A Tale of Three Moons: Is There Life in the Outer Solar System?

The cracked ice surface of Europa. Credit: NASA/JPL

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Until fairly recently, the search for life elsewhere in the solar system has focused primarily on Mars, as it is the most Earth-like of all the other planets in the solar system. The possibility of finding any kind of life farther out in the outer solar system was considered very unlikely at best; too cold, too little sunlight, no solid surfaces on the gas giants and no atmospheres to speak of on any of the moons apart from Titan.

But now, some of the places that were previously considered the least likely to hold life have turned out to be perhaps some of the most likely to provide habitable environments. Moons that were thought be cold and frozen for eons are now known to be geologically active, in surprising ways. One of them is the most volcanically active place known in the solar system. At least two others appear to have oceans of liquid water beneath their surfaces. That’s right, oceans. And geysers. On the surface, they are ice worlds, but below, they are water worlds. Then there’s the one with rain, rivers, lakes and seas, but made of liquid methane instead of water. Billions of kilometres farther out from the Sun than the Earth. Who would have thought? Let’s look at those last three in a bit more detail…

Ever since the film 2001: A Space Odyssey first came out, Europa has been the subject of fascination. A small, icy moon orbiting Jupiter, its depiction in that movie, as an inhabited world beneath its ice crust was like a sort of foreshadowing, before the Voyager and Galileo spacecraft gave us our first real close-up looks of this intriguing place. Its surface shell of ice is covered with long cracks and fissures, giving it an appearance much like ice floes at the poles on Earth. More surprising though, was the discovery that, also like on Earth, this ice cover most likely is floating on top of a deep layer of liquid water below. In Europa’s case though, the water layer appears to cover the entire moon, a global subsurface ocean. How is this possible? If there is liquid water, there must be heat (or high concentrations of salts or ammonia), and if you have water and heat, could there be something living in those waters? Gravitational tugging from Jupiter indeed appears to provide enough heat to keep the water liquid instead of frozen. The environment is now thought to be similar to ocean bottoms on Earth. No sunlight, but if there are volcanic vents generating heat and minerals, as on Earth, such a spot could be ideal for at least simple forms of life. On Earth, places like these deep in the oceans are brimming with organisms which don’t require sunlight to survive.

Water vapour geysers on Enceladus. Credit: NASA/JPL

Then there’s Enceladus. Another very small icy moon, orbiting Saturn. Geological activity was considered very unlikely on such a tiny world, only a few hundred kilometres in diameter. But then Cassini saw the geysers, plumes of material erupting from the south polar region through large, warmer cracks nicknamed “tiger stripes.” Cassini has now flown directly through the geysers, analyzing their composition, which is mostly water vapour, ice particles, salts and organics. The latest analysis based on the Cassini data indicates that they almost certainly originate from a sea or ocean of liquid water below the surface. Warm, salty water loaded with organics; could Enceladus be another possible niche for extraterrestrial life? As with Europa, only further missions will be able to answer these questions, but the possibilities are exciting.

Radar image of one of many methane lakes on Titan. Credit: NASA/JPL

Titan is even more fascinating in some ways, the largest moon of Saturn. It is perpetually shrouded in a thick smoggy atmosphere of nitrogen and methane, so the surface has never been visible until now, when Cassini, and its small lander probe Huygens, first looked below the smog and clouds. Titan is like an eerily alien version of Earth, with rain, rivers, lakes and seas, but being far too cold for liquid water (not much heat here), its “water cycle” is composed of liquid methane/ethane. Appearance-wise, the surface and geology look amazingly Earth-like, but the conditions are uniquely Titan. For that reason, it has long been considered that the chances of any kind of life existing here are remote at best. In the last few years however, some scientists are starting to consider the possibility of life forming in just such environments, using liquids other than water, even in such cold conditions. Could life occur in a liquid methane lake or sea? How would it differ from water-based life? Last year, a discovery was made which might be interpreted as evidence of methane-based life on Titan – a seeming disappearance of hydrogen from the atmosphere near the surface and a lack of acetylene on the surface. Previous theoretical studies had suggested that those two things, if ever found, could be evidence for methane-based lifeforms consuming the hydrogen and acetylene. All of this is still highly speculative, and while a chemical explanation is probably more likely according to the scientists involved, a biological one cannot be ruled out yet. Future proposed missions for Titan include a floating probe to land in one of the lakes and a balloon to soar over the landscape, pursuing such mysteries as never before. How cool is that?

