The James Webb Space Telescope folded up like origami to fit inside its rocket

Squeezing a telescope with a mirror wider than a school bus and a sunshield the size of a tennis court into a rocket nose cone barely five meters across sounds like an engineering contradiction. NASA and its partners solved that puzzle by designing the James Webb Space Telescope to fold up like an elaborate piece of origami, launch in a compact, wing-folded configuration, and then slowly unfurl itself in the vacuum of space over roughly two weeks. That deployment sequence, involving hundreds of individual mechanisms that all had to work correctly on the first try, remains one of the most complex single spacecraft operations ever attempted.

Why a Giant Telescope Had to Shrink to Fit a Rocket

Webb’s primary mirror measures 6.5 meters across, assembled from 18 hexagonal, gold-coated beryllium segments. No existing rocket fairing was wide enough to carry a rigid mirror of that size fully assembled. Engineers solved the problem by building the mirror in three hinged sections that folded inward against each other, much like a car’s side mirrors folding flat, so the whole assembly could tuck inside the narrow payload fairing of the rocket that ultimately carried it into space.

That mirror dwarfs the one aboard the Hubble Space Telescope, the observatory Webb was designed to succeed, and the sunshield presented an even harder folding challenge of its own. Made of five separate layers of a specialized material roughly the thickness of a human hair, the fully deployed shield spans about the length and width of a tennis court and is designed to block heat from the sun so the telescope’s instruments can operate at extremely cold temperatures. Getting a structure that large to fold into a stack thin enough to fit inside an Ariane 5 rocket required years of dedicated engineering and testing, including full-scale deployment rehearsals on the ground where technicians had to account for gravity behaving very differently than it would in orbit.

The Two-Week Unfolding Sequence in Orbit

After launching on December 25, 2021, from the European Space Agency’s spaceport in French Guiana, Webb spent roughly two weeks methodically transforming itself from a folded launch package into its full operational shape. Engineers on the ground commanded each stage of the process individually, releasing pins, extending booms, and tensioning cables in a carefully sequenced order because a single stuck mechanism could have crippled the mission before it ever captured an image.

The sunshield deployment alone involved separating and tensioning each of its five layers into precise, parallel sheets with small gaps between them, a step that had never been attempted at this scale in space before. Once the sunshield was fully tensioned, the telescope unfolded its secondary mirror on a tripod of extending struts, then swung out the two wing-like sections of the primary mirror and locked them into place, completing the transformation from a folded package into the recognizable honeycomb-mirrored telescope shape that has since become one of the most recognizable pieces of scientific hardware ever built.

Hundreds of Single-Point Failures With No Repair Option

Unlike Hubble, which orbits close enough to Earth that astronauts could service it by shuttle, Webb operates far beyond any current human reach, near a gravitationally stable location called the second Sun-Earth Lagrange point roughly 1.5 million kilometers from Earth. That distance meant engineers had no option to send a repair crew if a hinge jammed or a cable snagged during deployment, so every one of the mission’s many deployable mechanisms had to succeed without any possibility of an in-person fix.

Mission teams referred to the deployment period informally as an especially tense stretch of the mission, since so many individual steps each carried the potential to end the telescope’s usefulness if something failed to move as designed. The successful completion of the sequence, confirmed as each mirror segment and shield layer locked into its final position, cleared the way for months of additional mirror alignment before the telescope produced its first scientific images.

Months of Fine Alignment Before the First Images

Unfolding the telescope was only the first stage of preparing it for science. Once the 18 mirror segments were locked in their deployed positions, engineers spent additional months making microscopic adjustments to each segment so that all 18 individual mirrors would behave as a single, seamless optical surface. Tiny actuators behind each segment nudged them into alignment in increments smaller than the width of a human hair, a process that had to account for the telescope continuing to cool toward its final operating temperature throughout the calibration period.

That painstaking alignment work paid off when the telescope’s operators released its first full set of science images to the public in the summer of 2022, revealing distant galaxies and stellar nurseries in a level of infrared detail no previous space observatory had achieved. The images served as public proof that every fold, hinge, and latch involved in the origami-style deployment had performed exactly as engineers intended.

A Design Legacy Built on Overcoming Its Own Size

Webb is named for James E. Webb, who led NASA during much of the 1960s, and it was built through a partnership between NASA, the European Space Agency, and the Canadian Space Agency. The origami-inspired folding approach that made the telescope’s launch possible has since influenced how engineers think about deploying other large structures in space, from future space telescopes to expansive solar arrays, since the same core challenge, packing something too big for any rocket into a shape small enough to launch, applies well beyond a single mission.

This article was produced with the assistance of AI and reviewed by Morning Overview editors.

More from Morning Overview