James Webb Space Telescope marks deployment of all mirrors

NASA's James Webb Space Telescope, seen here in an artist's illustration, is wrapping up its month-long deployment process.
NASA's James Webb Space Telescope, seen here in an artist's illustration, is wrapping up its month-long deployment process. (Image credit: NASA)

NASA's massive new observatory has notched another milestone.

After nearly a full month in space, the James Webb Space Telescope, also known as JWST or Webb, is nearly at the end of its deployment work. The complicated series of deployments has seen the telescope transform from its tightly-folded launch configuration to what looks like a real observatory, although science observations remain months away.

"Just in from the @NASAWebb team: All 18 primary mirror segments and the secondary mirror are now fully deployed!" NASA Administrator Bill Nelson wrote in a tweet posted on Wednesday (Jan. 19). "Congratulations to the teams that have been working tirelessly since launch to get to this point. Soon, Webb will arrive at its new home, L2!"

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JWST's golden primary mirror includes 18 individual hexagonal segments, each controlled by seven actuators that allow precise movements. All 18 segments are now in their deployed positions several days sooner than scheduled.

Work began on the mirror segments on Jan. 12 and was expected to take about 10 days. But despite today's announcement, those mirror segments aren't quite ready to observe yet. First, NASA must conduct the painstaking process of fine-tuning every mirror's position to turn 18 individual views of the universe into one large ultra-powerful mirror.

The team behind Webb expects that the entire mirror process will take about three months, all told.

Webb has one more key deployment milestone to complete, a trajectory burn that will insert the observatory into orbit around a spot in space dubbed the Earth-sun Lagrange point 2, or L2. L2 is located nearly 1 million miles (1.5 million kilometers) away from Earth, on the side of the planet opposite the sun.

According to a NASA timeline, JWST is expected to complete this final arrival maneuver on Sunday (Jan. 23).

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Meghan Bartels
Senior Writer

Meghan is a senior writer at Space.com and has more than five years' experience as a science journalist based in New York City. She joined Space.com in July 2018, with previous writing published in outlets including Newsweek and Audubon. Meghan earned an MA in science journalism from New York University and a BA in classics from Georgetown University, and in her free time she enjoys reading and visiting museums. Follow her on Twitter at @meghanbartels.