Artist's illustration of the James Webb Space Telescope launched on December 25, 2021 (Credit: NASA)

The James Webb Space Telescope (Webb) — the world's largest and most complex science telescope — was successfully launched into space atop a European Ariane 5 rocket on December 25, 2021. The $10 billion revolutionary space observatory — a joint effort between NASA, the European Space Agency, and the Canadian Space Agency — is designed to detect the faint infrared light from the earliest stars and galaxies formed over 13.5 billion years ago.

"It's a time machine," NASA Administrator Bill Nelson said. "It's going to take us back to the very beginnings of the universe. We are going to discover incredible things that we never imagined.”

Webb will be able to look back to the formation of the earliest stars and planets (Credit: NASA)

Shortly after launch, the mission control team on Earth began a series of complex maneuvers to remotely open the massive 6,161.4 kg (13,584 lb) spacecraft. On December 28, 2021, the scientists successfully opened Webb's 70-foot sun shield, which had been neatly folded inside the payload section of the launch rocket. The tennis court-sized shield consists of five layers of thin plastic sheets, each about the width of a human hair. They are coated with reflective material to protect Webb from the light and heat of the Sun, Earth, and Moon.

"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 next challenge was opening Webb's primary mirror. The 21.3-foot-wide (6.5-meter) instrument comprised 18 gold-plated hexagonal segments arranged across a central post and two side wings. It had been tucked away inside the nose cone of the launch rocket. The tricky two-day process ended on January 8, 2022, after the mirror's final hexagonal piece was successfully locked into place.

"We have a deployed telescope on orbit," said Thomas Zurbuchen, NASA's associate administrator for science, told the Webb team after reaching the milestone. "A magnificent telescope the likes of which the world has never seen."

Webb is expected to reach its final destination — the Earth-Sun Lagrange Point 2 (L2) — on January 23, 2022. Located 930,000 miles away from Earth, L2 is perfectly aligned with the Sun and Earth. The gravity from the two large bodies pulling in the same direction will lock the telescope into perfect unison with Earth's yearly orbit around its star. Here, Webb's large sunshield will be able to fully protect the telescope from the light and heat of the Sun and Earth (and Moon), which could impede its ability to make infrared-light observations.

Webb will follow Earth's orbit around the Sun from L2 (Credit: NASA)

"A huge advantage of deep space (like L2), when compared to Earth orbit, is that we can radiate the heat away," said Jonathan P. Gardner, the Deputy Senior Project Scientist on the Webb Telescope mission and Chief of the Observational Cosmology Laboratory at NASA's Goddard Space Flight Center in Greenbelt, Md. "Webb works in the infrared, which is heat radiation. To see the infrared light from distant stars and galaxies, the telescope has to be cold. Webb's large sunshield will protect it from both Sunlight and Earthlight, allowing it to cool to 225 degrees below zero Celsius (minus 370 Fahrenheit)."

Once the spacecraft is in orbit, the mission team will begin testing its four scientific instruments. They are designed to detect and record infrared wavelengths from ancient stars and galaxies. The scientists will also perfectly align the segments of the primary mirror so it can act as a single, light-collecting surface. If all goes as expected, Webb will begin its historic five-year mission to observe the cosmos in late June or early July 2022.

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