Osterhagen Project
The Osterhagen Key was a device that was held by UNIT by the time of the New Dalek Empire's invasion of Earth.
After Earth fell to the Daleks, General Sanchez of UNIT gave the key to Martha Jones along with the prototype of Project Indigo to escape. Former Prime Minister Harriet Jones told Martha Jones not to use the key under any circumstances . (DW: The Stolen Earth)
The name was posibiliy derived either "Eastern City" or "Fossil City", depending on spelling. Also, "Osterhagen" is an anagram of "Earth's Gone", "Agent Horse" or "Shag No Tree".
If Osterhagen is split into two words, more possible meanings emerge:
"... it is also believed by some that the word 'Easter' derives from the old Saxon language word 'Oster' meaning 'to rise'..." http://www.mystical-www.co.uk/easter.htm
"Hagen (German form)... is a Burgundian warrior in tales about the Burgundian kingdom... Hagen is often identified as a brother or half-brother... In German tradition Hagen is especially grim, implacable, and violent and in two accounts one-eyed..." http://en.wikipedia.org/wiki/Hagen_(legend)
or perhaps Oster is actually Eostre? "The Pagan goddess 'Eastre' or 'Eostre', 'Spring' or 'Dawn' respectively..." http://www.mystical-www.co.uk/easter.htm
