HABITALBE-ZONE EARTH-SIZE PLANETS CONTINUE TO BE DISCOVERED



Relative sizes of all of the habitable-zone planets discovered to date alongside Earth. Left to right: Kepler-22b, Kepler-69c, Kepler-62e, Kepler-62f and Earth (except for Earth, these are artists' renditions). Image credit: NASA Ames/JPL-Caltech.

FROM:  NASA

MOFFETT FIELD, Calif. -- NASA's Kepler mission has discovered two new planetary systems that include three super-Earth-size planets in the "habitable zone," the range of distance from a star where the surface temperature of an orbiting planet might be suitable for liquid water.

The Kepler-62 system has five planets; 62b, 62c, 62d, 62e and 62f. The Kepler-69 system has two planets; 69b and 69c. Kepler-62e, 62f and 69c are the super-Earth-sized planets.

Two of the newly discovered planets orbit a star smaller and cooler than the sun. Kepler-62f is only 40 percent larger than Earth, making it the exoplanet closest to the size of our planet known in the habitable zone of another star. Kepler-62f is likely to have a rocky composition. Kepler-62e, orbits on the inner edge of the habitable zone and is roughly 60 percent larger than Earth.

The third planet, Kepler-69c, is 70 percent larger than the size of Earth, and orbits in the habitable zone of a star similar to our sun. Astronomers are uncertain about the composition of Kepler-69c, but its orbit of 242 days around a sun-like star resembles that of our neighboring planet Venus.

Scientists do not know whether life could exist on the newfound planets, but their discovery signals we are another step closer to finding a world similar to Earth around a star like our sun.

"The Kepler spacecraft has certainly turned out to be a rock star of science," said John Grunsfeld, associate administrator of the Science Mission Directorate at NASA Headquarters in Washington. "The discovery of these rocky planets in the habitable zone brings us a bit closer to finding a place like home. It is only a matter of time before we know if the galaxy is home to a multitude of planets like Earth, or if we are a rarity."

The Kepler space telescope, which simultaneously and continuously measures the brightness of more than 150,000 stars, is NASA's first mission capable of detecting Earth-size planets around stars like our sun. Orbiting its star every 122 days, Kepler-62e was the first of these habitable zone planets identified. Kepler-62f, with an orbital period of 267 days, was later found by Eric Agol, associate professor of astronomy at the University of Washington and co-author of a paper on the discoveries published in the journal Science.

The size of Kepler-62f is now measured, but its mass and composition are not. However, based on previous studies of rocky exoplanets similar in size, scientists are able to estimate its mass by association.

"The detection and confirmation of planets is an enormously collaborative effort of talent and resources, and requires expertise from across the scientific community to produce these tremendous results," said William Borucki, Kepler science principal investigator at NASA's Ames Research Center at Moffett Field, Calif., and lead author of the Kepler-62 system paper in Science. "Kepler has brought a resurgence of astronomical discoveries and we are making excellent progress toward determining if planets like ours are the exception or the rule."

The two habitable zone worlds orbiting Kepler-62 have three companions in orbits closer to their star, two larger than the size of Earth and one about the size of Mars. Kepler-62b, Kepler-62c and Kepler-62d, orbit every five, 12, and 18 days, respectively, making them very hot and inhospitable for life as we know it.

The five planets of the Kepler-62 system orbit a star classified as a K2 dwarf, measuring just two-thirds the size of the sun and only one-fifth as bright. At seven billion years old, the star is somewhat older than the sun. It is about 1,200 light-years from Earth in the constellation Lyra.

A companion to Kepler-69c, known as Kepler-69b, is more than twice the size of Earth and whizzes around its star every 13 days. The Kepler-69 planets' host star belongs to the same class as our sun, called G-type. It is 93 percent the size of the sun and 80 percent as luminous and is located approximately 2,700 light-years from Earth in the constellation Cygnus.

"We only know of one star that hosts a planet with life, the sun. Finding a planet in the habitable zone around a star like our sun is a significant milestone toward finding truly Earth-like planets," said Thomas Barclay, Kepler scientist at the Bay Area Environmental Research Institute in Sonoma, Calif., and lead author of the Kepler-69 system discovery published in the Astrophysical Journal.

When a planet candidate transits, or passes in front of the star from the spacecraft's vantage point, a percentage of light from the star is blocked. The resulting dip in the brightness of the starlight reveals the transiting planet's size relative to its star. Using the transit method, Kepler has detected 2,740 candidates. Using various analysis techniques, ground telescopes and other space assets, 122 planets have been confirmed.

