30 March 2006 Birmingham workshop 1

The Gaia Mission

A stereoscopic census of our Galaxy

30 March 2006 Birmingham workshop 2

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

30 March 2006 Birmingham workshop 3

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

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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

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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

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Planet detection

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Double-star detections

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ObservationalIsochrones

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The SMC

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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

30 March 2006 Birmingham workshop 12Catalogue

Schedule

2000 2004 2008 2012 2016 2020

Acceptance

Technology Development

Design, Build, Test

Launch

Observations

Analysis

Early Data

Concept & Technology Study ESA SCI 2000(4)

Re-Assessment: Ariane Soyuz

To L2Start of

Phase B2

30 March 2006 Birmingham workshop 13

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

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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

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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