Gaia is a mission that will conduct a census of one thousand million stars in our Galaxy. It will monitor each of its target stars about 70 times over a five-year period, precisely charting their positions, distances, movements, and changes in brightness. It is expected to discover hundreds of thousands of new celestial objects, such as extra-solar planets and failed stars called brown dwarfs. Within our own Solar System, Gaia should also identify tens of thousands of asteroids.

to boldly go and create a map of the neighbourhood in proper 3d
the next step after Hipparcos towards Star Trek's Astrometrics lab

parallax that