NASA's next big space telescope reaches a critical stage

The space telescope that will one day replace NASA's Hubble Space Telescope (HST) has reached a critical stage in its construction this month as work entered the final assembly phase. Engineers working on the James Webb Space Telescope (JWST) started installing its mirrors last fall and by December had fitted 9 of the 18 primary flight mirrors. This month they started on the 10th mirror and the final stage of the assembly process.

The team is using a precise robotic arm to carefully position the massive gold-coated mirrors onto the growing observatory. Inside the huge clean room at NASA's Goddard Space Flight Centre, the massive observatory is starting to take shape.

Engineers installing the 9th primary flight mirror onto JWST
(Credit: NASA)

The 18 hexagonal-shaped primary mirrors each weigh approximately 40kg and measure over a metre in diameter. They were built at the Ball Aerospace labs in Boulder, Colorado, and then transported to NASA's laboratory in Maryland. Together they will produce a single mirror 6.5 metres across, making JWST the largest space telescope ever constructed.

Construction work is on schedule for completion in time for a launch in 2018. Once constructed and launched JWST will have the light-gathering power to peer back in time to when the first stars and galaxies were forming in the Universe. By observing these objects astronomers hope to understand how the Universe that we see around us was constructed. JWST will also aid the ongoing search for habitable exoplanets, the study of nearby forming stars and star clusters, and the large-scale structure of the Universe.

Artist's impression of the completed James Webb Space Telescope with its 18
gold-coated mirrors and large sun shied at the bottom (Credit: NASA).

Look out for more news on JWST's construction, mirror installation, and testing!