NASA's Astrobiology Institute (NAI) announced that the SETI Institute has been selected as a new member of the NAI for a 5-year research program, "Changing Planetary Environments and the Fingerprints of Life."

Led by planetary geologist and Senior Research Scientist, Nathalie Cabrol, the team's work will address key questions.

How can we identify the signature of life not just here on Earth, but on Mars as well? How does a planet's changing environment impact the evidence for life?

"I am absolutely thrilled that the SETI Institute is joining the NAI. In the next five years, along with our partner institutions, we will focus on decoding the fingerprints of life, the biosignatures, in extreme environments here on Earth to help us look for life on Mars.

Our goal is to understand the survival of biosignatures from an early, wetter Mars to the harsh environment of the red planet today.

Understanding the role that the changing Martian environment has had on biosignatures will inform us on how to recognize these signatures, and how to explore them.

We bring to this ambitious quest new exploration tools and, with NASA's Mars 2020 on the horizon, the timing could not be more perfect," stated Cabrol.

"Personally and professionally, this is a tremendously exciting project because we aim to develop a roadmap to biosignature exploration for Mars for future missions."

"I am delighted at the news that the SETI Institute led team has been chosen as one of the new members in the NASA Astrobiology Institute."

"The team worked hard at putting together an outstanding proposal and it is a positive reflection on the process that is in place to review the proposals that their effort is recognized and rewarded by their professional peers."

"We look forward to an exciting five years of outstanding research under the aegis of this award," said David Black, President and CEO of the SETI Institute.

To model and test strategies for biosignature detection, Cabrol's team will conduct fieldwork in extreme environments on Earth that are analogous to sites on Mars where water once flowed.

Fieldwork will be done at Yellowstone National Park, sites in California and Chile, Axel Heiberg Island in the high Arctic, and Western Australia.

Each site is an analogue to Mars: volcanic and hydrothermal terrain, lake sediments, evaporates, and perennial cold springs.

Sites will be explored from satellites, air, ground, and at the microscopic level in the field and laboratory.

Understanding how to integrate this multi-scale information will help scientists learn how to select the best sites for discovering biosignatures on Mars.

Cabrol assembled a diverse team of experts in planetary science, robotics, laboratory experimentation, and exploration to conduct fieldwork, analyze samples, and develop a biosignature roadmap to guide the search for life on Mars.

In addition to more than a dozen scientists at the SETI Institute, her team brings together scientists from universities, government agencies and industry partners in the United States, Canada, Europe, Australia and South America.

Over the next 5 years, more than twenty scientists will work together to help answer the question of where, what and how to search for the right rocks on Mars to discover the fingerprints of life on the red planet.

Moonlets created and destroyed in Saturn's F ring

Cassini spied just as many regular, faint clumps in Saturn's narrow F ring (the outermost, thin ring), like those pictured here, as Voyager did but it saw hardly any of the long, bright clumps that were common in Voyager images. 

Credit: NASA /JPL-Caltech /SSI

There is an ongoing drama in the Saturnian ring system that causes small moons to be born and then destroyed on time scales that are but an eyeblink in the history of the solar system.

SETI Institute scientists Robert French and Mark Showalter have examined photos made by NASA's Cassini spacecraft and compared them to 30 year-old pictures made by the Voyager mission.

They find that there is a marked difference in the appearance of one of the rings, even over this cosmologically short interval, a difference that can be explained by the brief strut and fret of small moons.

"The F ring is a narrow, lumpy feature made entirely of water ice that lies just outside the broad, luminous rings A, B, and C," notes French.

"It has bright spots. But it has fundamentally changed its appearance since the time of Voyager. Today, there are fewer of the very bright lumps."

The bright spots come and go over the course of hours or days, a mystery that the two SETI Institute astronomers think they have solved.

"We believe the most luminous knots occur when tiny moons, no bigger than a large mountain, collide with the densest part of the ring," says French.

"These moons are small enough to coalesce and then break apart in short order."

The F ring is at a special place in the ring system, at a distance known as the Roche limit, named for French astronomer Edouard Roche who first pointed out that if a moon orbits too close to a planet, the difference in gravitational tug on its near and far side can tear it apart.

This happens at a distance dependent on the mass of the planet, and in the case of Saturn, happens to be at the location of the F ring.

Consequently, material here is caught between the yin and yang of forming small moons, and having them pulled apart.

The moons in question are typically no more than 3 miles (5 km) in size, and consequently can come together quickly.

This chaotic region is given additional stir by Prometheus, a moon that's roughly 60 miles (100 km) in size that orbits just inside the F ring.

Every 17 years, Prometheus aligns with the F ring in a way that emphasises its gravitational influence on the ring's particles, precipitating the formation of the mini-moons, or moonlets.

