Successor to Hubble, 'First Light' Instrument ready

All of JWST's mirror segments are now
complete 

One of Europe's main contributions to the James Webb Space Telescope (JWST) is built and ready to ship to the US.

The Mid-Infrared Instrument (Miri) will gather key data as the $9bn (£5.5bn) observatory seeks to identify the first starlight in the Universe - groupings of the first generation of stars to burst into life.

Webb will use its infrared detectors to look deeper into space than Hubble, and further back in time - to a period more than 13 billion years ago.

It will carry a 6.5m primary mirror (more than double the width of Hubble's main mirror), and a shield the size of a tennis court, 22m by 12m, to guard its sensitive vision from the heat and strong light of our Sun.

There will be a 300-degree difference in temperature between the two sides.

James Webb's instruments must be very cold to ensure their own infrared glow does not swamp the observations.

James Webb - regarded as the successor to Hubble - is due to launch in 2018 and the observing position will be 1.5 million km from Earth.