Context: The European Space Agency (ESA) has shut down its Gaia Space Observatory in March 2025. Gaia used its thrusters for the final time to slowly drift into its “retirement orbit” around the Sun.
Relevance of the Topic: Prelims: Key facts about Gaia Space Observatory.
About Gaia Space Observatory
- GAIA (Global Astrometric Interferometer for Astrophysics) is a space astrometry mission of ESA.
- Launched: 2013
- Location: Lagrange point 2 (around 1.5 million kilometres ‘behind’ the Earth, when viewed from the Sun)
- Aim: To create the most precise, three-dimensional map of the Milky Way galaxy.
- Gaia has tracked over 2 billion stars and space objects. The spacecraft is fitted with three instruments – an astrometer, a photometer and a spectrometer – that help interpret the location and motion of stars and other objects.
- Lagrange points are positions in a moving two-body system where the combined gravitational forces of two large bodies (such as the Sun and Earth or Earth and the Moon) acting on a third body of smaller mass cancel each other out.
- While absolute neutralisation is not achievable due to the influence of other celestial bodies (such as Moon, Mars, and Venus etc.), they provide a stable position where a spacecraft may be "parked" to make observations.
There are five Lagrange points located along the line connecting the two larger celestial bodies.
- L1 point: Located roughly 1.5 million kilometres from Earth. It provides an uninterrupted view of the Sun (the satellite can view the Sun without eclipses).
- L2 point: Provides an unobstructed view of the Universe and is stable enough for long-duration observations. Location for space-based observatories (James Webb Space Telescope).
- L3 point: Lies behind the Sun, opposite to Earth. Offers the potential to observe the far side of the Sun. Possible location for a future space-based observatory.
- L4 and L5 point: Stable locations but are relatively farther from Earth than L1.
Achievements of GAIA
- Data allowed recreation of a precise 3D map of the Milky Way galaxy; Help understand the shape of our galaxy.
- Uncovered a new kind of black hole – including one close to the Earth. Black holes were previously discovered by light emitted by materials falling in, but those discovered by Gaia can only be detected by their gravitational effects.
- Detected over 1,50,000 asteroids and projected their orbits, including those that may pose a threat to the Earth in the future.