The robots that helped build the James Webb Telescope

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A custom hexapod from PI was used to place the segments of the telescope’s mirror. | Source: NASA

Last week, NASA’s James Webb Space Telescope began preparing for a three-month long process of aligning the 18 hexagonal mirror segments that make up the telescope’s mirror. The process begins by moving each segment upwards by just 12.5 mm.

The James Webb Space Telescope is the largest telescope to ever be launched into space. With all of its mirror segments unfolded, it’s around the size of a tennis court.

NASA’s engineers had to place each hexagonal piece with extreme precision. To do so, they used a robotic arm that can move in six directions. The arm was controlled by a custom hexapod created by PI USA. The hexapod was placed at the end of the robotic arm to ensure that each piece was placed in the correct spot.

“In order for the combination of mirror segments to function as a single mirror they must be placed within a few millimeters of one another, to fraction-of-a-millimeter accuracy. A human operator cannot place the mirrors that accurately, so we developed a robotic system to do the assembly,” NASA’s James Webb Space Telescope Program Director Eric Smith said.

These mirrors were made for movin’, and that’s just what they’ll do.#ICYMI, last Friday we launched our mirror motor tracker. On https://t.co/1OTI2bYnfR, you can track our individual mirror segments as they move upward by 12.5 mm to prep for a 3-month mirror alignment process. pic.twitter.com/p2MdbjeaXQ

— NASA Webb Telescope (@NASAWebb) January 18, 2022

Placing the pieces required two teams of engineers to work simultaneously. The first was dedicated to controlling the robotic arm and maneuvering it around the structure of the telescope.

The other team worked to take measurements with lasers as the segments were placed, bolted and glued.

“Instead of using a measuring tape, a laser is used to measure distance very precisely,” Garry Matthews, Harris Corporation’s James Webb Space Telescope’s assembly integration and test director, said. “Based off of those measurements a coordinate system is used to place each of the primary mirror segments. The engineers can move the mirror into its precise location on the telescope structure to within the thickness of a piece of paper.”

The James Webb Space Telescope was launched in December 2021. It is designed to last in space for at least five and a half years. Ideally, however, NASA is hoping the telescope will continue operating for 10 years.

The telescope will build and expand on the work of the Hubble Space Telescope. It will orbit around one million miles from Earth to see some of the first galaxies formed in the universe.