Saturn’s moon Titan is already an object of fascination to astronomers: The moon has seasonal weather patterns, a thick atmosphere, and lakes of liquid methane on its surface, and some scientists think it’s one of the likeliest spots to find extraterrestrial life in our solar system. Now, researchers have found new evidence that the moon has cryovolcanoes, which, in the cold of the outer Solar System, would spew a slurry of ice and liquid hydrocarbons, instead of lava. “It’s as if it’s a sort of constant bubbling cauldron that occasionally explodes big time,” says Robert Nelson, a Cassini team scientist [Nature News].
The still-controversial theory regards an area of Titan called Hotei Arcus, which appears to fluctuate in brightness on timescales of several months…. The cryovolcanism idea was bolstered in 2008, when observations of Hotei Arcus by a radar instrument aboard NASA’s Cassini probe revealed structures that resembled lava flows [New Scientist]. The new findings, discussed at this week’s Lunar and Planetary Science Conference, are based on radar images taken by Cassini on recent flybys of the moon (radar is required to penetrate Titan’s thick methane atmosphere). Overlapping images were used to create a topographical map of Hotei Arcus; the map shows several lobe-like formations, more than 300 feet high, which researchers say resemble the oozing of a viscous, lava-like material.
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The Cassini space probe has detected a tiny moon nestled in one of Saturn’s outermost rings, making it the 61st known Saturnian satellite. The moonlet measures only about one-third of a mile in diameter, but researchers say the diminuitive moon is big enough to be the likely source of the dust that forms the ring, thus solving a mystery.
Cassini spotted the moonlet as a bright streak of light in the second to last ring from Saturn, which is called the G ring. “Before Cassini, the G ring was the only dusty ring that was not clearly associated with a known moon, which made it odd,” said [Cassini scientist] Matthew Hedman…. “The discovery of this moonlet, together with other Cassini data, should help us make sense of this previously mysterious ring” [CNN].
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The distinctive belt of asteroids between Mars and Jupiter may have been shaped during a game of planetary pinball almost 4 billion years ago. A new study suggests that the migration of the mighty gas giant planets tugged some asteroids into a ringed formation, and sent others spinning off. Jupiter, Saturn, Uranus, and Neptune, are thought to have been born close together before gravitational interactions with numerous pieces of rocky debris changed their trajectories. Their movement then caused the rocky debris to scatter like bowling pins, potentially explaining what battered the Earth, Moon, and Mars with so many craters some 3.8 billion years ago [New Scientist].
Astronomers have long wondered about the uneven distribution of debris within the asteroid belt, which has zones where there are far fewer asteroids than expected…. Some of those gaps, called Kirkwood gaps, are in zones where Jupiter or Saturn’s gravitational influence destabilises the asteroids so much that they are ejected from the belt, but many are in areas that are currently stable [Cosmos]. Researchers decided to test the theory that planetary migrations caused the gaps in the solar system’s early days.
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Following last week’s collision of two satellites in orbit, and then the fireball that mysteriously fell from the sky in Texas, has come a flurry of debate over what to do with all the potentially dangerous debris orbiting the Earth in space. Experts are in Vienna this week, as part of a meeting of the United Nations Committee on the Peaceful Uses of Outer Space, to discuss what to do with the vast amount of space debris, which includes millions of various-sized pieces of junk left during humanity’s messy first half-century of space exploration.
It’s a growing problem that no one knows how to deal with. Some suggest a cosmic cleanup is the way to go. Others say time, energy and funds are better spent on minimizing the likelihood of future crashes by improving information sharing [AP]. Richard Crowther, the British representative to this week’s U.N. meeting, says satellites should have a mechanism that automatically sends them back to Earth once their job is done, burning up safely in the earth’s atmosphere [Sky News]. Another solution, developed by the International Academy of Astronautics, proposes attaching balloons to pieces of debris to increase their atmospheric drag and bring them back to Earth faster. Another … foresees attaching a 10-mile (16-kilometer) electrodynamic tether to debris that would generate a current, which then could be controlled from the ground enabling technicians to bring it down [AP].