"These newborn moonlets will repeatedly crash through the F ring, like bumper cars, producing bright clumps as they careen through lanes of material," says Showalter.

"But this is self-destructive behaviour, and the moons, being just at the Roche limit, are barely stable and quickly fragmented."

This scenario can explain the rapid variation in the number of bright clumps in the F ring, but is it true?

If the periodic influence of Prometheus is causing the waxing and waning of the clumps, then there should be an increase in their prevalence over the next few years, a prediction that the astronomers will be checking with Cassini data.

In addition to the drama of moons that come and go over less than a human lifetime, studies of the ring system give insight into how solar systems in general are built.

"The sort of processes going on around Saturn are very similar to those that took place here 4.6 billion years ago, when the Earth and the other large planets were formed," notes French. "It's an important process to understand."

This research was published in the online edition of the journal Icarus on July 15, 2014.

More information: Robert S. French, Shannon K. Hicks, Mark R. Showalter, Adrienne K. Antonsen, Douglas R. Packard, "Analysis of clumps in Saturn's F ring from Voyager and Cassini," Icarus, Volume 241, October 2014, Pages 200-220, ISSN 0019-1035, dx.doi.org/10.1016/j.icarus.2014.06.035 . Preprint: arxiv.org/abs/1408.2548

SETI Kelper: Planet bonanza hints at worlds similar to our own

The artist concept depicts multiple-transiting planet systems, which are stars with more than one planet. 

The planets eclipse or transit their host star from the vantage point of the obplanetserver. This angle is called edge-on. 

Credit: NASA

For hunters, this has been a bountiful year. A team lead of astronomers at the SETI Institute and NASA Ames Research Center have used data from NASA's Kepler space telescope to uncover 715 new exoplanets.

The newly-verified objects orbit 305 different stars, and therefore include multi-world systems that are reminiscent of the Sun's own planetary family.

The announcement of these discoveries was followed by news that Kepler had also found the first Earth-size planet in the habitable zone of its star, Kepler 186f.

This is a significant milestone in the task of determining the prevalence of terrestrial planets in the Milky Way galaxy.

Jason Rowe

"These results are showing us that not only are Earth-sized planets common, but so are multi-planet systems containing potentially habitable worlds," notes Jason Rowe, a SETI Institute astronomer who co-led the study.

"Most of the new planets orbit their host star much closer than Mercury, but a few are beginning to bear a similarity to our own solar system."

The deluge of new planets has been intensified by a new analysis scheme called verification by multiplicity.

This technique can be applied to many planets at once, allowing the researchers to verify hundreds of new planetary systems in wholesale fashion, rather than teasing them from the Kepler data one-by-one as done in the past.

The new technique uses probability arguments based on the recognition that, of the 150,000 stars observed by Kepler, hundreds were found that have multiple planet candidates.

David Black

On this basis, the researchers are assured that their results are not distorted by binary stars that can mimic a multi-world system.

The new discoveries increase the total number of known exoplanets to over 1,700.

"From this work we've also learned that planets in these multiple systems are small, and their orbits are flat and circular, much like our own solar system," Rowe said.

On April 17th, the Kepler team announced the discovery of Kepler 186f, the first Earth-sized planet found in the habitable zone of its host star, marking a major milestone in determining the frequency of Earth-like planets in the Milky Way galaxy.

"Uncovering these worlds and showing that habitable worlds could be very common has increased the likelihood that there is life, perhaps abundant life, elsewhere in the cosmos," notes David Black, President and CEO of the SETI Institute.

Data collection from the Kepler mission ended in the spring of last year, due to the failure of a second on-board reaction wheel, essential to accurate pointing of the telescope.

However, on May 20th, NASA announced the approval of the K2 mission, intended to repurpose Kepler to use the pressure of sunlight hitting the side of the spacecraft to act as a third wheel.

"We can't continue to look at the original Kepler star field," said Douglas Caldwell, Kepler Instrument Scientist at the SETI Institute, "but spacecraft are built and operated by very smart people, and thanks to the hard work of the entire Kepler team we can now search for planets in a wide variety of environments and conditions, including star forming regions. Doing so will teach us more about how our own planetary system formed and evolved."

"The more we explore the more we find worlds among the stars that remind us of home," Rowe notes.

More information: Jason Rowe is presenting these results at this week's annual meeting of the Canadian Astronomical Society (CASCA) in Quebec: casca2014.craq-astro.ca/index_en.php

Kepler-186f: First potentially habitable Earth-sized planet confirmed - water

The artist's concept depicts Kepler-186f, the first validated Earth-size planet orbiting a distant star in the habitable zone, a range of distances from a star where liquid water might pool on the surface of an orbiting planet.

