Gaia mission

"Gaia" is a European Space Agency (ESA) astrometry space mission, and a successor to the ESA "Hipparcos" mission. It was included within the context of the ESA Horizon 2000 Plus long-term scientific programme in 2000. It is expected to be launched by the ESA in the second half of 2011, and will be operated in a Lissajous orbit around the Sun-Earth L₂ Lagrangian point.

"Gaia" will compile a catalogue of approximately one billion stars to magnitude 20. Its objectives comprise:
* astrometric (or positional) measurements, determining the positions, distances, and annual proper motions of stars with an accuracy of about 20 µas (microarcsecond) at 15 mag, and 200 µas at 20 mag
* spectrophotometric measurements, providing multi-epoch observations of each detected object
* radial velocity measurements.

"Gaia" will create an extremely precise three-dimensional map of stars throughout our Milky Way galaxy and beyond, and map their motions which encode the origin and subsequent evolution of the Milky Way. The spectrophotometric measurements will provide the detailed physical properties of each star observed, characterising their luminosity, effective temperature, gravity, and elemental composition. This massive stellar census will provide the basic observational data to tackle a wide range of important problems related to the origin, structure, and evolutionary history of our Galaxy. Large numbers of quasars, galaxies, extrasolar planets, and solar system bodies will be measured at the same time.

Gaia will also be capable of discovering asteroids with orbits that lie between Earth and the Sun, a region that is difficult for Earth-based telescopes to monitor since this region is only in the sky during or near the daytime. [ [http://www.esa.int/esaCP/SEMNXD25WVD_index_0.html ESA Portal - Mapping the Galaxy, and watching our backyard ] ]

References

Further reading

*Thorsten Dambeck in " Sky and Telescope", "Gaia's Mission to the Milky Way", March 2008, p. 36 - 39

External links

* [http://www.esa.int/science/gaia ESA Gaia mission]
* [http://sci.esa.int/gaia Gaia in Depth]
* [http://www.esa.int/SPECIALS/Operations/SEMK5HZTIVE_0.html Gaia page at ESA Spacecraft Operations]
* [http://www.rssd.esa.int/Gaia Gaia pages for the scientific community]
* [http://www.rssd.esa.int/SA-general/Projects/GAIA_files/LATEX2HTML/report.html Gaia Study Report] Summary of the scientific goals of the mission, March 2000
* [http://ad.usno.navy.mil/OBSS/MainFrame.html Origins Billion Star Survey (OBSS)] A similar project proposal as collaboration between NASA and U.S. Naval Observatory.