Posted on by Nancy Atkinson

Life on Titan Could Be Smelly and Explosive

Artist concept of Methane-Ethane lakes on Titan (Credit: Copyright 2008 Karl Kofoed). Click for larger version.

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Could there be life on Titan? If so, one astrobiologist says humans probably couldn’t be in the same room with a Titanian and live to tell about it. “Hollywood would have problems with these aliens” said Dr. William Bains. “Beam one onto the Starship Enterprise and it would boil and then burst into flames, and the fumes would kill everyone in range. Even a tiny whiff of its breath would smell unbelievably horrible. But I think it is all the more interesting for that reason. Wouldn’t it be sad if the most alien things we found in the galaxy were just like us, but blue and with tails?”

While giving an obvious nod to the recent movie “Avatar,” Bains’ research provides insight to the difficulties we might encounter – beyond cultural – if we ever meet up with alien life. There could be unintended harmful consequences for one species, or both.

Bains is working to find out just how extreme the chemistry of life can be. Life on Titan, Saturn’s largest moon, represents one of the more bizarre scenarios being studied. While images sent back by the Cassini/Huygens mission might make Titan look Earth-like and maybe even inviting, it has a thick atmosphere of frozen, orange smog. At ten times our distance from the Sun, it is a frigid place, with a surface temperature of -180 degrees Celsius. Water is permanently frozen into ice and the only liquid available is liquid methane and ethane.

So instead of water based-life (like us), life on Titan would likely be based on methane.

“Life needs a liquid; even the driest desert plant on Earth needs water for its metabolism to work. So, if life were to exist on Titan, it must have blood based on liquid methane, not water. That means its whole chemistry is radically different. The molecules must be made of a wider variety of elements than we use, but put together in smaller molecules. It would also be much more chemically reactive,” said Bains.

Additionally, Bains said a metabolism running in liquid methane would have to be built of smaller molecules than terrestrial biochemistry.

“Terrestrial life uses about 700 molecules, but to find the right 700 there is reason to suppose that you need to be able to make 10 million or more,” Bains said. “The issue is not how many molecules you can make, but whether you can make the collection you need to assemble a metabolism.”

Bains said doing such assembling is like trying to find bits of wood in a lumber-yard to make a table.

“In theory you only need 5,” he said. “But you may have a lumber-yard full of offcuts and still not find exactly the right five that fit together. So you need the potential to make many more molecules than you actually need. Thus the 6-atom chemicals on Titan would have to include much more diverse bond types and probably more diverse elements, including sulphur and phosphorus in much more diverse and (to us) unstable forms, and other elements such as silicon.”

Energy is another factor that would affect the type of life that could evolve on Titan. With Sunlight a tenth of a percent as intense on Titan’s surface as on the surface of Earth, energy is likely to be in short supply.

“Rapid movement or growth needs a lot of energy, so slow-growing, lichen-like organisms are possible in theory, but velociraptors are pretty much ruled out,” said Bains.

Whatever life may be on Titan, at least we know there won’t be a Jurassic Park.

Bains, whose research is carried out through Rufus Scientific in Cambridge, UK, and MIT in the USA, is presenting his research at the National Astronomy Meeting in Glasgow, Scotland on April 13, 2010.

Source: RAS NAM

Posted on by Nancy Atkinson

How Common are Solar Systems Like Ours?

Solar system montage. Credit: NASA

On the whole, we’d like to think we’re special, but we also hope we aren’t alone in the Universe. Astronomers have been trying to figure out just how common solar systems like ours are across the cosmos, and during one moment of epiphany one scientist figured out how to make the calculations. It took a worldwide collaboration of astronomers to do the work, but they concluded that about 10 – 15 percent of stars in the universe host systems of planets like our own, with several gas giant planets in the outer part of the solar system.

“Now we know our place in the universe,” said Ohio State University astronomer Scott Gaudi. “Solar systems like our own are not rare, but we’re not in the majority, either.”

The find comes from a collaboration headquartered at Ohio State called the Microlensing Follow-Up Network (MicroFUN), which searches the sky for extrasolar planets.

MicroFUN astronomers use gravitational microlensing — which occurs when one star happens to cross in front of another as seen from Earth. The nearer star magnifies the light from the more distant star like a lens. If planets are orbiting the lens star, they boost the magnification briefly as they pass by.

