A new look at the cosmos

IT IS A majestic beast. Its primary mirror, a tessellation of golden hexagons, resembles a honeycomb sitting on a pile of silver-paper wrappers. But the mirror is six and a half metres across and the wrappers, each as big as a tennis court, are actually a sunshield. This shield divides the craft into a cold side and a hot side. On the cold side sit the primary, a tripod-mounted secondary that reflects light gathered by the primary back through a hole in its centre, and a pack of instruments behind that hole to parse and analyse the incoming light. The hot side carries a solar array and the craft’s control systems. And all these things must fit into a rocket fairing a mere five metres across and then unfold in space, with nanometre precision, into the shape above.