for determining destination in order to make the technology man-portable. (TV: The Stolen Earth) Martha later used the device again, to teleport herself to the vicinity of the Osterhagen base in Germany, where it was last seen discarded by the door of the detonation control chamber. (TV: Journey's End)