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The next stop in the search for life in outer space will be Jupiter’s ice-covered moon Europa. NASA announced plans on Wednesday to launch a probe to the moon in 2020, a mission that could cost $3 billion and will focus on the possibility that in the gigantic ocean thought to be hidden under the moon’s thick cover of ice is a habitable zone where rudimentary forms of life could exist…. What makes Europa so important, said Robert Pappalardo, a senior research scientist at [NASA], is that “icy satellites are the most common potentially habitable environment in the outer solar system,” and therefore could be common throughout the universe. Understanding how they function, and whether they are indeed a good home for life, is key to answering the “are we alone” question” [Los Angeles Times].
After years of debate over the destination for NASA’s next flagship mission, the agency finally homed in on Europa, the smallest of Jupiter’s four large moons, because the mission would be easier to accomplish than other moons of interest orbiting Jupiter or Saturn.
The mission will seek to “produce a global map in preparation for a journey many years in the future that would land on the moon. Using radar and other devices, the probe will try to verify the thickness of the ice sheet and determine the presence of the ocean covering the 2,000-mile diameter moon. “Europa is tremendously exciting,” said Jim Green, director of the Planetary Sciences Division at NASA. “It may have more water underground than the Earth” [Los Angeles Times].
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Imagine a world where the average daytime temperature is -179°C, and torrential rains of liquid methane fall from the skies, forming vast but shallow pools that cover an area larger than the Great Lakes [ScienceNOW Daily News].
That’s the vision of the Saturnian moon Titan provided by the NASA spacecraft Cassini, which has been exploring Saturn and its satellites since 2004. In the latest findings, Cassini scientists have determined that Titan has seasonal weather patterns in which fierce storms fill up the methane lakes. “We see clouds that behave very much as clouds on Earth, and we see evidence of flooding on the surface, just as a lot of people in the [U.S.] Midwest saw last year” [National Geographic News], researcher Elizabeth Turtle said.
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Around 3.9 billion years ago a massive asteroid may have slammed into the moon with such force that it changed the satellite’s rotation, according to a new analysis by a pair of astrophysicists. The impact may have set the moon to spinning, so that it eventually settled down with a 180 rotation from its previous orientation. Currently, earthlings looking up at the moon always see its same side; the other “dark side” of the moon is pointed away as a result of synchronous rotation, a sort of orbital lockstep that keeps the moon rotating once for every lap it takes around Earth [Scientific American]. The new findings suggest that Earth had a different view of the moon 3.9 billion years ago, although there was probably no life on the planet to take notice.
The researchers came to this surprising conclusion by analyzing the moon’s craters. According to earlier computer simulations, the moon’s western hemisphere as viewed from Earth should have about 30 per cent more craters than the eastern hemisphere. That’s because the west always faces in the direction in which the moon orbits, which makes it more likely to be hit by debris, for the same reason that more raindrops strike a moving car’s front windshield than its rear [New Scientist]. When researchers examined the age of the craters, however, they found a more complex scenario. The western hemisphere did have the greatest concentration of young impact basins, but the eastern hemisphere had most of the old craters. This suggests that the eastern hemisphere was once positioned to receive a heavy bombardment, and that the moon once had a different orientation.
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Which celestial bodies are more likely to host extraterrestrial life: Saturn’s hazy moon Titan and water-spewing moon Enceladus, or Jupiter’s icy moons Europa and Ganymede, which may have liquid oceans beneath their frozen crusts? That’s the difficult question facing NASA and the European Space Agency (ESA) as they try to decide where to send the next planetary probe. By the end of this month, agency officials plan to pick a destination for a massive mission, costing nearly US$4 billion, to be launched around 2020 for the distant reaches of the Solar System. The battle pits Titan, which recent discoveries have made the cool new kid on the block, against Jupiter’s moon Europa, which has long sat atop community wish lists [Nature News].
