James Webb sunshield fully deployed

The tennis court-sized sunshield was folded to fit inside the payload area of an Arianespace Ariane 5 rocket’s nose cone prior to launch on December 25, 2021. The Webb team began remotely deploying the sunshield three days after launch of the NASA mission, which will seek the light from the first galaxies in the early universe and explore our own solar system as well as exoplanets.

In a statement, Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate said: “This is the first time anyone has ever attempted to put a telescope this large into space.

“Webb required not only careful assembly but also careful deployments. The success of its most challenging deployment – the sunshield – is an incredible testament to the human ingenuity and engineering skill that will enable Webb to accomplish its science goals.”

The five-layered sunshield will protect the telescope from the light and heat of the Sun, Earth, and Moon. NASA said each plastic sheet is about as thin as a human hair and coated with reflective metal, providing protection of over SPF one million.

The five layers reduce exposure from the Sun from over 200kW of solar energy to a fraction of a watt. This will keep Webb’s scientific instruments at temperatures of 40K, which is cold enough to see the infrared light that Webb will observe.

James Webb Space Telescope nears completion

James Webb telescope layers up for the sun

“Unfolding Webb’s sunshield in space is an incredible milestone, crucial to the success of the mission,” said Gregory L. Robinson, Webb’s program director at NASA headquarters. “Thousands of parts had to work with precision for this marvel of engineering to fully unfurl. The team has accomplished an audacious feat with the complexity of this deployment – one of the boldest undertakings yet for Webb.”

The unfolding and tensioning of the sunshield involved 139 of Webb’s 178 release mechanisms, 70 hinge assemblies, eight deployment motors, roughly 400 pulleys, and 90 individual cables.

“The sunshield is remarkable as it will protect the telescope on this historic mission,” said Jim Flynn, sunshield manager at Northrop Grumman, NASA’s primary contractor for Webb. “This milestone represents the pioneering spirit of thousands of engineers, scientists, and technicians who spent significant portions of their careers developing, designing, manufacturing, and testing this first-of-its-kind space technology.”

The world’s largest and most complex space science observatory has another five-and-a-half months of setup ahead, including deployment of the secondary mirror and primary mirror wings, alignment of the telescope optics, and calibration of the science instruments. After that, Webb will deliver its first images.

The Webb observatory is an international partnership with the ESA (European Space Agency) and the Canadian Space Agency.