Oh, and the moon that is the most volcanically active place in the solar system? Io, although with the only known forms of liquid there being extremely hot lavas on that sulfuric hothouse, the chances of life are still thought to be unbelievably slim. But that’s ok when you start to find out that worlds with oceans and lakes, etc. may be much more common than previously imagined…

Mystery of the Martian Rilles

Credit: ASU / NASA / JPL

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When the first spacecraft flew by Mars in the 1960’s, the images returned revealed a relatively uninteresting-looking place, featureless in some areas and pockmarked with craters in most others. It looked a lot like the Moon. Later flybys and orbiting probes, however, gave us a closer look at other regions on the planet, providing a glimpse of what Mars is really like: a world of mountains, volcanoes, canyons, craters, old riverbeds and polar ice caps. It is little surprise then, that these striking geologic features captured scientists’ attention the most, and so areas like Hesperia Planum, a flat, relatively dull-looking plain, have received less attention over the years.

But there is a mystery in this region in the form of geologic features called rilles. No one has been able to figure out where they came from or how they formed.

 The rilles in Herperia Planum are a series of about a dozen narrow, sinuous channels. They are up to a few hundred meters wide, and hundreds of kilometers long, but don’t appear to have any sources or destinations. The assumption has been that they were most likely created by lava flows, like their counterparts on the Moon. But apart from one very small volcano, there is little evidence of any volcanism in Hesperia Planum, which makes the appearance these rilles difficult to explain.

Another explanation could be water, but again, there are no obvious sources or other indications of past water in this region.

These enigmatic features have been the subject of study by scientists from the University at Buffalo, State University of New York. Geologist Tracy Gregg and her student Carolyn Roberts have been comparing them to rilles on the Moon, and their preliminary findings were presented today at the Annual Meeting of The Geological Society of America, in Minneapolis, and they hope to find some answers in further study and collaboration with other scientists.

“On the Moon we see these same kinds of features and we know that water couldn’t have formed them there,” Gregg said. “Everybody assumed these were huge lava flows, But if it turns out to be a lake deposit, it’s a very different picture of what Mars was doing at that time.”

So, were they formed by water, lava or something else? If it turned out to be water, that would of course be more interesting in terms of the search for possible habitable areas in Mars’ past.

Whichever explanation turns out to be correct, or even a different one, it will be one more piece of evidence which helps to further our understanding of this fascinating world, so much like our own in some ways, yet utterly alien in others

The paper is available here and additional photos are here.

Source: EurekAlert

A Meteorite Visits the Comettes

This 88-gram (3.5 oz.) meteorite broke through the roof of the Comette family

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When your last name is Comette, I’m sure the occasional astronomy-themed joke is never far away. But it’s no joke that the Comette family living in Draveil, a suburb south of Paris, was paid a visit by a real extraterrestrial a couple of weeks ago – in the form of an 88-gram (3.5 oz.) meteorite that broke through their roof!

The Comettes were on vacation at the time, so didn’t realize their house had been struck by a space rock until they noticed a leak in the roof. When they called in a roofer it was discovered that a thick tile had been completely broken through.

The meteorite was found wedged in insulation.

Mineral scientist Alain Carion investigated the meteorite and determined that it’s an iron-rich chondrite, a 4.57-billion-year-old remnant of the early Solar System that most likely came from the main asteroid belt between the orbits of Mars and Jupiter. About 3/4 of all meteorites that have been observed landing on Earth are chondrites.

While obviously not impossible, the odds of your home being hit my a meteorite are incredibly slim. Only 145 meteorites have been documented landing in the US in the past 200 years. On March 26, 2003, just before midnight, hundreds of fragments of a large meteorite fell in the Park Forest area of Chicago. Several fell through roofs of houses and one punched a hole in the roof of the fire station. One large piece weighing about 2.5 kg (5.5 lb) crashed into a bedroom, narrowly missing a boy who was asleep in his bed! On September 23, 2003, a 20 kg (44 lb) stone meteorite tore straight through a two-storey house in New Orleans and came to rest in the basement. (Source: University of New Mexico Institute of Meteoritics.)

Only about 50 meteorites have been found in France over the past four centuries, and none has ever before been discovered less than 80 km (50 miles) from Paris.

While they could attempt to sell the meteorite that struck their home, possibly fetching several hundred euros for it, the Comettes have decided to keep their otherworldly visitor.

“A piece of the history of space of which we know nothing, but which is fascinating, has fallen on us,” Mrs. Comette told the Le Parisien newspaper. “It’s like a fairytale, and less likely than winning the lottery, we’re told.”

Read more on The Guardian or on The Local.

Image found on Stargazers Lounge.

