Herschel Space Observatory
http://sci.esa.int/science-e/www/obj...objectid=31361

It will be the first space observatory covering the full far infrared and sub-millimetre waveband, and its telescope will have the largest mirror ever deployed in space. It will be located 1.5 million kilometres away from Earth at the second Lagrange point of the Earth-Sun system. Herschel's three and a half metre mirror will collect the light from distant and poorly known objects, such as newborn galaxies thousands of millions of light-years away...