The discovery of Kepler-186f confirms that Earth-size planets exist in the habitable zone of other stars and signals a significant step closer to finding a world similar to Earth.

The artistic concept of Kepler-186f is the result of scientists and artists collaborating to help imagine the appearance of these distant worlds. 

Credit: Danielle Futselaar.

The first Earth-sized exoplanet orbiting within the habitable zone of another star has been confirmed by observations with both the W. M. Keck Observatory and the Gemini Observatory.

The initial discovery, made by NASA's Kepler Space Telescope, is one of a handful of smaller planets found by Kepler and verified using large ground-based telescopes.

It also confirms that Earth-sized planets do exist in the habitable zone of other stars.

"What makes this finding particularly compelling is that this Earth-sized planet, one of five orbiting this star, which is cooler than the Sun, resides in a temperate region where water could exist in liquid form," says Elisa Quintana of the SETI Institute and NASA Ames Research Center who led the paper published in the current issue of the journal Science.

The region in which this planet orbits its star is called the habitable zone, as it is thought that life would most likely form on planets with liquid water.

Steve Howell, Kepler's Project Scientist and a co-author on the paper, adds that neither Kepler (nor any telescope) is currently able to directly spot an exoplanet of this size and proximity to its host star.

"However, what we can do is eliminate essentially all other possibilities so that the validity of these planets is really the only viable option."

With such a small host star, the team employed a technique that eliminated the possibility that either a background star or a stellar companion could be mimicking what Kepler detected.

To do this, the team obtained extremely high spatial resolution observations from the eight-meter Gemini North telescope on Mauna Kea in Hawai`i using a technique called speckle imaging, as well as adaptive optics (AO) observations from the ten-meter Keck II telescope, Gemini's neighbour on Mauna Kea.

Together, these data allowed the team to rule out sources close enough to the star's line-of-sight to confound the Kepler evidence, and conclude that Kepler's detected signal has to be from a small planet transiting its host star.

The diagram compares the planets of the inner solar system to Kepler-186, a five-planet system about 500 light-years from Earth in the constellation Cygnus. 

The five planets of Kepler-186 orbit a star classified as a M1 dwarf, measuring half the size and mass of the sun. 

The Kepler-186 system is home to Kepler-186f, the first validated Earth-size planet orbiting a distant star in the habitable zone—a range of distances from a star where liquid water might pool on the surface of an orbiting planet. 

The discovery of Kepler-186f confirms that Earth-size planets exist in the habitable zone of other stars and signals a significant step closer to finding a world similar to Earth. 

Kepler-186f is less than ten percent larger than Earth in size, but its mass and composition are not known. 

Kepler-186f orbits its star once every 130-days and receives one-third the heat energy that Earth does from the sun, placing it near the outer edge of the habitable zone. 

The inner four companion planets all measure less than fifty percent the size of Earth. Kepler-186b, Kepler-186c, Kepler-186d, and Kepler-186e, orbit every three, seven, 13, and 22 days, respectively, making them very hot and inhospitable for life as we know it. 

The Kepler space telescope, which simultaneously and continuously measured the brightness of more than 150,000 stars, is NASA's first mission capable of detecting Earth-size planets around stars like our sun. 

Kepler does not directly image the planets it detects. The space telescope infers their existence by the amount of starlight blocked when the orbiting planet passes in front of a distant star from the vantage point of the observer. 

The artistic concept of Kepler-186f is the result of scientists and artists collaborating to help imagine the appearance of these distant Credit: Credit: NASA Ames/SETI Institute/JPL-CalTech.

More information: "An Earth-Sized Planet in the Habitable Zone of a Cool Star," by E.V. Quintana et al. Science, 2014.

NASA tests Zoe, the new Mars rover prototype, in Chile

NASA scientists said Friday they were testing a prototype of a robot the US space agency hopes to send to Mars in 2020 in Chile's Atacama desert.

NASA hopes to use this kind of rover to explore life-friendly sites found by Curiosity, the rover already searching for signs of life on Mars.

It has been there since last August.

The researchers say the desert, the driest spot on Earth, mimics the conditions of the Red Planet, and the agency has used it in the past to test space-bound equipment.

The robot, controlled remotely from the US, will continue testing through Sunday.

The solar-powered 771-kilogram (1,700-pound) machine is equipped with cameras and a drill able to dig up to a meter (three feet) deep.

It is testing its sensors, its cameras, its ability to store energy, as it searches for evidence of microbial life in the desert.

The Zoe robot will use a one-meter drill, shown here protruding above the robot's solar cell deck, to search for subsurface life in Chile's Atacama Desert. 

Carnegie Mellon University's Robotics Institute and the SETI Institute are leading the NASA-sponsored field experiment. 

Credit: Carnegie Mellon University