JWST: First Light — an interactive Space Academy mission

The James Webb Space Telescope launched on December 25, 2021, aboard an Ariane 5 rocket from Europe's spaceport in French Guiana, ending decades of development and beginning one of the riskiest deployments in the history of spaceflight. Webb was built to see in infrared light, the wavelengths that pierce cosmic dust and carry the stretched, ancient glow of the universe's first galaxies. To do that it needed a 6.5-meter, 18-segment gold-coated mirror and a tennis-court-sized sunshield keeping its instruments near 40 kelvin, colder than minus 230 degrees Celsius, so the telescope's own heat could not blind it. But the observatory was far too large to fly fully assembled, so it launched folded, with a deployment sequence that carried 344 single points of failure — pins that had to release, latches that had to lock, motors and mechanisms that had to perform flawlessly, with no possibility of a repair crew; NASA engineers noted that the great majority of those failure points were tied to deployment mechanisms, and the primary mirror alone relied on 178 release mechanisms. Over about two weeks the sunshield tensioned and the mirror wings swung into place, and roughly a month after launch Webb coasted into its operating orbit near the Sun-Earth L2 Lagrange point, about 1.5 million kilometers from Earth.

About half a year of unfolding, cooling, and painstaking mirror alignment followed before Webb was ready to see. On July 11 and 12, 2022, NASA, ESA, and the Canadian Space Agency unveiled its first full-color images and spectra, and each one was a discovery in its own right. Webb's First Deep Field, a 12.5-hour composite of the galaxy cluster SMACS 0723, was the deepest, sharpest infrared image of the universe taken to that point — a view covering a patch of sky about the size of a grain of sand held at arm's length, yet crowded with thousands of galaxies. The cluster's gravity acted as a lens, bending and magnifying the light of far more distant galaxies behind it, some of them seen as they were within roughly a billion years of the Big Bang.

Webb's power was not limited to pictures. Turning to WASP-39 b, a puffy, scorching gas giant about 700 light-years away, the telescope's NIRSpec instrument read the starlight filtering through the planet's atmosphere during transit and found a clear feature in the infrared — reported in 2022 as the first unambiguous detection of carbon dioxide in any exoplanet atmosphere, alongside water and other molecules identified in Webb's early observations of the world. It was a measurement of an alien world's air made largely from a subtle dip in a spectrum, using the same transmission-spectroscopy technique that may one day search small rocky planets for signs of life. And in the Carina Nebula about 7,600 light-years away, Webb's infrared eye pierced the dust of the 'Cosmic Cliffs' — a wall of gas whose tallest peaks tower some seven light-years high — to reveal newborn protostars, jets, and outflows largely hidden from visible-light telescopes. Three datasets, three discoveries: the deep, ancient universe, the air of a distant world, and the birth of stars, all among Webb's first released observations. First light was not one picture but a new way of seeing, one that will keep unveiling the cosmos for decades to come.