Anna ZhouAlso known as: Osterhagen 5Race: HumanHome Planet: EarthHome Era: 21st centuryAppearances: Doctor Who: Series 4: Journey's EndActor: Elizabeth TanAnna Zhou was a UNIT soldier of the UNIT branch in China in the early 21st Century. She survived the Dalek attack on the Chinese base and was given an Osterhagen Key and made it to Osterhagen Station 5. She waited for Martha Jones to finish her transmission to the Dalek's, however since Martha was teleported away they could not activate the Osterhagen System. The Osterhagen system was 25 nuclear warhead under the Earth's crust, designed to destroy the Earth in the event of severe suffering of human beings. (DW: Journey's End)Source: Doctor Who Tardis Index File - Wikia Entertainment