This morning, the European Space Agency’s Gaia mission blasted off from Europe’s Spaceport in Kourou, French Guiana, on the head of a Soyuz rocket. This space observatory aims to study approximately 1 billion stars, roughly 1% of the Milky Way Galaxy, and create the most accurate map yet of the Milky Way. In so doing, it will also answer questions about the origin and evolution of our home Galaxy.

As the successor to the Hipparcos mission – an ESA astrometry satellite that was launched in 1989 and operated until 1993 – it is part of ESA’s Horizon 2000 Plus long-term scientific program. Repeatedly scanning the sky, Gaia will observe each of the billion stars an average of 70 times each over the five years and measure the position and key physical properties of each star, including its brightness, temperature and chemical composition.

The Soyuz VS06 launcher, operated by Arianespace, lifted off at 09:12 GMT (10:12 CET). About ten minutes later, after separation of the first three stages, the Fregat upper stage ignited, delivering Gaia into a temporary parking orbit at an altitude of 175 km. A second firing of the Fregat 11 minutes later took Gaia into its transfer orbit, followed by separation from the upper stage 42 minutes after liftoff.

Gaia is now en route towards an orbit around a gravitationally-stable virtual point in space called L2 Lagrange Point, some 1.5 million kilometres beyond Earth.  Tomorrow, engineers will command Gaia to perform the first of two critical thruster firings to ensure it is on the right trajectory towards its L2 home orbit. About 20 days after launch, the second critical burn will take place, inserting it into its operational orbit around L2.

Jean-Jacques Dordain, ESA’s Director General, had this to say about the launch:

Gaia promises to build on the legacy of ESA’s first star-mapping mission, Hipparcos, launched in 1989, to reveal the history of the galaxy in which we live.

ESA’s Gaia project scientist Timo Prusti expressed similar sentiments, highlighting how the Gaia mission’s ultimate purpose is to advance our understanding of the cosmos:

Along with tens of thousands of other celestial and planetary objects, this vast treasure trove will give us a new view of our cosmic neighbourhood and its history, allowing us to explore the fundamental properties of our Solar System and the Milky Way, and our place in the wider Universe.

By taking advantage of the slight change in perspective that occurs as Gaia orbits the Sun during a year, it will measure the stars’ distances and their motions across the sky. This motions will later be put into “rewind” to learn more about where they came from and how the Milky Way was assembled over billions of years from the merging of smaller galaxies, and into “fast forward” to learn more about its ultimate fate.

This is an especially ambitious mission when you consider that of the one billion stars Gaia will observe, 99% have never had their distances measured accurately. The mission will also study 500,000 distant quasars and will conduct tests of Einstein’s General Theory of Relativity. So as the mission continues and more data comes in, scientists and astronomers will be able to construct more detailed models of how the universe was created, and perhaps how it will end…

The current consensus is that the universe began with a creation event known as The Big Bang. However, the question of how it will end, either through a “Big Crunch” event – where the expansion of the universe will eventually cease and all matter will collapse back in on itself – or simply continue to expand until all stars and galaxies consume their fuel and burn out, remains something of a mystery.

Personally, I call Big Crunch, mainly because I like to the think that our universe is one of many. Not just in the parallel dimension sense, but in the temporal sense as well. Like the city of Ilium (aka. Troy), existence as we know it is built upon the foundations of countless others, stretching backwards and forwards into infinity…

Deep stuff, man! In the meantime, enjoy this video of the Gaia’s mission’s liftoff, courtesy of the ESA:

Sources: universetoday.com, esa.int