NIRSpec on the James Webb Space Telescope

The James Webb Space Telescope (JWST) is a joint NASA, ESA and CSA science mission scheduled for launch mid 2013. This Hubble successor mission is heading to explore the origin on of the universe back to a time frame of 300 million years after the big pang. NIRSpec a multi object spectrograph is developed by EADS Astrium under ESA contract is one of the four instruments on board. In the paper an overview on the functions, major performance, design and technology features will be given combined with a presentation of the development status.