LONDON-Europe’s space mission to uncover the secrets of the “dark Universe” has reached a key milestone.

The test model of the Euclid telescope has just emerged from a chamber where it was subjected to the kind of conditions experienced in orbit.

It was a critical moment for engineers because the successful trial confirms the observatory’s design is on track.

Euclid, due for launch in 2022, will map the cosmos for clues to the nature of dark matter and dark energy.

These phenomena appear to control the shape and expansion of the Universe but virtually nothing is known about them.

The €800m venture, led by the European Space Agency (Esa), will be one of a group of new experiments to come online in the next few years.

Scientists are hopeful these next-generation technologies will provide the insights that have so far eluded them.

The finished observatory has a sunshield and white baffle to shade its observations. The Structural and Thermal Model (STM) of Euclid is a near-clone of the real thing, or “flight model” (FM).

To the lay person, it’s actually hard to tell the difference. But the telescope mirrors inside this copy, for example, are unpolished spares, and its “scientific instruments” don’t contain the full complement of components and electronics.

Its job is to run ahead of the FM in the assembly process to find and fix any issues that might arise in the use of materials and the integration of equipment.

“I’ve seen many Structural and Thermal Models in my career and I think this is the most beautiful because it’s actually nearly all made from flight hardware,” Giuseppe Racca, Esa Euclid project manager, told BBC News.

One of the most important stages for the test model is when it goes in a vacuum chamber and is confronted with the challenging temperatures - both hot and cold - that occur in space.

For the Euclid STM, this thermal-vac evaluation was conducted throughout August at a factory in Cannes, France, belonging to Thales Alenia Space (TAS).

Engineers will now shake the model and blast it with noise to gain the additional assurance that the design can withstand a rocket ride to orbit.

“We should finish the campaign by the end of October and then we will take the lessons learned and apply those to the flight model,” said TAS project manager Paolo Musi.

The observatory is currently running about a year-and-a-half behind schedule. Problems have arisen in a number of areas, but Esa now believes the path ahead looks robust.