The $10bn telescope was launched at Christmas. It is already more than halfway towards its destination approximately one million miles from Earth.
The 6.1-tonne telescope is so large that its sunshield and now-iconic primary gold-plated mirror had to be folded for launch for opening up in space.
Its sunshield protects the telescope’s IR sensing instrumentation from solar radiation with five thin, reflective layers of different shapes and sizes, keeping it below its maximum temperature of -233°C. It is necessary to keep the telescope this cool to prevent its instruments being overwhelmed by its own IR signal. The shield, designed by Northrop Grumman, is intended to transmit just 23mW of 300kW of incident solar radiation.
It is especially unwieldy, kite-shaped, and spans 21.1m by 14.6m when fully spread. When fully open, the layers are opened wider at the edges to help reflect heat outwards. The sunshield has proved a technical challenge, with tears appearing...