The National Aeronautics and Space Administration said the review focused on subsystems in the unit's optical telescope element, or OTE, which is the "eye" of the Webb observatory. The telescope consists of a 21.3-foot primary mirror; secondary, tertiary and fine steering mirrors; along with supporting structures, deployable tower and control electronics.
"The successful completion of the Optical Telescope Element Preliminary Design Review is a significant milestone in the telescope's development which demonstrates it's full feasibility and which allows the team to move on to final, detailed designs," said Lee Feinberg, NASA manager of the OTE.
During the review, scientists also presented a plan for the final assembly and verification of the telescope. That includes all subsystems, backplane, thermal controls and hardware for sub-assemblies, as well as simulated space environment testing at the Johnson Space Center.
The James Webb Space Telescope -- a collaboration of NASA, the European Space Agency and the Canadian Space Agency -- is expected to be launched in 2013.
2014: The Year in Music [PHOTOS]