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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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Researchers have unveiled the clearest images yet of the massive cyclone that revolves over Saturn’s south pole, and revealed that the southern storm is matched by an equally powerful cyclone at the planet’s north pole. Time-lapse images, taken by the Cassini spacecraft, show that the northern cyclone has wind speeds of 325 miles per hour, more than twice as fast as Earth’s strongest hurricanes. Says Cassini scientist Kevin Baines: “In a lot of ways, these are the most powerful cyclones ever seen…. They would expand over the whole planet if it was the Earth” [Discovery News].

The source of heat that powers these massive storms is not yet clear; Earth’s cyclones draw heat from the oceans that they drift across, but Saturn’s fixed cyclones have no bodies of water at their bases. They may be driven by Saturn’s internal heat, which can create giant weather patterns by causing massive parcels of atmospheric gases, most likely ammonium hydrosulfide, to rise and fall. It’s also possible that sunlight trapped in the planet’s atmosphere could drive the motions [Science News].

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Yesterday, the Messenger space probe swooped down and flew 124 miles from the surface of the innermost planet, Mercury, furiously snapping more than 1,200 pictures of a side of the planet that has never before been seen by a spacecraft. Today, after the NASA probe turned its antenna back towards Earth, it began sending home remarkable photos of Mercury’s pockmarked surface.

The second Mercury flyby of Oct. 6 comes after a first flyby on Jan. 14, which looked at a different side of the planet. “When these data have been digested and compared, we will have a global perspective of Mercury for the first time,” said [astronomer] Sean Solomon…. Launched in August 2004, MESSENGER - short for MErcury Surface, Space ENvironment, GEochemistry, and Ranging - is the first spacecraft in 33 years to greet Mercury up close since NASA’s earlier Mariner 10 mission of the 1970s [SPACE.com].

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On October 19, NASA will launch the small Interstellar Boundary Explorer (IBEX) into orbit on a mission to map the turbulent edge of our solar system, where the solar wind slams into interstellar space. While it won’t actually travel beyond all the planets to investigate the solar system’s far reaches, the coffee table-sized spacecraft must escape the area where Earth’s magnetic field reigns, which could interfere with its measurements. The $169 million observatory is due to climb 200,000 miles (322,000 kilometers) above Earth and settle into orbit there for a mission of at least two years. For comparison, the moon orbits about 240,000 miles (385,000 km) from Earth [SPACE.com].

The edge of the solar system is currently being explored directly by the Voyager 1 and Voyager 2 spacecrafts; both Voyagers launched 31 years ago and recently passed the point where the solar wind is slowed by interactions with the interstellar plasma, a point known as the termination shock. These crafts “are mak­ing fas­ci­nat­ing ob­serva­t­ions of the lo­cal con­di­tions at two points be­yond the ter­mina­t­ion shock that show to­tally un­ex­pected re­sults and chal­lenge many of our no­tions,” said [IBEX researcher David] Mc­Co­mas [World Science].

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The solar wind, a steady stream of charged subatomic particles that stream out from the sun at a speed of one million miles per hour, has dwindled to its weakest state since recording began, researchers say. While researchers already knew that solar winds fluctuate in 11-year cycles, the current doldrums trump the declines seen over the past 50 years. “We know that the sun has been this cool before, this inactive before,” said [physicist] Nancy Crooker…. “But that was prior to the Space Age, so we didn’t have actual physical measurements until now” [SPACE.com].

The data was collected by the first solar explorer, the Ulysses probe, which was launched in 1990 as a joint venture between NASA and the European Space Agency. The 17-year-old space probe, which circles the sun from a distance of about 337 million miles, has been studying the environment above and below the poles of the sun. It is just months away from shutting down because of freezing fuel [AP].

