habitable zone Archives

April 17, 2014December 23, 2015 by Jason Major

Kepler Has Found the First Earth-Sized Exoplanet in a Habitable Zone!

Artist's rendering of Kepler-186f (Credit: NASA Ames/SETI Institute/Caltech)

It’s truly a “eureka” moment for Kepler scientists: the first rocky Earth-sized world has been found in a star’s habitable “Goldilocks” zone, the narrow belt where liquid water could readily exist on a planet’s surface without freezing solid or boiling away. And while it’s much too soon to tell if this really is a “twin Earth,” we can now be fairly confident that they do in fact exist.

The newly-confirmed extrasolar planet has been dubbed Kepler-186f. It is the fifth and outermost planet discovered orbiting the red dwarf star Kepler-186, located 490 light-years away. Kepler-186f completes one orbit around its star every 130 days, just within the outer edge of the system’s habitable zone.

The findings were made public today, April 17, during a teleconference hosted by NASA.

“This is the first definitive Earth-sized planet found in the habitable zone around another star,” says lead author Elisa Quintana of the SETI Institute at NASA Ames Research Center. “Finding such planets is a primary goal of the Kepler space telescope. The star is a main-sequence M-dwarf, a very common type. More than 70 percent of the hundreds of billions of stars in our galaxy are M-dwarfs.”

A visualization of the “unseen” red dwarfs in the night sky. Credit: D. Aguilar & C. Pulliam (CfA) — A visualization of the many “unseen” red dwarfs in the night sky. (CLICK FOR ANIMATION) Credit: D. Aguilar & C. Pulliam (CfA)

Unlike our Sun, which is a G-type yellow dwarf, M-dwarf stars (aka red dwarfs) are much smaller and dimmer. As a result their habitable zones are much more confined. But, being cooler stars, M-dwarfs have long lifespans, offering planets in their habitable zones — like Kepler-186f — potentially plenty of time to develop favorable conditions for life.

In addition, M-dwarfs are the most abundant stars in our galaxy; 7 out of 10 stars in the Milky Way are M-dwarfs, although most can’t be seen by the naked eye. Finding an Earth-sized planet orbiting one relatively nearby has enormous implications in the hunt for extraterrestrial life.

“M dwarfs are the most numerous stars,” said Quintana. “The first signs of other life in the galaxy may well come from planets orbiting an M dwarf.”

Still, there are many more conditions on a planet that must be met for it to be actually habitable. But size, composition, and orbital radius are very important first steps.

“Some people call these habitable planets, which of course we have no idea if they are,” said Stephen Kane, an assistant professor of physics and astronomy at San Francisco State University in California. “We simply know that they are in the habitable zone, and that is the best place to start looking for habitable planets.”

Scale comparison of the Kepler-186 system to our inner Solar System ( — Scale comparison of the Kepler-186 system and the inner Solar System (NASA Ames/SETI Institute/Caltech)

As far as the planetary system’s age is concerned — which relates to how long life could have potentially had to evolve on Kepler-186f’s surface — that’s hard to determine… especially with M-dwarf stars. Because they are so stable and long-lived, once they’re formed M-dwarfs essentially stay the same throughout their lifetimes.

“We know it’s probably older than a few billion years, but after that it’s very difficult to tell,” BAERI/Ames scientist Tom Barclay told Universe Today. “That’s the problem with M-dwarfs.”

A comparison of the Kepler 186 and Solar systems (NASA/Ames) — A comparison of the Kepler 186 and Solar systems (Presentation slide, NASA/Ames)

The exoplanet was discovered via the transit method used by NASA’s Kepler spacecraft, whereby stars’ brightnesses are continually monitored within a certain field of view. Any dips in luminance reveal the likely presence of a passing planet.

Because of its small size — just slightly over 1 Earth radius — and close proximity to its star, Kepler-186f can’t be observed directly with current telescope technology.

The Gemini North telescope on the summit of Mauna Kea (Gemini Observatory/AURA)

“However, what we can do is eliminate essentially all other possibilities so that the validity of these planets is really the only viable option,” said Steve Howell, Kepler project scientist and a co-author on the paper.

Using the latest advanced imaging capabilities of the Gemini North and Keck II observatories located atop Mauna Kea in Hawaii, astronomers were able to determine that the signals detected by Kepler were from a small orbiting planet and not something else, such as a background or companion star.

“The Keck and Gemini data are two key pieces of this puzzle,” Quintana said. “Without these complementary observations we wouldn’t have been able to confirm this Earth-sized planet.”

Kepler-186f joins the other 20 extrasolar worlds currently listed in the Habitable Exoplanets Catalog, maintained by the Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo. To date 961 exoplanets have been confirmed through Kepler observations, with 1,696 total confirmed altogether. (Source)

Artist's conception of the Kepler Space Telescope. Credit: NASA/JPL-Caltech — Artist’s conception of the Kepler Space Telescope. Credit: NASA/JPL-Caltech

Whether Kepler-186f actually resembles Earth or not, this discovery provides more information on the incredible variety of planetary systems to be found even in our little corner of the galaxy.

“The diversity of these exoplanets is one of the most exciting things about the field,” Kane said. “We’re trying to understand how common our solar system is, and the more diversity we see, the more it helps us to understand what the answer to that question really is.”

The SETI Institute’s Allen Telescope Array has surveyed the Kepler-186 system for any potential signals but so far none has been detected. Further observations are planned.

“Kepler-186f is special because we already know that a planet of its size and distance is capable of supporting life.”
– Elisa Quintana, research scientist, SETI Institute

The team’s paper, “An Earth-sized Planet in the Habitable Zone of a Cool Star” by Elisa V. Quintana et al., will be published in the April 18 issue of Science.

Learn more about the Kepler mission here, and read more about this discovery in NASA’s news release here and on the W.M. Keck website here.

Watch some video excerpts of team interviews and data renderings below:

Also, you can download the slides used in the NASA teleconference here.

Sources: San Francisco State University, Gemini Observatory, W.M. Keck Observatory, and SETI news releases

February 6, 2014December 23, 2015 by Ken Kremer

You are Here! Curiosity’s 1st Photo of Home Planet Earth from Mars

You are here! – As an Evening Star in the Martian Sky
This evening-sky view taken by NASA’s Mars rover Curiosity shows the Earth and Earth’s moon as seen on Jan. 31, 2014, or Sol 529 shortly after sunset at the Dingo Gap inside Gale Crater.
Credit: NASA/JPL-Caltech/MSSS/TAMU
See more imagery of the Earth and Moon below!
Story updated[/caption]

18 months into her mission to discover a habitable zone on the Red Planet, NASA’s Curiosity rover has at last looked back to the inhabited zone of all humanity and snapped her 1st image of all 7 Billion Earthlings living on the Home Planet.

“Look Back in Wonder… My first picture of Earth from the surface of Mars,” tweeted Curiosity today.

You are there! See yourselves in the spectacular imagery from the Red Planet’s surface at the ‘Dingo Gap’ inside Gale Crater – above and below.

Car sized Curiosity captured the evocative image of Earth as an evening star in the Martian sky just days ago on Jan. 31, 2014, or Sol 529, some 80 minutes after sunset.

And what’s more is that the evening sky view even includes the Earth’s Moon!

