In News:

The European Space Agency (ESA) has officially retired its Gaia space observatory after over nine years of pioneering work in astrometry. Launched in December 2013, Gaia was designed to create the most detailed three-dimensional map of the Milky Way galaxy, transforming our understanding of its structure, evolution, and constituents.

About Gaia

• Mission Objective: Gaia aimed to precisely measure the positions, distances, motions, and physical properties of over 2 billion stars within the Milky Way. Its data helps scientists study the galaxy’s formation, predict its future evolution, and explore celestial phenomena.
• Orbit & Technology: Stationed at the second Lagrange point (L2), about 1.5 million kilometers from Earth, Gaia operated beyond the disturbances of Earth’s atmosphere, sun, and moon. Equipped with twin telescopes focusing light onto a nearly one-billion-pixel digital camera—the largest ever deployed in space—the observatory had three key instruments: an astrometer, photometer, and spectrometer to measure stellar positions, brightness, and compositions.

Major Contributions and Discoveries

• 3D Galactic Map: Gaia revealed the warped and wobbling nature of the Milky Way’s disc, mapped its spiral arms and central bulge, and detailed its dynamic evolution shaped by ancient galactic collisions. These findings shed light on events influencing the formation of stars including our Sun.
• New Black Holes: The mission identified previously unseen black holes detectable only by their gravitational influence, marking a first in astronomical observations.
• Asteroid Cataloguing: Gaia tracked the paths of over 150,000 asteroids, enabling better prediction of their trajectories and potential threats to Earth.
• Legacy and Data: Although Gaia has mapped approximately 2% of the galaxy’s stars so far, its extensive data sets continue to be processed and released, promising decades of future scientific breakthroughs.

End of Mission and Legacy

In March 2025, ESA safely deactivated Gaia by draining its energy and shifting it to a retirement orbit around the Sun, ensuring it does not interfere with upcoming missions. While the spacecraft’s active observations have ended, Gaia’s rich data legacy remains invaluable to astronomers worldwide.