During his talk at the American Astronomical Society meeting in Washington, DC today, Gaudi said, “Planetary microlensing basically is looking for planets you can’t see around stars you can’t see.”

This method is especially good at detecting giant planets in the outer reaches of solar systems — planets analogous to our own Jupiter.

This latest MicroFUN result is the culmination of 10 years’ work — and one sudden epiphany, explained Gaudi and Andrew Gould, professor of astronomy at Ohio State.

Ten years ago, Gaudi wrote his doctoral thesis on a method for calculating the likelihood that extrasolar planets exist. At the time, he concluded that less than 45 percent of stars could harbor a configuration similar to our own solar system.

Then, in December of 2009, Gould was examining a newly discovered planet with Cheongho Han of the Institute for Astrophysics at Chungbuk National University in Korea. The two were reviewing the range of properties among extrasolar planets discovered so far, when Gould saw a pattern.

“Basically, I realized that the answer was in Scott’s thesis from 10 years ago,” Gould said. “Using the last four years of MicroFUN data, we could add a few robust assumptions to his calculations, and we could now say how common planet systems are in the universe.”

The find boils down to a statistical analysis: in the last four years, the MicroFUN survey has discovered only one solar system like our own — a system with two gas giants resembling Jupiter and Saturn, which astronomers discovered in 2006 and reported in the journal Science in 2008.

“We’ve only found this one system, and we should have found about eight by now — if every star had a solar system like Earth’s,” Gaudi said.

The slow rate of discovery makes sense if only a small number of systems — around 10 percent — are like ours, they determined.

“While it is true that this initial determination is based on just one solar system and our final number could change a lot, this study shows that we can begin to make this measurement with the experiments we are doing today,” Gaudi added.

As to the possibility of life as we know it existing elsewhere in the universe, scientists will now be able to make a rough guess based on how many solar systems are like our own.

Our solar system may be a minority, but Gould said that the outcome of the study is actually positive.

“With billions of stars out there, even narrowing the odds to 10 percent leaves a few hundred million systems that might be like ours,” he said.

At the AAS conference today, Gaudi was awarded the Helen B. Warner Prize for Astronomy.

Source: AAS, EurekAlert

Posted on by Nancy Atkinson

Signs of Life Detected on the Moon?

Image from the Moon Impact Probe of the lunar surface. Credit: ISRO

A website based in India has reported researchers with the Chandrayaan-1 mission may have found “signs of life in some form or the other on the Moon.” DNAIndia.com quoted Surendra Pal, associate director of the Indian Space Research Organization (ISRO) Satellite Centre as saying that Chandrayaan-1 picked up signatures of organic matter on parts of the Moon’s surface. “The findings are being analyzed and scrutinized for validation by ISRO scientists and peer reviewers,” Pal said.

Sources in India say Chandrayaan project director M. Annadurai later commented that the story was broken very prematurely. However, he did not dismiss the idea.

At a press conference Tuesday at the American Geophysical Union fall conference, scientists from NASA’s Lunar Reconnaissance Orbiter also hinted at possible organics locked away in the lunar regolith. When asked directly about the Chandrayaan-1 claim of finding life on the Moon, NASA’s chief lunar scientist, Mike Wargo, certainly did not dismiss the idea either but said, “It is an intriguing suggestion, and we are certainly very interested in learning more of their results.”

Chandrayaan-1’s Moon Impact Probe, or MIP impacted the within the Shackleton Crater on the Moon’s south pole on Nov. 14, 2008. An anonymous Chandrayaan-1 scientist said MIP’s mass spectrometer detected chemical signatures of organic matter in the soil kicked up by the impact.

“Certain atomic numbers were observed that indicated the presence of carbon components. This indicates the possibility of the presence of organic matter (on the Moon),” a senior scientist told DNAIndia.

The scientist added the source of the organics could be comets or meteorites which have deposited the matter on the Moon’s surface but the recent discovery by another impact probe — the LCROSS mission — of ice in the polar regions of the Moon also “lend credence to the possibility of organic matter there.”

Undoubtedly, getting from carbon compounds directly to organics is a bit of a stretch, but amino acids have been detected in comets and were also found in pieces of the asteroid 2008 TC3 that landed in Africa over a year ago. Over the millennia, the Moon has been bombarded by comet and asteroid hits.

We’ll keep you posted on any official announcements by ISRO.

