- Gaia was retired after running out of cold gas propellant needed for sky scanning.
- The spacecraft created a 3D map of the Milky Way, measuring 1.46 billion objects.
- Gaia’s data will continue to be released, with final updates expected in the 2030s.
- The spacecraft was moved to a retirement orbit to avoid cluttering the L2 point.
- Gaia’s contributions have been cited in over 20,000 scientific papers.
Gaia’s Retirement Marks the End of a Historic Mission
On March 27, 2025, the European Space Agency (ESA) sent its final commands to the Gaia spacecraft, instructing it to shut down its communication systems and central computer. This marked the end of an 11-year mission that revolutionized our understanding of the Milky Way. Gaia, one of ESA’s most successful missions, was retired after exhausting its cold gas propellant, which was essential for its sky-scanning operations.
Why Gaia Was Retired
Gaia’s last observation was made on January 15, 2025. After this, the ESA team conducted several weeks of testing before directing the spacecraft to leave its position at the L2 Lagrange point, a stable orbital location 1.5 million kilometers from Earth. L2 is a highly sought-after spot for space missions due to its gravitational stability and proximity to Earth, which allows for efficient communication and solar power usage. However, its distance makes repair missions impossible, meaning spacecraft stationed there must operate autonomously.
Keeping L2 Clear for Future Missions
L2 is currently home to several other significant missions, including the James Webb Space Telescope, the European Euclid mission, and the Chinese Chang’e 6 orbiter. To prevent clutter and ensure the area remains usable, Gaia used its thrusters to push itself into a “retirement orbit” around the Sun, where it will no longer interfere with other spacecraft. As part of its decommissioning, the Gaia team embedded farewell messages in its software and sent the names of approximately 1,500 individuals who contributed to the mission.
Gaia’s Achievements
Launched in 2013, Gaia’s primary mission was to create a detailed 3D map of the Milky Way. It achieved this by measuring the precise positions, motions, brightness, and variability of 1.46 billion celestial objects. These data provided critical insights into the distances, temperatures, and types of millions of stars, significantly advancing our understanding of galactic structure. Gaia’s findings have been cited in over 20,000 scientific papers, making it one of the most impactful space missions in history.
Legacy of Gaia’s Data
Although Gaia’s active mission has ended, its data will continue to shape astronomy for decades. The Gaia collaboration has released three data sets so far, with two more planned. The fourth release is expected in late 2026, and the final release, encompassing the entirety of Gaia’s observations, is slated for the 2030s. These data sets will remain a vital resource for astronomers, enabling further discoveries about our galaxy and beyond.
A Tribute to Gaia
Gaia’s contributions to astronomy are unparalleled. Its data have been used in approximately five scientific papers daily, underscoring its significance. As we bid farewell to this remarkable spacecraft, we extend our gratitude to the thousands of scientists, engineers, and support staff who made this mission possible. Gaia’s legacy will endure, continuing to illuminate the mysteries of the cosmos.