Annotated evening-sky view taken by NASA's Mars rover Curiosity shows the Earth and Earth's moon - enlarged in inset - as seen on Jan. 31, 2014, or Sol 529 shortly after sunset at the Dingo Gap sand dune. Credit: NASA/JPL-Caltech/MSSS/TAMU — Annotated evening-sky view taken by NASA’s Mars rover Curiosity shows the Earth and Earth’s moon – enlarged in inset – as seen on Jan. 31, 2014, or Sol 529 shortly after sunset at the Dingo Gap sand dune. Credit: NASA/JPL-Caltech/MSSS/TAMU

Earth shines brilliantly as the brightest beacon in the Martian twilight sky view taken from the 1 ton rovers current location at the edge of a sand dune dubbed the ‘Dingo Gap.’

“A human observer with normal vision, if standing on Mars, could easily see Earth and the moon as two distinct, bright “evening stars,” said NASA in a statement issued today.

Curiosity’s View Past Tall Dune at edge of ‘Dingo Gap’ This photomosaic from Curiosity’s Navigation Camera (Navcam) taken at the edge of the entrance to the Dingo Gap shows a 3 foot (1 meter) tall dune and valley terrain beyond to the west, all dramatically back dropped by eroded rim of Gale Crater. View from the rover’s current position on Sol 528 (Jan. 30, 2014). The rover team may decide soon whether Curiosity will bridge the dune gap as a smoother path to next science destination. Credit: NASA/JPL-Caltech/Marco Di Lorenzo/Ken Kremer- kenkremer.com — 1st Curiosity Snapshot of Earth taken from here –
Curiosity’s View Past Tall Dune at edge of ‘Dingo Gap’ sand dune
This photomosaic from Curiosity’s Navigation Camera (Navcam) taken at the edge of the entrance to the Dingo Gap shows a 3 foot (1 meter) tall dune and valley terrain beyond to the west, all dramatically back dropped by eroded rim of Gale Crater. View from the rover’s current position on Sol 528 (Jan. 30, 2014). The rover team may decide soon whether Curiosity will bridge the dune gap as a smoother path to next science destination.
Credit: NASA/JPL-Caltech/Marco Di Lorenzo/Ken Kremer- kenkremer.com

Curiosity used both of her high resolution mast mounted color cameras to collect a series of Earth/Moon images flittering across the Martian sky.

The Earth and the Moon in this evening-sky view taken by Curiosity’s telephoto Mastcam right -eye camera on Jan. 31, 2014, or Sol 529 shortly after sunset at the Dingo Gap. Moon’s brightness was enhanced to aid visibility. Credit: NASA/JPL-Caltech/MSSS/TAMU

Processing has removed the numerous cosmic ray strikes – see raw image below.

Right now Curiosity’s handlers are pondering whether to climb over the 1 meter tall sand dune and cross into the smooth terrain of the valley beyond the ‘Dingo Gap’ – as an alternate path to minimize damaging encounters with sharp edged Martian rocks that are puncturing holes and ripping tears into the robots six wheels.

To be clear, these are not the first images of the Earth from Mars orbit or Mars surface.

NASA’s Mars Exploration Rover Spirit imaged Earth from the surface in March 2004, soon after landing in Gusev Crater in January 2004.

Two of NASA’s other Red Planet explorers also imaged Earth; Mars Global Surveyor in 2003 and Mars Reconnaissance Orbiter in 2007.

More recently, NASA’s Cassini orbiter at Saturn spied the Earth and Moon during the Wave at Saturn event in July 2013 from a distance of 898 million miles (1.44 billion kilometers).

And still more images of the Earth from NASA’s Mariner 10 and Juno Jupiter orbiter in my recent planetary exploration story – here

The most famous and distant of all is the ‘Pale Blue Dot’ image of Earth taken by NASA’s Voyager 1 probe in 1990 from about 6 billion kilometers (3.7 billion miles) away.

Meanwhile, NASA’s sister rover Opportunity is exploring clay mineral outcrops by the summit of Solander Point on the opposite side of Mars at the start of her 2nd Decade investigating the Red Planet’s mysteries.

Stay tuned here for Ken’s continuing Curiosity, Opportunity, Chang’e-3, SpaceX, Orbital Sciences, LADEE, MAVEN, MOM, Mars and more planetary and human spaceflight news.

Ken Kremer

Curiosity Mastcam raw image showing the Earth in the Martian twilight sky on Jan. 31, 2014 above Gale crater rim amidst numerous cosmic ray strikes. Credit: NASA/JPL-Caltech/MSSS — Curiosity Mastcam raw image showing the Earth in the Martian twilight sky on Jan. 31, 2014 amidst numerous cosmic ray strikes. . Credit: NASA/JPL-Caltech/MSSS

Curiosity photographed You and all of humanity looking from somewhere above the eroded rim of Gale Crater - a portion of which is seen in this photomosaic taken by the same Mastcam camera on Feb 1, 2014, Sol 530, at the Dingo Gap sand dune. Credit: NASA/JPL-Caltech/MSSS/Marco Di Lorenzo/Ken Kremer- kenkremer.com — Curiosity photographed You and all of humanity looking from somewhere above the eroded rim of Gale Crater – a portion of which is seen in this photomosaic taken by the same Mastcam camera on Feb 1, 2014, Sol 530, at the Dingo Gap sand dune. Credit: NASA/JPL-Caltech/MSSS/Marco Di Lorenzo/Ken Kremer- kenkremer.com

Photomosaic shows new holes and tears in several of rover Curiosity’s six wheels caused by recent driving over sharp edged Martian rocks on the months long trek to Mount Sharp. Raw images taken by the MAHLI camera on Curiosity’s arm on Jan. 31, 2014 (Sol 529) were assembled to show some recent damage to several of its six wheels. Credit: NASA / JPL / MSSS / Marco Di Lorenzo / Ken Kremer- kenkremer.com

January 23, 2014December 23, 2015 by Ken Kremer

Opportunity Discovers That Oldest Rocks Reveal Best Chance for Martian Life

Pancam false-color view acquired on Sol 3066 (Sept. 8 2012) of fine-scale layering in the Whitewater Lake locality that is indicative of an ancient aqueous environment on Mars. Veneers have been resistant to wind erosion and enhanced the layered appearance of the outcrop. Layers are typically several millimeters thick. Credit: NASA/JPL-Caltech/Cornell/Arizona State University

After a decade of roving relentlessly on the Red Planet, NASA’s Opportunity rover discovered rocks that preserve the best evidence yet that ancient Mars was the most conducive time period for the formation of life on our Solar System’s most Earth-like Planet, according to the science leaders of the mission.

Opportunity found the rocks – laden with clay minerals – barely over half a year ago in the spring of 2013, at an outcrop named ‘Whitewater Lake’ along an eroded segment of a vast crater named Endeavour that spans some 22 kilometers (14 miles) in diameter.

“These rocks are older than any we examined earlier in the mission, and they reveal more favorable conditions for microbial life than any evidence previously examined by investigations with Opportunity,” says Opportunity Deputy Principal Investigator Ray Arvidson, a professor at Washington University in St. Louis.

Opportunity investigated the rocks at a spot dubbed Matejivic Hill where researchers believe iron-rich smectite was produced in an aqueous environment some 4 billion years ago that was relatively benign and with a nearly neutral pH – thus offering potential life forms a habitable zone with a far better chance to originate and thrive for perhaps as long as hundreds of millions of years.

The new scientific findings are being published in the journal Science on Jan. 24, which just happens to exactly coincide with Opportunity’s landing on the Red Planet ten years ago at Meridiani Planum.

