Gaia satellite, cartographer of the Milky Way

It is the height at which one embraces the landscape. The dominant tree in the forest… The third delivery of the Gaia space astronomy mission marks a new breakthrough in the study of the composition, formation and evolution of our galaxy.

Launched in 2013, this European Space Agency (ESA) satellite systematically analyzes light from the brightest objects in the sky to create a three-dimensional map of about 1% of the Milky Way. On June 13, it took a decisive step by presenting the first complete version of its catalog to the scientific community. In total, 1.8 billion stars and millions of other bodies, he was only able to identify the location and distance of the celestial vault.

A survey such as this is of great importance given all the importance it has had in astronomy, the branch of astronomy devoted to measuring the position and motion of the stars. “The previous inventory by ESA’s Hipparcos mission between 1989 and 1993 covered only 1,20,000 of the 200 billion stars in our galaxy”François Mignard, science manager at Kia France, recalls.

It is a real tour de force. The Gaia satellite was designed and manufactured under contract authority to succeed in positioning objects in the celestial vault with an accuracy of 7 to 30 microseconds, equivalent to an angle of the thickness of a hair at a distance of 1,000 kilometers. Astrium (the former name of the Space Systems branch of Airbus-TS), scanned the sky with its two telescopes for thirty-four months with a set of ultra-sensitive CCD detectors.

During this period, he used his three instruments—astronomical, spectrophotometric, and spectroscopic—to gather information on the order of several petabytes, unique in the history of astronomy, from no less than seventy times the light from each source. Once on Earth, this massive amount of raw data, comparable (in one year) to that produced by the LHC particle physics experiments at CERN in Geneva, was processed in six computer centers, including one at the National Center. Space Studies (CNES) in Toulouse; Later classified and dismantled into a European consortium, 430 scientists were formed, including one hundred Frenchmen.

You should read 83.4% of this article. The following is for subscribers only.