Farewell, Gaia! Spacecraft operations come to an end

The European Space Agency (ESA) has operated its Gaia spacecraft after more than a decade, which are now being used to highlight the mysteries of the galaxy at our home.

On 27 March 2025, Gaia’s control team at the European Space Operations Center of ESA carefully closed the subcutam of the spacecraft and sent it to the “orbit of retirement” around the Sun.

Although the operation of the spacecraft is now over, scientific exploitation of Gaia’s data has just begun.

Gaia’s stellar contribution

Launched in 2013, Gaia has changed our understanding of the universe by making accurate mapping of about 2 billion stars and other astronomical objects positions, distances, motions and qualities. It has provided the largest, most accurate multi-dimensional map of our galaxy, which reveals its structure and development in unprecedented detail.

The mission highlighted the evidence of the previous galactic merger, identified new star groups, contributed to the discovery of exoplanets and black holes, maps millions of quasters and galaxies, and tracked hundreds of thousands of asteroids and comets. This also enabled the creation of the best visualization of how our galaxy could see an external observer.

Johannes Sahlman, a scientist at the Gaia Project, says, “Gaia’s comprehensive data release is a unique treasure for astrophysical research, and affects almost all subjects in astronomy.”

“Planned for data release 4, 2026, and the final Gaia Legacy Catalog, has been planned for not releasing before the end of 2030, will continue to shape our scientific understanding of the universe for the coming decades.”

Saying goodbye is never easy

Gaia has crossed her lifetime of five years, and its fuel reserves are decreasing. The GAAI team carefully considered how it is best to deal with ESA’s efforts to deal with the responsibility of their missions.

They wanted to find a path to prevent Gaia from returning to their east home near the scientifically valuable second lagrange point (L2) and reduce any possible intervention with other missions in the area.

“Closing a spacecraft at the end of your mission seems like a simple enough job,” says Gaia SpaceCraft operator Tiago Nogira. “But the spacecraft doesn’t really want to stop.”

“Gaia was designed to face failures such as radiation storms, micromatorite effects, or loss of communication with the Earth. It has several fruitless systems that ensure that it can always operate and restart in the event of disruptions.”

“We had to formulate a decomitioning strategy, in which it was to be systematically separated and disabled the layers of excesses, which have protected Gaia for so long, because we do not want it to be activated again in the future and if its solar panels get sunlight then start transmitting again.”

On 27 March 2025, the Gaia Control Team runs through this series. A final use of Gaia’s thrusters took the spacecraft away from L2 and in a stable retirement orbit around the sun that would reduce the opportunity that it comes within 10 million km of the Earth for at least the next century.

The team then secured safely and replaced the spacecraft’s equipment and subcutam one by one, before it deliberately corrupts its onboard software. Communication subcutam and central computers were finally passive.

Spacecraft operations engineer, Julia Fortuno says, “Today, I was in charge of corrupting Gaia’s processor module to ensure that the onboard software would never restart again.”

“I have mixed feelings amidst enthusiasm for the operation of these important lives and the grief of saying goodbye to a spacecraft that I have worked for more than five years. I am very happy to be a part of this incredible mission.”

Gaia’s final transmission for ESOC mission control marked the conclusion of a deliberate and careful orchestrated farewell for a spacecraft, which has tirelessly mapped the sky for more than a decade.

A permanent inheritance

Although Gaia is now silent, its contribution to astronomy will continue to shape research for decades. Its vast and expansion data is a treasure for archive scientists, which refines the knowledge of galactic archeology, stellar development, exoplanets and more.

Gaia, a workhears of galactic exploration, charts maps that will trust future explorers to make new discoveries. The Star Trackers on ESA’s Euclid spacecraft uses gaia data to properly orient the spacecraft. ESA’s upcoming Plato Mission will detect exoplanets around stars characterized by Gaia and may follow on the new exoplanetary system discovered by Gaia.

The Gaia Control Team also used the last week of the spacecraft to run through a series of technology tests. The team tested the microscopic system of Gaia under various challenging circumstances to check that it was over ten years old in the rigid environment of space. The results can benefit the development of future ESA missions, which depend on similar propulsion systems, such as the Lisa mission.

In memory of Gaia forever

The Gaia spacecraft holds a deep emotional significance for those who worked on it. As part of its decomitioning, the names of about 1,500 team members who contributed to their mission, were used to transmit some back-up software stored in Gaia’s onboard memory.

Personal farewell messages were also written in the memory of the spacecraft, making sure that the Gaia will always take a piece of her team with it as it flows through space.

As the Gaia Mission Manager Uve Lemors said: “We will never forget Gaia, and Gaia will never forget us.”