Matejivic Hill is located on the Cape York rim segment of Endeavour crater. See locations on our Opportunity route map below.

“The punch line here is that the oldest rocks Opportunity has examined were formed under very mild conditions — conditions that would have been a much better niche for life, and also much better for the preservation of organic materials that would have been produced,” said Arvidson at a NASA media briefing today, Jan. 23.

Opportunity rover discovered phyllosilicate clay minerals and calcium sulfate veins at the bright outcrops of ‘Whitewater Lake’, at right, imaged by the Navcam camera on Sol 3197 (Jan. 20, 2013, coinciding with her 9th anniversary on Mars. “Copper Cliff” is the dark outcrop, at top center. Darker “Kirkwood” outcrop, at left, is site of mysterious “newberries” concretions. This panoramic view was snapped from ‘Matijevic Hill’ on Cape York ridge at Endeavour Crater. Credit: NASA/JPL-Caltech/Cornell/Marco Di Lorenzo/Ken Kremer

Immediately after landing on Mars on Jan.24, 2004 inside Eagle crater, the six wheeled robot found rocks within her eyesight that provided concrete evidence that eons ago Mars was much warmer and wetter compared to the cold, arid conditions that exist today.

Although those sulfate rich rocks proved that liquid water once flowed on the surface of the Red Planet, they also stem from a time period with a rather harsh environment that was extremely acidic, containing significant levels of sulfuric acid that would not be friendly to the formation or sustainability of potential Martian life forms.

“Evidence is thus preserved for water-rock interactions of the aqueous environments of slightly acidic to circum-neutral pH that would have been more favorable for prebiotic chemistry and microorganisms than those recorded by younger sulfate-rich rocks at Meridiani Planum,” Ardivson wrote in the Science paper, of which he is the lead author, along with many other team members.

NASA's Opportunity Mars rover recorded the component images for this self-portrait near the peak of Solander Point and about three weeks before completing a decade of work on Mars. The rover's panoramic camera (Pancam) took the images during the interval Jan. 3, 2014, to Jan. 6, 2014. Credit: NASA/JPL-Caltech/Cornell/Arizona State University — NASA’s Opportunity Mars rover recorded the component images for this self-portrait near the peak of Solander Point and about three weeks before completing a decade of work on Mars. The rover’s panoramic camera (Pancam) took the images during the interval Jan. 3, 2014, to Jan. 6, 2014. Credit: NASA/JPL-Caltech/Cornell/Arizona State University

The science team directed Opportunity to Matejivic Hill and the ‘Whitewater Lake’ area of outcrops based on predictions from spectral observations collected from the CRISM spectrometer aboard one of NASA’s spacecraft circling overhead the Red Planet – the powerful Mars Reconnaissance Orbiter (MRO).

Opportunity arrived at Mars barely 3 weeks after her twin sister, Spirit on 3 January 2004.

The long lived robot has been methodically exploring along the rim of Endeavour crater since arriving in August 2011.

The newly published results from Opportunity correlate very well with those from sister rover Curiosity which likewise found a habitable zone where drinkable water once flowed on the opposite side of Mars.

The combined discoveries from the golf cart sized Opportunity and the SUV sized Curiosity tell us that the presence of liquid water was widespread on ancient Mars.

“The more we explore Mars, the more interesting it becomes. These latest findings present yet another kind of gift that just happens to coincide with Opportunity’s 10th anniversary on Mars,” said Michael Meyer, lead scientist for NASA’s Mars Exploration Program.

“We’re finding more places where Mars reveals a warmer and wetter planet in its history. This gives us greater incentive to continue seeking evidence of past life on Mars.”

Opportunity is currently investigating a new cache of clay mineral outcrops by the summit of Solander Point, a rim segment just south of Cape York and Matejivic Hill.

These outcrops were likewise detected by the CRISM spectrometer aboard MRO. The hunt for these outcrops was detailed in earlier discussions I had with Ray Arvidson.

Opportunity by Solander Point peak - her 1st mountain climbing adventure. NASA’s Opportunity rover captured this panoramic mosaic on Dec. 10, 2013 (Sol 3512) near the summit of “Solander Point" on the western rim of Endeavour Crater where she is investigating outcrops of potential clay minerals. Assembled from Sol 3512 navcam raw images. Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer-kenkremer.com — Opportunity by Solander Point peak – her 1st mountain climbing adventure. NASA’s Opportunity rover captured this panoramic mosaic on Dec. 10, 2013 (Sol 3512) near the summit of “Solander Point” on the western rim of Endeavour Crater where she is investigating outcrops of potential clay minerals. Assembled from Sol 3512 navcam raw images. Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer-kenkremer.com

Today marks Opportunity’s 3555th Sol or Martian Day roving Mars – for what was expected to be only a 90 Sol mission.

So far she has snapped over 188,200 amazing images on the first overland expedition across the Red Planet.

Her total odometry stands at over 24.07 miles (38.73 kilometers) since touchdown on Jan. 24, 2004 at Meridiani Planum.

Read more about sister Spirit – here and here.

Meanwhile on the opposite side of Mars, Opportunity’s younger sister rover Curiosity is trekking towards gigantic Mount Sharp. She celebrated 500 Sols on Mars on New Years Day 2014.

And a pair of new orbiters are streaking to the Red Planet to fortify the Terran fleet- NASA’s MAVEN and India’s MOM.

Finally, China’s Yutu rover is trundling across pitted moonscapes.

Stay tuned here for Ken’s continuing Opportunity, Curiosity, Chang’e-3, LADEE, MAVEN, Mars rover and MOM news.

Ken Kremer

Opportunity by Solander Point peak – 2nd Mars Decade Starts here! NASA’s Opportunity rover captured this panoramic mosaic on Dec. 10, 2013 (Sol 3512) near the summit of “Solander Point” on the western rim of Endeavour Crater where she starts Decade 2 on the Red Planet. She is currently investigating outcrops of potential clay minerals formed in liquid water on her 1st mountain climbing adventure. Assembled from Sol 3512 navcam raw images. Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer-kenkremer.com

Traverse Map for NASA’s Opportunity rover from 2004 to 2014. This map shows the entire path the rover has driven during a decade on Mars and over 3540 Sols, or Martian days, since landing inside Eagle Crater on Jan 24, 2004 to current location by f Solander Point summit at the western rim of Endeavour Crater. Rover will spnd 6th winter here atop Solander. Opportunity discovered clay minerals at Esperance - indicative of a habitable zone. Credit: NASA/JPL/Cornell/ASU/Marco Di Lorenzo/Ken Kremer — Traverse Map for NASA’s Opportunity rover from 2004 to 2014
This map shows the entire path the rover has driven during a decade on Mars and over 3540 Sols, or Martian days, since landing inside Eagle Crater on Jan 24, 2004 to current location by f Solander Point summit at the western rim of Endeavour Crater. Rover will spnd 6th winter here atop Solander. Opportunity discovered clay minerals at Esperance – indicative of a habitable zone. Credit: NASA/JPL/Cornell/ASU/Marco Di Lorenzo/Ken Kremer

November 4, 2013December 23, 2015 by Nancy Atkinson

22% of Sun-like Stars have Earth-sized Planets in the Habitable Zone

The "Goldilocks" zone around a star is where a planet is neither too hot nor too cold to support liquid water. Ilustration by Petigura/UC Berkeley, Howard/UH-Manoa, Marcy/UC Berkeley.

