Kepler Completes Prime Mission

The Kepler Spacecraft has concluded its prime mission and will move on to conduct an additional four-year extended mission. To date, the space-based telescope has discovered 105 confirmed worlds. Image Credit: NASA/JPL-Caltech

NASA’s Kepler mission marked two major milestones this week as the space telescope scans the heavens for planets like our own. The first of these, the completion of Kepler’s prime mission (which lasted for three and a half years) was quickly followed by the second milestone – the beginning of its extended mission which might last four years.

To date, Kepler has been used by researchers in discovering more than 2,300 potential planets and has confirmed more than 100.

Kepler was launched in 2009 from Cape Canaveral Air Force Station’s Space Launch Complex 17B, located in Florida. Photo Credit: Ball Aerospace

Kepler has so far identified hundreds of possible Earth-sized worlds, some of which reside in the habitable zone, the region in a solar system where liquid water could exist on a planet’s surface. This is according to a press release issued by the space agency.

This data gleaned from Kepler’s findings could provide scientists with their first opportunity to find Earth-like planets. None of the current candidates is precisely Earth-like. The general guidelines that define the term “Earth-like” include, but are not limited to the following: the planets must be similar in size to our home and they must roughly have orbits around their parent stars that last approximately one Earth year.

Since Kepler came online it has measured the light emitted by distant stars, more than 150,000 of them so far. When a planet moves in front of, or “transits” its star, the light from the star is blocked and scientists can gauge the size of the planet by the amount of light blocked.

“The initial discoveries of the Kepler mission indicate at least a third of the stars have planets and the number of planets in our galaxy must number in the billions,” said William Borucki, Kepler principal investigator at NASA’s Ames Research Center in Moffett Field, Calif. “The planets of greatest interest are other Earths and these could already be in the data awaiting analysis. Kepler’s most exciting results are yet to come.”

The Kepler Telescope was launched on March 6, 2009 from Cape Canaveral Air Force Station’s Space Launch Complex 17B atop a United Launch Alliance Delta II rocket. Kepler’s mission was to survey a section of the sky to determine how many potential habitable worlds there might be in our galaxy.

Kepler reviews the light of thousands of stars to see if any of them dim as exoplanets transit in front of the star. The process has been extremely successful and has revolutionized what we know about solar system formation. Image Credit: NASA / GSFC

Within a few months of beginning its primary mission Kepler had already detected five exoplanets. Not Earth-like planets, but what are known as “hot Jupiters” – massive gas giants that orbit very close to their parent star. This was just the start, Kepler’s accomplishments since coming online include:

  • Aug. 2010, researchers announced that they had discovered the first star with more than one planet orbiting it. Dubbed Kepler-9, this system allowed scientists to study and measure gravitational interactions between the planets as they transit their star. This is important because it allows scientists to calculate the mass of these planets.
  • Jan. 2011, the first undeniably rocky planet was discovered outside of our own solar system. The planet, named Kepler-10b, was estimated as being about  1.4 times the size of Earth.
  • Feb. 2011, the Kepler team announced that it had found an extra-solar system that was packed with planets. Kepler-11 bears some similarity to our own solar system. It has been estimated to have at least six planets, all larger than Earth – and all orbiting closer than Venus does to our own Sun.
  • Sept. 2011, the “force” was strong with Kepler as it discovered a system right out of one of George Lucas’ movies – Tatooine. In Star Wars, this fictional world orbited a binary star system (two stars orbiting one another). Kepler-16b exists in the real world and was a herald of things to come. Since its discovery six other binary systems were found to have planets orbiting them.
  • Feb. 2012, Kepler’s total reached more than 1,000 new exoplanet candidates. This total includes hundreds of planetary systems.

“Kepler’s bounty of new planet discoveries, many quite different from anything found previously, will continue to astound,” said Jack Lissauer, planetary scientist at Ames. “But to me, the most wonderful discovery of the mission has not been individual planets, but the systems of two, three, even six planets crowded close to their stars, and, like the planets orbiting about our sun, moving in nearly the same plane. Like people, planets interact with their neighbors and can be greatly affected by them. What are the neighborhoods of Earth-size exoplanets like? This is the question I most hope Kepler will answer in the years to come.”


Video courtesy of NASA Ames

Kepler’s extended mission was awarded in April of this year. It is hoped that, during the telescope’s extended mission countless new worlds will be discovered, possibly more like our own. For those that were among the first to discover worlds orbiting distant stars, Kepler is proving to be a mission that is answering some of mankind’s most ancient questions.

“The Earth isn’t unique, nor the center of the universe,” said Geoff Marcy, professor of astronomy at the University of California at Berkeley. “The diversity of other worlds is greater than depicted in all the science fiction novels and movies. Aristotle would be proud of us for answering some of the most profound philosophical questions about our place in the universe.”

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