The Cassini Image Hall of Fame

 

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If you’re reading this, you’re probably very well aware of the Cassini mission. Launched in 1997, the Cassini spacecraft arrived at Saturn in June of 2004 and has been faithfully returning image after beautiful image of Saturn, its rings and its very extended family of moons ever since – not to mention all the groundbreaking scientific discoveries it’s made about the Saturnian system… and our solar system as a whole. Cassini truly is a rock star in the world of robotic space exploration, and now it has its own Hall of Fame to show off some of its best work!

The Cassini mission site put up by JPL/Caltech regularly features news and images from the mission, even including the latest downlinked raw image data from the spacecraft. In this way anyone can keep up with what Cassini is seeing and when, far before the images are included in NASA’s Planetary Data System. The new Cassini Image Hall of Fame showcases the “best of the best” from the mission, and is a great way to revisit Cassini’s past discoveries. (With so much happening at Saturn, sometimes it’s easy to forget all the amazing things Cassini has brought to our attention!)

Revisit the best of the best images of Saturn

If you’re a fan of Saturn (and really, who isn’t?) be sure to check this out. With the current mission extended into 2017 there’s sure to be lots more additions to the Hall of Fame on the way, too!

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

Click here to see the Hall of Fame images.

Also, be sure to visit the hard-working Cassini imaging team’s homepage at http://ciclops.org… they are the ones responsible for all these fantastic images in the first place!

 

Astronomers Discover a Dark Alien World

Artist's rendering of TrES-2b, an extremely dark gas giant. Credit: David Aguilar (CfA)

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An exoplanet has been discovered by astronomers that reflects less than one percent of the light it receives from its parent star. Less reflective than black acrylic paint, this planet is literally darker than coal!

TrES-2b is a Jupiter-sized gas giant orbiting the star GSC 03549-02811, about 750 light-years away in the direction of the constellation Draco. First discovered in 2006 by the Trans-Atlantic Exoplanet Survey (TrES), its unusual darkness has been identified by researchers led by David Kipping from the Harvard-Smithsonian Center for Astrophysics (CfA) and David Spiegel from Princeton University, using data from NASA’s Kepler spacecraft.

Kepler has located more than 1,200 planetary candidates in its field of view. Additional analysis will reveal whether any other unusually dark planets lurk in that data. (Image: NASA/Kepler mission/Wendy Stenzel)

The team monitored the brightness of the TrES-2 system as the planet orbited its star and detected a subtle dimming and brightening due to the planet’s changing phase. A more reflective planet would have shown larger brightness variations as its phase changed.

The dark exoplanet is tidally locked with its star and orbits it at a distance of only 5 million kilometers (3.1 million miles), keeping it heated to a scorching 1000º C (1,832º F). Too hot for the kinds of reflective ammonia clouds seen on Jupiter, TrES-2b is wrapped in an atmosphere containing light-absorbing chemicals like vaporized sodium and potassium, or gaseous titanium oxide. Still, this does not completely explain its extremely dark appearance.

“It’s not clear what is responsible for making this planet so extraordinarily dark,” stated co-author David Spiegel of Princeton University. “However, it’s not completely pitch black. It’s so hot that it emits a faint red glow, much like a burning ember or the coils on an electric stove.”

Regardless of its faint glow TrES-2b is still much darker than any planet or moon in our solar system.

The new work appears in a paper in the journal Monthly Notices of the Royal Astronomical Society. Read the news release here.

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Jason Major is a graphic designer, photo enthusiast and space blogger. Visit his website Lights in the Dark and follow him on Twitter @JPMajor and on Facebook for more astronomy news and images!

Juno Blasts off on Science Trek to Discover Jupiter’s Genesis

JUNO blasts off for Jupiter on Aug. 5 from Cape Canaveral Air Force Station at 12:25 p.m. EDT. Credit: Alan Walters (awaltersphoto.com)

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NASA’s solar powered Juno spacecraft blasted off today (Aug.5)from Cape Canaveral today to begin a 2.8 billion kilometer science trek to discover the genesis of Jupiter hidden deep inside the planet’s interior.

Upon arrival at Jupiter in July 2016, JUNO will fire its braking rockets and go into polar orbit and circle the planet 33 times over about one year. The goal is to find out more about the planets origins, interior structure and atmosphere, observe the aurora, map the intense magnetic field and investigate the existence of a solid planetary core.

The spacecraft is healthy and the solar panels successfully deployed.

Check out the photo album of Juno’s launch from the Universe Today team of Alan Walters and Ken Kremer.

