JAMES WEBB SPACE TELESCOPE: FIRST LIGHT MACHINE
Imagine a time machine so powerful that you could peer back 13.5 billion years into the past to witness the ‘birth’ of the universe and watch as the greatest origin story of all unfolds. The James Webb Space Telescope (JWST), fondly referred to as a ‘First Light Machine,’ is designed to look across the farthest reaches of the cosmos to the beginning of time itself, to observe the first stars and galaxies that coalesced from the primordial gas of the Big Bang.
JWST is the largest, most powerful, and most complex space observatory ever built. A Swiss Army Knife of unparalleled proportions, its scientific instruments will study every phase of cosmic history, observe a part of space and time never seen before, and detect possible bio-signatures of life on exoplanets.
A technical achievement of astronomical magnitude, the James Webb Space Telescope embodies unprecedented precision, power management, and sensor technology, enabling it to reveal the faint infrared signals from an ancient, early universe. A shrine of human ingenuity, the spacefaring telescope is designed to view the heavens from an entirely different perspective and make discoveries that will fundamentally alter and transform our understanding of the cosmos and our place in it.
The Webb observatory can peer into the past because telescopes show us how things were—not how they are right now.
A SCIENTIFIC MARVEL BUILT ON GLOBAL COLLABORATION AND DIVERSITY
JWST represents an enormous leap forward in technology, international collaboration, and the quest to understand the great cosmic expanse. Thirty years in the making, the $10 billion mission’s innovators and participants include 14 countries, the space agencies of the United States, Canada, and Europe, thousands of engineers, and hundreds of scientists, along with 300 universities, organizations, and leading technology companies, including Analog Devices, Inc. (ADI).
During the telescope’s first year of operation, approximately 6000 hours are allocated for General Observer (GO) programs proposed by scientists—a third of which are women from 40 different nations across the globe.
PRIMARY MIRROR SIZE: 21.3 ft. across and comprised of 18 gold-plated hexagonal deployable segments
SUNSHIELD: 69.5 ft. × 46.5 ft. five-layer deployable shield is the size of a tennis court
LOCATION IN SPACE: Orbiting the Sun around the second Lagrange point (L2), approximately one million miles from Earth
INSTRUMENTS: Near-infrared Camera (NIRCam), near-infrared spectrograph (NIRSpec), mid-infrared instrument (MIRI), and near-infrared imager and slitless spectrograph (NIRISS) with the fine guidance sensor (FGS)
WAVELENGTHS: Visible, near infrared, mid-infrared (0.6 micrometers to 28.5 micrometers)
TRAILBLAZING IN THE INFRARED
Wielding a mirror six times the size of the Hubble Space Telescope and technology one-hundred times more sensitive, JWST will be able to do things that its famed predecessor simply couldn’t. Its primary mirror will gather light from a part of the electromagnetic spectrum Hubble and the human eye are blind to—the infrared—and show us otherwise hidden regions of space.
Hubble sees primarily in the visible part of the spectrum and is limited to what it can discern. JWST focuses in the near and mid-infrared and sees with much greater clarity and sensitivity than ever before.
Image Courtesy NASA
Light is stretched as the universe expands through a process called cosmological redshifting. Starlight emitted supereons ago in the shorter ultraviolet and visible wavelengths is now stretched to the much longer wavelengths of the infrared. The further the star, the older the region, the more light is redshifted. Viewing in the infrared helps astronomers see closer back to the very beginning of time itself and observe the formation of ancient suns and galaxies as they first appeared.
With its longer wavelength, infrared radiation can penetrate dense molecular clouds, whose dust blocks most of the light detectible by visible range astronomical instruments. A primordial universe comes into view with unprecedented resolution and clarity for the first time.
A SWISS ARMY KNIFE
On December 25, 2021, the James Webb Space Telescope was launched into space aboard an ESA Ariane 5 rocket. During the observatory’s one-month journey to its L2 orbital destination, the five membrane layered sunshield unfolded using an elaborate system of motors, pulleys, and cables. Later, the telescope’s secondary mirror extended, followed by the unfolding of the primary’s 18 segmented hexagonal mirrors.
The alignment of the mirrors began once the craft cooled down to an operating temperature of less than –380° Fahrenheit (40 kelvins). In the final months of commissioning, the telescope pointed at representative science targets to test, characterize, and calibrate all four scientific instruments, followed by routine science operations.
Parked on the far side of the Sun and Earth, JWST orbits in a position known as L2—the second Lagrange point—where gravitational forces and the orbital motion of a body balance one another, reducing the amount of fuel needed for a spacecraft to remain in orbit. At L2, the Sun is mostly eclipsed by the Earth’s shadow, with only a corona showing.
SURVIVAL IN A HOSTILE ENVIRONMENT
One million miles from Earth, JWST’s breakthrough technology operates in the harshest, most inaccessible environment with searing deep-space high radiation and frigid temperatures of below –370° Fahrenheit. These conditions would impair all but the most hardened electronic components. Repair and rescue missions are impossible at this great distance, so technical failures are not permitted.
NASA required the highest level of reliability and rad-hardened components that could withstand both high energy charged particle interactions and a large total ionizing radiation dose over a long period. So engineers selected Analog Devices’ radiation-hardened precision, power management, and sensor component technology to integrate into the JWST system.
