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Heading to space was just the beginning for the James Webb Space Telescope.
Heralded as NASA’s premier space observatory of the next decade, the telescope launched on Christmas Day – and it still has a ways to go before it’s in orbit and observing the universe.
The agency refers to this process as “29 days on the edge” while the observatory unfolds its massive sunshield and reaches a special point in orbit that is a million miles away from Earth.
The Webb telescope will look at every phase of cosmic history, including the first glows after the Big Bang that created our universe and the formation of the galaxies, stars and planets that fill it today. Its capabilities will enable the observatory to peer inside the atmospheres of exoplanets and investigate faint signals from the first galaxies formed 13.5 billion years ago.
In order to accomplish all of these things, NASA built its most complex telescope yet – and everything has to work flawlessly before it can get started.
During the 29 days, Webb will set up shop, unfurling its giant gold mirror and the protective tennis court-size sunshield. This process involves thousands of parts that must function harmoniously, in the right sequence. Fortunately, each step can be controlled from the ground in case there are issues.
So far, Webb is already off to a great start. The spacecraft has already made two of three critical course correction burns to ensure it’s on the right trajectory.
It also used less propellant than planned due to the precision of the telescope’s launch aboard the Ariane 5 rocket, so “the observatory should have enough propellant to allow support of science operations in orbit for significantly more than a 10-year science lifetime,” according to NASA.
The mission was designed to last for five years. But as we’ve seen with other telescopes that successfully outlasted their expected timeline, like Spitzer and Hubble, scientists are hedging a bet the same may be true for Webb.
On December 26, Webb released its antenna assembly, including a high-data-rate dish antenna, that will serve as the telescope’s way of sending back 28.6 gigabytes of science data twice a day.
Astronomers, including those with The Virtual Telescope Project, have even been able to track Webb’s journey since launch, sharing images and video of the observatory against a backdrop of stars.
Protection from the sun
Now, Webb is starting to take a familiar shape – the one it will be once everything is fully deployed. The spacecraft has unfolded and latched pallet structures that will ultimately lead to the rollout of the sunshield, a process that is expected to continue through Sunday. The team also extended the Deployable Tower Assembly, which creates distance between two halves of the spacecraft.
The observatory is comprised of three main elements.
One is the Integrated Science Instrument Module, which holds Webb’s suite of four instruments. These instruments will mainly be used for capturing images or spectroscopy – breaking down light into different wavelengths to determine physical and chemical components.
The Optical Telescope Element, the main eye of the observatory, includes the mirrors and backplane, or spine, that supports the mirrors.
Then there is the Spacecraft Element, which includes the spacecraft bus and sunshield. The bus includes the six main subsystems needed to operate the spacecraft, including propulsion, electrical power, communication, data and thermal controls.
The massive five-layer sunshield will protect Webb’s giant mirror and instruments from the sun’s heat because they need to be kept at a very frigid negative 370 degrees Fahrenheit (negative 188 degrees Celsius) to be able to observe the universe as designed.
The successful setup of the sunshield is critical to Webb’s ability to function – and it’s also one of the most challenging spacecraft deployments NASA has ever attempted, according to the agency.
“There are 50 major deployments that transform Webb from its stowed, launch configuration into an operational observatory,” said Michael McElwain, Webb observatory project scientist at NASA’s Goddard Space Flight Center in Maryland, in a statement.
“While these steps have been tested on the ground and operationally rehearsed in the Mission Operations Center, these critical activities must be executed for a successful mission. Best wishes to our team, and stay cool, Webb!”
The next steps
Webb will next release its sunshield covers, extend booms and stretch the five layers of the sunshield into place, if all goes according to plan.
Then, there is the mirror – considered to be Webb’s trademark.
The telescope comes equipped with a mirror that can extend 21 feet and 4 inches (6.5 meters) – a massive length that will allow the mirror to collect more light from the objects it observes once the telescope is in space. The mirror includes 18 hexagonal gold-coated segments, each 4.3 feet (1.32 meters) in diameter.
It’s the largest mirror NASA has ever built, but its size created a unique problem. The mirror was so large that it couldn’t fit inside a rocket. So engineers designed the telescope as a series of moving parts that can fold origami-style and fit inside a 16-foot (5-meter) space for launch.
This is the next series of crucial steps for Webb – making sure all of those mirrors unfold and lock together to create one giant mirror.
All of these steps are expected to finish by the end of next week.
Finally, Webb will make one more trajectory adjustment to insert itself into an orbit that reaches beyond the moon.
While that rounds out the 29 days, the telescope will go through a period of commissioning in space that lasts for six months, which involves cooling down the instruments, alignment and calibration. All of the instruments will go through a checkout process to see how they are functioning.
Webb will begin to collect data and its first images later in 2022, and those are expected to be released in June or July, forever changing the way we see and understand the universe.