Sources: BAUT Forum, DNA India, AGU press conference

Posted on by Nancy Atkinson

New Findings On Allen Hills Meteorite Point to Microbial Life

Scientists caused quite a stir in 1996 when they announced a meteorite had been found in Antarctica that might contain evidence for microscopic fossils of Martian bacteria. While subsequent studies of the now famous Allen Hills Meteorite shot down theories that the Mars rock held fossilized alien life, both sides debated the issue and the meteorite is still being studied. Now, Craig Covault in Spaceflightnow.com reports that a new look at ALH84001 provides “evidence that supports the existence of life on the surface of Mars, or in subsurface water pools, early in the planet’s history.” Covault says we can expect a public announcement by NASA Headquarters within a few days.

Research using a more advanced High Resolution Electron Microscopy than was in existence when the initial findings were made 13 years ago has provided the new evidence. Covault reported that the “laboratory sensors are being focused directly on carbonate discs and associated tiny magnetite crystals present inside the meteorite Allen Hills ALH 84001.” The data reveal information that counters a “wide range of opposing theories as to why the finding should not be supported as biological in origin.”

The new findings were reported in the November issue of the respected journal Geochimica et Cosmochimica Acta, the journal of the Geochemical and Meteoritic Society. The authors include Kathie Thomas-Keprta, Simon Clement, David McKay (who led the original team), Everett Gibson and Susan Wentworth, all of the Johnson Space Center.

Covault said the new work centers on what is called magnetic bacteria that on Earth, and Mars as well, leave distinctively-shaped remnants in the rock. These features test with a high chemical purity more like a biological feature than geological.

For more details, read the article on Spaceflightnow.com

Exciting! Stay tuned…

Posted on by Nicholos Wethington

Vatican Holds Conference on Extraterrestrial Life

Though it may seem an unlikely location to happen upon a conference on astrobiology, the Vatican recently held a “study week” of over 30 astronomers, biologists, geologists and religious leaders to discuss the question of the existence of extraterrestrials. This follows the statement made last year by the Pope’s chief astronomer, Father Gabriel Funes, that the existence of extraterrestrials does not preclude a belief in God, and that it’s a question to be explored by the Catholic Church. The event, put on by the Pontifical Academy of Sciences, took place at the Casina Pio IV on the Vatican grounds from November 6-11.

The conference was meant to focus on the scientific perspective on the subject of the existence of extraterrestrial life, and pulled in perspectives from atheist scientists and Catholic leaders alike. It was split into eight different segments, starting with a topics about life here on Earth such as the origins of life, the Earth’s habitability through time, and the environment and genomes. Then the detection of life elsewhere, search strategies for extrasolar planets, the formation and properties of extrasolar planets was discussed, culminating in the last segment, intelligence elsewhere and ‘shadow life’ – life with a biochemistry completely different than that found on Earth.

Speakers at the event included notable physicist Paul Davies and Jill C. Tarter, the Director of the Center for SETI Research. Numerous astrobiologists and astronomers researching extrasolar planets also were in attendance to give lectures. The whole series of speech abstracts and a list of participants is available in a brochure on the Vatican site, here.

The event was held to mark the International Year of Astronomy, and the participants hope to collect the lectures into a book. Father Gabriel Funes, the chief astronomer of the Vatican, said in an interview to the Vatican paper, Osservatore Romano last year:

“Just like there is an abundance of creatures on earth, there could also be other beings, even intelligent ones, that were created by God. That doesn’t contradict our faith, because we cannot put boundaries to God’s creative freedom. As saint Francis would say, when we consider the earthly creatures to be our “brothers and sisters”, why couldn’t we also talk about a “extraterrestrial brother”? He would still be part of creation.”

Even with the discovery of over 400 exoplanets, the question of extraterrestrial life still remains to be answered in our own Solar System. It is a pertinent question for the religious and non-religious alike. Though it wasn’t answered at this most recent conference, the existence of life outside what we know here on Earth has an equal impact on the findings of science as it does the meaning of religion. This event certainly brought the two under the same roof for what were surely some interesting and fruitful conversations.

