For the world’s most advanced space telescope, and the thousands of people who’ve worked on it over the decades, the starting gun has fired.

After more than a quarter-century of planning, designing, building, waiting—and of obsessively testing the most complex space observatory ever assembled—the mammoth James Webb Space Telescope finally launched at 7:20 a.m. eastern time on December 25.

Whether that flaming rocket ride represents a year-end gift to science or a catastrophic conclusion to 2021 depends on the weeks ahead. For JWST’s mission to succeed, the telescope must execute an intricate series of carefully choreographed maneuvers during its first month in space. Even a single misstep could compromise the entire mission. And the telescope must