“Jupiter is the Rosetta Stone of our solar system,” said Scott Bolton, Juno’s principal investigator from the Southwest Research Institute in San Antonio. “It is by far the oldest planet, contains more material than all the other planets, asteroids and comets combined and carries deep inside it the story of not only the solar system but of us. Juno is going there as our emissary — to interpret what Jupiter has to say.”

Juno was launched atop a powerful Atlas V rocket augmented by 5 solid rocket boosters – built by United Launch Alliance

JUNO blasts off for Jupiter on Aug. 5. Credit: Alan Walters (awaltersphoto.com)

“Today, with the launch of the Juno spacecraft, NASA began a journey to yet another new frontier,” NASA Administrator Charles Bolden said. “The future of exploration includes cutting-edge science like this to help us better understand our solar system and an ever-increasing array of challenging destinations.”

Juno Launch - View from the VAB Roof
Atlas V liftoff with JUNO to Jupiter on Aug. 5 from Cape Canaveral Air Force Station. Credit: Ken Kremer
Juno Launch - View from the VAB Roof
Atlas V liftoff with JUNO to Jupiter on Aug. 5 from Cape Canaveral Air Force Station. Credit: Ken Kremer (kenkremer.com)
Juno Launch - View from the VAB Roof
JUNO blasts off for Jupiter on Aug. 5 atop an Atlas V rocket from Cape Canaveral Air Force Station at 12:25 p.m. EDT.

Credit: Ken Kremer (kenkremer.com)

Send Ken your Juno launch photos to post at Universe Today

Read my continuing features about Juno
Juno Jupiter Orbiter poised at Launch Pad for Aug. 5 Blastoff
JUNO Orbiter Mated to Mightiest Atlas rocket for Aug. 5 Blastoff to Jupiter
Solar Powered Jupiter bound JUNO lands at Kennedy Space Center

JUNO Orbiter Mated to Mightiest Atlas rocket for Aug. 5 Blastoff to Jupiter

Hoisting Juno at Launch Pad 41 to bolt atop most powerful Atlas Rocket. At Space Launch Complex 41, a crane is lowered over the nose of the Atlas payload fairing enclosing the Juno spacecraft in preparation for its lift to the top of the Atlas rocket stacked in the Vertical Integration Facility. Juno is scheduled to launch Aug. 5 aboard the most powerful ever United Launch Alliance Atlas V rocket from Cape Canaveral Air Force Station in Florida. The solar-powered spacecraft will orbit Jupiter's poles 33 times to find out more about the gas giant's origins, structure, atmosphere and magnetosphere and investigate the existence of a solid planetary core. Credit: NASA/Cory Huston

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In less than one week’s time, NASA’s $1.1 Billion Juno probe will blast off on the most powerful Atlas V rocket ever built and embark on a five year cruise to Jupiter where it will seek to elucidate the mysteries of the birth and evolution of our solar system’s largest planet and how that knowledge applies to the remaining planets.

The stage was set for Juno’s liftoff on August 5 at 11:34 a.m. after the solar-powered spacecraft was mated atop the Atlas V rocket at Space Launch Complex 41 at Cape Canaveral and firmly bolted in place at 10:42 a.m. EDT on July 27.

“We’re about to start our journey to Jupiter to unlock the secrets of the early solar system,” said Scott Bolton, the mission’s principal investigator from the Southwest Research Institute in San Antonio. “After eight years of development, the spacecraft is ready for its important mission.”

Inside the Vertical Integration Facility at Space Launch Complex 41, the Juno spacecraft, enclosed in an Atlas payload fairing, is in position on top of its Atlas launch vehicle. The spacecraft was prepared for launch in the Astrotech Space Operations' payload processing facility in Titusville, Fla. Credit: NASA/Cory Huston

The launch window for Juno extends from Aug. 5 through Aug. 26. The launch time on Aug. 5 opens at 11:34 a.m. EDT and closes at 12:43 p.m. EDT. Juno is the second mission in NASA’s New Frontiers program.

JUNO’s three giant solar panels will unfurl about five minutes after payload separation following the launch, said Jan Chodas, Juno’s project manager at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif.

The probe will cartwheel through space during its five year trek to Jupiter.

Upon arrival in July 2016, JUNO will fire its braking rockets and go into polar orbit and circle Jupiter 33 times over about one year. The goal is to find out more about the planet’s origins, interior structure and atmosphere, observe the aurora, map the intense magnetic field and investigate the existence of a solid planetary core.

