WASHINGTON — Engineers at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, installed the first of 18 beryllium-coated mirror segments that will make up the James Webb Space Telescope’s 6.5-meter primary mirror.

Ball Aerospace Corp. fabricated the mirror segments, which are now being installed by Harris Corp., onto a telescope backplane manufactured by Orbital ATK.  Northrop Grumman is building JWST for NASA under a $3.5 billion prime contract.

Harris will complete the mirror installation “early next year,” NASA wrote in a Nov. 25 press release.

JWST’s primary mirror will not go into environment testing at the Johnson Space Center in Houston until 2017. NASA is still performing space-environment tests there on a pathfinder mirror, the last of which is not expected to be completed until some time in 2016.

JWST, an infrared successor to the visible-spectrum Hubble Space Telescope, is set to launch in October 2018 aboard a European Ariane 5 rocket. The flagship-class observatory is expected to cost nearly $9 billion, including five years of operation.

Engineers at the Johnson Space Center in Houston prepare a replica of the James Webb Space Telescope's primary mirror for cryogenic environment tests. Credit: NASA/Chris Gunn
Engineers at the Johnson Space Center in Houston prepare a replica of JWST’s primary mirror for cryogenic testing. Tests on the flight mirror will start in 2017. Credit: NASA/Chris Gunn Credit: NASA/Chris Gunn
Engineers at the Johnson Space Center in Houston prepare a replica of JWST’s primary mirror for cryogenic testing. Tests on the flight mirror will start in 2017. Credit: NASA/Chris Gunn Credit: NASA/Chris Gunn

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Dan Leone is a SpaceNews staff writer, covering NASA, NOAA and a growing number of entrepreneurial space companies. He earned a bachelor’s degree in public communications from the American University in Washington.