Source: Physorg, Pontifical Academy of Sciences

Posted on by Nicholos Wethington

Mars Explorers May Use AI to Become ‘Cyborg Astrobiologists’

Future Mars astronauts. Image Credit: Patrick McGuire

Ever heard of a ‘Cyborg Astrobiologist’? Probably not. But I bet you’ll want to be one after learning that future exploration of Mars (and other planets, for that matter) may employ the use of artificial intelligence integrated into spacesuits to enhance the ability of astronauts in taking scientific data while exploring. The AI assistance could help future astronauts exploring planets to recognize differences in their surroundings as being due to the presence of life. Does this sound like something from 50 years from now? Well, a prototype model has already been tested, and has shown the principle behind this idea to be sound.

University of Chicago geoscientist Patrick McGuire and his team have developed the basic systems needed for such a spacesuit, using mostly off-the shelf technology. The system uses a Hopfield neural network to analyze data taken in by a either a camera phone or a microscope. The AI system employs a ‘novelty detection algorithm’ which analyzes images from either imaging device, and is able to identify features in images that are out of place.

The Hopfield system compares patterns against ones it has already seen, and learns from this process to correctly identify novel patterns that could be of interest. The full prototype spacesuit has a wearable computer that houses the AI system, which uses Bluetooth to receive data from a cell phone camera or is connected to a USB digital microscope.

The system was tested at the Mars Desert Research Station (MDRS) in the San Rafael Swell of Utah, which is maintained by the Mars Society. The MDRS is a semi-arid desert with “greenish, grey or light gray mudstone,
limestone, siltstone and sandstone, partially inter-bedded by white sandstone layers”. For the last two weeks of February 2009, two members of McGuire’s team tested the wearable technology, which was able to successfully learn to identify patches of lichen from a background of rock, and identify different color patterns that signified different rock formations.

Another test, conducted in September of 2005 at Rivas Vaciamadrid in Spain, utilized a USB digital microscope to image rocks with lichen on them. As you can see in the image below, the AI system was able to identify as uncommon the spores of the lichen, which are about 1mm in diameter.The Hopfield AI system was able to successfully identify lichen spores imaged by a digital microscope as a novel feature on rock formations in Rivas Vaciamadrid, Spain. Image Credit: Patrick McGuire arXiv:0910.5454

There are still some bugs to be worked out, though, as the system detected cast shadows in rough terrain our low standing Sun as novel features, the researchers wrote in their paper, The Cyborg Astrobiologist: Testing a Novelty-Detection Algorithm on Two Mobile Exploration Systems at Rivas Vaciamadrid in Spain and at the Mars Desert Research Station in Utah, available on Arxiv. The researchers also tested a head-mounted digital microscope display, but instead opted for a tripod due to the blurriness associated with the head movement of the researcher wearing the suit.

Though it may be a while until there are any Martian astronauts utilizing such a system – let alone Martian astronauts with the title of ‘Cyborg Astrobiologist’ – the combination of the AI with imaging systems could start to prove very useful on future orbital surveyors of Mars. Additionally, these systems could be used to collect and analyze data outside of the visible light spectrum, which could be incredibly useful for both robotic and human explorers.

Source: Physorg, Arxiv

Posted on by Nicholos Wethington

Bacteria Could Survive in Martian Soil

Certain strains of bacteria, including Bacilus Pumilus, may be able to survive on the Martian surface. Image credit: NASA

Multiple missions have been sent to Mars with the hopes of testing the surface of the planet for life – or the conditions that could create life – on the Red Planet. The question of whether life in the form of bacteria (or something even more exotic!) exists on Mars is hotly debated, and still requires a resolute yes or no. Experiments done right here on Earth that simulate the conditions on Mars and their effects on terrestrial bacteria show that it is entirely possible for certain strains of bacteria to weather the harsh environment of Mars.

A team led by Giuseppe Galletta of the Department of Astronomy at the University of Padova simulated the conditions present on Mars, and then introduced several strains of bacteria into the simulator to record their survival rate. The simulator – named LISA (Laboratorio Italiano Simulazione Ambienti) – reproduced surface conditions on Mars, with temperatures ranging from +23 to -80 degrees Celsius (73 to -112 Fahrenheit), a 95% CO2 atmosphere at low pressures of 6 to 9 millibars, and very strong ultraviolet radiation. The results – some of the strains of bacteria were shown to survive up to 28 hours under these conditions, an amazing feat given that there is nowhere on the surface of the Earth where the temperatures get this low or the ultraviolet radiation is as strong as on Mars.