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The European Space Agency (ESA) is considering a space mission called Marco Polo, in which a spacecraft would land on a small asteroid, drill into its surface to collect samples of rock and dust, and then fly back to Earth where it would drop its sample capsule down to the surface. Two satellite manufacturing companies are currently conducting a feasibility study; if ESA signs off on the proposal, Marco Polo could sail off into space in 2017.

Asteroids are chunks of debris left over from the chaotic mass that spun around the young Sun during the formation of the Solar System about 4.6 billion years ago. The rest of the material coalesced into planets [The Daily Mail]. Researchers say that studying the composition of an asteroid could give them insight into how the solar system formed. The roughly $430 million mission would also serve as a warm-up for a hypothetical round-trip journey to Mars, as it would enable the development of technology needed for getting up and down from a large planetary body with a much bigger gravitational pull [Telegraph].

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Our sun, which lies 26,000 light years from the center of the the Milky Way, may have been born in a different part of the galaxy and later migrated to its current position, about halfway towards the galaxy’s outer edge. A new study defies the conventional wisdom that stars spend their entire lifespans in the same galactic region, and calls into question astronomers’ theory that galaxies have certain fixed “habitable zones” where life is more likely to evolve.

“Our view of the extent of the habitable zone is based in part on the idea that certain chemical elements necessary for life are available in some parts of a galaxy’s disk but not others,” said [lead researcher] Rok Roskar…. “If stars migrate, then that zone can’t be a stationary place” [Astrobiology Magazine].

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In between Mars and Jupiter, the spacecraft Rosetta buzzed by an asteroid on Friday and snapped photos of the chunk of rock as it hurtled through space. The European Space Agency’s spacecraft flew to within 500 miles of the Steins asteroid, getting a close-up view of the diamond-shaped Steins asteroid, a gray, 3-mile (5-km) wide rock that appears in images as a pock-marked [rock] with multiple craters that ultimately will help determine its age [SPACE.com].

Researchers hope that the Rosetta’s observations of the asteroid will shed light on the processes that shaped our solar system. The rocks are often referred to as “space rubble” because they represent the leftovers that were never incorporated into planets when the Solar System formed 4.6 billion years ago. As with comets, they may contain very primitive materials that have not undergone the constant recycling experienced by, for example, Earth rocks. Rosetta data should therefore help researchers understand better how our local space environment has evolved over time [BBC News].

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Astronomers have spotted an icy object near Neptune that they say hails from the distant Oort Cloud, the distant reservoir of asteroids that encircles the solar system out beyond the orbit of Pluto. The object, at least 30 miles wide, is on the return leg of a 22,500-year journey around the sun, astronomers announced today [SPACE.com].

The new object is about 60 miles in diameter. “It’s basically a comet, but it never gets close enough to the Sun to develop a long, bright tail of evaporated gas and dust,” [lead researcher Andrew] Becker said in a statement [Reuters]. Researchers say the newly discovered voyager, which is currently going by the unromantic name 2006 SQ372, is the first object ever sighted from the inner Oort Cloud, a region that astronomers know very little about.

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The Cassini spacecraft that has been busily exploring Saturn and its moons swooped to within 30 miles of the tiny moon Enceladus yesterday, and has already begun sending back images of the fissures near the moon’s south pole. The icy moon, which is about 310 miles wide, has tantalized scientists with geyser-like eruptions of icy water vapor that were first spotted in 2005…. The eruptions produce a halo of frozen water vapor and gas that replenishes Saturn’s E-ring as Enceladus circles the planet [SPACE.com].

The Cassini took images of the fissures, which scientists call the moon’s “tiger stripes,” in the infrared spectrum as well, to gain further information about the temperatures in the vents; previous studies had shown temperatures there can reach a relatively balmy -135 degrees Fahrenheit, which is 200 degrees Fahrenheit warmer than the rest of the moon. While the material sprayed out of the fissures consists of frozen water vapor, scientists disagree on whether an internal ocean of [liquid] water, life’s crucial ingredient, hides within the tiny moon [USA Today].

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