Unveiling the Legacy: The Conclusion of the Gaia Mission’s Groundbreaking Science Operations

The European Space Agency (ESA) has announced the end of its Gaia mission. Launched in December 2013, Gaia set out to survey the sky, gathering data on billions of stars and objects. With its fuel running low, the spacecraft’s main observational phase is complete.

Gaia’s journey has been remarkable. Its mission focused on astrometry, which measures the positions and movements of stars with incredible precision. In doing so, it constructed the most detailed 3D map of our galaxy, the Milky Way, mapping about one billion celestial objects, including stars, comets, and asteroids. The data collected over the years has revolutionized our understanding of astronomy and astrophysics.

ESA’s Director of Science, Carole Mundell, highlighted this achievement, saying, “Today marks the end of science observations. Gaia has exceeded all expectations, providing invaluable insights into the Milky Way’s origin and evolution.”

Operating from the Sun-Earth L2 Lagrange point, about 1.5 million kilometers from Earth, Gaia faced challenges along the way. It survived a hit from a micrometeorite in 2024, which compromised its protective cover, and dealt with a solar storm that temporarily disrupted its sensors. Both times, Gaia bounced back and continued to gather data.

Gaia features three main instruments: the astrometric instrument, which pinpoints star locations; the radial velocity spectrometer, which measures star velocities; and the photometric instrument, which gathers color information to determine stellar properties like mass and temperature. Together, these tools have allowed Gaia to create an unprecedented map of the Milky Way.

Notably, Gaia tracked the orbits of over 150,000 asteroids, even discovering potential moons. It has also revealed a new type of black hole. Although its primary science operations are over, Gaia still has data to process and release.

The next major release, known as Data Release 4 (DR4), is slated for 2026. This release will be substantial, containing about 500 terabytes of data covering the mission’s first 5.5 years. This data will include more binary stars and exoplanets.

Following DR4, there will be a final Data Release 5 (DR5) expected by the end of the decade, encompassing a total of 10.5 years of data. “We are excited to prepare these datasets for the scientific community,” said Antonella Vallenari, a key member of the data processing team.

Gaia still has some fuel left, allowing for around 15 more days of operation. Instead of taking new measurements, the spacecraft will conduct technology tests to help improve future missions. These tests will provide insights into its systems and could influence the design of forthcoming projects that require similar precision, such as LISA.

Ultimately, Gaia will be moved to a heliocentric orbit safe from Earth’s influence after its mission concludes. Although its active mission is coming to a close, the data collected will continue to fuel scientific discovery for many years to come.

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