James Webb enters the 'freezer'

The door has closed on the colossal chamber that will test the James Webb Space Telescope before it goes into orbit.

The successor to Hubble has been locked tight inside the thermal vacuum facility to check it can focus light properly under the conditions it will experience in orbit.

Nasa engineer Juli Lander and Northrop Grumman, external astrophysicist Alberto Conti spoke with our science correspondent Jonathan Amos.

Juli explained first the origins of the Johnson Space Center's famous Chamber A.