How common are planets like Earth? That’s been a question astronomers and dreamers have pondered for decades, and now, thanks to the Kepler spacecraft, they have an answer. One in five Sun-like stars in our galaxy have Earth-sized planets that could host life, according to a recent study of Kepler data.

“What this means is, when you look up at the thousands of stars in the night sky, the nearest sun-like star with an Earth-size planet in its habitable zone is probably only 12 light years away and can be seen with the naked eye. That is amazing,” said UC Berkeley graduate student Erik Petigura, who led the analysis of the Kepler and Keck Observatory data.

The Kepler telescope’s mission was to try and find small rocky planets with the potential for hosting liquid water and perhaps the ingredients needed for biology to take hold. For four years, the space telescope monitored the brightness of more than 150,000 stars, recording a measurement every 30 minutes.

Analysis by UC Berkeley and University of Hawaii astronomers shows that one in five sun-like stars have potentially habitable, Earth-size planets. (Animation by UC Berkeley/UH-Manoa/Illumina Studios)

For a recent focused study, scientists concentrated on 42,000 sun-like stars (G and K type stars), looking for periodic dimmings that occur when a planet transits — or crosses in front of — its host star. A team of scientists from the Kepler mission and the Keck telescope in Hawaii have announced that from that survey, they found 603 planets, 10 of which are Earth size and orbit in the habitable zone, where conditions permit surface liquid water.

Since there are about 200 billion stars in our galaxy, with 40 billion of them like our Sun, noted planet-hunter Geoff Marcy said that gives us about 8.8 billion Earth-size planets in the Milky Way.

But Marcy also cautioned that Earth-size planets in Earth-size orbits are not necessarily hospitable to life, even if they orbit in the habitable zone of a star where the temperature is not too hot and not too cold.

“Some may have thick atmospheres, making it so hot at the surface that DNA-like molecules would not survive. Others may have rocky surfaces that could harbor liquid water suitable for living organisms,” Marcy said. “We don’t know what range of planet types and their environments are suitable for life.”

Analysis of four years of precision measurements from Kepler shows that 22±8% of Sun-like stars have Earth-sized planets in the habitable zone. If these planets are as prevalent locally as they are in Kepler field, then the distance to the nearest one is around 12 light-years.Credit: Petigura/UC Berkeley, Howard/UH-Manoa, Marcy/UC Berkeley.

All of the potentially habitable planets found in their survey are around K stars, which are cooler and slightly smaller than the sun, Petigura said. But the team’s analysis shows that the result for K stars can be extrapolated to G stars like the sun.

The Kepler spacecraft is now crippled because of faulty gyroscopes, but scientists say had Kepler survived for an extended mission, it would have obtained enough data to directly detect a handful of Earth-size planets in the habitable zones of G-type stars.

If the stars in the Kepler field are representative of stars in the solar neighborhood, then the nearest (Earth-size) planet is expected to orbit a star that is less than 12 light-years from Earth and can be seen by the unaided eye. Future instrumentation to image and take spectra of these Earths need only observe a few dozen nearby stars to detect a sample of Earth-size planets residing in the habitable zones of their host stars.

“For NASA, this number – that every fifth star has a planet somewhat like Earth – is really important, because successor missions to Kepler will try to take an actual picture of a planet, and the size of the telescope they have to build depends on how close the nearest Earth-size planets are,” said Andrew Howard, astronomer with the Institute for Astronomy at the University of Hawaii. “An abundance of planets orbiting nearby stars simplifies such follow-up missions.”

Further reading: Institute for Astronomy, University of Hawaii; UC Berkeley; Keck Observatory; NASA; PNAS.

September 3, 2013December 23, 2015 by Jason Major

Kepler Can Still Hunt For Earth-Sized Exoplanets, Researchers Suggest

Illustration of the Kepler spacecraft. Kepler's mission is over, but all of the exoplanets it found still need to be confirmed in follow-up observations. (NASA/Kepler mission/Wendy Stenzel)

Kepler may not be hanging up its planet-hunting hat just yet. Even though two of its four reaction wheels — which are crucial to long-duration observations of distant stars — are no longer operating, it could still be able to seek out potentially-habitable exoplanets around smaller stars. In fact, in its new 2-wheel mode, Kepler might actually open up a whole new territory of exoplanet exploration looking for Earth-sized worlds orbiting white dwarfs.

An international team of scientists, led by Mukremin Kilic of the University of Oklahoma’s Department of Physics and Astronomy, are suggesting that NASA’s Kepler spacecraft should turn its gaze toward dim white dwarfs, rather than the brighter main-sequence stars it was previously observing.

“A large fraction of white dwarfs (WDs) may host planets in their habitable zones. These planets may provide our best chance to detect bio-markers on a transiting ex- oplanet, thanks to the diminished contrast ratio between the Earth-sized WD and its Earth-sized planets. The James Webb Space Telescope is capable of obtaining the first spectroscopic measurements of such planets, yet there are no known planets around WDs. Here we propose to take advantage of the unique capability of the Kepler space- craft in the 2-Wheels mode to perform a transit survey that is capable of identifying the first planets in the habitable zone of a WD.”

– Kilic et al.

Any bio-markers — such as molecular oxygen, O2 — could later be identified around such Earth-sized exoplanets by the JWST, they propose.

Will Kepler be able to find the first Earth-sized exoplanet orbiting a white dwarf? (Illustration of Kepler 22b. Credit: NASA/Ames/JPL-Caltech) — Will Kepler be able to find the first Earth-sized exoplanet — or even an exomoon — orbiting a white dwarf? (Illustration of Kepler 22b. Credit: NASA/Ames/JPL-Caltech)

Because Kepler’s precision has been greatly reduced by the failure of a second reaction wheel earlier this year, it cannot accurately aim at large stars for the long periods of time required to identify the minute dips in brightness caused by the silhouetted specks of passing planets. But since white dwarfs — the dim remains of stars like our Sun — are much smaller, any eclipsing exoplanets would make a much more pronounced effect on their apparent luminosity.

In effect, exoplanets ranging from Earth- to Jupiter-size orbiting white dwarfs as close as .03 AU — well within their habitable zones — would significantly block their light, making Kepler’s diminished aim not so much of an issue.

“Given the eclipse signature of Earth-size and larger planets around WDs, the systematic errors due to the pointing problems is not the limiting factor for WDHZ observations,” the team assures in their paper “Habitable Planets Around White Dwarfs: an Alternate Mission for the Kepler Spacecraft.”

Even smaller orbiting objects could potentially be spotted in this fashion, they add… perhaps even as small as the Moon.

The team is proposing a 200-day-long survey of 10,000 known white dwarfs within the Sloan Digital Sky Survey (SDSS) area, and expects to find up to 100 exoplanet candidates as well as other “eclipsing short period stellar and sub-stellar companions.”

“If the history of exoplanet science has taught us anything, it is that planets are ubiquitous and they exist in the most unusual places, including very close to their host stars and even around pulsars… Currently there are no known planets around WDs, but we have never looked at a sufficient number of WDs at high cadence to find them through transit observations.”

– Kilic et al.

Read the team’s full report here, and learn more about the Kepler mission here.

NASA’s Ames Research Center made an open call for proposals regarding Kepler’s future operations on August 2. Today is the due date for submissions, which will undergo a review process until Nov. 1, 2013.

Added 9/4: For another take on this, check out Paul Gilster’s write-up on Centauri Dreams.

