ICYMI: All You Need to Know About the World’s Most Powerful Telescope

On April 13, NASA announced Webb’s successful cooldown to operating temperature, negative 447 degrees Fahrenheit, and is now calibrating its instruments to begin taking photos of the first moments after the big bang.
Since Christmas Day 2021, Webb has traveled 1 million miles away from Earth, crossing multiple milestones on its journey. Join FLYING as we break down Webb’s mission thus far.

After a series of delays, space enthusiasts received the best gift of all: Webb’s successful launch into the stars.

The massive telescope rode aboard the European Space Agency’s (ESA) Ariane 5 rocket from its spaceport in French Guiana, South America. Webb, the delicate and exceedingly expensive machine that it is, had to be folded into the rocket’s payload fairing—with inches to spare.

During the launch, the Ariane 5 rocket’s lower composite stage boosters produced 300,000 pounds of thrust and achieved nearly 27 minutes of powered flight. After leaving the atmosphere, the fairing jettisoned, relieving the upper stage of nearly 6,000 pounds.

“I want to congratulate the team on this incredible achievement—Webb’s launch marks a significant moment not only for NASA, but for thousands of people worldwide who dedicated their time and talent to this mission over the years,” said Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA Headquarters in Washington. “Webb’s scientific promise is now closer than it ever has been. We are poised on the edge of a truly exciting time of discovery, of things we’ve never before seen or imagined.”

Three days after Webb’s launch, the satellite began unfolding its tennis court-sized sunshields, measuring about the same thickness as a human hair.

The three-day unfolding of the sunshield was the first of many major instrument deployments, all of which had only one shot to deploy successfully.

According to NASA, the sunshield is necessary for the highly-sensitive instruments to pick up extremely faint heat signatures from across the universe. The five stacked layers bring down its “cold side” to nearly negative 394 degrees Fahrenheit, while the “hot side” sits at a simmering 230 degrees Fahrenheit.

“This is the first time anyone has ever attempted to put a telescope this large into space,” said Zurbuchen from the agency’s headquarters in Washington. “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.”

Webb’s most iconic piece, the 18-segment primary mirrors, successfully deployed on January 9.

The mirrors are coated in a 100-nanometer layer of gold, applied using vacuum vapor deposition, and will allow Webb to capture incredibly faint infrared light. Altogether, the primary mirror measures around 21 feet across, dwarfing its predecessor—the Hubble Space Telescope.

Once deployed, each mirror segment tested its actuators, beginning a months-long alignment process.

“Today, NASA achieved another engineering milestone decades in the making. While the journey is not complete, I join the Webb team in breathing a little easier and imagining the future breakthroughs bound to inspire the world,” said NASA Administrator Bill Nelson. “The James Webb Space Telescope is an unprecedented mission that is on the precipice of seeing the light from the first galaxies and discovering the mysteries of our universe. Each feat already achieved and future accomplishment is a testament to the thousands of innovators who poured their life’s passion into this mission.”

In late January, Webb’s month-long journey finally concluded, parking in an orbit 1 million miles away from Earth.

On approach, Webb fired its onboard thrusters for nearly five minutes, as part of its final course correction. The telescope now orbits around the second Lagrange point, known as L2.

Unlike the Hubble Space Telescope, Webb is too far away for any crewed repairs to be made. NASA, and its thousands of collaborators, only had one chance for every instrument deployment—with no room for error.

“During the past month, JWST has achieved amazing success and is a tribute to all the folks who spent many years and even decades to ensure mission success,” said Bill Ochs, Webb project manager at NASA’s Goddard Space Flight Center. “We are now on the verge of aligning the mirrors, instrument activation and commissioning, and the start of wondrous and astonishing discoveries.”

On February 11, NASA completed its first stage of mirror alignment and sent back the very first images from Webb—including a selfie.

Webb set its sights on a single star, but the image features 18 different spots of light. Since the 18-segment primary mirrors weren’t aligned yet, NASA used computer software to digitally align each point to create a unified image of the target star.

“In addition to enabling the incredible science that Webb will achieve, the teams that designed, built, tested, launched, and now operate this observatory have pioneered a new way to build space telescopes,” said Lee Feinberg, Webb optical telescope element manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

In its most recent update, Webb has reached its target operating temperature of negative 447 degrees Fahrenheit.

The sunshields did most of the heavy lifting when it came to cooling, but the telescope's electrically powered cryocooler pushed it to just the right temperature. But why does Webb need to be so cold? Objects with heat emit small traces of infrared light, which could pollute Webb’s highly sensitive cameras.

For now, NASA has begun making adjustments in order to take more test photos of the stars. According to the agency, we should expect the very first full images from Webb this summer.

“I am immensely proud to be part of this group of highly motivated, enthusiastic scientists and engineers drawn from across Europe and the U.S.,” said Alistair Glasse, MIRI instrument scientist at the UK Astronomy Technology Centre in Edinburgh, Scotland. “This period is our ‘trial by fire’ but it is already clear to me that the personal bonds and mutual respect that we have built up over the past years is what will get us through the next few months to deliver a fantastic instrument to the worldwide astronomy community.”