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The final layers of the James Webb Space Telescope’s sunshade were robotically pulled taut with a system of motors, cables, and pulleys Tuesday, clearing a major milestone before unfolding mirrors to collect light from the oldest galaxies in the universe.

The James Webb Space Telescope deployed the first of its two primary mirror wings Friday to unfold the observatory’s reflective surface to its full 21.3-foot (6.5-meter) diameter. The second mirror wing unfolded Saturday.

Mission controllers started the delicate work of tightening the five razor-thin layers of the James Webb Space Telescope’s sunshade Monday. Managers said the nearly $10 billion observatory is “hunky-dory” after pausing deployments over the weekend to adjust the observatory’s power levels and ensure motors needed for the tensioning are in tip-top shape.

Engineers activating the James Webb Space Telescope decided Sunday to hold off tightening up the observatory’s critical sunshade to allow more time to check out the performance of its power systems and overall behavior now that several major deployments are complete.

Flying outbound from Earth at a distance of more than 400,000 miles, the James Webb Space Telescope extended two booms Friday and unfurled the mission’s five-layer sunshield to the size of a tennis court, notching a major milestone for the observatory after a nail-biting New Year’s Eve for astronomers and engineers on Earth.

The third test launch of Russia’s heavy-lift Angara A5 rocket Dec. 27 was marred by an upper stage failure that stranded a dummy payload in a low orbit.

The James Webb Space Telescope opened covers that protected the mission’s folded sunshield Thursday, and deployed a momentum flap to help the observatory balance against the unending light pressure from the sun.

China launched two classified Shiyan satellites Dec. 23 into a geostationary transfer orbit aboard a Long March 7A rocket, one of the country’s newest launch vehicles. The mission took off from China’s Wenchang launch base on Hainan Island.

The James Webb Space Telescope extended a four-foot tower Wednesday to give the observatory’s mirrors and instruments, designed to function at cryogenic temperatures, enough separation from the hot side of the spacecraft after the mission’s sunshield deploys over the next few days.