February 20, 2014
ESA Selects PLATO Mission To Join The Hunt For Extrasolar Planets
[ Watch the Video: The Newest Exoplanet Hunter - PLATO ]
April Flowers for redOrbit.com - Your Universe Online
One of the hottest topics in 21st century science is the exploration of planets around stars other than our own Sun. These planets are known as extrasolar planets, or "exoplanets." One of the key goals of such research is to discover and learn about the properties of Earth-like worlds in the Sun's neighborhood. The European Space Agency (ESA) is preparing a new space mission, named Planetary Transits And Oscillations Of Stars (PLATO), to do exactly that. Scheduled for launch in 2024, ESA expects PLATO to return firm discoveries of Earth-like planets at Earth-like distances from stars similar to our Sun after collecting three years worth of observational data.
PLATO was selected for implementation as part of ESA's Cosmic Vision 2015-2025 Program out of five "M3" type missions proposed at the regular meeting of the ESA Science Program Committee this month. The mission is scheduled to last six years.
As yet, not one single Earth-like exoplanet in a habitable zone around a star similar to our Sun has been found or characterized. If successful, PLATO will be a pioneer in finding new worlds for humanity to explore.
Don Pollaco, University of Warwick professor of physics and leader of the PLATO Science consortium, commented in a recent statement, “This is fantastic news for Europe, PLATO will allow the first systematic survey of nearby planets for indications from advanced life forms (as well as slime). A few years ago this would have been science fiction and now it’s coming to pass as science fact.”
Many UK organizations will be participating in developing the instrument: e2V Technology and UCL will supply the Charge-Coupled Devices (CCD) sensors, much of the imaging software will come from Cambridge University, and Open University will handle Public Outreach.
Dr. Heike Rauer of the German Aerospace Center (DLR) will lead the PLATO mission. “PLATO will begin a completely new chapter in the exploration of extrasolar planets,” Dr Rauer confidently predicts. “We will find planets that orbit their star in the life-sustaining ‘habitable’ zone: planets where liquid water is expected, and where life as we know it can be maintained.”
So that detailed comparisons with our own solar system can be made, PLATO will measure the sizes, masses, and ages of planetary systems it finds. “In the last 20 years more than one thousand exoplanets have been discovered, with quite a few multi-planetary systems among them,” Rauer explained. “But almost all of these systems differ significantly from our Solar System in their properties, because they are the easiest-to-find examples. PLATO firmly will establish whether systems like our own Solar System, and planets like our own Earth are common in the Galaxy.”
PLATO will use the periodic dimming of the detected starlight, caused by a planet orbiting in front of the star and blocking PLATO's view of a fraction of the starlight, to detect exoplanets. This will be accomplished with an array of 34 separate 12-centimeter telescopes and cameras mounted on an observing platform in the space probe, which will be used to investigate approximately a million stars spread out over half the sky. These “eyes" can be combined in many different configurations, giving PLATO unprecedented capabilities to simultaneously observe both bright and dim objects. Positioned at one of the Lagrangian Points (specifically L2), where the gravitational pull of the Sun and the Earth cancel each other out, PLATO will stay at a fixed position in space. L2 is approximately 930 million miles beyond Earth, as seen from the Sun.
PLATO will also use astroseismology to measure tiny changes in detected starlight that are caused by small vibrations in the host stars. The vibrations reveal the internal structure of the vibrating body, just like on Earth. We are able to learn the age of the vibrating star and the planets orbiting it with astroseismology.
PLATO's measurements, coupled with ground-based radial velocity observations, will allow researchers to calculate a planet's mass and radius, and therefore its density. These measurements will provide an indication of its composition, needed to properly describe a planet. “The observation of planets in many different states of their evolution will give us clues for the past and the future of our own planetary system,” Dr Rauer remarked. “By no means do we know all about the youth of our Solar System.”
Only by knowing the measurement of both the radius and mass of a planet may scientists distinguish between a “mini-Neptune” with a high gas content, but a low density – like the two outermost planets in the Solar System – or a rocky planet with an iron core, like the Earth. The habitability of a planet cannot be determined without this information, and these two fundamental parameters are not known with sufficient precision for most exoplanets.
With its array of telescopes and the largest camera-sensor ever flown in space (comprised of 136 CCD sensors with a combined area of 0.9 square meters), PLATO is a completely new type of space telescope. The spaceship's placement will give it the advantage of continuous observation without the interruption of sunrise, or the blurring caused by the Earth's atmosphere.
These unique attributes should allow PLATO to discover planets smaller than Earth, and planets at distances from their host stars similar to the Earth-Sun distance. Only a few such small planets are known at star-planet distances comparable or greater than Earth's. The catalogue of potentially habitable planets that PLATO will build will form the basis for follow-up measurements to confirm discoveries of new planets, using the European Southern Observatory’s European Extremely Large Telescope (E-ELT), or the next generation of large space telescopes, like NASA's James Webb Space Telescope.
“PLATO, with its unique ability to hunt for Sun–Earth analogue systems, will build on the expertise accumulated with a number of European missions, including CoRot and Cheops,” added Alvaro Giménez, ESA’s Director of Science and Robotic Exploration.
“Its discoveries will help to place our own Solar System’s architecture in the context of other planetary systems."