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Gaia is the ESA mission dedicated to determine positions, distances, movements and characteristics physiques of more than a billion stars in our Galaxy, at a very high precision. These data will produce a 3D dynamic map of the Galaxy. The main aim of the mission is to provide the clues about the history and evolution of our Galaxy. Moreover, other scientific objectives include:

  • The detection and orbital classification of tens of thousands of extra-solar planetary systems.

  • A survey of objects ranging from huge numbers of minor bodies in our Solar System to galaxies in the nearby Universe.

  • A number of stringent new tests of general relativity and cosmology.


Gaia is considered one of ESA's cornerstone missions. Thanks to the extreme precision of its astrometric observations, and the technical challenge that has supposed, its results will condition and even revolutionize astrophysics in the next decades. Gaia is also the finest example of a technology in which Europe is the absolute leader in the field of space astrometry.

Gaia conducts an astronomical census of a billion stars,, allowing astronomers to build the most accurate three-dimensional map to date of the celestial objects in our Galaxy. The payload consists of:

  • A double telescope, with a common structure and a common focal plane where all the astrometric, photometric and spectroscopic observations arrive.

  • An ultra-stable Silicon-carbide (SiC) structure supporting the mirrors, instruments and focal plane.

  • A large common focal plane with an array of 106 CCDs, the largest ever sent to space.


Gaia was successfully launched on December 19, 2013 from the French Guyana and it is now at a distance of 1,5 million kilometres from Earth in the opposite direction to the Sun. This special location, known as the Lagrange point L2, keeps pace with Earth as we orbit the Sun.

L2 offers a stable thermal environment, under moderate levels of radiation, and a clear view of the Universe because the Sun, the Earth and the Moon are always outside the instruments fields of vision. An operational lifetime of five years is planned.

IEEC’s Contribution

The experience of the group from Universitat de Barcelona (ICCUB-IEEC) in the space sector begins with the Hipparcos satellite (1989-1993, ESA's first astrometric mission). The group has contributed significantly from its beginnings to the Gaia mission, in its concept and design as well as in the core processing and data simulations. The team also leads the coordination unit that is in charge of the creation, management and diffusion of the final catalogue of Gaia.

Now in the operational phase, the group contributes to the daily analysis of the satellite observations, participates in the photometric study of the stars and, with the support of the Marenostrum supercomputer, manages and analyses billions of observations in the reduction chain together with five other European Data Centres.

The group has participated in the creation and implementation of an optimized data compression system on board the satellite to maximize the data transfer to Earth. Excellent results have been obtained, compressing the data in a factor of 2,5 on average, requiring less than 10% of the processor on board Gaia. This is an important milestone in data compression systems for scientific satellites.

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