NASA has proposed sending both an orbiter and a robotic explorer to Mars in the next decade to follow up on the recent report that Mars “hotspots” emit plumes of methane gas, which could be produced by either geothermal reactions or by deeply buried bacteria that breathe out methane as a waste product. That exciting phenomenon, which is still being debated by Mars experts, was observed by researchers using ground-based telescopes to measure seasonal fluctuations of gases on the planet. Researchers say closer observations would have a much better chance of determining whether the methane does signal the ultimate prize: extraterrestrial life.
NASA officials sketched out their proposal at a meeting of Mars scientists, but stressed that plans could change. The current idea is to launch the Mars Science Orbiter in 2016 followed by a exobiology lander or rover mission launched during a particularly juicy launch window in 2018 (the best since the Spirit and Opportunity rovers)…. The plan would also follow a natural progression: MSO would map the methane; the lander or rover would go after it with a suite of astrobiological instruments [Nature blog].
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Astrobiologists searching for the ultimate prize on Mars–extraterrestrial life–should send a robot scout straight to the mighty Martian volcano Olympus Mons, geologists say in a new study. New research shows that liquid water probably once sloshed beneath the 15-mile-high volcano. It may still be there, and it may be nice and warm, thanks to volcanic heat. “Olympus Mons is a favored place to find ongoing life on Mars,” said the study’s lead author, geophysicist Patrick McGovern…. “An environment that’s warm and wet, and protected from adverse surface conditions, is a great place to start looking” [Wired].
Rising three times higher than Mount Everest, Olympus Mons was active at least 40 million years ago, and perhaps more recently [ABC Science]. For the new study published in Geology, researchers used computer modeling to investigate how the volcano formed, looking particularly at its asymmetrical slopes. They concluded that the Martian volcano has one steep side and one long, gradual slope because of variations in the underlying sediment. The gradual slope probably formed because it slid on something slippery like water-rich clay, they say, and pockets of water could still be trapped deep beneath the surface.
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While astronomers have found more than 300 planets beyond our solar system in the last 15 years, none of those “exoplanets” has been a likely candidate for extraterrestrial life. The exoplanets discovered thus far are all either too close to the hot sun or too far away and therefore too frigid to host life as we know it. But Alan Boss says it’s just a matter of time before we find Earth-like planets in the “Goldilocks zone”: he calculates that 100 billion of them may exist within our own Milky Way galaxy. And NASA’s Kepler satellite, which is expected to launch on March 5, may be the key to finding them, he says.
Boss, an astrophysicist and author of the new book “The Crowded Universe: The Search for Living Planets,” says that if any of the billions of Earth-like worlds he believes exist in the Milky Way have liquid water, they are likely to be home to some type of life. “Now that’s not saying that they’re all going to be crawling with intelligent human beings or even dinosaurs,” he said. “But I would suspect that the great majority of them at least will have some sort of primitive life, like bacteria or some of the multicellular creatures that populated our Earth for the first 3 billion years of its existence” [CNN].
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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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A rocky world about twice the size of Earth has been detected orbiting a sun-like star 390 light years away from our solar system. While the “super-Earth” is hot and inhospitable to life as we know it, its discovery puts researchers firmly on the path towards finding other habitable planets. “For the first time, we have unambiguously detected a planet that is ‘rocky’ in the same sense as our own Earth” [Wired News], said project scientist Malcolm Fridlund. The exciting find was made by the CoRoT satellite, which was launched by the French space agency to scan the skies for exoplanets (planets outside our solar system). The results were announced at a CoRoT symposium in Paris.
CoRoT team member Suzanne Aigrain explains that the planet is so close to its parent star that it orbits around it once every 20 hours, and is subject to inferno-like conditions. “It’s likely that there is a solid surface somewhere,” says Aigrain. But the extreme surface temperatures of around 1000°C [around 1800 degrees Fahrenheit] could mean that the planet is host to vast lava fields and boiling oceans. It also may be ‘tidally locked’ to its parent star, leaving one face bathed in constant, searing sunlight while the other is shrouded in continuous night. “It would be a very odd place to set foot on,” she says [Nature News].
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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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It’s entirely possible that researchers may have detected the first ever evidence of extraterrestrial life. Researchers who spent seven years studying the atmosphere of Mars say they glimpsed discrete plumes of methane gas rising from the surface of the planet in 2003, which could have been produced by bacteria living deep underground. On Earth, a class of bacteria known as methanogens breathes out methane as a waste product [The New York Times].
Before the public could get too excited, the researchers noted that that the biological explanation is just one of two possibilities–there’s also geological processes to consider. The methane could have been produced by geothermal chemical reactions involving water and heat like those in the hot springs of Yellowstone…. [N]o signs of recent volcanism, or even any hot spots, have been spotted on Mars [The New York Times], but ancient volcanic activity could have left methane deposits trapped underground, and puffs of that gas could be routinely released. Finally, the source could be a process known as serpentinisation that occurs at low temperatures and occurs when rocks rich in the minerals olivine and pyroxene react chemically with water, releasing methane [BBC News].
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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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Dead stars surrounded by fields of dust from pulverized asteroids may seem to make up a forbidding and ominous picture, but researchers who studied six such star systems say the dust should actually fuel the optimism of people who dream of finding extraterrestrial life. The dust’s composition suggests that rocky planets like our own Earth may be common in the universe, researchers say, which ups the chance that life as we know it has evolved somewhere out there.
