The European Space Agency's (ESA) planned Euclid mission, which aims to study dark matter and dark energy, has reached a key pre-flight milestone. The endeavour has now passed its preliminary design review, allowing the team to actually start building the spacecraft.

The Euclid mission was first proposed back in 2007, and more recently (in 2011) was selected as one of two medium class mission in the ESA's Cosmic Vision program. It's designed to provide insights that will help scientists evaluate current models for the formation and evolution of the Universe, looking specifically at dark matter and dark energy.

The spacecraft will work to map the shapes, positions and movements of some two billion galaxies spanning more than one third of the night sky, providing astronomers with a huge amount of data.

Since its selection in 2011, the mission has been carefully studied and refined, with the team evaluating key technical designs, as well as building a testing particular components. The very concept of the mission was also put under scrutiny, with careful assessment of whether the six-year mission will provide the desired level of results. The review had a positive outcome, allowing the operation to start taking steps towards launch.

Having passed the preliminary design review landmark, the hardware of the spacecraft can now begin taking shape. The construction phase is now full-speed ahead, with Airbus Defense & Space working on the payload module, which will include a 1.2-m (3.9-ft) telescope, while the Euclid Consortium will build two science instruments for the mission.

Looking down the line, the Euclid mission will face another evaluation in two years time, known as the critical design review. By that stage, the major hardware components will have been finished and tested, and construction of the full instrument will begin.

Assuming everything goes to plan, the mission will be ready for launch in December 2020, launching from Kourou, French Guiana, atop a Soyuz rocket.

Source: ESA