By Zaina Adamu, CNN
Could there be extraterrestrial life in our own Milky Way galaxy?
NASA’s Kepler mission, using an orbiting telescope equipped with a 95-megapixel camera and 42 charge-coupled devices, discovered that worlds, one-half to twice the size of Earth, exist in our galaxy.
Kepler is the first mission with the potential to identify Earth-sized planets that exist near the habitable zones of their stars, a landmark in astronomy because the finding could lead scientists to discover that, indeed, life exists in other places besides Earth.
The way Kepler detects planets is similar to how we detect Venus and Mercury from Earth. Every so often, there are events where Venus and Mercury pass the sun, briefly blocking a bit of the sunlight coming to Earth. From our perspective, each of these events, called a transit, is seen as a slow-moving black speck traveling across the sun.
The Kepler telescope searches for changes in the brightness of stars, which could provide evidence that planets are orbiting them.
Once a planet is found, its size can be measured using Kepler’s Third Law of planetary motion, a calculation based on the amount of light lost from a star and the star’s size. Additionally, the star’s temperature can help determine if the planet might be habitable.
Since its launch in March 2009, the Kepler telescope has found more than 2,300 planet candidates.
Other mission highlights include the discovery of the first rocky planet outside the solar system. Kepler scientists found that planets with similar terrain could be widespread in the Milky Way.
“The initial discoveries of the Kepler mission indicate that at least a third of the stars have planets, and that the number of planets in our galaxy must number in the billions,” said William Borucki, Kepler principal investigator at NASA’s Ames Research Center. “The planets of greatest interest are other Earths,and they could already be in the data awaiting analysis. Kepler’s most exciting results are yet to come.”
But there have been some setbacks along Kepler’s journey.
In July, increased friction caused one of Kepler’s four reaction wheels to malfunction. The reaction wheels help control the spacecraft's attitude, the direction in which it is pointed.
“We don't know what caused the wheel to die, but we are continuing to investigate,” said Steve Howell, project scientist for the mission.
Kepler will probably continue its mission with only three wheels because “as far as science and the mission’s objectives, it has had no impact whatsoever,” said Howell.
In a Spaceflight Now article, however, Borucki suggested that if another wheel stops working, the mission would end permanently.
More recently, engineers found that the spacecraft was not in finepoint for a small period of its mission, meaning that the telescope wasn't able to point itself with enough precision to take accurate scientific information. In trying to correct that anomaly, Kepler detected a bigger issue and put itself in safe mode until the telescope's team was able to assess the problem and successfully execute a recovery process.
The spacecraft is now operating as it should and the mission, originally slated to end earlier this year, has been extended for another four years.
This extension will allow Kepler to find other worlds that are in the "Goldilocks zone," not too far from and not too close to their host stars – similar to Earth.
“The Earth isn’t unique, nor the center of the universe. The diversity of other worlds is greater than depicted in all the science fiction novels and movies,” Geoff Marcy, professor of astronomy at the University of California, Berkeley, told NASA. “Aristotle would be proud of us for answering some of the most profound philosophical questions about our place in the universe.”
Kepler mission’s operation phase is directed by the Ames Research Center in Moffett Field, California. NASA’s Jet Propulsion Laboratory managed the development and launch of the spacecraft.