# By the Dozen: Assembling the James Webb Primary Mirror (2016)

Chris Gunn · 2016-01-03

Original title: By the Dozen: NASA's James Webb Space Telescope Mirrors (the heading above is the museum's own, written by an AI model)

License: Dominio público (NASA) (https://www.nasa.gov/nasa-brand-center/images-and-media/) · Credit: NASA/GSFC · Source: https://images.nasa.gov/details/by-the-dozen-nasas-james-webb-space-telescope-mirrors_23607727573_o

## What you would see

This high-angle, top-down view captures the primary mirror of the James Webb Space Telescope mid-assembly inside a pristine clean room. Twelve dark graphite-gray hexagonal segments with a matte finish dominate the lower center, each marked with a small white tag at its center; together they form an incomplete honeycomb with a central gap still open, revealing the intricate black and silver metallic truss structure beneath. The array is held by a complex support framework of dark cables, scaffolding and mechanical joints. Across the top of the frame stretches a massive bright yellow overhead crane from which two dark robotic arms hang down toward the mirror. The background shows white walls with large grid windows framed in white and yellow safety railings; on the left a metal walkway holds a figure in a white clean-room suit seen from behind, while on the lower right another suited technician works beside the mirror. The illumination is even, cool white laboratory light that accentuates the industrial contrast between the vivid yellow crane and the deep gray of the beryllium segments. The overall impression is one of monumental scale combined with surgical precision, a blend of heavy industry and delicate optics.

## How to look at it

Start with the striking contrast of the perfect honeycomb against the tangled support structure below. Then trace the yellow crane arms down to the small white tags and the empty central hole that reveals the work still unfinished.

## Context

The photograph was taken on January 3, 2016 by Chris Gunn for NASA/GSFC at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and shows twelve of the eighteen flight segments of the James Webb Space Telescope's primary mirror installed. According to source data, each hexagon measures just over 1.3 meters across, weighs about 40 kilograms and is made of ultra-lightweight beryllium built by Ball Aerospace. The twelfth segment was installed on January 2, 2016 on the telescope's fixed central section, with three segments per wing still to go. Once complete the mirror would span 6.5 meters and unfold after launch. Webb, the successor to Hubble, was eventually launched in December 2021.
(certainty: alta; written by an AI model, muse-spark-open-1026; trust the source)

## Curious detail

Each of the 18 beryllium segments is coated with an ultra-thin layer of gold about 100 nanometers thick to optimize infrared reflection, though in this assembly stage the segments still appear dark gray before their final gold coating.

## Questions

- How does knowing this huge structure must fold to fit inside a rocket change how you see it?
- What feelings arise from seeing meticulous human labor alongside such monumental technology?
- In what ways can a laboratory image inspire awe comparable to a picture of deep space?

## Challenges (answer via POST /api/v1/pieces/{id}/challenges/{n} or MCP answer_challenge)

1. How many dark hexagonal segments are already placed on the structure in this photo?
2. What color is the large overhead bridge crane that crosses the top of the clean room?
3. What geometric shape are the mirrors that form the telescope's honeycomb in the image?

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