In advance of that decision, the space agencies have released details of the dueling proposals. The potential Saturn mission would follow up the remarkable discoveries made by the Nasa/Esa Cassini-Huygens mission which continues to operate at the ringed planet…. Cassini has sent back data that indicates Titan is akin to a primitive – albeit frozen – Earth. It has a thick atmosphere and is rich in organic (carbon-rich) molecules [BBC News]. The plan calls for an orbiter that would release a hot air balloon to drift in Titan’s hazy atmosphere and would drop a lander to the surface, where it could float on one of moon’s lakes of liquid ethane and methane. The orbiter would also dip into the atmosphere of Enceladus, which has fired imaginations with the revelation that it has geysers that spew jets of icy water into space.
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The planet Venus may not have always been the hot and barren ball of rock that we see today. A new analysis of its surface indicates that it might once have had oceans of liquid water–which could have allowed for a brief flourishing of microbial life.
Researchers examined nighttime infrared emissions coming from Venus’ surface, and found that the planet’s highland regions emit less infrared radiation than its lowland regions. One interpretation of this lower infrared emission from the highlands, say the authors, is that they are composed largely of ‘felsic’ rocks, particularly granite. Granite, which on Earth is found in continental crust, requires water for its formation…. “This is the first direct evidence that early in the history of the Solar System, Venus was a habitable planet with plenty of water,” says [astrobiologist] Dirk Schulze-Makuch…. “The question is how long Venus remained habitable. But this gives new impetus for the search for microbial life in Venus’s lower atmosphere” [Nature News].
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The space probe Cassini, our emissary to Saturn and its fascinating satellites, has made several new discoveries that lend further credence to the idea that microbial life could evolve on the icy moon Enceladus or the moon Titan, with its lakes of methane. During a flyby of Enceladus Cassini snapped pictures of the moon’s surface and the cracks in its icy crust from which jets of water vapor routinely burst upward. The new pictures suggest that the cracks form when the crust splits and spreads apart in a way that is similar to the mid-ocean ridges central to the tectonic system on our own planet. On Earth the spreading of the sea floor is driven by molten rock; Nasa scientists speculate that the liquid beneath the south pole of Enceladus may be water. “Bit by bit, we’re accumulating the evidence that there is liquid water on Enceladus” [Telegraph], said Cassini scientist Carolyn Porco.
Enceladus is already known to have some of the fundamental chemistry required to make and sustain life. Liquid water currently is the major missing ingredient. Dr Porco commented: “We first discovered this region in early 2005 and now it’s nearly four years later, so it’s still kind of brand new; but already there are some of us who really want to go back with a spacecraft that focuses on the south pole of Enceladus and investigates whether or not it is a site of either pre-biotic or biotic processes” [BBC News].
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When NASA’s Cassini spacecraft swooped past Saturn’s moon Enceladus last year, it got a close-up view of the water vapor and ice plumes that stream away from the small moon. After analyzing the data, researchers say the evidence suggests that the material in the plumes originates as liquid water trapped beneath the moon’s icy surface, which increases the possibility that microbial, extraterrestrial life could exist in the lakes. “We think liquid water is necessary for life and there is more evidence that there is liquid water there,” said lead researcher Candice Hansen…. Scientists are aware of only three places where liquid water exists near the surface of a planet or other body – Earth, Jupiter’s moon Europa and now Enceladus [Telegraph].
Researchers identified four distinct jets within the plume where the water vapor appears to be traveling faster than 1,300 miles per hour. Such high speeds imply that the jets are fed by pressurised water vapour that shoots through narrow openings – which act like rocket nozzles – in the moon’s icy surface. The simplest way to generate such pressures is by evaporating a reservoir of liquid water that lies close to the moon’s surface [New Scientist], researchers say.
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NASA engineers have finally tested an “interplanetary Internet” that could be crucial for future communications with rovers and astronauts exploring the moon, Mars, or other planets. NASA says the system would rely on probes and orbiters to serve as relay stations, or routers, to send communications around the solar system. The space agency has been working for 10 years on the project with Vint Cerf, one of the Internet’s key inventors and now chief Internet evangelist for Google [AP].
