Gaia stands for Global Astrometric Interferometer for Astrophysics, although the mission has been around long enough the name is no longer representative of the methods used to conduct the science objectives. Now Gaia has been delayed for just a little longer.
So what happened? Gaia was delivered to the Kourou launch site to be readied for a November launch. Then just a couple days ago ESA announced the delay because of “a technical issue” identified in another satellite already in orbit. All we (and really need to) know about the specific issues for the delay is there is concern about components used in two of the transponders used to generate “timing signals” for downlinking the science telemetry.
ESA in a prudent move has decided to return the spacecraft to Europe to replace and verify the potentially faulty components. In a mission that has been “on the books since the year 2000, a month or two to “get it right” is the right thing to do.
measure the positions of ~1 billion stars both in our Galaxy and other members of the Local Group, with an accuracy down to 24 μas
perform spectral and photometric measurements of all objects
derive space velocities of the Galaxy’s constituent stars using the stellar distances and motions
create a three-dimensional structural map of the Galaxy.
More about this exciting mission is outlined in ESA’s Gaia Fact Sheet.