Mirror signal manoeuvres space telescope into focus

Nasa has begun the months-long process of bringing its newly launched James Webb space telescope into focus, a task due for completion by early summer. Mission control engineers at Nasa’s Goddard space flight centre in Greenbelt, Maryland, began by sending their initial commands to tiny motors called actuators that slowly position and fine-tune the telescope’s principal mirror. Consisting of 18 hexagonal segments of gold-plated beryllium metal, the primary mirror measures 6.5 metres in diameter – a much larger lightcollecting surface than Webb’s predecessor, the Hubble telescope. The segments had been folded together to fit inside the cargo bay of the rocket that carried the telescope to space.