Analog Devices has a 50-year history providing rigorously-tested, high tolerance, rad-hardened components critical to the success of NASA’s geostationary satellites, fly-bys, and landing missions to the planets. Some of the same components developed as far back as 1974 are still being used today—most recently on the Mars Perseverance and JWST. “It’s a testament to the longevity of ADI’s product innovation and our commitment to not obsoleting products,” said Bryan Goldstein, Vice President, Aerospace, Defense, and RF Products, ADI.
“We’re helping to safeguard the success of the mission by supporting spacecraft operational systems and the 11 scientific instruments with 123 radiation-hardened components. Many have a long track record of use on NASA deep space missions.”
GM, Aerospace, Defense, and RF Products | Analog Devices, Inc.
THE ENGINEERING CHALLENGE: PRECISION, POWER MANAGEMENT, AND SENSING SOLUTIONS
Breakthrough advances, innovations, and inventions were needed across precision, power management, and sensor technology to ensure the James Webb Space Telescope's success.
Through a process called wavefront sensing and control, the JWST’s NIRCam instrument measures any imperfections in the alignment of the mirrors that might prevent them from working as a single mirror. One hundred and thirty-two actuators and tiny mechanical motors help to achieve a single perfect focus, allowing the mirror segments to align as one. The alignment process must be repeatable, as the mirror needs to be realigned each time the telescope turns and points at a different object in space.
Any heat generated by JWST’s systems could interfere with the faint signals captured by the telescope. A thermal control subsystem maintains the crafts bus operating temperature, ensuring the observatory is always at the proper temperature. Working like the world’s most effective refrigerator, the cryocooler pumps warmth-absorbing gas through the mid-infrared detector (MIRI). The instrument must be kept at –447° Fahrenheit (7 kelvins)—colder than JWST’s counterparts—to see farther into the infrared.
The Webb observatory’s real sensing magic comes from a unison of three main elements—the size of the mirror, the infrared detector, and the filter wheel. The bigger the mirror, the more energy reflected back to the detector—and JWST has the largest mirror ever put in orbit.
The process is simple, in theory, but complex in its details. The mirror collects light and directs it to the various science instrument that filter or spectroscopically disperse it before focusing the light onto the detectors. The detectors are where light is absorbed and converted into electronic voltages to be measured and later analyzed.
The infrared detectors are exotic semiconductor devices made of unusual materials with highly unusual properties. That’s one of the reasons they are cooled to near absolute zero. The MIRI detector, for example, is a charge-coupled device with an unprecedented 1024 × 1024 pixels made of arsenic doped silicon. Each pixel sensor records a voltage based on how much light strikes it.
SUPPLYING THE TECHNOLOGY BUILDING BLOCKS
ADI technology is supporting larger aspects of the JWST mission by providing the foundational microelectronic building blocks for JWST's circuitry- including operational amplifiers and converters for basic signal conditioning, filtering, and gain blocks. Chris Chipman, Product Line Manager, Aerospace, Defense and RF Products, ADI added, “We've given NASA a variety of components to support the signal chain— such as data converter, amplifier, voltage regulator and reference products.”
ADI solutions are supporting various housekeeping, health monitoring functions, and onboard power management to ensure the appropriate voltage and current are supplied to the various subsystems.
SPINOFFS: THE IMPACT BACK ON EARTH
The James Webb Space Telescope acts as a high tech extension of human vision, delivering never-before-seen images of the universe. Now, a new technology, first developed to help construct the advanced space telescope, is employed by eye doctors back here on Earth.
The groundbreaking process, designed for precisely and rapidly measuring JWST’s mirrors after grinding them, was fine-tuned and applied to the world of eye surgery. Developed by Johnson & Johnson, iDESIGN is used to create a high definition map of a patient’s eye to help guide a surgeon performing LASIK corrective eye surgery. Compared to previous eye-mapping technology, iDESIGN provides surgeons with five times more data points while mapping eye aberrations and irregularities. High definition mapping results in more accurate measurements, resulting in more accurate treatment, improved surgical precision, and better quality of vision and life after laser vision correction.
Improving human vision is just one of many space spinoffs derived from the technology developed for the Webb Observatory. Rad-hardened components, initially designed for space, are also used for medical purposes like radiation therapy for treating cancer. Another spinoff is used in supporting non-carbon-based energy sources, like nuclear power. Chris Chipman said, “They are also used in applications using high energy particles, like in CERN’s linear accelerators, where they recently found evidence of Higgs Boson—the ‘God’ particle.”
WHAT'S TO COME
The observatory and the scientific instruments aboard are designed to answer specific scientific questions. It will surely forge additional questions to be addressed in future missions and observatories, such as the next adventure in astronomy—the Nancy Grace Roman Space Telescope. The expansion of our knowledge about the origin of the universe and the detection of planets potentially harboring life will affect all of humanity. But the James Webb Space Telescope holds the potential for an even bigger impact—one that may change the trajectory of industries and directly affect our daily lives. New discoveries in space and those on Earth are the birthplace of new ideas that translate into disruptive new technologies, applications, and surprises that we can't even imagine today.
Stay tuned with ADI Signals+ as the James Webb Space Telescope revolutionizes astronomy.