July 17, 2013December 23, 2015 by David Dickinson

Water-Trapped Worlds Possible Around Red Dwarf Stars?

An artist's concept of a rocky world orbiting a red dwarf star. (Credit: NASA/D. Aguilar/Harvard-Smithsonian center for Astrophysics).

Hunters of alien life may have a new and unsuspected niche to scout out.

A recent paper submitted by Associate Professor of Astronomy at Columbia University Kristen Menou to the Astrophysical Journal suggests that tidally-locked planets in close orbits to M-class red dwarf stars may host a very unique hydrological cycle. And in some extreme cases, that cycle may cause a curious dichotomy, with ice collecting on the farside hemisphere of the world, leaving a parched sunward side. Life sprouting up in such conditions would be a challenge, experts say, but it is — enticingly — conceivable.

The possibility of life around red dwarf stars has tantalized researchers before. M-type dwarfs are only 0.075 to 0.6 times as massive as our Sun, and are much more common in the universe. The life span of these miserly stars can be measured in the trillions of years for the low end of the mass scale. For comparison, the Universe has only been around for 13.8 billion years. This is another plus in the game of giving biological life a chance to get underway. And while the habitable zone, or the “Goldilocks” region where water would remain liquid is closer in to a host star for a planet orbiting a red dwarf, it is also more extensive than what we inhabit in our own solar system.

Gliese 581- an example of a potential habitable zone around a red dwarf star contrasted with our own solar system. (Credit: ESO/Henrykus under a Wikimedia Creative Commons Attribution 3.0 Unported license).

But such a scenario isn’t without its drawbacks. Red dwarfs are turbulent stars, unleashing radiation storms that would render any nearby planets sterile for life as we know it.

But the model Professor Menou proposes paints a unique and compelling picture. While water on the permanent daytime side of a terrestrial-sized world tidally locked in orbit around an M-dwarf star would quickly evaporate, it would be transported by atmospheric convection and freeze out and accumulate on the permanent nighttime side. This ice would only slowly migrate back to the scorching daytime side and the process would continue.

Could these types of “water-locked worlds” be more common than our own?

The type of tidal locking referred to is the same as has occurred between the Earth and its Moon. The Moon keeps one face eternally turned towards the Earth, completing one revolution every 29.5 day synodic period. We also see this same phenomenon in the satellites for Jupiter and Saturn, and such behavior is most likely common in the realm of exoplanets closely orbiting their host stars.

The study used a dynamical model known as PlanetSimulator created at the University of Hamburg in Germany. The worlds modeled by the author suggest that planets with less than a quarter of the water present in the Earth’s oceans and subject to a similar insolation as Earth from its host star would eventually trap most of their water as ice on the planet’s night side.

Kepler data results suggest that planets in close orbits around M-dwarf stars may be relatively common. The author also notes that such an ice-trap on a water-deficient world orbiting an M-dwarf star would have a profound effect of the climate, dependent on the amount of volatiles available. This includes the possibility of impacts on the process of erosion, weathering, and CO₂ cycling which are also crucial to life as we know it on Earth.

Thus far, there is yet to be a true “short list” of discovered exoplanets that may fit the bill. “Any planet in the habitable zone of an M-dwarf star is a potential water-trapped world, though probably not if we know the planet possesses a thick atmosphere.” Professor Menou told Universe Today. “But as more such planets are discovered, there should be many more potential candidates.”

Hard times in harsh climes-an artist's conception of the daytime side of a world orbiting a red dwarf star. — Hard times in harsh climes-an artist’s conception of the daytime side of a world orbiting a red dwarf star. (Credit: NASA/JPL-Caltech).

Being that red dwarf stars are relatively common, could this ice-trap scenario be widespread as well?

“In short, yes,” Professor Menou said to Universe Today. “It also depends on the frequency of planets around such stars (indications suggest it is high) and on the total amount of water at the surface of the planet, which some formation models suggest should indeed be small, which would make this scenario more likely/relevant. It could, in principle, be the norm rather than the exception, although it remains to be seen.”

Of course, life under such conditions would face the unique challenges. The daytime side of the world would be subject to the tempestuous whims of its red dwarf host sun in the form of frequent radiation storms. The cold nighttime side would offer some respite from this, but finding a reliable source of energy on the permanently shrouded night side of such as world would be difficult, perhaps relying on chemosynthesis instead of solar-powered photosynthesis.

On Earth, life situated near “black smokers” or volcanic vents deep on the ocean floor where the Sun never shines do just that. One could also perhaps imagine life that finds a niche in the twilight regions of such a world, feeding on the detritus that circulates by.

Some of the closest red dwarf stars to our own solar system include Promixa Centauri, Barnard’s Star and Luyten’s Flare Star. Barnard’s star has been the target of searches for exoplanets for over a century due to its high proper motion, which have so far turned up naught.

The closest M-dwarf star with exoplanets discovered thus far is Gliese 674, at 14.8 light years distant. The current tally of extrasolar worlds as per the Extrasolar Planet Encyclopedia stands at 919.

This hunt will also provide a challenge for TESS, the Transiting Exoplanet Survey Satellite and the successor to Kepler due to launch in 2017.

Searching for and identifying ice-trapped worlds may prove to be a challenge. Such planets would exhibit a contrast in albedo, or brightness from one hemisphere to the other, but we would always see the ice-covered nighttime side in darkness. Still, exoplanet-hunting scientists have been able to tease out an amazing amount of information from the data available before- perhaps we’ll soon know if such planetary oases exist far inside the “snowline” orbiting around red dwarf stars.

Read the paper on Water-Trapped Worlds at the following link.

July 7, 2013December 23, 2015 by Ken Kremer

Opportunity rover marks Magic Moment on 10th Year since Launch with Mountain Goal in View

Opportunity rover’s view across Botany Bay to Solander Point – her next destination – as NASA celebrates 10 Years since blastoff for Mars on July 7, 2003. The rover will climb up Solander Point because it which may harbor clay minerals indicative of a past Martian habitable environment. This pancam mosaic was assembled from raw images taken on Sol 3348 (June 24, 2013.
Credit: NASA/JPL/Cornell/ASU/Marco Di Lorenzo/Ken Kremer (kenkremer.com)[/caption]

Today, NASA’s Opportunity rover marks a magical moment celebrating 10 years since launching to Mars on July 7, 2003 and with her impending Mountain destination filling the camera’s eye view.

The now legendary robot has vastly exceeded everyone’s expectations. Back in 2003 the science team promised us a mere 90 day ‘warranty’ following the suspenseful airbag landing on Jan. 24, 2004 at Meridiani Planum.

Today is Martian Day (or Sol) 3360. That amounts to a life expectancy and exploration ‘bonus’ of more than 37 times beyond the design lifetime.

Launch of NASA’s 2nd Mars Exploration Rover, Opportunity, aboard a Delta II Heavy rocket to Mars on July 7, 2003 at 11:18 p.m. EDT from Pad 17-B at Cape Canaveral Air Force Station, Fla. Credit: NASA

Opportunity’s twin sister Spirit blasted off three weeks earlier in June 2003 and continued functioning until 2010.

“I never thought we’d achieve nine months!” Principal Investigator Prof. Steve Squyres of Cornell University told me recently on the occasion of the rovers 9th anniversary on Mars in January 2013.

As you read this, the now decade old rover Opportunity is blazing a trail toward’s the oldest geological deposits she has ever explored – at a place called Solander Point, a raised ridge along the eroded rim of huge Endeavour Crater.

