Euclid Shedding light on the dark Universe PRO

A new European space telescope launching this month will tackle the mysteries of dark matter and dark energy, reports Govert Schilling

- Govert Schilling

Leaf through this issue of BBC Sky at Night Magazine, look at the numerous eye-catching photographs and marvel at the beauty of the cosmos. Then realise that everything we can see with astronomical telescopes - stars, nebulae, galaxies - amounts to a mere 5 per cent of the total content of the Universe. The remaining 95 per cent is composed of two mysterious components: dark energy - the 'force' behind the accelerating expansion of the Universe - and dark matter. We know they exist, but their true nature eludes us.

Enter Euclid, the next space mission in the Cosmic Vision science programme of the European Space Agency (ESA). Due to launch into space in the first half of July from Cape Canaveral in Florida, this ambitious space telescope will focus on the dark Universe by mapping and studying no less than two billion galaxies. "Nothing like this has ever been done before," says Euclid's independent legacy scientist Ivan Baldry of Liverpool John Moores University.

Euclid's observations will reveal the expansion history of our Universe (which is governed by dark energy) and the three-dimensional distribution of mass (which mainly consists of dark matter). As a bonus, the mission will check whether Albert Einstein's general theory of relativity is the right formulation of gravity on cosmic scales. According to project manager Giuseppe Racca at ESTEC (ESA's science and technology centre in Noordwijk, the Netherlands), "This combination is the unique selling point of Euclid".

The road to launch

The Euclid mission was selected in 2011 and formally adopted by ESA in the summer of 2012. NASA became a partner in the project in early 2013. At present, the Euclid consortium has about 2,000 members from 13 European countries plus the United States.