The protocols (the language computers use to speak to each other) used for our terrestrial Internet won’t work for deep space, because they assume that the network’s nodes will be connected continuously, and that messages will travel swiftly. But communication between objects in space are frequently disrupted by solar storms and obstructing planets, and sending a message from Earth to Mars can take up to 20 minutes. So engineers at NASA’s Jet Propulsion Laboratory worked with Cerf to come up with a new protocol, called Disruption-Tolerant Networking (DTN).
With the new communications design, each network node is designed to hold onto data packets, instead of discard them, until a destination path can be found. “The incentive to use Internet-like protocols over space links was to take advantage of automated routing,” [said NASA's Leigh Torgerson]. “With standard space-link communications, the ground sends commands to spacecraft to tell it what time and what data to send. It’s very hands-on-intensive” [Computerworld].
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On October 6, NASA’s Messenger space probe swooped down to within 125 miles of the surface of Mercury, and the just-released images from that flyby are shaking up astronomers’ ideas about the planet’s geologic history. The remarkable pictures reveal a vast patch of lava, indicating that the planet was shaped by a long age of volcanic eruptions. Astronomers used to dismiss Mercury, the planet closest to the sun, as mere “dead rock,” little more than a target for cosmic collisions that shaped it, said MIT planetary scientist Maria Zuber. “Now, it’s looking a lot more interesting,” said Zuber [AP].
Messenger’s cameras spotted a crater of about 60 miles in diameter that was not as deep as other nearby craters, and determined that it had been filled in with a huge amount of solidified lava. To get an idea of how much, Zuber explains, you could imagine the entire Baltimore-Washington region covered with a layer of solidified lava about 12 times the height of the Washington monument. “So it’s a great, great deal of vulcanism,” she says. “That’s an awful lot of volcanic material in one place for such a little planet” [NPR News]. Researchers think the eruption happened between 3.8 and 4 billion years ago.
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The nearest planetary system to our own has two asteroid belts in addition to a previously known ice belt, according to the latest observations by NASA’s Spitzer Space Telescope. The location and structure of the asteroid belts relative to the system’s central star, Epsilon Eridani, suggests the existence of earth-like planets. “We certainly haven’t seen it yet, but if its solar system is anything like ours, then there should be planets like ours,” says astronomer Massimo Marengo of the Harvard-Smithsonian Center for Astrophysics [USA Today].
The Epsilon Edidani system has long been of interest to astronomers and science fiction fans alike because of its proximity (10.5 light-years) and resemblance to our solar system. The newly discovered asteroid belts give the system an appearance even more like our own. The inner asteroid belt looks identical to ours in terms of material, and it orbits at 3 astronomical units (AU) from Epsilon Eridani — the same distance between the sun and the rocky asteroid belt between Mars and Jupiter. (An astronomical unit equals the average Earth-sun distance of 93 million miles, or about 150 million km.) Epsilon Eridani’s second asteroid belt is 20 AU from the star, or about where Uranus is in relation to our sun, and it is crowded with as much mass as Earth’s moon [Science News]. The outer asteroid belt was captured directly by Spitzer’s infrared cameras and the inner asteriod belt, though too far from the cameras, was indicated by the thermal energy from its infrared emissions.
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On Sunday, a small space probe with a big mission took off from Earth in a flawless launch, setting off on a two-year assignment to map the edge of our solar system. The Interstellar Boundary Explorer soared into space aboard an Orbital Space Sciences Pegasus rocket that fired as planned at 12:48 p.m. CDT, moments after dropping from the belly of a modified airliner that flew across the South Pacific near Kwajalein Atoll [San Antonio Express-News].
The $169 million NASA probe will settle into a long, elliptical orbit around Earth that takes it beyond the interference of our planet’s magnetosphere, and almost as far as the moon. From there the IBEX will record the impacts of particles that are formed at the edge of our solar system’s protected space, a region known as the heliosphere. The solar wind, a stream of charged particles spewing from the sun at 1 million miles per hour, carves out a protective bubble around the solar system. This bubble … shields against most dangerous cosmic radiation that would otherwise interfere with human spaceflight [AP]. At the edge of the heliosphere, the solar wind slows down as it slams into interstellar space; IBEX will observe the particles created in this “termination shock” to chart the solar system’s perimeter.
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