Webb instruments to go super-cold

The instruments for the James Webb Space Telescope are about to enter their third and final cryo-vac test at Nasa's Goddard Space Flight Center.

Assuming this goes well, they will then be joined to the main telescope structure. The launch is still set for late 2018.

Begoña Vila, a systems engineer with the US space agency, described the current status of the instruments to our correspondent Jonathan Amos.