It was previously selected in 2014 as part of the ESA's Cosmic Vision Programme, but the launch date has been pushed out two years from 2024 to 2026.
The ultimate aim of the mission will be to detect Earth-size planets or super Earths orbiting around stars in the habitable zone, this is an area with conditions that might support liquid water and an atmosphere.
The project is being led by Professor Don Pollacco, an astrophysicists from the University of Warwick in the UK.
"The launch of PLATO will give us the opportunity to contribute to some of the biggest discoveries of the next decade answering fundamental questions about our existence, and could eventually lead to the detection of extra-terrestrial life," Professor Pollacco said in a recent interview.
34 small wide-field telescopes will be launched in 2026. The onboard cameras will use transit photometry, a popular method of detecting planets by analyzing the starlight. If the brightness falls periodically, there's a good chance that it's caused by a planet crossing the star and partially blocking its light. It'll give researchers a way to estimate the size of the planet and compare it to Earth's radius.
Researchers hope that they will be able to identify promising habitable planets.
Now that the mission has been granted a green light, industry leaders will be given a chance to make bids to build components of the space telescopes and its software platform.
ESA are not the only ones searching for extraterrestrial life, NASA had a similar mission called Kepler. Scientists recently finished sorting possible exoplanets and they found 219 possible candidates, ten of them are around the same size as Earth and lie in the habitable zone.
This means that there are now over 4,000 exoplanets in total.
It's still unknown if any of those planets have the right conditions to support life.