The dust in question was found surrounding small, dense white dwarf stars. As stars like our own sun near the end of their life, they puff up into red giants that consume their innermost planets and jostle the orbits of outer planets and asteroids. Eventually the stars blow off their outer layers and shrink down into white dwarfs. Occasionally, a perturbed asteroid will wander too close to the white dwarf, whose gravity rips the rocky body to shreds, forming debris [SPACE.com].
That debris is what researchers studied with NASA’s Spitzer Space Telescope. By viewing the stars through a spectrograph, which separates out light from different wavelengths, the scientists were able to observe the telltale signatures of certain chemicals in the light. Since that starlight is passing through the film of the asteroid debris, the light picked up signatures of the asteroids’ composition, too [Wired News]. Lead researcher Michael Jura announced at the ongoing American Astronomical Society meeting that the composition of the asteroid dust was remarkably similar to that of the rocky planets in our solar system.
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In another promising sign that primitive life could have once existed on the surface of Mars, researchers have found deposits of a mineral that suggest that the planet once had life-friendly bodies of liquid water. The mineral, carbonate, has previously been detected in only trace quantities on Mars, but new data from the Mars Reconnaissance Orbiter’s spectrometer shows deposits in a rock outcropping in a region of valleys called the Nili Fossae. Since acidic conditions can prevent carbonates from forming, the discovery suggests that the rocks were created in neutral-pH water that might have provided a cosy habitat for life [New Scientist].
Water ice currently exists on Mars, and over the past few years researchers have accumulated evidence of liquid lakes and streams in the planet’s distant past. Most evidence has pointed to a period when water on the planet’s surface formed clay-rich minerals, followed by a time of drier conditions, when salt-rich, acidic water affected much of the planet. These later conditions would have proven difficult for any Martian life — if it ever existed — to endure or to leave any traces for scientists to find. Because carbonates dissolve quickly in acid, finding them shows at least some areas of the planet escaped the acid bath [SPACE.com].
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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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A sugar molecule essential to life as we know it has been found in the far reaches of the Milky Way, scientists report. Astronomers working with the IRAM radio dish array in France report the presence of glycolaldehyde—a simple sugar found in RNA—in a region of our galaxy known to churn out stars. The molecule appears to have formed with all of the other stuff that makes up planets, suggesting that many other worlds are seeded with some of life’s ingredients right from birth [ScienceNOW Daily News].
Glycoladehyde is a building block of ribose, a component of RNA. Many scientists believe RNA preceded DNA in vesting the earliest forms of life with reproductive capabilities; thus the finding of glycoladehyde has particular significance for those searching for extraterrestrial life. The astronomers detected radio and microwave signatures of glycolaldehyde within the core of what appears to be a coalescing disk of dust and gas in a star-forming region called G31.41+0.31, about 26,000 light-years away. The sugar molecule can apparently form in a simple reaction between carbon monoxide molecules and dust grains [ScienceNOW Daily News]. The astronomers believe the molecules they see are a few hundred thousand years old.
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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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For the first time, carbon dioxide has been detected in the atmosphere of an exoplanet, astronomers working with the Hubble Space Telescope report. Although the Jupiter-sized planet, which closely orbits the star HD 189733 about 63 light-years from Earth, is much too hot to support life, scientists are hailing the discovery as an exciting technical achievement. “In that context, the carbon dioxide measurement constitutes a dress rehearsal …for our long-term goal of trying to detect signs of life or signs of habitability on terrestrial-mass planets or super Earths in the habitable zone,” [Science News] says Mark Swain of NASA’s Jet Propulsion Laboratory.
Researchers deduced the presence of carbon dioxide by measuring the planet’s light spectrum with the Hubble’s Near Infrared Camera and Multi-Object Spectrometer (NICMOS). To isolate the light spectrum coming from the planet, researchers used a method known as “secondary transit.” This involves recording the light spectrum of the planet and its star, and then measuring the spectrum of the star alone while the planet is hidden behind it. The difference of the two spectra is the spectrum of the light coming directly from the planet [Nature News]. Unlike previous measurements that focused on the mid-infrared range, NICMOS took measurements in the near-infrared range, enabling detection of the carbon dioxide signature.
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New data from NASA’s Mars Odyssey orbiter supports the long-debated theory that Mars once (or twice) had vast frozen oceans on its surface. The location of certain mineral deposits suggests massive erosion and ancient shorelines. A group of researchers now believes Mars had at least two oceans – one about three and a half billion years ago that was 20 times the size of the Mediterranean and a smaller one about two billions years ago. “These were not like the oceans we know,” says [researcher Victor] Baker. “These were transient bodies that existed long enough to accumulate sediment”, but were not present for billions of years of geologic history, as Earth’s oceans have been [New Scientist].
The Mars Odyssey orbiter identified the mineral deposits using a gamma-ray spectrometer, which can detect elements a third of a metre below Mars’s surface. It found enriched potassium, thorium and iron, lying in shoreline-type patterns, where researchers already suspected water used to lie [Canwest News Service]. Until now, however, their suspicions were mainly based on geographical features such as smooth plains surrounded by higher, more rugged terrain. The new data, to be published in Planetary and Space Science, shows minerals heavily concentrated in the soil below the proposed shoreline and less concentrated above, suggesting erosion of sediments into a large body of water. But study coauthor James Dohm says the new evidence isn’t a smoking gun: “It’s consistent with this ocean potential – it doesn’t confirm it, necessarily,” Dohm said. “I think it’s a significant piece of the puzzle” [Tucson Citizen].
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