Zee Media Bureau

Paris: European Space Agency on Thursday launched its Gaia mission which will provide a three-dimensional picture of the Milky Way galaxy, measuring appropriate positions and distances of more than a billion stars.

The satellite successfully lifted off on a Soyuz-STB-Fregat rocket from ESA’s space base in Kourou, French Guiana.

The star surveying satellite separated from the last of the rocket’s four stages 42 minutes after launch.

The 740-million-euro ($1.02-billion) gadget, Gaia`s primary goal is to carry out an "astronomical census", locating the position of a billion stars, or around one percent of all the stars in the Milky Way.

By repeating the observations as many as 70 times throughout its mission, the telescope can help astronomers calculate the distance, speed, direction and motion of these stars.

Gaia, using a six-sided "optical bench" three metres (10 feet) across to snare glimmers of light, is 200 times more sensitive than Hipparcos in measuring the angles that, through triangulation, determine a star`s position.

Gaia`s secondary objectives are equally stunning. By monitoring the "wobble" in stellar light as a planet passes in front of a star, it can add to knowledge about worlds beyond the Solar System.

By some estimates, it could detect as many as 50,000 planets within a distance of 150 light years from the Sun, or 10 times more than have been observed since the first was spotted in 1995.

Gaia will also be turning its eyes to our own Solar System, scouring its chill, dark fringes and the asteroid belt between Mars and Jupiter to help the search for any rocks that may one day threaten Earth.

Other potential bounty includes real-time observations of exploding stars, called supernovae, in distant galaxies and insights into strange "failed" stars, known as brown dwarves that drift listlessly through interstellar space after failing to gain enough mass to ignite.

Gaia may provide a useful test of Einstein`s theory of general relativity, which says that a star`s position will appear to move slightly as a result of light from it that is deflected by a passing, massive object.

After launch, Gaia will take up position at the so-called Lagrange point L2, located 1.5 million kilometres (937,000 miles) from the Earth.

L2 is a position that gives it year-round observation of the cosmos without the view being disturbed by the Sun, Earth or Moon.

It is the go-to place for space observatories. L2 has been used by Europe`s Herschel and Planck telescopes and is designated as the slot for NASA`s eagerly-awaited James Webb Space Telescope (JWST).

To stay at L2, the spacecraft will have to perform tiny manoeuvres every month, scrutinised by a network of telescopes on Earth to ensure a hoped-for accuracy of 100 metres (yards).

One of the biggest challenges will be processing what Jean-Yves Le Gall, head of France`s National Centre of Space Studies (CNES), calls "an absolute flood" of data.

Gaia will provide the equivalent of more than 30,000 CD-ROMs.

Sorting this stuff and turning it into useable data -- galaxy maps and star catalogues -- will take years.

Six centres have been set up around Europe to handle the deluge, including a supercomputer in Toulouse, southwestern France, capable of carrying out six thousand billion operations a second.

(With Agency inputs)