KU Leuven and the pioneering star-mapping project


The recently launched Gaia satellite will create the largest and most detailed map ever of the Milky Way

Future generations will reap rewards of landmark project

Over the next five years, a new satellite from the European Space Agency (ESA) will create the largest and most precise map ever of the Milky Way. ESA recently launched this Gaia space telescope from its base in Kourou, French Guiana. Several Belgian knowledge centres and companies worked on the star-mapping project – among them experts from the University of Leuven (KU Leuven), who analyse the way stars “breathe”.

You may have heard of the Hubble Space Telescope, the satellite that has been recording images of our galaxy since 1990. “But while the Hubble could be compared to a large photo camera in space, the goal of Gaia is much more ambitious,” says Joris De Ridder, head of KU Leuven’s Institute of Astronomy. “The Gaia satellite will map the characteristics of one billion stars, which constitutes about 1% of all the stars in the Milky Way.”

The foundations for the Gaia project were laid two decades ago, when ESA began thinking about a successor for the Hipparcos satellite, which completed the space agency’s first star-mapping mission. Between 1989 and 1993, Hipparcos – named after the Greek astronomer Hipparchus – observed the position of approximately 100,000 stars.

On its orbit around our sun, some 1.5 million kilometres away, Gaia will observe the position and brightness of the stars with extremely sensitive measuring equipment. The instruments on board can, for instance, measure the thickness of a hair from 1,000 kilometres away.

Gaia is expected to produce more than one million gigabytes of information, or 200,000 DVDs' worth of data. This information will help scientists gain new insights into the birth, composition and evolution of our galaxy.

In the space of five years, Gaia will observe each star a combined 100 times. It will measure the position and key physical properties of each star, such as its brightness, temperature and chemical composition. It will also measure each star’s distance and its speed of motion. 

Virtual space expoloration

Through computer simulations, researchers will be able to reconstruct a star’s history, going back hundreds of millions of years. The satellite might also spot new planets in other solar systems and objects that could pose a potential threat to the Earth, like asteroids.

The generation of our grandchildren will reap the rewards

- Joris De Ridder

In the next few years, researchers will also process Gaia satellite data to create a 3D map of the Milky Way, enabling everyone to explore this virtual space universe from their computers.

A team led by De Ridder at the Leuven Institute of Astronomy developed the software that the ESA satellite will use to analyse so-called starquakes. “Certain stars have a way of expanding and shrinking that makes it seem like they are breathing,” explains De Ridder. “This flickering of stars happens on a regular basis, unlike earthquakes.”

Because Gaia will measure the brightness variations of a billion stars – and this about a hundred times – the computers need to be so artificially intelligent that they can automatically recognise the starquakes. The nature of this “breathing rhythm” gives researchers clues about the interior of a star, which helps them classify the stars as, for example, light, heavy, old or young.

“We estimate that Gaia will help us classify about 100 million stars of the total amount of one billion stars,” says De Ridder.

The cost of the Gaia mission is €740 million, to which Belgium – mostly though the Belgian Science Policy Office (Belspo) – contributed about €20 million. According to De Ridder, that’s money well-spent. “This kind of fundamental research may seem overly expensive because it doesn’t have immediate practical results, but the generation of our grandchildren will reap the rewards.”

In designing Gaia, the engineers used a material known as silicon carbide to protect the satellite instruments from high temperatures. This material is both incredibly hard and resistant to deformities.

“It’s the first time that this material has been used on such an industrial scale, and this expertise could lead to future innovations,” De Ridder says. The Gaia space telescope is also protected by a sun shield made of solar cells, which generate energy for the instruments on board.

The KU Leuven team – which also worked on Nasa’s Kepler satellite – wasn’t the only research group in Flanders to collaborate on the Gaia telescope. The University of Antwerp and the Royal Observatory of Belgium helped classify stellar objects and define their characteristics.


KU Leuven and the pioneering star-mapping project

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University of Leuven

Established almost six centuries ago, the University of Leuven (KU Leuven) is one of the oldest universities in the Low Countries. International rankings consistently place it among the best universities in Europe.
Papal founding - It was founded as a Catholic university by Pope Martin V in 1425.
Bright minds - Over the centuries, it attracted famous scholars like Justus Lipsius, Andreas Vesalius, Desiderius Erasmus and Gerard Mercator.
Micro and nano - KU Leuven is home to the Interuniversity Microelectronics Centre (imec), a world-class research centre in micro- and nanoelectronics.
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