Exoplanets

Kepler Mission Announces 461 New Planet Candidates, Two in Habitable Zone

MOUNTAIN VIEW, Calif. - NASA's Kepler mission Monday announced the discovery of 461 new planet candidates. Four of the potential new planets are less than twice the size of Earth and orbit in their sun's "habitable zone," the region in the planetary system where liquid water might exist on the surface of a planet. 

Based on observations conducted from May 2009 to March 2011, the findings show a steady increase in the number of smaller-size planet candidates and the number of stars with more than one candidate. 

"There is no better way to kick off the start of the Kepler extended mission than to discover more possible outposts on the frontier of potentially life-bearing worlds," said Christopher Burke, Kepler scientist at the SETI Institute in Mountain View, Calif., who is leading the analysis. 

Since the last Kepler catalog was released in February 2012, the number of candidates discovered in the Kepler data has increased by 20 percent and now totals 2,740 potential planets orbiting 2,036 stars. The most dramatic increases are seen in the number of Earth-size and super Earth-size candidates discovered, which grew by 43 and 21 percent respectively. 

The new data increase the number of stars discovered to have more than one planet candidate from 365 to 467. Today, 43 percent of Kepler's planet candidates are observed to have neighbor planets. 

"The large number of multi-candidate systems being found by Kepler implies that a substantial fraction of exoplanets reside in flat multi-planet systems," said Jack Lissauer, planetary scientist at NASA's Ames Research Center in Moffett Field, Calif. "This is consistent with what we know about our own planetary neighborhood." 

The Kepler space telescope identifies planet candidates by repeatedly measuring the change in brightness of more than 150,000 stars in search of planets that pass in front of, or "transit," their host star. At least three transits are required to verify a signal as a potential planet. 

Scientists analyzed more than 13,000 transit-like signals to eliminate known spacecraft instrumentation and astrophysical false positives, phenomena that masquerade as planetary candidates, to identify the potential new planets. 

Candidates require additional follow-up observations and analyses to be confirmed as planets. At the beginning of 2012, 33 candidates in the Kepler data had been confirmed as planets. Today, there are 105. 

"The analysis of increasingly longer time periods of Kepler data uncovers smaller planets in longer period orbits-- orbital periods similar to Earth's," said Steve Howell, Kepler mission project scientist at Ames. "It is no longer a question of will we find a true Earth analogue, but a question of when." 

The complete list of Kepler planet candidates is available in an interactive table at the NASA Exoplanet Archive. The archive is funded by NASA's Exoplanet Exploration Program to collect and make public data to support the search for and characterization of exoplanets and their host stars. 

Ames manages Kepler's ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed Kepler mission development. Ball Aerospace and Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with JPL at 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 the Kepler science data. Kepler is NASA's 10th Discovery Mission and is funded by NASA's Science Mission Directorate at the agency's headquarters in Washington. 

JPL manages NASA's Exoplanet Exploration Program. The NASA Exoplanet Archive is hosted at the Infrared Processing and Analysis Center at the California Institute of Technology. 

For information about the NASA Exoplanet Archive, visit: http://exoplanetarchive.ipac.caltech.edu/index.html .
For information about the Kepler mission, visit: http://www.nasa.gov/kepler .

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NASA Doubles Down on Exoplanets and the SETI Institute Will Be Part of the Search

MOUNTAIN VIEW -- NASA's Astrophysics Explorer Program has selected the Transiting Exoplanet Survey Satellite (TESS) Mission to fly in 2017. TESS will follow in the footsteps of NASA’s pioneering Kepler Mission, continuing the groundbreaking work of discovering Earth-size exoplanets. NASA selected TESS and another explorer mission after a competition that evaluated proposals for the best scientific value and most feasible development plans.

TESS will use an array of four telescopes to perform an all-sky survey to discover transiting exoplanets of all sizes in orbit around the nearest and brightest stars in the sky. Its goal is to identify terrestrial planets in the habitable zones of nearby stars that are best suited for extensive follow up observations and characterization. TESS will collect 10 times as much data during its two-year mission as Kepler did during its first two years. SETI Institute scientist Jon M. Jenkins, co-investigator for data processing for both TESS and Kepler, will lead the development, design and operations of the TESS Data Processing Group (DPG) at NASA Ames Research Center. The DPG will process the raw pixel data downlinked by TESS to detect the minuscule signatures of transiting exoplanets. The DPG team will leverage the experience of the Science Operations Center of the Kepler Mission to develop a data processing facility that meets the rigorous requirements of the TESS mission at a low cost.

“It’s extremely exciting to learn that the profound voyage of discovery that Kepler began in 2009 will continue with a mission to discover Earth’s closest cousins,” said Jon Jenkins. Most exoplanets discovered by Kepler are hundreds of lights years from Earth.

The principal investigator of TESS is George Ricker of the Massachusetts Institute of Technology in Cambridge MA. TESS is managed by NASA’s Goddard Space Flight Center in MD. NASA Ames Research Center (CA) provides the Data Processing Group.

