Final answer:
The ESA's Gaia mission, launched in 2013, is aimed at creating a detailed 3D map of the Milky Way by accurately measuring the positions, parallaxes, and brightness of 1 billion stars within 30,000 light-years.
Step-by-step explanation:
The European Space Agency (ESA) launched the Gaia mission in December 2013, succeeding the Hipparcos satellite with the aim of creating a precise three-dimensional map of our galaxy. Gaia has the capability to observe fainter stars and measure their positions with an accuracy approximately 200 times greater than Hipparcos. Over the course of its five-year mission, Gaia is tasked with observing 1 billion stars within roughly 30,000 light-years from Earth approximately 70 times each. This extensive mapping allows determination of the stars' positions, parallaxes, and brightness, which are crucial for understanding the structure and dynamics of the Milky Way. Not only will Gaia provide a detailed 3D map of a significant portion of the Milky Way, but it will also contribute to our knowledge of cosmic distances, achieving a level of measurement precision down to a few ten-millionths of an arcsecond.