A new European space observatory could join the hunt for life-bearing planets beyond our solar system if it is selected for full development next year.

The PLATO (Planetary Transits and Oscillations of Stars) observatory is one of three missions that sharing a £3.65 million (about $5.8 million U.S.) development grant from the U.K. Space Agency, British space officials have said. These missions are part of the European Space Agency's Cosmic Vision program, which places heavy emphasis on space science.

In June 2011, ESA will choose two of the three missions to be fully developed for launch between 2014 and 2020. The two other missions competing with PLATO are Euclid, which would examine the nature of dark energy and dark matter, and Solar Orbiter, which would travel closer to the sun than any previous solar-observing mission.

PLATO is designed to search for alien planets orbiting stars beyond our solar system in the Milky Way galaxy. [The Strangest Alien Planets]

The discovery of planets that could harbor life "is one of the major scientific and philosophical challenges of our time," said Don Pollacco of Queen's University Belfast in the U.K., principal investigator of the international PLATO Science Consortium, which includes seven U.K. institutions. "The mission would focus on solar systems close enough to be scanned for bio-signatures, or signs of life by later missions and ground-based telescopes."

The PLATO spacecraft would use the transit technique to search for alien planets, which looks for subtle changes in the luminosity of a star's emitted light.

This faint dimming could indicate that the star hosts a planet, which, at the point when the light changes, is transiting in front of the star and partially obscuring its light.

If the PLATO mission is chosen to be fully developed, the U.K. and other ESA member states will design the spacecraft's scientific instruments and finance its construction.

"We envisage that the new PLATO spacecraft would be launched between 2017 and 2020, on a Russian Soyuz Fregat rocket," Pollacco said. "We hope it will be powerful enough to detect rocky planets in the habitable zones of sun-like stars, those regions around a star where liquid water can exist. In other words, it could find new earths."