The Hubble Space Telescope is a tough act to follow. In the three decades since it launched, in 1990, the still-active space observatory has captured spectacular imagery of the cosmos and shed new light on its deepest mysteries in unprecedented detail. Topics like dark energy and exoplanets were merely a figment of the imagination when Hubble first prepared for takeoff, and it captivated the imaginations of generations of people curious about the universe’s origins and science’s paramount question: Are we alone?
Hubble’s success partially explains why NASA took its time to prepare its successor, the bigger and more powerful James Webb Space Telescope, which launched from French Guiana in December 2021. (Its namesake, James Webb, helped create the Apollo program in the 1960s.) Originally projected to launch in 2007, the telescope’s extremely intricate design cost $10 billion and required more than a decade of finessing to ensure the spacecraft wouldn’t quickly become space junk. The mission had 344 single-point failures, meaning that if any of the actions didn’t work, it would fail. For NASA and its partners, the European Space Agency and Canadian Space Agency, the stakes couldn’t be higher.
So the initial batch of findings feels universally triumphant. (Some NASA astronomers were reportedly in tears.) The first image, revealed Monday by President Joe Biden, offers the deepest view into the universe’s past—and the oldest documented light in the history of the universe, about 13 billion years old. It reveals a lustrous and crystal-clear vision of a distant patch of sky with emergent galaxies burning into visibility 600 million years after the Big Bang. Other images, rendered at a staggering 150 million pixels, reveal never-before-seen details of the galaxy group Stephan’s Quintet, the breathtaking process of planetary nebulae being extracted from a dying star, and a stellar nursery, the glittering curtain of dust and gas known as the “Cosmic Cliffs” that serves as one of the Milky Way’s cradles of star birth.
“When you have an observatory as transformational as Webb, the most exciting discoveries are likely to be the ones that we don’t even anticipate,” Dr. Mike McElwain, an astrophysicist at NASA, tells Live Science. “Webb’s infrared eyes on the universe will enable us to see space where we were previously blind. Its unprecedented infrared sensitivity will help astronomers compare the earliest galaxies to today’s grand spirals and ellipticals, helping us to understand how galaxies assemble over billions of years.”
How does Webb achieve such stellar image quality compared to Hubble? Each telescope is built on the same principles—a large primary mirror that captures as much light as possible from objects in galaxies far, far away—but Webb’s mirror is nearly three times bigger, improving performance by a factor of six. Achieving this required some design ingenuity. A mirror of that size would be too heavy to launch into space, so NASA constructed 18 hexagonal segments in beryllium, a lightweight metal found in high-speed aircrafts. Once polished, the mirror segments were coated with a layer of pure gold to maximize reflectivity at infrared wavelengths. Folded up at launch, the sunshield unfolded like origami on the way to its final destination, an orbital sweet spot called L2.
Webb’s true specialty will be the ability to perceive infrared waves, which have longer wavelengths than light on the visible spectrum. This is another step up from Hubble—it allows Webb to register light from the most distant galaxies, revealing what these galaxies looked like at the dawn of the universe. Webb’s increased sensitivity will shed new light on how these galaxies formed and study the black holes at their center. It will also reveal the secrets behind the lifecycle of stars, which are cocooned in dust at their baby stage, as well as document the chemical makeup of exoplanets—a tactic that could potentially lead to the discovery of life. Infrared wavelengths remove the opaque dust from sight, allowing astronomers to get a glimpse inside star formation, among other things. NASA hopes this revelation will teach us about the origins of our own sun and solar system.
But if there’s one lesson Hubble taught us during over 30 years of observation it’s this: the biggest discoveries will be ones we don’t even yet know we are looking for.