The National Aeronautics and Space Administration, with the help of other space agencies, has finished installing the first out of 18 flight mirrors on the James Webb Space Telescope, which is intended to replace the Hubble Space Telescope by 2018.

Assembled as one, the 18 mirror sections will form a large 21.3-foot mirror, estimated to be completed in early 2016. NASA dubbed the James Webb Space Telescope the astronomy field’s premier observatory of the upcoming decade.

“This first-mirror installation milestone symbolizes all the new and specialized technology that was developed…[to] make the next big steps in the search for life beyond Earth on exoplanets,” said astronaut John Grunsfeld, NASA's Science Mission Directorate associate administrator.

The Hubble’s successor is poised to continue studying the universe, such as the first luminous cosmos glows, the first galaxies and stars and the evolution of the solar system.

The mirrors, built by Colorado-based Ball Aerospace & Technologies Corporation and installed by New York’s Harris Corporation, are composed of super lightweight beryllium, selected for mechanical and thermal qualities at cryogenic temperature levels. A slender gold coating envelops each segment for reflecting infrared light.

Each of the 18 primary mirror sections, which will unfold and adjust to shape post-launch, measures almost 4.2 feet (1.3 meters) diagonally. In contrast, the Hubble’s mirror measures only 8 feet (2.4 meters) in diameter as a whole.

Extreme precision in the mirrors’ alignment is necessary for the telescope to work well. While expected to operate at outstandingly cold temperatures, the backplane should not move over 38 nanometers or about one thousandth of human hair diameter.

The space telescope’s biggest feature, according to NASA, is a five-layer sunshield around the size of a tennis court that will reduce the sun’s heat over a million times.

Optical telescope element manager Lee Feinberg said the beginning of the installation of the primary mirror segments marks the telescope’s final assembly stage.

Earlier in November, engineers at the Goddard Space Flight Center also successfully finished deploying the wings or side sections of the backplane structure folding up. The wings and the telescope structure are crucial as they make up the carbon fiber framework poised to hold the 18 mirror segments and the primary mirror’s tower.

The space telescope in the works is a project led by NASA in partnership with the Canadian Space Agency and the European Space Agency.

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