Nov. 14, 2012
J.D. Harrington
Headquarters, Washington
202-358-5241
j.d.harrington@nasa.gov
Michele Johnson
Ames Research Center, Moffett Field, Calif.
650-604-4789
michele.johnson@nasa.gov
RELEASE: 12-394
NASA'S KEPLER COMPLETES PRIME MISSION, BEGINS EXTENDED MISSION
WASHINGTON -- NASA is marking two milestones in the search for planets
like Earth; the successful completion of the Kepler Space Telescope's
3 1/2- year prime mission and the beginning of an extended mission
that could last as long as four years.
Scientists have used Kepler data to identify more than 2,300 planet
candidates and confirm more than 100 planets. Kepler is teaching us
the galaxy is teeming with planetary systems and planets are
prolific, and giving us hints that nature makes small planets
efficiently.
So far, hundreds of Earth-size planet candidates have been found as
well as candidates that orbit in the habitable zone, the region in a
planetary system where liquid water might exist on the surface of a
planet. None of the candidates is exactly like Earth. With the
completion of the prime mission, Kepler now has collected enough data
to begin finding true sun-Earth analogs -- Earth-size planets with a
one-year orbit around stars similar to the sun.
"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."
NASA's Kepler Space Telescope searches for planet candidates orbiting
distant suns, or exoplanets, by continuously measuring the brightness
of more than 150,000 stars. When a planet candidate passes, or
transits, in front of the star from the spacecraft's vantage point,
light from the star is blocked. Different sized planets block
different amounts of starlight. The amount of starlight blocked by a
planet reveals its size relative to its star.
Kepler was launched March 6, 2009. Its mission was to survey a portion
of the galaxy to determine what fraction of stars might harbor
potentially habitable, Earth-sized planets. Planets orbiting in or
near habitable zones are of particular interest.
Kepler began the search for small worlds like our own on May 12, 2009,
after two months of commissioning. Within months, five exoplanets,
known as hot Jupiters because of their enormous size and orbits close
to their stars, were confirmed.
Results from Kepler data continue to expand our understanding of
planets and planetary systems. Highlights from the prime mission
include:
-- 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 by Yale University that 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.
"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."
In April 2012, NASA awarded Kepler an extended mission through as late
as 2016. More time will enable the continued the search for worlds
like our own -- worlds that are not too far and too close to their
sun.
"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."
Ames manages Kepler's ground system development, mission operations
and science data analysis. NASA's Jet Propulsion Laboratory in
Pasadena, Calif., managed the Kepler mission development. Ball
Aerospace & Technologies Corp. in Boulder, Colo., developed the
Kepler flight system and supports mission operations with the
Laboratory for Atmospheric and Space Physics at the University of
Colorado in Boulder. The Space Telescope Science Institute in
Baltimore archives, hosts and distributes Kepler science data. Kepler
is NASA's 10th Discovery Mission and funded by NASA's Science Mission
Directorate at the agency's headquarters in Washington.
For more information about NASA's Kepler mission, visit:
http://www.nasa.gov/kepler
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