Scientists are a step closer to finding planets Earth-like after a UK-backed mission was given the green light to continue development after passing a critical milestone review.

Planned to launch in 2026, Planetary Transits and Oscillations of stars - nicknamed 'PLATO' will monitor thousands of relatively bright stars over a large area of the sky, searching for tiny, regular dips in brightness as their planets transit in front of them.

Astronomers have so far found over 3,000 planets beyond our Solar System which are called exoplanets, but none, as yet, has been shown to be truly Earth-like in terms of its size and distance from a Sun similar to our own.

But PLATO’s innovative design is set to change all that.

Its suite of 26 small telescopes and cameras, reminiscent of the compound eye of an insect, will allow it to ‘stare’ at a large number of the nearest and brightest stars, with the aim of discovering Earth-sized planets orbiting Sun-like stars.

HeraldScotland: PLATO optical bench entering the Large Space Simulator (ESTEC) for the thermos-elastic deformation test (TED) in September 2021. Credit: ESAPLATO optical bench entering the Large Space Simulator (ESTEC) for the thermos-elastic deformation test (TED) in September 2021. Credit: ESA

The UK Space Agency has invested £25 million in innovative science for the European Space Agency mission, ensuring UK scientists and engineers, led by the University of Warwick, will take part in all aspects of the mission.

Caroline Harper, Head of Space Science at the UK Space Agency, said: "The critical milestone review has confirmed the maturity of the design and the robustness of the build schedule for both the science instruments and the spacecraft they will fly on, so it is now full speed ahead for PLATO.

"The mission offers the exciting potential for a rocky planet with life signatures to be detected using innovative sensors, electronics and software developed in the UK, on a mission with UK science leadership."

The next major milestone for PLATO is the spacecraft critical design review in 2023, which will verify the detailed design of the complete spacecraft before proceeding with its assembly.

After launch, PLATO will travel to Lagrange point 2 in space, 1.5 million km beyond Earth in the direction away from the Sun.

From this point, the telescope will observe more than 200 000 stars during its four-year nominal mission.

Professor Don Pollacco, from the University of Warwick, which leads the PLATO Science Management Consortium, said: "The PLATO project involves the serial production of complicated components and is challenging to both academia and industry.

"Any production errors will lead to greater costs and delays so passing this milestone is reaffirming confidence in the hundreds of scientists and engineers that are working on this mission.

"Our dream of finding lots of planets like the Earth that we can examine in detail is one step closer."