To see the first stars and galaxies in the early universe, the James Webb Space Telescope
will need to look more than 13 billion light years into space.
Set for launch in 2018, the project was nearly scrubbed in 2011 before being revived by funding from Congress. Recently, Ball Aerospace completed fabrication of the mirrors, a major milestone in the complex telescope's development. Named for former NASA administrator James Webb, the telescope's primary flower-like folding mirror is made up of 18 individual, highly polished, hexagonal gold coated beryllium segments that will capture the faintest traces of infrared light from distant galaxies.
Because warm objects give off infrared light, or heat, if the telescope's mirror was the same temperature as the Hubble Space Telescope's, the faint infrared light from distant galaxies would be lost in the infrared glow of the mirror. Instead, the Webb telescope requires extremely cold temperatures, with its mirrors at around -220 degrees C.
To keep Webb cold, it will be sent into deep space, far from the Earth. Sun shields will shade the mirrors and instruments from the sun's heat, keeping the telescope as cold as possible for maximum clarity.