Astronomers all over the world are cheering and breathing a sigh of relief today. Two weeks after launch, the last of the hundreds of components of the James Webb Space telescope have finally unfolded in space. Each mirror, cable, wire and motor is now in its intended place. The telescope is the most powerful space observatory ever built. To discuss this milestone, The World’s Carol Hills is joined by space scientist Martin Barstow from the University of Leicester. He is the chair of the Space Telescope Institute Council, which operates the James Webb Space Telescope.