CAPE CANAVERAL—Two weeks after the James Webb Space Telescope (JWST) was launched into orbit, the final segment of its 21-ft.-dia. primary mirror—the largest mirror ever flown on a space observatory—was rotated into position, completing NASA’s risky and most technically complicated series of in-space deployments.
The gold-plated mirror, comprised of 18 beryllium segments, was too big to fit inside a payload fairing for launch so it was designed with two panels, each containing three mirror segments, that were folded down, similar to leaves on a drop-leaf table.
The port-side wing was released and latched into place on Jan. 7, clearing the way for the second and final telescope deployment on Jan. 8. The starboard wing joined the primary mirror plane shortly before 10:30 a.m. EST, followed by nearly three hours of latchings to permanently secure the structure.
At 1:17 p.m. EST the long-awaited call came from Deployment Operations Lead Paul Reynolds with Northrop Grumman, the prime JWST contractor: “We have a fully deployed JWST observatory.”
With that, flight controllers at the Space Telescope Science Institute in Baltimore broke into cheers and applause, a live feed on NASA TV showed. “These last two weeks have been totally amazing,” said Webb Project Manager Bill Ochs. “Thousands of people have worked on JWST to get us here.”
After a 25-year development, test and manufacturing effort, JWST was launched by an Arianespace Ariane 5 rocket from French Guiana on Dec. 25 and released on a trajectory toward the second Earth-Sun Lagrange point (L2), located about 1 million mi. from Earth.
As the primary mirror took its final form on Jan. 8, JWST was nearly three-quarters of the way to L2, a gravitationally stable point where spacecraft need little fuel to maintain orbit. NASA and its partners—the European and Canadian space agencies—in the $11 billion JWST program hope the telescope will have enough fuel to operate long past its 5-10 yr. design life.
Good performance by the Ariane 5 rocket and smaller-than-expected trajectory correction maneuvers days after launch indicate JWST could have enough propellant to last 20 years, Ochs told reporters during a Jan. 8 press conference.
JWST is expected to fire its steering thrusters for a third and final course correction maneuver on Jan. 23 and fall into a halo orbit around L2. Once the mirror and science instruments have cooled to operational temperatures of nearly -400F, optical alignment and instrument calibrations will take place. The first science images are expected to be released in late June.
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