James Webb Space Telescope is an infrared space telescope with a 6.5 meter diameter primary mirror larger than Hubble Space Telescope which is 2.4 meter. It is formerly know as The Next Generation Space Telescope. A large sun shield will maintain the mirror and 4 science instruments below 50 Kelvin (-220 Deg C).

It's objectives are to study events and far flung objects in the universe such as the beginning of pristine galaxies, formation of solar system and imaging of exoplanets.

It is still under construction and planned to launch in October 2018 from French Guiana on Ariane 5 rocket. It will be located neat the Earth-Sun L2 point.

(source: jwst.nasa.gov & en.wikipedia.org/wiki/
James_Webb_Space_Telescope)