Opportunity has surpassed the halfway point in the traverse from the rim segment she has explored the past 22 months at ‘Cape York’ to her next rim segment destination at Solander.

From tip to tip, Cape York and Solander Point lie 1.2-mile (2-kilometer) apart along the western rim of Endeavour Crater. Both are raised portions of 14-mile-wide (22-kilometer-wide) Endeavour.

The rover has less than half a mile (800 meters) to go to finish the Martian dash from one rim segment to the next across an area called ‘Botany Bay’.

This view from July 2, 2013 (Sol 3355) shows the terrain that NASA's Mars Exploration Rover Opportunity is crossing in a flat area called "Botany Bay" on the way toward "Solander Point," which is visible on the horizon. Credit: NASA/JPL-Caltech — This view from July 2, 2013 (Sol 3355) shows the terrain that NASA’s Mars Exploration Rover Opportunity is crossing in a flat area called “Botany Bay” on the way toward “Solander Point,” which is visible on the horizon. Credit: NASA/JPL-Caltech

“We are making very good progress crossing ‘Botany Bay,’ said John Callas of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., who is project manager for the mission now entering its 2nd decade.

The flat terrain of fractured, light-toned bedrock is devoid of treacherous dunes and is easy to drive across, almost like a highway, which simplifies the daily planning by the rovers Earthly handlers.

“The surface that Opportunity is driving across in Botany Bay is polygonally fractured outcrop that is remarkably good for driving,” said Brad Joliff, an Opportunity science team member and long-term planner at Washington University in St. Louis. “The plates of outcrop, like a tiled mosaic pavement, have a thin covering of soil, not enough to form the wind-blown ripples we’ve had to deal with during some other long treks. The outcrop plates are light-toned, and the cracks between them are filled with dark, basaltic soil and our old friends the ‘blueberries.”

The “blueberries” are hematite-rich, erosion-resistant concretions about the size of BB’s that Opportunity discovered when she first opened her eyes at her Eagle crater landing site. During the multi year crater hopping tour that ensued, the rover continued finding patches of blueberries all the way to Endeavour crater.

1st color panorama taken by Opportunity after landing inside Eagle Crater on Jan. 24, 2004. Credit: NASA/JPL/Cornell

Opportunity is expected to arrive at Solander’s foothills sometime in August – before the onset of the next southern hemisphere Martian winter, her 6th altogether.

Opportunity will scale Solander to continue the science quest in search of additional evidence of habitable environments with the chemical ingredients necessary to sustain Martian microbial life.

“Right now the rover team is discussing the best way to approach and drive up Solander,” Ray Arvidson told Universe Today. Arvidson is the mission’s deputy principal scientific investigator from Washington University in St. Louis, Mo.

‘Solander Point’ offers roughly about a 10 times taller stack of geological layering compared to ‘Cape York.’

Solander also offers north facing slopes where Opportunity’s solar wings can more effectively soak up the sun’s rays to generate life giving electrical power.

The robot remains in excellent health.

The total driving distance exceeds 23 miles (37 kilometers). She has snapped over 181,000 images.

Meanwhile on the opposite side of Mars at Gale Crater, Opportunity’s younger sister rover Curiosity also discovered a habitable environment originating from a time when the Red Planet was far warmer and wetter billions of years ago.

And like Opportunity, Curiosity is also trekking towards a mountain rich in sedimentary layers, hoping to unveil the mysteries of Mars past.

Ken Kremer

Opportunity captures spectacular panoramic view ahead to her upcoming mountain climbing goal, the raised rim of “Solander Point” at right, located along the western edge of Endeavour Crater. It may harbor clay minerals indicative of a habitable zone. The rise at left is "Nobbys Head" which the rover just passed on its southward drive to Solander Point from Cape York. This pancam photo mosaic was taken on Sol 3335, June 11, 2013 shows vast expanse of the central crater mound and distant Endeavour crater rim. Credit: NASA/JPL/Cornell/ASU/Marco Di Lorenzo/Ken Kremer (kenkremer.com) See full panoramic scene below — Opportunity captures spectacular panoramic view ahead to her upcoming mountain climbing goal, the raised rim of “Solander Point” at right, located along the western edge of Endeavour Crater. It may harbor clay minerals indicative of a habitable zone. The rise at left is “Nobbys Head” which the rover just passed on its southward drive to Solander Point from Cape York. This pancam photo mosaic was taken on Sol 3335, June 11, 2013 shows vast expanse of the central crater mound and distant Endeavour crater rim. Credit: NASA/JPL/Cornell/ASU/Marco Di Lorenzo/Ken Kremer (kenkremer.com)

Traverse Map for NASA’s Opportunity rover from 2004 to 2013. This map shows the entire path the rover has driven during more than 9 years and over 3360 Sols, or Martian days, since landing inside Eagle Crater on Jan 24, 2004 to current location heading south to Solander Point from Cape York ridge at the western rim of Endeavour Crater. Credit: NASA/JPL/Cornell/ASU/Marco Di Lorenzo/Ken Kremer — Traverse Map for NASA’s Opportunity rover from 2004 to 2013
This map shows the entire path the rover has driven during more than 9 years and over 3360 Sols, or Martian days, since landing inside Eagle Crater on Jan 24, 2004 to current location heading south to Solander Point from Cape York ridge at the western rim of Endeavour Crater. Credit: NASA/JPL/Cornell/ASU/Marco Di Lorenzo/Ken Kremer

June 11, 2013December 23, 2015 by Ken Kremer

Opportunity Rover Discovers Martian Habitable Zone Favorable for Pre-biotic Chemistry

Opportunity captures a panoramic view of the road ahead to the raised rim of Solander Point (at left) which is some 0.8 mile (1.3 km) away. Arrival is targeted for August. It features a thick strata of ancient rocks which may harbor clay minerals indicative of a habitable zone and northerly tilted slopes to maximize power generation from the solar panels during upcoming 6th winter season at Endeavour crater rim. This navcam photo mosaic was taken on Sol 3330, June 6, 2013. Credit: NASA/JPL/Cornell//Marco Di Lorenzo/Ken Kremer (kenkremer.com)

On the cusp of the 10th anniversary since launching to the Red Planet, NASA’s long lived Opportunity rover has discovered a habitable zone on Mars that once coursed with ‘drinkable water’ and possesses the chemical ingredients necessary to support a path to potential Martian microbes.

At a rock called “Esperance”, Opportunity found a cache of phyllosilicate clay minerals that typically form in neutral, drinkable water that is not extremely acidic or basic.

The finding ranks as “One of my personal Top 5 discoveries of the mission,” said Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for NASA’s rover mission at a media briefing.

And despite her advancing age Opportunity remains healthy after surviving in excess of an incredible 3333 Sols, or days, trekking across the alien and ever harsh Martian crater plains.

Furthermore the intrepid robot just sat sail on a southerly course for a new destination called “Solander Point” where researches hope to find more even evidence of habitable environments since they already spotted deeper stakes of ancient rocks transformed by water eons ago. See our current photo mosaics showing Solander Point as Opportunity roves across the crater floor – above and below by Marco Di Lorenzo and Ken Kremer.

After weeks of trying, the rover deployed the robotic arm to drill at a sweet spot inside “Esperance” and collected convincing X-Ray spectroscopic data in the area she just investigated in May 2013 around the eroded rim of giant Endeavour Crater.

“Esperance is rich in clay minerals and shows powerful evidence of water alteration,” Squyres elaborated.

