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James Webb Space Telescope mirror installation halfway complete

James Webb Space Telescope_ESA posted on SpaceFlight Insider

Artist’s rendition of the James Webb Space Telescope in space. Image Credit: NASA / Goddard

NASA recently announced that the ninth flight mirror of the James Webb Space Telescope (JWST) has been installed. This marks the halfway point of the segmented primary mirror’s completion. Engineers working in the massive clean room at NASA’s Goddard Space Flight Center used a robotic arm to place the mirror onto the telescope structure. The first of 18 mirror segments was installed in November.

“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.

This overhead shot of the James Webb Space Telescope shows the nine primary flight mirrors installed on the telescope structure in a clean room at NASA's Goddard Space Flight Center in Greenbelt, Maryland. Photo Credit: NASA's Goddard Space Flight Center/Chris Gunn

This overhead shot of the James Webb Space Telescope shows the nine primary flight mirrors installed on the telescope structure in a clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Photo Credit: Chris Gunn / NASA’s Goddard Space Flight Center

Each hexagonal-shaped segment measures just over 4.2 feet (1.3 meters) across and weighs approximately 88 pounds (40 kilograms). Once they are pieced together, the 18 primary mirror segments will work together as one large 21.3-foot (6.5-meter) mirror. Full installation of the mirror segments is expected to be completed early in 2016.

The mirror segments are made of ultra-lightweight beryllium, which was chosen because of its thermal and mechanical properties at extremely low temperatures. Each segment also has a thin gold coating, chosen for its ability to reflect infrared light.

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 being performed by Harris corporation of Rochester, New York, which is leading integration and testing for the telescope.

If everything goes according to plan, the JWST is scheduled to be launched on an Ariane 5 rocket from the spaceport located in Kourou, French Guiana, in October 2018. It is after the spacecraft reaches its destination in space that the real action will begin.

Once there, the 18 segments of the primary mirror should unfold and adjust. The JWST’s largest feature is a five-layered Sun shield the size of a tennis court that attenuates heat from the Sun – by more than a million times. The JWST’s four scientific instruments have detectors that are capable of recording extremely faint signals.

Unlike the Hubble Space Telescope, the JWST will not orbit the Earth but will orbit the Sun at a distance of 1 million miles (approximately 1.5 million kilometers) from the Earth – a location that is called the second Lagrange point, or “L2”. This orbit will let the telescope stay in line with the Earth as it moves around the Sun, allowing the satellite’s large sunscreen to protect the space observatory from the light and heat of the Sun, Earth, and Moon.

Video courtesy of NASA



Jim Sharkey is a lab assistant, writer and general science enthusiast who grew up in Enid, Oklahoma, the hometown of Skylab and Shuttle astronaut Owen K. Garriott. As a young Star Trek fan he participated in the letter-writing campaign which resulted in the space shuttle prototype being named Enterprise. While his academic studies have ranged from psychology and archaeology to biology, he has never lost his passion for space exploration. Jim began blogging about science, science fiction and futurism in 2004. Jim resides in the San Francisco Bay area and has attended NASA Socials for the Mars Science Laboratory Curiosity rover landing and the NASA LADEE lunar orbiter launch.

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