What are the objectives of the GAIA mission and satellite?

[Astronuc]

The GAIA mission has been mentioned in a few threads. It's supposed to be launched in 2013.

Gaia overview - http://www.esa.int/export/esaSC/120377_index_0_m.html

Mission

Gaia will conduct a census of a thousand million stars in our Galaxy, monitoring each of its target stars about 70 times over a five-year period. It will precisely chart 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 observe hundreds of thousands of asteroids.

Additional scientific benefits include the detection and characterisation of tens of thousands of extra-solar planetary systems, a comprehensive survey of objects ranging from huge numbers of minor bodies in our Solar System, through galaxies in the nearby Universe, to about 500 000 distant quasars. It will also provide stringent new tests of Albert Einstein’s general relativity theory.

http://www.esa.int/esapub/br/br163/br163.pdf

ESA Science and Technology: GAIA
http://sci.esa.int/science-e/www/area/index.cfm?fareaid=26

Gaia Payload Module Integration Completed
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=50764

ORBIT:
Lissajous-type orbit around L2

OBJECTIVES:
To create the largest and most precise three dimensional chart of our Galaxy by providing unprecedented positional and radial velocity measurements for about one billion stars in our Galaxy and throughout the Local Group.

Sept 17, 2012 - Gaia’s instruments installed and ready for testing
http://www.esa.int/esaSC/SEMIJ6DY37H_index_0.html

http://www.esa.int/SPECIALS/Operations/SEMK5HZTIVE_0.html

Tentative date: August 2013?

 

[berkeman]

Interesting. I wonder what they use to keep such accurate track of the pointing direction and orientation...?

 

[mfb]

Observations of stars itself and relative measurements between them.

In order to build
the celestial map with the required accuracy, a few micro-arcsecond, it has been
demonstrated that we have to recover the attitude of the spacecraft and calibrate
the instruments with the same accuracy. It can only be obtained considering the
strong correlation between all the unknowns through all the observations. Gaia
will be calibrated by adjusting all the parameters to fit all the measurements as
best as possible.
[...]
A discussion with Ulrich Bastian conviced
me that the attitude function, which we would like to approximate, is essentially
random over timescales of more than a minute or so.

http://www.ari.uni-heidelberg.de/gaia/documents/Sparseness_structure.pdf