James Webb Space Telescope Mirror Installation Reaches Halfway Point

As history closes in on 2015, assembly of NASA’s James Webb Space Telescope (JWST) reached a historic milestone as the installation of the primary mirrors onto the telescope structure reached the halfway point to completion and marks the final assembly phase of the colossal observatory. Technicians have just installed the ninth of 18 primary flight mirrors onto the mirror holding backplane structure at the agency’s Goddard Space Flight Center in Greenbelt, Maryland. The team is using a robotic arm to carefully but diligently attach each mirror to the structure of the colossal observatory that will eventually become the most powerful telescope ever sent to space. “This fall we start installing every mirror,” said Sandra Irish, JWST lead structural engineer during a recent interview with Universe Today at the NASA Goddard clean room facility. The painstaking assembly work to piece the mirrors together began when the first unit was successfully installed onto the central segment just before the Thanksgiving 2015 holiday. Working inside the massive clean room at NASA Goddard dedicated to the task, the engineering team manipulates the huge robotic arm to precisely lift and lower each gold coated mirror into place onto the observatory’s critical mirror holding backplane assembly. The actual flight mirror backplane is comprised of three segments – the main central segment and a pair of outer wing-like segments holding three mirrors each. One by one the team has first been populating the 12 unit central segment of the telescope structure with the primary mirrors at a pace of roughly two per week since the installations started some five weeks ago. The pair of foldable side mounted wings at both sides, each holding a trio of mirrors, remain empty as of now. The wings have been unfolded from the stowed-for-launch configuration to the “deployed” configuration to carry out the mirror installation. They will be folded back over into launch configuration for eventual placement inside the payload fairing of the Ariane V ECA booster rocket that will launch JWST. Each of the 18 hexagonal-shaped primary mirror segments measures just over 4.2 feet (1.3 meters) across and weighs approximately 88 pounds (40 kilograms). In space, the individual mirrors will unfold into several sections and work together as one large 21.3-foot (6.5-meter) mirror, unprecedented in size and light gathering capability. To complete the entire mirror installation process onto the backplane assembly will take several months and continue into early 2016, Irish told Universe Today. The flight structure and backplane assembly serve as the $8.6 Billion Webb telescopes backbone. The telescope will launch from the Guiana Space Center in Kourou, French Guiana in 2018. The telescopes primary and secondary flight mirrors had previously arrived at Goddard and the teams had practiced the installation using flight spares and engineering units. “The years of planning and practicing is really paying dividends and the progress is really rewarding for everyone to see,” said NASA’s Optical Telescope Element Manager Lee Feinberg, in a statement. “This starts the final assembly phase of the telescope.” The mirrors were built by Ball Aerospace & Technologies Corp., in Boulder, Colorado. Ball is the principal subcontractor to Northrop Grumman for the optical technology and lightweight mirror system. The installation of the mirrors onto the telescope structure is performed by Harris Corporation of Rochester, New York. Harris Corporation leads integration and testing for the telescope, according to NASA. “Then next April 2016 we will install the ISIM science module inside the backplane structure,” Irish elaborated. The Webb Telescope is a joint international collaborative project between NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA). NASA has overall responsibility and Northrop Grumman is the prime contractor for JWST. Watch for more on JWST construction and mirror installation. Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news. Ken Kremer

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