UPSC CURRENT AFFAIRS – 28th March 2025
Europe’s space agency retires Gaia, the cartographer of the cosmos: Its mission & significance

Why in News?
The Gaia Mission (2013-2025) by the European Space Agency (ESA) revolutionized astrometry, creating a 3D map of the Milky Way.
Introduction
- The European Space Agency’s (ESA) Gaia mission, launched in December 2013, was one of the most ambitious space observatories dedicated to astrometry—the precise measurement of celestial bodies.
- Over the past decade, Gaia revolutionized the understanding of the Milky Way, mapping its structure, motion, and evolution.
- The mission was officially shut down on March 27, 2025, after providing unprecedented astronomical data that will continue to shape scientific research for years to come.
Gaia Mission: Objectives and Achievements
- Primary Goal: To create the most precise three-dimensional map of the Milky Way galaxy.
- Observational Data:
- Recorded 3 trillion observations of over 2 billion stars and celestial objects.
- Contributed to 13,000+ scientific publications.
- Provided insights into the shape, motion, and history of the galaxy.
Position and Instruments
- Lagrange Point 2 (L2): Gaia was placed 1.5 million km behind Earth, away from planetary and solar interference, ensuring unobstructed cosmic observation.
- Twin Telescopes and Billion-Pixel Camera:
- Used a photometer, spectrometer, and astrometer to precisely analyze star positions and motions.
- Largest digital camera in space with nearly a billion pixels.
Major Discoveries by Gaia
- Mapping the Milky Way’s Structure and Evolution
- Confirmed that the Milky Way has a central bar and spiral arms.
- Revealed that the galactic disc is warped and wobbles, likely due to collisions with smaller satellite galaxies.
- Helped reconstruct the past interactions and future evolution of the galaxy.
- Discovery of a New Type of Black Hole
- Unlike traditional black holes detected via radiation, Gaia identified “truly black” holes using gravitational effects.
- One of the black holes detected is the closest to Earth discovered so far.
- Tracking Asteroids and Planetary Defense
- Mapped the orbits of 150,000+ asteroids, including those potentially hazardous to Earth.
Gaia’s End-of-Mission and Legacy
- On March 27, 2025, ESA deactivated Gaia by draining its energy sources and moving it into a retirement orbit around the Sun.
- A bulk of its data is still being processed and will be released in phases:
- First five-and-a-half years’ data will be published in 2026.
- Final dataset expected by the end of the decade.
Future Prospects in Space Astrometry
- Despite its vast scope, Gaia mapped only about 2% of the estimated 100 billion stars in the Milky Way, highlighting the need for future missions.
- The data collected will aid upcoming astronomical projects and space missions focused on dark matter, exoplanet discovery, and galactic evolution.
Conclusion
- Gaia’s contributions have transformed modern astronomy, setting new standards in precision space mapping.
- Its legacy will continue to drive scientific advancements, shaping humanity’s understanding of the cosmos and our place within it.

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