The scientific goal to be fulfilled by PLATO is the probing of stellar structure and evolution by asteroseismology, the study of the global oscillations of stars. The frequencies of these oscillations, which can be either trapped acoustic waves or internal gravity waves or a mixture of the two, depend on the radially varying density and internal speed of sound of the star. Thus, measurements of oscillation frequencies can be used to detect the structure of their upper layers. These information can be obtained by high-precision photometric measurements performed by PLATO which will generate information to determine stellar masses up to an accuracy of 10%, stellar radii up to 1-2% and stellar ages up to 10%.
One major and crucial advantage of PLATO over other planet detection mission such as CoRoT and Kepler is its ability to observe in many directions of the sky. PLATO will therefore perform two different observation phases during its mission, long continuous pointing phases which is devoted to small planets within habitable zone of solar like stars as well as short duration pointing phases which are devoted to shorter-period planet detection. Two fields within the galactic plane will be observed via long pointing phases which can last up to 3 years each. Afterwards the short observation phase will cover several areas along the galactic disk where one measurement shall last between 2 and 5 months.
The PLATO mission shall explore:
• The conditions for planet formation and the emergence of life
• The solar system origin and its behavior
• Fundamental physics of the universe
• Its origin and composition.
Major science goals of the PLATO mission are:
• Photometric monitoring of a large number of bright stars for the detection of planetary transits and the determination of the planetary radii (around 2% accuracy)
• Asteroseismology for the determination of stellar masses, radii, and ages (up to 10% of the main sequence lifetime)
• Ground-based radial velocity follow-up observations for the determination of the planetary masses (around 10% accuracy)
• Identification of bright targets for spectroscopic follow-up observations of planetary atmospheres with other ground and space facilities.