big to look at the dimmest galaxies in the universe. the james webb telescope is not just built by scientists to look into the univery, it s taking humanity on a journey. we re going to enter a completely new part of observational space where we ve never trod before. and every time we ve done this as a species we ve discovered new things. we have just received the 18 hexagon that s make up the big mirror that collects the starlight and focuses in on the camera. gold has very unique properties in terms of reflecting infrared led. this is an infrared telescope. that s why we choose gold. i think people want us to build this telescope because they want to know how we got here. i want to know how we got here. you know, we started the james webb telescope to look at the cosmos and the early universe. but we discovered there s so much more powerful, that it can do new things. and we re seeing teams of people
reporter: with more than 300 single points of failure and each one could prove to be fatal to the mission s success. we wouldn t have built a telescope this big unless we needed to. you have to if you want to look at the dimmest galaxies in the universe. reporter: webb will be launching on a european rocket from french guyana. a nod to the french partners. but getting here has cost nearly $9 billion more than initially projected and it s about a decade overdue. was there ever a moment where you thought, man, i just don t know if this is going to happen. there were numerous existential crises both technical and programmatic through the life of the mission. but i guess we re all eternal optimists. and we persevered and made it happen. reporter: kristen fisher, cnn, washington. the cnn film the hunt for