August 10, 2022

James Webb Space Telescope has finished unfolding its massive mirror

James Webb Space Telescope has finished unfolding its massive mirror
James Webb Space Telescope has finished unfolding its massive mirrorJames Webb Space Telescope has finished unfolding its massive mirror

The space telescope has successfully completed a series of crucial steps to achieve full deployment, and will now continue to its final destination 1.5 million kilometres away from Earth

Space 10 January 2022

An artist’s impression of the full deployed James Webb Space Telescope

NASA GSFC/CIL/Adriana Manrique Gutierrez

The James Webb Space Telescope (JWST) is fully assembled. Its 6.5 metre-wide primary mirror, made up of gold-plated hexagonal reflectors, was rotated into place over the weekend.

Locking the mirror in place marks the final step of JWST’s long unfurling, after it was packed and launched aboard an Ariane 5 rocket from French Guiana on 25 December. The JWST is the most advanced telescope ever put into space, and will see further back into the universe than ever before to image the  first stars.

It was a mercifully smooth operation to unpack JWST. On 4 January, JWST operators completed the spacecraft’s most critical manoeuvre – the unfolding and tensioning of its sunshield, which protects the telescope’s sensitive instruments from the sun’s powerful radiation.

Advertisement

Then, on 5 January, JWST’s secondary mirror was extended out in front on three long poles, before its primary mirror’s second side panel was unfolded on 8 January, marking the end of all major deployments.

Though the largest, most complex operations have gone smoothly, there are still some boxes to tick before JWST arrives at its destination, a gravitationally stable orbit called L2, 1.5 million kilometres from Earth.

The telescope needs to make a third course correction burn to push it precisely into L2. The first two course corrections used less fuel than expected, thanks to the accuracy of the Ariane 5 rocket. This means the JWST should last “significantly” longer than its expected 10-year operation time, according to NASA engineers. JWST scientists hope that the third burn, scheduled for late January, will go just as smoothly.

JWST’s 18 gold-plated mirrors will also need to be adjusted to align the telescope optics. NASA engineers will move 126 mirror motors over a period of several months in order to flex them into place. Once the alignment is complete, the scientific instruments will undergo a final calibration before being ready to image the deep universe in May or June this year.

“We are thrilled that the complex telescope unfolding worked successfully,” said Günther Hasinger at the European Space Agency (ESA), in a statement. “Now we hold our breath for the optics alignment, the instrument commissioning, and finally the fascinating first science results.”

As JWST moves into position, the telescope will cool itself to an operating temperature, of -223°C with its sunshield blocking any light from the sun, Earth or moon. It will then look far into space, in the infrared part of the spectrum, to see stars and planets as we’ve never seen them before.

Sign up to our free Launchpad newsletter for a voyage across the galaxy and beyond, every Friday

More on these topics: