After more than a decade of unraveling the secrets of our galaxy, the European Space Agency (ESA) has officially concluded the Gaia mission. On March 27, mission control powered down the spacecraft’s subsystems and guided it into a “retirement orbit” around the Sun, signaling the end of its operations and the beginning of an intensive scientific exploitation phase of the data it collected.

Although Gaia’s mission in space has come to an end, its legacy continues. ESA engineers and scientists are now fully focused on processing the vast amount of data gathered during the mission. The next wave of scientific publications, based on this data, is not expected to be released before the end of the decade, around 2030.

The decision to retire Gaia stemmed from its dwindling fuel supply. ESA carefully evaluated the best way to decommission the spacecraft in a responsible and sustainable manner. Initial plans considered methods to prevent Gaia from drifting back toward its original orbit near the second Lagrange point (L2), a stable position in space where it had operated since launch. However, the final strategy prioritized dismantling and deactivating the spacecraft’s redundant systems to ensure that it could never accidentally reactivate.

In its final maneuver, ESA executed a series of passivation activities, using the spacecraft’s thrusters one last time to place Gaia into a safe and stable heliocentric orbit. Following that, engineers shut down all instruments and subsystems, and deliberately corrupted its onboard software to render the spacecraft permanently inactive.

“Shutting down a spacecraft may seem like a straightforward task, but in reality, spacecraft are designed to avoid being turned off,” ESA explained in an official statement. “Gaia’s final transmission to the European Space Operations Centre (ESOC) marked the end of a carefully planned farewell to a spacecraft that has mapped the stars tirelessly for over twelve years.”

A Pillar of Modern Astronomy

Gaia’s impact on modern astronomy is profound and ongoing. The data it gathered remains a goldmine for researchers seeking to better understand the structure and evolution of our galaxy. Its precise measurements continue to influence studies in galactic archaeology, stellar evolution, and even the search for exoplanets.

Moreover, the star maps created by Gaia will serve as a foundation for future generations of astronomers and space missions. These maps are expected to aid in new discoveries for decades to come. ESA also highlighted Gaia’s remarkable engineering—its ability to withstand radiation storms, micrometeoroid impacts, and temporary losses of communication with Earth stands as a testament to its robust design.

A Legacy of Groundbreaking Discoveries

Launched in 2013, Gaia was tasked with an ambitious goal: to map the Milky Way in unprecedented detail. Over the years, the spacecraft exceeded expectations, tracking the positions, motions, distances, and characteristics of nearly two billion stars and other celestial bodies. It delivered the most detailed and expansive multidimensional map of our galaxy ever produced, offering insight into its composition, dynamics, and history.

Thanks to Gaia, astronomers have been able to trace the motion of stars, uncover the remnants of ancient galactic mergers, and explore the mysterious outer regions of the Milky Way. The spacecraft has played a key role in identifying exoplanets, refining the distance scale of the universe, and deepening our understanding of stellar life cycles.

As the scientific community now turns its attention to Gaia’s vast data archives, the mission’s true potential is just beginning to unfold. Though the spacecraft’s journey has ended, the knowledge it brought back will continue to light the way for generations of cosmic explorers.