reports that NASA’s upcoming James Webb Space Telescope cleared a major hurdle in its $8.7 billion development.

The “ultrasophisticated” mirror system for the telescope has been completed by Ball Aerospace in Boulder, Colo., and the mirrors are ready for delivery.

A ceremony was held at Ball on Aug. 15 to commemorate the completion of the 18 beryllium mirror segments for what will eventually be the replacement for NASA’s legendary Hubble Space Telescope.

The James Webb Space Telescope is due to lift off into space in late 2018. When it launches, it will be several times larger than Hubble and the largest mirror ever launched into space.