“This is the most powerful evidence we found for neutral pH water.”

“Clay minerals only tend to form at a more neutral pH. This is water you could drink,” Squyres gushed.

These finding represent the most favorable conditions for biology that Opportunity has yet seen in the rock histories it has encountered after nearly a decade roving the Red Planet.

“This is water that was much more favorable for things like pre-biotic chemistry – the kind of chemistry that could lead to the origin of life,” Squyres stated.

Opportunity snapped this color view of 'Solander Point' on June 1, 2013 (Sol 3325) looking south to her next destination which she should reach in august. The solar powered robot will spend the upcoming 6th winter season on northerly tilted slopes exploring the thick strata of ancient rocks. Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ. — Opportunity snapped this color view of ‘Solander Point’ on June 1, 2013 (Sol 3325) looking south to her next destination which she should reach in August. The solar powered robot will spend the upcoming 6th winter season on northerly tilted slopes exploring the thick strata of ancient rocks. Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.

Esperance is unlike any rock previously investigated by Opportunity; rich in aluminum, which is strongly indicative of clay minerals, perhaps like montmorillonite.

Most rocks inspected to date by Opportunity were formed in an environment of highly acidic water that is extremely harsh to most life forms.

“If you look at all of the water-related discoveries that have been made by Opportunity, the vast majority of them point to water that was a very low pH – it was acid,” Squyres explained.

Esperance was found on ‘Cape York’, a hilly segment of the western rim of Endeavour crater which spans 14 miles (22 km) across. The robot arrived at the edge of Endeavour crater in mid-2011 and will spend her remaining life driving around the scientifically rich crater rim segments.

The pale rock in the upper center of this image, about the size of a human forearm, includes a target called "Esperance," which was inspected by NASA's Mars Exploration Rover Opportunity. Data from the rover's alpha particle X-ray spectrometer (APXS) indicate that Esperance's composition is higher in aluminum and silica, and lower in calcium and iron, than other rocks Opportunity has examined in more than nine years on Mars. Preliminary interpretation points to clay mineral content due to intensive alteration by water. Credit: NASA/JPL-Caltech/Cornell/Arizona State Univ — The pale rock in the upper center of this image, about the size of a human forearm, includes a target called “Esperance,” which was inspected by NASA’s Mars Exploration Rover Opportunity. Data from the rover’s alpha particle X-ray spectrometer (APXS) indicate that Esperance’s composition is higher in aluminum and silica, and lower in calcium and iron, than other rocks Opportunity has examined in more than nine years on Mars. Preliminary interpretation points to clay mineral content due to intensive alteration by water. Credit: NASA/JPL-Caltech/Cornell/Arizona State Univ

NASA’s new Curiosity rover also recently discovered clay minerals and a habitable environment at Gale Crater – on the other side of Mars – stemming from a time when Mars was warmer and wetter billions of years ago.

Over time Mars became the cold and dry place it is today. Scientists hope the rovers provide clues to Mars dramatic transformation.

The solar powered rover is now driving as quick as possible to reach the northerly tilled slopes of ‘Solander Point’ in August, before the onset of the next Martian winter.

‘Solander Point’ offers a much taller stack of geological layering than ‘Cape York.’ Both areas are raised segments of the western rim of Endeavour Crater.

“There’s a lot to explore there. In effect, it’s a whole new mission,” said Ray Arvidson, the mission’s deputy principal scientific investigator from Washington University in St. Louis, Mo.

'Esperance' Target Examined by Opportunity in May 2013. The pale rock called "Esperance," has a high concentration of clay minerals formed in near neutral water indcating a spot favorable for life. Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ. — ‘Esperance’ Target Examined by Opportunity in May 2013. The pale rock called “Esperance,” has a high concentration of clay minerals formed in near neutral water indcating a spot favorable for life. Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.

Opportunity and her twin “Spirit” were launched to Mars on planned 90 day missions.

Both rovers have far exceeded everyone’s wildest expectations. Spirit endured more than 6 years inside Gusev Crater until succumbing to the bone chilling Martian winter in 2011.

Opportunity established a new American driving record for a vehicle on another world on May 15, 2013 (Sol 3309) and made history by driving ahead from this point at Cape York. This navcam mosaic shows the view forward to her next destinations of Solander Point and Cape Tribulation along the lengthy rim of huge Endeavour crater spanning 14 miles (22 km) in diameter. Opportunity discovered clay minerals at Cape York and stands as the most favorable location for Martian biology discovered during her entire nearly 10 year long mission to Mars. Credit: NASA/JPL/Cornell/Kenneth Kremer/Marco Di Lorenzo — NASA’s Opportunity Mars rover discovered clay minerals at Cape York ridge along the rim of Endeavour crater – seen in this photo mosaic – which stands as the most favorable location for Martian biology discovered during her entire nearly 10 year long mission to Mars. Opportunity also established a new American driving record for a vehicle on another world on May 15, 2013 (Sol 3309) and made history by driving ahead from this point at Cape York. This navcam photo mosaic shows the view forward to her next destinations of Solander Point and Cape Tribulation along the lengthy rim of huge Endeavour crater spanning 14 miles (22 km) in diameter.
Credit: NASA/JPL/Cornell/Ken Kremer (kenkremer.com)/Marco Di Lorenzo

Opportunity has lasted more than 37 times beyond the three month “warranty”.

“This is like your car not lasting 200,000 miles, or even a million miles. You’re talking about a car that lasts 2 million miles without an oil change,” Callas said. “At this point, how long Opportunity lasts is anyone’s guess.”

“Remember, the rover continues to operate in a very hostile environment, where we have extreme temperature changes every day, and the rover could have a catastrophic failure at anytime,” said John Callas, of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., project manager for the Mars Exploration Rover Project.

“So every day is a gift.”

And don’t forget to “Send Your Name to Mars” aboard NASA’s MAVEN orbiter- details here. Deadline: July 1, 2013

Ken Kremer

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Learn more about Mars, Curiosity, Opportunity, MAVEN, LADEE, CIBER, Conjunctions and NASA missions at Ken’s upcoming lecture presentations

June 11: “Send your Name to Mars on MAVEN” and “LADEE Lunar & Antares Rocket Launches from Virginia”; NJ State Museum Planetarium and Amateur Astronomers Association of Princeton (AAAP), Trenton, NJ, 730 PM.

June 12: “Send your Name to Mars on MAVEN” and “LADEE Lunar & Antares Rocket Launches from Virginia”; Franklin Institute and Rittenhouse Astronomical Society, Philadelphia, PA, 8 PM.

June 23: “Send your Name to Mars on MAVEN” and “CIBER Astro Sat, LADEE Lunar & Antares Rocket Launches from Virginia”; Rodeway Inn, Chincoteague, VA, 8 PM

Opportunity captures the eerie Martian scenery looking south across Botany Bay from the southern tip of Cape York to her next destination - Solander Point, about 1 mile (1.6 km) away. This navcam photo mosaic was taken on Sol 3317, May 23, 2013. Credit: NASA/JPL/Cornell//Marco Di Lorenzo/Ken Kremer (kenkremer.com) — Opportunity captures the eerie Martian scenery looking south across Botany Bay from the southern tip of Cape York to her next destination – Solander Point, about 1 mile (1.6 km) away. This navcam photo mosaic was taken on Sol 3317, May 23, 2013. Credit: NASA/JPL/Cornell//Marco Di Lorenzo/Ken Kremer (kenkremer.com)

January 14, 2013December 23, 2015 by Jason Major

A Moon With Two Suns: Making Art from Science

A view of Kepler 47c and binary stars. ©Digital Drew. All rights reserved.

