Sunday, August 16, 2009

The Kepler Mission

Since the dawn of intelligent man, we as a race have asked several questions pertaining to the heavens, and to the meaning of life. In 2012, NASA’S Kepler Mission will bring us one step closer to answering one of these timeless questions: “are we alone?” Launched in March of this year, the Kepler Mission was not only named after the great mathematician and astronomer, Johannes Kepler, it also celebrates the 400th anniversary of the publication of his first two laws on planetary motion.

The Kepler spacecraft will search for Earth-like planets using a technique known as the Transit Method of Detecting Extrasolar Planets. A transit occurs when a planet crosses in front of its host star as viewed by an observer. These transits dim the brightness of a star which allow for the detection of extrasolar planets. This change in brightness is very difficult to detect by terrestrial planets, such as Earth, because they only dim their host star by 100 parts per million, lasting only 2 to 16 hours. In order for an extrasolar transit to be observed from our solar system, the orbit must be viewed edge on. The probability of observing such a planet is less than 1%. To increase the chances of observing a transiting terrestrial planet, the Kepler spacecraft will observe 100,000 of our neighboring stars. Because any planet in the habitable zone will require an orbit close to that of one Earth year, Kepler will need to observe any transits discovered amongst these 100,000 stars for at least 3.5 years to determine if the transit is periodic enough to be a planet.

The precision of the spacecraft was recently tested by observing a known exoplanet called HAT-P-7. This planet orbits a star 1000 light years away in approximately 2.2 days. Not only was Kepler able to observe transit with the precision necessary for the detection of an Earth sized planet, the light given off by this planet was also observed. This is the first time light from an exosolar planet has been observed, this light can provide information about the planet’s atmosphere.

The Kepler Mission may not be able to directly determine whether or not we are alone in the universe, but it will be able to tell us if we have neighboring planetary systems, containing planets, capable of sustaining life. When compared to all the stars in the universe, even one discovery amongst the relatively small sample space of 100,000 stars will be significant enough for us to rethink our meaning and place in the universe.

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