Farewell, Gaia! Spacecraft operations come to an finish

Gaia’s stellar contributions

Launched in 2013, Gaia has reworked our understanding of the cosmos by exactly mapping the positions, distances, motions, and properties of almost two billion stars and different celestial objects. It has offered the most important, most exact multi-dimensional map of our galaxy ever created, revealing its construction and evolution in unprecedented element.

The mission uncovered proof of previous galactic mergers, recognized new star clusters, contributed to the invention of exoplanets and black holes, mapped hundreds of thousands of quasars and galaxies, and tracked lots of of hundreds of asteroids and comets. It additionally enabled the creation of the most effective visualisation of how our galaxy would possibly look to an out of doors observer.

“Gaia’s intensive information releases are a singular treasure trove for astrophysical analysis, and affect virtually all disciplines in astronomy,” says Gaia Mission Scientist Johannes Sahlmann.

“Data release 4, deliberate for 2026, and the ultimate Gaia legacy catalogues, deliberate for launch no sooner than the tip of 2030, will proceed shaping our scientific understanding of the cosmos for many years to return.”

Saying goodbye is rarely straightforward

Gaia far exceeded its deliberate lifetime of 5 years, and its gasoline reserves are dwindling. The Gaia crew fastidiously thought-about how greatest to eliminate the spacecraft consistent with ESA’s efforts to responsibly eliminate its missions.

They wished to discover a solution to forestall Gaia from drifting again in direction of its former residence close to the scientifically worthwhile second Lagrange level (L2) of the Solar-Earth system and minimise any potential interference with different missions within the area.

“Switching off a spacecraft on the finish of its mission appears like a easy sufficient job,” says Gaia Spacecraft Operator Tiago Nogueira. “However spacecraft actually don’t need to be switched off.”

“Gaia was designed to face up to failures similar to radiation storms, micrometeorite impacts or a lack of communication with Earth. It has a number of redundant techniques that ensured it might at all times reboot and resume operations within the occasion of disruption.”

“We needed to design a decommissioning technique that concerned systematically choosing aside and disabling the layers of redundancy which have safeguarded Gaia for thus lengthy, as a result of we don’t need it to reactivate sooner or later and start transmitting once more if its photo voltaic panels discover daylight.”

On 27 March 2025, the Gaia management crew ran by way of this sequence of passivation actions. One last use of Gaia’s thrusters moved the spacecraft away from L2 and right into a secure retirement orbit across the Solar that may minimise the possibility that it comes inside 10 million km Earth for at the least the following century.

The crew then safely deactivated and switched off the spacecraft’s devices and subsystems one after the other, earlier than intentionally corrupting its onboard software program. The communication subsystem and the central pc had been the final to be deactivated.

“As we speak, I used to be in command of corrupting Gaia’s processor modules to be sure that the onboard software program won’t ever restart once more as soon as we’ve switched off the spacecraft,” says Spacecraft Operations Engineer, Julia Fortuno.

“I’ve blended emotions between the thrill for these necessary end-of-life operations and the disappointment of claiming goodbye to a spacecraft I’ve labored on for greater than 5 years. I’m very pleased to have been a part of this unimaginable mission.”

Gaia’s last transmission to ESOC mission management marked the conclusion of an intentional and punctiliously orchestrated farewell to a spacecraft that has tirelessly mapped the sky for over a decade.

The ultimate instructions have been despatched to Gaia. That is the final time that the spacecraft will ever hear from its crew on Earth. The ultimate instructions embody these to close down the spacecraft’s communication techniques and central pc.

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— ESA Operations (@operations.esa.int) March 27, 2025 at 9:56 AM

An enduring legacy

Although Gaia itself has now gone silent, its contributions to astronomy will proceed to form analysis for many years. Its huge and increasing information archive stays a treasure trove for scientists, refining information of galactic archaeology, stellar evolution, exoplanets and far more.

A workhorse of galactic exploration, Gaia has charted the maps that future explorers will depend on to make new discoveries. The star trackers on ESA’s Euclid spacecraft makes use of Gaia information to exactly orient the spacecraft. ESA’s upcoming Plato mission will discover exoplanets round stars characterised by Gaia and will observe up on new exoplanetary techniques found by Gaia.

The Gaia management crew additionally used the spacecraft’s last weeks to run by way of a sequence of technology tests. The crew examined Gaia’s micro propulsion system beneath totally different difficult situations to look at the way it had aged over greater than ten years within the harsh surroundings of house. The outcomes might profit the event of future ESA missions counting on comparable propulsion techniques, such because the LISA mission.

Without end in Gaia’s reminiscence

The Gaia spacecraft holds a deep emotional significance for many who labored on it. As a part of its decommissioning, the names of round 1500 crew members who contributed to its mission had been used to overwrite among the back-up software program saved in Gaia’s onboard reminiscence.

Private farewell messages had been additionally written into the spacecraft’s reminiscence, making certain that Gaia will eternally carry a chunk of its crew with it because it drifts by way of house.

As Gaia Mission Supervisor Uwe Lammers put it: “We’ll always remember Gaia, and Gaia will always remember us.”