Artist's view of the Kepler space telescope. Image Credit/NASA
NASA’s prolific Kepler alien planet hunter has received a potential four-year extension to continue its search for Earth-like worlds circling within the habitable zones of distant stars.
The Kepler space telescope’s just ending 3 1/2 year prime mission has produced more than 2,300 exo-planet candidates and more then a 100 confirmations.
The habitable zone is considered to be the orbital region around a star that would allow water — if it’s present on the alien world — to exist as a liquid, one of the requirements for life on Earth. None of the planet candidates discovered by Kepler to date is exactly like the Earth. But with the completion of the prime mission, Kepler has now gathered enough data to being identifying sun-Earth matches. These planets would orbit stars like the sun over a one-year period.
Nonetheless the debate over whether stars with planets are rare is over.
“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.”
Kepler 47 is a double star system with multiple planets, one of them in the habitable zone. Image credit/NASA
Kepler was launched with much fanfare on March 6, 2009 and placed on an orbital course around the sun that allows the telescope to monitor more than 150,000 stars in the Milky Way galaxy.
Kepler introduced a new approach to the space-based search for alien worlds. Kepler’s detectors note small changes in the light emitted by stars, which correspond to the crossing of planets. The largest planets dim the light more.
Here are some of the mission highlights so far as provided by NASA:
* In August 2010, scientists confirmed the discovery of the first planetary system with more than one planet transiting the same star. The Kepler-9 system opened the door to measurement of gravitational interactions between planets as observed by the variations in their transit timing. This powerful new technique enables astronomers, in many cases, to calculate the mass of planets directly from Kepler data, without the need for follow-up observations from the ground.
*In January 2011, the Kepler team announced the discovery of the first unquestionably rocky planet outside the solar system. Kepler-10b, measuring 1.4 times the size of Earth, is the smallest confirmed planet with both a radius and mass measurement. Kepler has continued to uncover smaller and smaller planets, some almost as small as Mars, which tells us small rocky worlds may be common in the galaxy.
*In February 2011, scientists announced Kepler had found a very crowded and compact planetary system a star with multiple transiting planets. Kepler-11 has six planets larger than Earth, all orbiting closer to their star than Venus orbits our sun. This and other subsequently identified compact multi-planet systems have orbital spacing relative to their host sun and neighboring planets unlike anything envisioned prior to the mission.
*In September 2011, Kepler data confirmed the existence of a world with a double sunset like the one famously portrayed in the film “Star Wars” more than 35 years ago. The discovery of Kepler-16b turned science fiction into science fact. Since then, the discoveries of six additional worlds orbiting double stars further demonstrated planets can form and persist in the environs of a double-star system.
*In December 2011, NASA announced Kepler’s discovery of the mission’s first planet in a habitable zone. Kepler-22b, about 2.4 times the size of Earth, is the smallest-radius planet yet found to orbit a sun-like star in the habitable zone. This discovery confirmed that we are getting continually closer to finding planets like our own.
*In February 2012, the Kepler team announced more than 1,000 new transiting planet candidates for a cumulative total of 2,321. The data continues the trend toward identifying smaller planets at longer orbital periods, similar to Earth. The results include hundreds of planetary systems.
* Recently, citizen scientists participating in Planet Hunters, a program led byYaleUniversitythat enlists the public to comb through Kepler data for signs of transiting planets, made their first planet discovery. The joint effort of amateur astronomers and scientists led to the first reported case of a planet orbiting a double star. The three bodies in turn are being orbited by a second distant pair of stars.
Johannes Kepler Image Credit/NASA
The mission was named for Johannes Kepler, a 16th and 17th century German mathematician and astronomer who struggled professionally and personally to pioneer the science of planetary motion.