The European Space Agency (ESA) has just terminated the Gaia mission. Launched in 2013, this probe will have constituted an essential instrument in the field of astronomy by making it possible to study the position, movement and composition of nearly 2 billion celestial objects. Although the mission enters a passivation phase after data collection ends, Gaia’s influence on space science remains immense and its discoveries will continue to fuel research for many years to come.
The objectives and ambitions of the Gaia mission
Gaia’s ambition was to produce the most precise and complete 3D map of the Milky Wayour galaxy. At its launch, the ESA mission aimed to create a detailed census of stars, but also to study asteroids, comets and nearby galaxies. The final objective was to understand the structure of our galaxy as well as its evolution.
Very quickly, the probe made the difference. Positioned in a stabilized orbit at point Lagrange 2 (L2), a stable point in the Earth-Sun system, Gaia was equipped with a high-performance optical telescope and sophisticated detectors capable of very precisely measuring the angular positions of celestial objects. Using ultra-sensitive sensors and cutting-edge optics, it could continuously observe billions of stars.
One of its main objectives was to measure the stellar parallaxthat is to say the apparent movement of stars when observed from two different positions in the Earth’s orbit. This phenomenon makes it possible to determine the distances of stars with unprecedented precision. Gaia used this method to measure the distance of billions of stars, a major breakthrough in mapping our galaxy.
The probe not only measured the position of the stars, but also their brightness. Using its highly precise photometric instruments, it was able to detect subtle variations in the light emitted by stars, which helped determine crucial information about their size, temperature and composition.
Finally, it was equipped with spectrometers to analyze starlight and deduce information about their chemical composition, their age and stage of evolution. This spectrum of data has made it possible to create detailed models of stellar populations, and to better understand the formation and evolution of our galaxy.
Notable publications
Over the years, Gaia has released several landmark data sets in the scientific world. The first publication of data, in 2016, made it possible to observe 1.1 billion stars with impressive precision. To this were added the following publications, in 2018 and 2022, which extended this study to nearly two billion stars and celestial objects.
-These data have been crucial to improving understanding of the dynamics of the Milky Way and its close neighbors. This precise mapping will have made it possible to create a detailed 3D version of our galaxythus revealing previously invisible structures and behaviors. The mission will also have made it possible to deduce its exact shape and to refine the understanding of its history and its composition.
Major discoveries
Among the most notable discoveries, Gaia brought to light the presence of hundreds of thousands of binary stars invisible to the naked eye. The in-depth study of binary stars, which orbit around a common center of gravity, has made it possible to clarify the methods for calculating stellar masses and orbital dynamics, in particular those of dead stars such as white dwarfs and black holes. These discoveries have made it possible to better understand the interactions between these objects, often invisible or poorly understood until now.
In addition, the mission made it possible to better understand the enigma of dark matter by analyzing how this invisible matter influences the movements of stars in the Milky Way. This was one of the greatest observational challenges, but Gaia opened new avenues for testing theories around this matter and refining existing cosmic models.
A planned end, but a lasting legacy
Although Gaia’s data collection is now complete, its scientific impact is far from complete. In fact, only a third of the data collected has been published and the mission will continue to fuel research in the years to come.
The next big step will be the publication of mission data as part of the fourth wave (GR4), expected before mid-2026. This data is expected to surpass that of the third publication (GR3) in terms of volume and quality by providing a colossal amount of new information for astronomers. Additionally, the mission’s final publication, the fifth publication (GR5), will be expected by the end of the 2020s, providing a comprehensive analysis of ten and a half years of data.
Related News :