After over a decade of stellar service, ESA’s Gaia spacecraft has been retired – but its legacy is just beginning.
From mapping nearly two billion stars to uncovering galactic secrets, Gaia revolutionized our understanding of the Milky Way. As the spacecraft now orbits the Sun in silent retirement, its vast treasure of data will continue to fuel cosmic discoveries for generations. With personal farewell messages etched into its memory, Gaia carries a piece of humanity with it as it drifts among the stars.
Gaia Mission Comes to a Close
The European Space Agency (ESA) has officially shut down its Gaia spacecraft after more than a decade in space. Since its launch in 2013, Gaia has been collecting detailed data that is now helping scientists uncover the structure and history of our galaxy.
On March 27, 2025, mission controllers at ESA’s European Space Operations Centre carefully powered down the spacecraft’s systems and moved it into a stable “retirement orbit” around the Sun.
Although Gaia’s operational mission is complete, its scientific journey is far from over. The data it collected will continue to drive new discoveries for years to come.
Revolutionizing Our View of the Galaxy
Over its lifetime, Gaia revolutionized our view of the cosmos. It precisely measured the positions, distances, motions, and characteristics of nearly two billion stars and countless other celestial objects. The result is the most detailed, multi-dimensional map of the Milky Way ever made, offering an unprecedented view of its structure and evolution.
Gaia’s data revealed signs of ancient galactic collisions, identified new star clusters, and contributed to the discovery of exoplanets and black holes. It also charted millions of distant quasars and galaxies and tracked hundreds of thousands of asteroids and comets in our Solar System. Thanks to Gaia, astronomers have even been able to create visualizations of the Milky Way as it might appear from the outside.
“Gaia’s extensive data releases are a unique treasure trove for astrophysical research, and influence almost all disciplines in astronomy,” says Gaia Project Scientist Johannes Sahlmann.
“Data release 4, planned for 2026, and the final Gaia legacy catalogs, planned for release no earlier than the end of 2030, will continue shaping our scientific understanding of the cosmos for decades to come.”
A Careful and Emotional Goodbye
Gaia far exceeded its planned lifetime of five years, and its fuel reserves are dwindling. The Gaia team carefully considered how best to dispose of the spacecraft in line with ESA’s efforts to responsibly dispose of its missions.
They wanted to find a way to prevent Gaia from drifting back towards its former home near the scientifically valuable second Lagrange point (L2) of the Sun-Earth system and minimize any potential interference with other missions in the region.
This video shows the different orbits of the Euclid, Webb and Gaia space telescopes around the second Lagrange point of the Sun-Earth system.
Shutting Down a Stubborn Spacecraft
“Switching off a spacecraft at the end of its mission sounds like a simple enough job,” says Gaia Spacecraft Operator Tiago Nogueira. “But spacecraft really don’t want to be switched off.”
“Gaia was designed to withstand failures such as radiation storms, micrometeorite impacts or a loss of communication with Earth. It has multiple redundant systems that ensured it could always reboot and resume operations in the event of disruption.”
“We had to design a decommissioning strategy that involved systematically picking apart and disabling the layers of redundancy that have safeguarded Gaia for so long, because we don’t want it to reactivate in the future and begin transmitting again if its solar panels find sunlight.”
One Last Push into the Sun’s Embrace
On March 27, 2025, the Gaia control team ran through this series of passivation activities. One final use of Gaia’s thrusters moved the spacecraft away from L2 and into a stable retirement orbit around the Sun that will minimize the chance that it would come within 10 million km of Earth for at least the next century.
The team then safely deactivated and switched off the spacecraft’s instruments and subsystems one by one, before deliberately corrupting its onboard software. The communication subsystem and the central computer were the last to be deactivated.
Saying Farewell, Byte by Byte
“Today, I was in charge of corrupting Gaia’s processor modules to make sure that the onboard software will never restart again once we have switched off the spacecraft,” says Spacecraft Operations Engineer, Julia Fortuno.
“I have mixed feelings between the excitement for these important end-of-life operations and the sadness of saying goodbye to a spacecraft I have worked on for more than five years. I am very happy to have been part of this incredible mission.”
Gaia’s final transmission to ESOC mission control marked the conclusion of an intentional and carefully orchestrated farewell to a spacecraft that has tirelessly mapped the sky for over a decade.
Data That Will Illuminate the Future
Though Gaia itself has now gone silent, its contributions to astronomy will continue to shape research for decades. Its vast and expanding data archive remains a treasure trove for scientists, refining knowledge of galactic archaeology, stellar evolution, exoplanets and much more.
A workhorse of galactic exploration, Gaia has charted the maps that future explorers will rely on to make new discoveries. The star trackers on ESA’s Euclid spacecraft uses Gaia data to precisely orient the spacecraft. ESA’s upcoming Plato mission will explore exoplanets around stars characterized by Gaia and may follow up on new exoplanetary systems discovered by Gaia.
The Gaia control team also used the spacecraft’s final weeks to run through a series of technology tests. The team tested Gaia’s micro propulsion system under different challenging conditions to examine how it had aged over more than ten years in the harsh environment of space. The results may benefit the development of future ESA missions relying on similar propulsion systems, such as the LISA mission.
Eternal Messages in the Stars
The Gaia spacecraft holds a deep emotional significance for those who worked on it. As part of its decommissioning, the names of around 1500 team members who contributed to its mission were used to overwrite some of the backup software stored in Gaia’s onboard memory.
Personal farewell messages were also written into the spacecraft’s memory, ensuring that Gaia will forever carry a piece of its team with it as it drifts through space.
As Gaia Mission Manager Uwe Lammers put it: “We will never forget Gaia, and Gaia will never forget us.”