What would it look like on a hypothetical icy moon orbiting the exoplanet Kepler 47c? Perhaps something like this.

This is an illustration by an artist who goes by the name Digital Drew on Flickr. Drew creates landscapes of imagined alien worlds orbiting stars (and sometimes planets) that actually exist in the Universe. With 3D software, a little science and a lot of imagination, Drew shows us what skies might look like on other planets.

Kepler 47c (KOI-3154.02) is a Neptune-sized exoplanet orbiting a binary star pair 4,600 light-years away. It is part of the first circumbinary system ever discovered — one of at least two planets orbiting a pair of stars. In the image here, Kepler 47c is seen at upper left.

What makes this exoplanet so exciting is that it is within the habitable zone around the stellar pair. So even though the planet itself may be a gas giant and thus not particularly suitable for life, any moons it has in orbit just might be.

While its slightly smaller planetary companion Kepler 47b orbits much too closely to the twin suns for water to exist as a liquid, 47c’s orbit is much farther out, completing one revolution every 303 days. Mainly illuminated by a star like our Sun but about 15% dimmer, this is a region where you could very well find a large rocky moon with conditions similar to Earth’s.

Fly a spacecraft over its higher elevations and you just might see a scene like this, a double sunset over a glacier-filled valley with a crescent gas giant dominating the sky. (Makes one wonder what the balmier regions might look like!)

“Unlike our sun, many stars are part of multiple-star systems where two or more stars orbit one another. The question always has been — do they have planets and planetary systems? This Kepler discovery proves that they do. In our search for habitable planets, we have found more opportunities for life to exist.”

– William Borucki, Kepler mission principal investigator (Sept. 2012)

And as more giant planets are discovered within their system’s habitable zones, the more there’s a chance that habitable moons could exist — or perhaps even be more common than habitable planets! Just recently the citizen science project Planet Hunters announced the potential exoplanet PH2 b, a Jupiter-sized world that orbits within a habitable zone. In our Solar System Jupiter has lots of moons; PH2 b could very well have a large number of moons of its own, any number of them with liquid water on their surfaces and temperatures “just right” for life.

While it will likely be quite some time before we see any direct observations of an actual exomoon, and possibly never from one, we must rely on the work of artists like Digital Drew to illustrate the many possibilities that exist.

See more of Drew’s work on his Flickr page here, and read more about the discovery of the Kepler 47 system here.

Inset image: Diagram of the Kepler 47 system compared to the inner Solar System. Credit: NASA/JPL-Caltech/T. Pyle.

November 8, 2012December 23, 2015 by Jason Major

Astronomers Find Tantalizing Hints of a Potentially Habitable Exoplanet

Dwarf star HD 40307 is now thought to host at least 6 exoplanet candidates… one of them well within its habitable zone. (G. Anglada/Celestia)

Located 43 light-years away in the southern constellation Pictor, the orange-colored dwarf star HD 40307 has previously been found to hold three “super-Earth” exoplanets in close orbit. Now, a team of researchers poring over data from ESO’s HARPS planet-hunting instrument are suggesting that there are likely at least six super-Earth exoplanets orbiting HD 40307 — with one of them appearing to be tucked neatly into the star’s water-friendly “Goldilocks” zone.

HARPS (High Accuracy Radial velocity Planet Searcher) on ESO’s La Silla 3.6m telescope is a dedicated exoplanet hunter, able to detect the oh-so-slight wobble of a star caused by the gravitational tug of orbiting planets. Led by Mikko Tuomi of the UK’s University of Hertfordshire Centre for Astrophysics Research, a team of researchers reviewed publicly-available data from HARPS and has identified what seems to be three new exoplanets in the HD 40307 systems. The candidates, designated with the letters e, f, and g, all appear to be “super Earth” worlds… but the last one, HD 40307 g, is what’s getting people excited, as the team has calculated it to be orbiting well within the region where liquid water could exist on its surface — this particular star’s habitable zone.

In addition, HD 40307 g is located far enough away from its star to likely not be tidally locked, according to the team’s paper. This means it wouldn’t have one side subject to constant heat and radiation while its other “far side” remains cold and dark, thus avoiding the intense variations in global climate, weather and winds that would come as a result.

“The star HD 40307, is a perfectly quiet old dwarf star, so there is no reason why such a planet could not sustain an Earth-like climate.”
– Guillem Anglada-Escudé, co-author.

“If the signal corresponding to HD 40307 g is a genuine Doppler signal of planetary origin, this candidate planet might be capable of supporting liquid water on its surface according to the current definition of the liquid water habitable zone around a star and is not likely to suffer from tidal locking.” (Tuomi et al.)

If HD 40307 g is indeed confirmed, it may very well get onto the official short list of potentially habitable worlds outside our Solar System — although those others are quite a bit closer to the mass of our own planet.

UPDATE: HD 40307 g has been added to the Planetary Habitability Laboratory’s Habitable Exoplanets Catalog, maintained by the PHL at the University of Puerto Rico at Arecibo. It’s now in 4th place of top exoplanets of interest based on similarity to Earth. According to Professor Abel Mendez Torres of the PHL, “Average temperatures might be near 9°C (48°F) assuming a similar scaled-up terrestrial atmosphere. It might also experience strong seasonal surface temperature shifts between -17° to 52°C (1.4° to 126°F) due to its orbital eccentricity. Nevertheless, these extremes are tolerable by most complex life, as we know it.” (Read more here.)

While the other planetary candidates in the HD 40307 system are positioned much more closely to the star, with b, c, d, and e within or at the equivalent orbital distance of Mercury, g appears to be in the star’s liquid-water habitable zone, orbiting at 0.6 AU in an approximately 200-day-long orbit. At this distance the estimated 7-Earth-mass exoplanet receives around 62-67% of the radiation that Earth gets from the Sun.

Representation of the liquid water habitable zone around HD 40307 compared to our Solar System (Tuomi et al., from the team’s paper.)

Although news like this is exciting, as we’re always eagerly anticipating the announcement of a true, terrestrial Earthlike world that could be host to life as we know it, it’s important to remember that HD 40307 g is still a candidate — more observations are needed to not only confirm its existence but also to find out exactly what kind of planet it may be.

“A more detailed characterization of this candidate is very unlikely using ground based studies because it is very unlikely [sic] to transit the star, and a direct imaging mission seems the most promising way of learning more about its possible atmosphere and life-hosting capabilities,” the team reports.

Read: How Well Can Astronomers Study Exoplanet Atmospheres?

Still, just finding potential Earth-sized worlds in a system like HD 40307’s is a big deal for planetary scientists. This system is not like ours, yet somewhat similar planets have still formed… that in itself is a clue to what else may be out there.

“The planetary system around HD 40307 has an architecture radically different from that of the solar system… which indicates that a wide variety of formation histories might allow the emergence of roughly Earth-mass objects in the habitable zones of stars.”

The team’s paper will be published in the journal Astronomy & Astrophysics. http://arxiv.org/pdf/1211.1617v1.pdf

Another researcher on the team, Guillem Anglada-Escudé of Germany’s Universität Göttingen, assembled this tour of the HD 40307 system (not including g) via Celestia.

Inset image: current potentially habitable exoplanets. Credit: PHL @ UPR Arecibo.