The Gaia Mission a stereoscopic census of our Galaxy

The Gaia Mission

• A stereoscopic census of our Galaxy

Aims of the mission

• To observe the 6D phase-space map of our galaxy with sufficient accuracy to enable the first detailed reconstruction of its history

• Positions and kinematics of objects to distances of several tens of kpc need to be studied to enable this: parallaxes, proper motions and radial velocities required
• Classification of each object from photometry

How can this be done?

• One large survey of all 109 stars brighter than V=20, over 5 to 6 years, covering each object on average about 80 times, providing:

• Astrometry, using the Hipparcos principle
• Photometry, using dispersion spectra
• Radial velocities, medium-resolution spectrograph

The payload

• Telescope

• 35-m focal length telescope with two apertures, folded up in a 3m diameter satellite

• Focal plane

• 0.5 square meter covered with 103 CCDs
• Operating in TDI mode (Time-delayed integration), following images passing over the CCDs

Scientific potential

• Solar system: census of smaller bodies

• Nearby stars: Detection of planets

• Star clusters: observational isochrones

• Galactic structure: history of the galaxy

• Distances globular clusters, LMC & SMC

• Fundamental physics: reference frames

Planet detection

Double-star detections

Observational Isochrones

The SMC

The schedule

• Phase B2 has started

• Phase C will start end 2006

• Launch scheduled for end 2011

• Operations at L2

• Mission duration 5 to 6 years

• Final mission products around 2020

The data processing

• The Gaia Data Processing and Analysis Consortium is in the process of being created

• Consists of 8, relatively independent, coordination units, assigned to specific tasks
• 3 data processing, 3 data analysis, and 2 support units
• DPAC executive for coordination and planning of activities

The size of the job

• We expect of order 1012 observations

• Calibration is in first instance towards an internally defined system

• Extensive iterations required in astrometry, photometry and radial velocities

• Processing requirements of order 100000 observations per second

UK involvement

• Photometric data processing

• Software developments and implementation
• Cambridge, Leicester, Edinburgh

• Radial velocity data processing

• Software developments
• MSSL

• Gaia Science Team

• Floor van Leeuwen, IoA Cambridge
• Mark Cropper, MSSL

• Industry: E2V will manufacture all CCDs