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Gaia (spacecraft) - Wikipedia

Gaia (spacecraft)

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Gaia is a retired space observatory of the European Space Agency (ESA) that was launched in 2013 and operated until March 2025. The spacecraft was designed for astrometry: measuring the positions, distances and motions of stars with unprecedented precision,12 and the positions of exoplanets by measuring attributes about the stars they orbit such as their apparent magnitude and colour.3 As of 2026, the mission data processing continues, aiming to construct the largest and most precise 3D space catalogue ever made, totalling approximately 1 billion astronomical objects, mainly stars, but also planets, comets, asteroids and quasars, among others.4

To study the precise position and motion of its target objects, the spacecraft monitored each of them about 70 times5 over the five years of the nominal mission (2014–2019), and about as many during its extension.67 Due to its detectors degrading more slowly than initially expected, the data acquisition phase of the mission was given an extension,8 lasting until March 27, 2025, when scientists at the ESA switched off Gaia after more than a decade of service.9 Gaia targeted objects brighter than magnitude 20 in a broad photometric band that covered the extended visual range between near-UV and near infrared;10 such objects represent approximately 1% of the Milky Way population.5 Additionally, Gaia was expected to detect thousands to tens of thousands of Jupiter-sized exoplanets beyond the Solar System using astrometry,11121314 500,000 quasars outside this galaxy and tens of thousands of known and new asteroids and comets within the Solar System.151617

Even though the telescope was decommissioned in 2025, the Gaia mission continues to analyse the collected data to create a precise three-dimensional map of astronomical objects throughout the Milky Way and map their motions, which encode the origin and subsequent evolution of the Milky Way. The spectrophotometric measurements provide detailed physical properties of all stars observed, characterising their luminosity, effective temperature, gravity and elemental composition. This massive stellar census is providing the basic observational data to analyse a wide range of important questions related to the origin, structure and evolutionary history of the Milky Way Galaxy. As of 2026, the last scheduled data release is not expected before the end of 2030.

The successor to the Hipparcos mission (operational 1989–1993), Gaia is part of ESA’s Horizon 2000+ long-term scientific program. Gaia was launched on 19 December 2013 by Arianespace using a Soyuz ST-B/Fregat-MT rocket flying from Kourou in French Guiana.1819 The spacecraft operated in a Lissajous orbit around the Sun – Earth L Lagrangian point. The science observation officially ended on 15 January 2025.20

Printed 2026-06-28.

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Footnotes

  1. “ESA Gaia home”. ESA. Retrieved 23 October 2013. ↩

  2. Spie (2014). “Timo Prusti plenary: Gaia: Scientific In-orbit Performance”. SPIE Newsroom. doi:10.1117/2.3201407.13. ↩

  3. Bohan, Elise; Dinwiddie, Robert; Challoner, Jack; Stuart, Colin; Harvey, Derek; Wragg-Sykes, Rebecca; Chrisp, Peter; Hubbard, Ben; Parker, Phillip; et al. (Writers) (February 2016). Big History. Foreword by David Christian (1st American ed.). New York: DK. p. 77. ISBN 978-1-4654-5443-0. OCLC 940282526. ↩

  4. Overbye, Dennis (1 May 2018). “Gaia’s Map of 1.3 Billion Stars Makes for a Milky Way in a Bottle”. The New York Times. Retrieved 1 May 2018. ↩

  5. “ESA Gaia spacecraft summary”. ESA. 20 May 2011. ↩ ↩2

  6. “A billion pixels for a billion stars”. BBC Science and Environment. BBC. 10 October 2011. ↩

  7. “We have already installed the eye of ‘Gaia’ with a billion pixels to study the Milky Way”. Science Knowledge. 14 July 2011. Archived from the original on 6 April 2016. ↩

  8. “Gaia: fact sheet”. ESA. 24 June 2013. ↩

  9. Miller, Katrina (27 March 2025). “Farewell to Gaia, the Milky Way’s Cartographer”. The New York Times. ISSN 0362-4331. Retrieved 29 March 2025. ↩

  10. “Expected Nominal Mission Science Performance”. European Space Agency. Retrieved 20 November 2019. ↩

  11. Wenz, John (10 October 2019). “Lessons from scorching hot weirdo-planets”. Knowable Magazine. Annual Reviews. doi:10.1146/knowable-101019-2. Retrieved 4 April 2022. ↩

  12. “Gaia Science Objectives”. European Space Agency. 14 June 2013. ↩

  13. Perryman, Michael; Hartman, Joel; Bakos, Gáspár Á.; Lennart, Lindegren (10 December 2014). “Astrometric exoplanet detection with Gaia”. The Astrophysical Journal. 797 (14). ↩

  14. Lammers, Caleb; Winn, Joshua N. (January 2026). “On the Exoplanet Yield of Gaia Astrometry”. The Astronomical Journal. 171 (18). ↩

  15. “Gaia’s mission: solving the celestial puzzle”. University of Cambridge. University of Cambridge. 21 October 2013. ↩

  16. “ESA’s Gaia… Launches With A Billion Pixel Camera”. Satnews.com. 19 December 2013. ↩

  17. “Gaia space telescope to detect killer asteroids”. thehindubusinessline.com. 19 December 2013. ↩

  18. “Announcement of Opportunity for the Gaia Data Processing Archive Access Co-Ordination Unit”. ESA. 19 November 2012. ↩

  19. “Arianespace to launch Gaia; ESA mission will observe a billion stars in our galaxy”. Press releases. Arianespace. 16 December 2009. Archived from the original on 18 September 2010. ↩

  20. “Last starlight for ground-breaking Gaia”. esa.int. European Space Agency. 15 January 2025. ↩

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