Early in the mission, the Kepler telescope primarily found large, gaseous giants in very close orbits of their stars. Known as "hot Jupiters," these are easier to detect due to their size and very short orbital periods. Earth would take three years to accomplish the three transits required to be accepted as a planet candidate. As Kepler continues to observe, transit signals of habitable zone planets the size of Earth orbiting stars like the sun will begin to emerge.

Ames is responsible for 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 & 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 was funded by the agency's Science Mission Directorate.

For more information about the Kepler mission and to view the digital press kit, visit:

ASTROBIOLOGIST GRINSPOON ANSWERS QUESTIONS

Photo:  Earth Cousins.  Credit:  CIA World Factbook.

FROM: U.S. LIBRARY OF CONGRESS

Inquiring Minds: An Interview with Astrobiologist David H. Grinspoon
November 29, 2012 by Erin Allen
(The following is a guest post by Jason Steinhauer, a program specialist in the Library’s John W. Kluge Center, as part of the blog series, "Inquiring Minds.")
American astrobiologist David H. Grinspoon began on November 1 as the inaugural Baruch S. Blumberg NASA/Library of Congress Chair in Astrobiology at the Library’s
John W. Kluge Center.

This unique position was established through an interagency agreement between the Library of Congress and the NASA Astrobiology Institute (NAI) for research into the origins, evolution, distribution and future of life in the universe, and the societal and humanistic implications of such inquiry. The chair is named for Baruch S. Blumberg, late Kluge Center Scholars Council member, Nobel Laureate and founding director of the NAI.

Grinspoon is curator of astrobiology at the Denver Museum of Nature & Science, adjunct professor at the University of Colorado, widely published writer, and currently serves on the Science Team for the Curiosity Rover mission to Mars.

Q:
Tell us about what you’ll be researching at the Library of Congress.
 
A: My intention is to study the Anthropocene Era from an astrobiology perspective. The Anthropocene is the phrase that some scientists are using to refer to the geological era that is defined by human activity. It’s still controversial among geologists, as it acknowledges that we are having a global-scale impact on the Earth and looks at humans as a geological force. I intend to apply the perspective of astrobiology, which is a deep time way of looking at life on Earth, towards the question of the Anthropocene. What does the human phenomenon on Earth look like viewed from an interplanetary perspective?

Q: Can you explain astrobiology and deep time a bit?

A: Astrobiology is the science of life in the Universe. It’s an attempt to scientifically deal with the question of whether or not we’re alone in the universe, looking at the past of life, the present of life and the future of life. It’s an interdisciplinary study incorporating astronomy, biology and the Earth sciences. We’re studying our own history, but over a timescale of billions of years and including not just Earth but the other planets as well, which gives us more perspective on the possible stories and fates of worlds like our own.

Q: How does one become an astrobiologist?

A: Astrobiology is a new field. It draws on the heritage of exobiology. People come from a wide range of scientific backgrounds. My particular background is planetary science. I study how planets work. There’s been a growing sense of the need to include biology as an integral part of the way planets evolve. More recently I’ve been folding biology into my research about planetary history

Q: Were you always interested in outer space?

A: I was. I’m a child of Apollo. I was thrilled by the astronauts landing on the moon when I was in fourth grade. I was a science fiction geek from an early age, enthralled by the questions of life in the universe. As I got older I learned that space exploration was real. I wanted to get involved in that. I knew I wanted to be a scientist. Now I’m on the science teams of spacecraft that are currently operating at Mars and Venus. Living the dream!

Q: What are you most excited to look at in the Library of Congress collections?

A: I’m very excited to explore the papers of notable scientists. I’m going to integrate the history of science into my research, and so it’s exciting to be able to find primary material. Beyond that, astrobiology is such a multi-disciplinary field with elements of philosophy, history, theology and spirituality that can be folded into this study. I feel so incredibly fortunate to have the resources of the Library at hand.

Q: Part of your role will be to organize public events. What are the ways that the public can get involved in astrobiology?

A: Astrobiology is a great point of contact for science outreach. The public is naturally interested in extra-terrestrial life. Astrobiology provides an accessible point of access that leads to deeper questions. In the museum where I work in Denver, astrobiology has been a great way to bring the public interest into scientific questions. Here at the Library, through workshops and colloquia I hope to explore the boundaries of science and the humanities. How do we illuminate the meaning of human existence through our science and its philosophical and spiritual dimensions? Collaboration with others at the Library and in Washington makes this an ideal place to do that.