JWST's Mirror Unfolds Without A Hitch. World's Largest Telescope Is Now Fully Deployed

Artist’s impression of JWST fully deployed. Image Credit: NASA GSFC/CIL/Adriana Manrique Gutierrez

The main mirror of JWST successfully unfolded over the weekend with one side deployed on January 7 and the other on January 8. All the major deployments of the JWST, the largest and most powerful telescope ever sent to space, are now completed. The main task left to achieve is getting to its operational orbit, about 1.5 million kilometers (almost 1 million miles) from Earth.

The mirror is composed of 18 hexagonal segments made of beryllium, a metal that is both strong and light. Each segment weighs approximately 20 kilograms (46 pounds) and the whole area of the telescope is six times larger than Hubble’s main mirror. The mirror is 6.5 meters (21 feet 4 inches) across. If Hubble had such a big mirror it would have been too heavy to launch.

The segments are also coated in a thin layer of gold. The reason for it is that gold is an excellent reflector of infrared light, which the telescope will primarily observe.

The telescope is named after controversial NASA administrator James Webb, who ran the American space agency between 1961 and 1968. JWST is considered the successor of Hubble and it is 100 times more sensitive than the veteran telescope. Its power and capabilities will allow studying the cosmos like never before, from investigating exoplanets to observing, for the first time, the first stars and first galaxies that ever existed.

“The successful completion of all of the Webb Space Telescope’s deployments is historic,” Gregory L. Robinson, Webb program director at NASA Headquarters, said in a statement. “This is the first time a NASA-led mission has ever attempted to complete a complex sequence to unfold an observatory in space – a remarkable feat for our team, NASA, and the world.”

The team is now employing the 126 actuators on the backsides of the segments to flex each mirror into alignment, a process that will take months to complete and forms part of the many checks and calibrations required before the science mission commences in full this summer.

“I am so proud of the team – spanning continents and decades – that delivered this first-of-its-kind achievement,” said Thomas Zurbuchen, associate administrator for the Science Mission Directorate in NASA Headquarters in Washington. “Webb’s successful deployment exemplifies the best of what NASA has to offer: the willingness to attempt bold and challenging things in the name of discoveries still unknown.”

JWST is a joint project between, NASA, the European Space Agency (ESA), and the Canadian Space Agency.


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