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Science & Exploration

Gaia factsheet

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ESA / Science & Exploration / Space Science / Gaia

Fast facts

Name: Gaia

Mission: To determine the position and velocity of a billion stars, creating the largest and most precise 3D map of the Milky Way

Launch date: 2013

Mission end: nominal mission end after 5.5 years (2019), including 0.5 years commissioning.

Launch vehicle: Soyuz-Fregat

Launch mass: 2030 kg, including 710 kg of payload, a 920 kg service module and 400 kg of propellant.

Dimensions: 10 m across, with solar array deployed

Orbit: Lissajous-type orbit around L2

Instruments: Astro (2 identical telescopes and imaging system); BP/RP (Blue and Red Photometers) and RVS (Radial Velocity Spectrometer)

Partnerships: Gaia is a fully European mission designed, built and operated by ESA.
The Gaia Data Processing and Analysis Consortium (DPAC) will process the raw data to be published in the largest stellar catalogue ever made.


Primary mission objectives:
- Measure the positions and velocity of approximately one billion stars in our Galaxy
- Determine their brightness, temperature, composition and motion through space
- Create a three-dimensional map of the Galaxy


Additional discoveries expected:
-hundreds of thousands of asteroids and comets within our Solar System
-seven thousand planets beyond our Solar System
-tens of thousands of ‘failed’ stars, called brown dwarfs
-twenty thousand exploding stars, called supernovae
-hundreds of thousands of distant active galaxies, called quasars.


Gaia mission facts
- Gaia will observe one billion stars about 70 times each over five years. That’s an average of 40 million observations a day!
- One billion stars amounts to about 1 percent of the stars populating the Milky Way.
- Of the one billion stars Gaia will observe, 99% have never had their distances measured accurately.
- Gaia will carry the largest digital camera into space with nearly one billion pixels. By comparison, smart phone cameras have around 10 million pixels.
- Gaia will detect celestial objects that are a million times fainter than the unaided human eye can see.
- For objects 4000 times fainter than the naked eye limit, Gaia will measure their positions to an accuracy of 24 microarcseconds, comparable to measuring the diameter of a human hair at a distance of 1000 km. Gaia’s predecessor, Hipparcos, could have measured the diameter of a human hair at a distance of 20 km.
- The nearest stars will have their distances measured to the extraordinary accuracy of 0.001%. Even stars near the Galactic Centre, some 30 000 light-years away, will have their distances measured to within an accuracy of 20%.
- The Gaia Data Processing and Analysis Consortium (DPAC) consists of more than 400 individuals who will contribute some 2000 person-years of effort to the Gaia data processing exercise.
- By the end of the mission, the data archive will exceed 1 Petabyte (1 million Gigabytes), equivalent to about 200 000 DVDs worth of data.

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