Hoisting Juno inside the payload fairing at Space Launch Complex 41. Credit: NASA/Cory Huston

“Juno will become the first polar orbiting spacecraft at Jupiter. Not only are we over the poles, but we’re getting closer to Jupiter in our orbit than any other spacecraft has gone,” Bolton elaborated at a briefing for reporters at the Kennedy Space Center. “We’re only 5,000 kilometers above the cloud tops and so we’re skimming right over those cloud tops and we’re actually dipping down beneath the radiation belts, which is a very important thing for us. Because those radiation belts at Jupiter are the most hazardous region in the entire solar system other than going right to the sun itself.”

“Jupiter probably formed first. It’s the largest of all the planets and in fact it’s got more material in it than all the rest of the solar system combined. If I took everything in the solar system except the sun, it could all fit inside Jupiter. So we want to know the recipe.”

Watch for my continuing updates and on-site launch coverage of Juno, only the 2nd probe from Earth to ever orbit Jupiter. Galileo was the first.

Hubble: One in a Million

For those of you bummed that Hubble’s one millionth observation didn’t include an eye-popping image, Daniel Pendick from the Geeked on Goddard Blog has put together a video of over 200 classic Hubble images, with the funky music from the “Planets” album by the band One Ring Zero. “Planets” is a collection of new compositions to represent the solar system and beyond. Gustav Holst its not, but it is “an eclectic and quirky journey from Mercury to Pluto, with influences as diverse as gypsy violin, Pink Floyd and David Bowie, Electric Light Orchestra, and even klezmer,” said Pendick on the 365 Days of Astronomy podcast. Enjoy!

Hello, Helene!

Color composite of Helene from June 18, 2011 flyby. NASA / JPL / SSI / J. Major

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On June 18, 2011, the Cassini spacecraft performed a flyby of Saturn’s moon Helene. Passing at a distance of 6,968 km (4,330 miles) it was Cassini’s second-closest flyby of the icy little moon.

The image above is a color composite made from raw images taken with Cassini’s red, green and blue visible light filters. There’s a bit of a blur because the moon shifted position in the frames slightly between images, but I think it captures some of the subtle color variations of lighting and surface composition very nicely!

3D anaglyph of Helene assembled by Patrick Rutherford.

At right is a 3D anaglyph view of Helene made by Patrick Rutherford from Cassini’s original raw images … if you have a pair of red/blue glasses, check it out!

Cassini passed from Helene’s night side to its sunlit side. This flyby will enable scientists to create a map of Helene so they can better understand the moon’s history and gully-like features seen on previous flybys.

(When Cassini acquired the images, it was oriented such that Helene’s north pole was facing downwards. I rotated the image above to reflect north as up.)

Helene orbits Saturn at the considerable distance of 234,505 miles (377,400 km). Irregularly-shaped, it measures 22 x 19 x 18.6 miles (36 x 32 x 30 km).

Helene is a “Trojan” moon of the much larger Dione – so called because it orbits Saturn within the path of Dione, 60º ahead of it. (Its little sister Trojan, 3-mile-wide Polydeuces, trails Dione at the rear 60º mark.) The Homeric term comes from the behavioral resemblance to the Trojan asteroids which orbit the Sun within Jupiter’s path…again, 60º in front and behind. These orbital positions are known as Lagrangian points (L4 and L5, respectively.)

Read more on the Cassini mission site here.

An irregular crescent: Cassini's flyby of Helene on June 18, 2011.

Images: NASA / JPL / Space Science Institute.

Worlds Apart: Planet and Moon Align

Conjunction of Jupiter and Phobos from Mars Express (rotated so north is up.)

Here’s a cool animation showing Mars’ little moon Phobos passing in front of distant Jupiter from the viewpoint of ESA’s Mars Express orbiter:

The conjunction event occurred on June 1.

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Only 21 km (13 miles) across at the widest, the irregularly-shaped Phobos may have been created by a large impact on Mars in its distant past, a chunk of the planet’s crust thrown into orbit. Mars Express most recently performed a close flyby of Phobos back on January 9, passing it at a distance of only 100 km (62 miles).

What’s really amazing to think about is the distances between these two worlds – about 529 million km! But those kinds of distances are no hindrance to vision out in space, especially when the farther object is a giant planet like Jupiter.

The images were taken with Mars Express’ High Resolution Stereo Camera (HRSC), which was kept centered on Jupiter during the conjunction. A total of 104 images were taken over a span of 68 seconds to create the animation.

“By knowing the exact moment when Jupiter passed behind Phobos, the observation will help to verify and even improve our knowledge of the orbital position of the martian moon.”

– ESA

Read the news release on the ESA Space Science site here.

All images shown here were processed at the Department of Planetary Sciences and Remote Sensing at the Institute of Geological Sciences of the Freie Universität Berlin. Credit: ESA/DLR/FU Berlin (G. Neukum)