Jon Jenkins is a senior researcher at the Carl Sagan Center of the SETI Institute and Kepler Mission Analysis Lead at NASA Ames Research Center.

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Has Kepler Found Ideal SETI-target Planets?

By Franck Marchis, Senior research scientist

Mountain View - NASA's Kepler mission has discovered a new planetary system that is home to five small planets around a slightly smaller star than our Sun. Two of them are super-Earth planets, most likely made of rock or ice mixed with rock, which are located in the habitable zone of their host star. This discovery is providing a target for the SETI search, since if life has thrived on these worlds and reached a point where civilization has developed complex technology, it may be detectable.

When the NASA Kepler mission was launched on March 9, 2007, the Delta II rocket was carrying the hope of a large community of scientists who dedicate their work to studying extra-solar planets, planets in orbit around other stars. The Kepler mission's main scientific objective is exploration of the structure and diversity of planetary systems. It accomplishes this goal by staring almost constantly at a large field composed of about 150,000 stars to detect small dips in brightness due to the transits of a planet.

Kepler has already been a successful NASA mission with the discovery of 2,740 planet candidates with estimated sizes from Mercury to larger than Jupiter. A fifth of these planet candidates are also called "super-Earths", a new class of planets, without analog in our solar system, with a radius between 1.25 to 2 times the radius of our planet. 

Today, in a scientific article published in Science magazine and through a NASA press conference, the Kepler team announced the discovery of a multiple planet system, composed of 5 Earth-sized and super-Earth planets orbiting a K-type star. 

The detection of these planets was indirect since Kepler astronomers observed the attenuation of the host star's brightness due to the passage of a planet in the line of sight, and not the planets themselves. The authenticity of this multiple planet system was confirmed by a statistical analysis based on previous detections of multiple planets by Kepler.

“By estimating the rate of false-positives due the remote possibility of additional planet-hosting stars in the photometric aperture we have strong confidence that we have discovered two genuine transiting super-Earth planets in the habitable zone  of their host star.  Such calculations are only possible because of the thousands of additional transiting extrasolar planets that Kepler has discovered” said Jason Rowe, Research Scientist at the Carl Sagan Center of the SETI Institute and co-author of the work 

The outermost planet, named Kepler-62f (radius about 1.4 times Earth’s radius and a period of 267 Earth days) is located in the habitable zone of the star, a region around the star where a rocky planet with an atmosphere similar to Earth could host liquid water on its surface. The team expanded the definition of the Habitable Zone by taking into account the evolution of the brightness of the host star. Their calculations suggest that Kepler-62e (radius about 1.6 times Earth’s radius and a period of 122 Earth days) was also in the habitable zone so that liquid water could have existed on its surface, too. 

Similar to Venus and Mars that are believed to have lost their surface water 1 billion years and 3.8 billion years ago respectively, before our sun was more luminous, the host star's habitable zone was broader in the past. The Kepler team's calculations suggest that Kepler-62e (radius about 1.6 times Earth’s radius and a period of 122 Earth days) is also in the habitable zone so that liquid water could exist on its surface, too. 

“These discoveries move us farther down the road to discovering planets similar to Earth. While we don’t know if Kepler-62e and f are rocky or whether they have liquid water pooling on their surfaces, their existence shows that the incidence of small worlds in the habitable zone of sun-like stars is high. Thus we can look forward to the discovery and detailed characterization of Earth’s cousins in the years and decades to come by future missions and telescopes.“ said Jon Jenkins Senior Scientist at the Carl Sagan Center of the SETI Institute and also co-author of the work.

Both Goldilocks planets’ masses remain unknown since they are too small to produce detectable gravitational effects on the host star and between themselves. However, considering a lower upper limit for their mass and the age of the star, estimated to be 7 billion years, the team suggests that both planets are solid and either made of a dry rocky material, like Earth, or a large body of water surrounding a core of iron and rock (a water world).

Kepler discoveries are an amazing opportunity to focus the search for technosignatures conducted at the Center for SETI Research led by Gerry Harp. Kepler provides the detection of exoworlds that could host water on their surfaces and potentially life. Unfortunately, the planets of the Kepler-62 system are too distant (850 light-years from Earth) to be fully characterized, and no direct measurement of their atmospheric composition is possible with current technologies.

"Since December of 2011, the SonATA program to search for extraterrestrial intelligence with the Allen Telescope Array has been focusing on the Kepler exoplanet candidates and especially those planets expected to be within the "Habitable Zone" of their stars. Our surveys improve on previous, generally narrowband SETI by covering the radio frequency range where Earth's atmosphere is most transparent, including many frequencies never before observed. We expect to complete a meaningful survey of these stars in less than 1 year -- be sure to check back soon." says Gerry Harp, Director of the Center for SETI Research.

Related Information

  • Jon Jenkins is a senior researcher at the Carl Sagan Center of the SETI Institute and leader of the Kepler Analysis team located at NASA Ames
  • Jason Rowe is a research scientist at the Carl Sagan Center of the SETI Institute and part of the Kepler Science Office located at the NASA-Ames Research Center.
  • Gerry Harp is the Director of the Center for SETI Research


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