Two of the strains of bacteria tested – Bacillus pumilus and Bacillus Nealsonii – are both commonly used in laboratory tests of extreme environmental factors and their effects on bacteria because of their ability to produce endospores when stressed. Endospores are internal structures of the bacteria that encapsulate the DNA and part of the cytoplasm in a thick wall, to prevent the DNA from being damaged.

Galletta’s team found that the vegetative cells of the bacteria died after only a few minutes, due to the low water content and high UV radiation. The endospores, however, were able to survive between 4 and 28 hours, even when exposed directly to the UV light. The researchers simulated the dusty surface of Mars by blowing volcanic ash or dust of red iron oxide on the samples. When covered with the dust, the samples showed an even higher percentage of survival, meaning that it’s possible for a hardy bacterial strain to survive underneath the surface of the soil for very long periods of time. The deeper underneath the soil an organism is, the more hospitable the conditions become; water content increases, and the UV radiation is absorbed from the soil above.

Given these findings, and all of the rich data that came in last year from the Phoenix lander – especially the discovery of perchlorates –  continuing the search for life on Mars still seems a plausible endeavor.

Though this surely isn’t a confirmation of life on Mars, it shows that even life that isn’t adapted to the conditions of the planet could potentially hold out against the extreme nature of the environment there, and bodes well for the possibility of Martian bacterial life forms. The LISA simulations also indicate the importance of avoiding cross-contamination of bacteria from Earth to Mars on any scientific missions that travel to the planet. In other words, when we finally are able to definitively test for life on our neighboring planet, we don’t want to find out that our Earth bacteria have killed off all the native lifeforms!

Sources: Arxiv papers here and here.

Posted on by Nancy Atkinson

Organic Molecules Detected in Exoplanet Atmosphere

Artist concept of exoplanet HD 209458b. Credit: NASA/JPL-Caltech/T. Pyle (SSC)

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The basic chemistry for life has been detected the atmosphere of a second hot gas planet, HD 209458b. Data from the Hubble and Spitzer Space Telescopes provided spectral observations that revealed molecules of carbon dioxide, methane and water vapor in the planet’s atmosphere. The Jupiter-sized planet – which occupies a tight, 3.5-day orbit around a sun-like star — is not habitable but it has the same chemistry that, if found around a rocky planet in the future, could indicate the presence of life. Astronomers are excited about the detection, as it shows the potential of being able to characterize planets where life could exist.

HD 209458b is in the constellation Pegasus.

“It’s the second planet outside our solar system in which water, methane and carbon dioxide have been found, which are potentially important for biological processes in habitable planets,” said researcher Mark Swain of JPL. “Detecting organic compounds in two exoplanets now raises the possibility that it will become commonplace to find planets with molecules that may be tied to life.”

Over a year ago, astronomers detected these same organic molecules in the atmosphere of another hot, giant planet, called HD 189733b, using the same two space telescopes. Astronomers can now begin comparing the chemistry and dynamics of these two planets, and search for similar measurements of other candidate exoplanets.

The detections were made through spectroscopy, which splits light into its components to reveal the distinctive spectral signatures of different chemicals. Data from Hubble’s near-infrared camera and multi-object spectrometer revealed the presence of the molecules, and data from Spitzer’s photometer and infrared spectrometer measured their amounts.

“This demonstrates that we can detect the molecules that matter for life processes,” said Swain. Astronomers can now begin comparing the two planetary atmospheres for differences and similarities. For example, the relative amounts of water and carbon dioxide in the two planets is similar, but HD 209458b shows a greater abundance of methane than HD 189733b. “The high methane abundance is telling us something,” said Swain. “It could mean there was something special about the formation of this planet.”

Rocky worlds are expected to be found by NASA’s Kepler mission, which launched earlier this year, but astronomers believe we are a decade or so away from being able to detect any chemical signs of life on such a body.

If and when such Earth-like planets are found in the future, “the detection of organic compounds will not necessarily mean there’s life on a planet, because there are other ways to generate such molecules,” Swain said. “If we detect organic chemicals on a rocky, Earth-like planet, we will want to understand enough about the planet to rule out non-life processes that could have led to those chemicals being there.”

“These objects are too far away to send probes to, so the only way we’re ever going to learn anything about them is to point telescopes at them. Spectroscopy provides a powerful tool to determine their chemistry and dynamics.”

For more information about exoplanets and NASA’s planet-finding program, check out PlanetQuest.

Source: Spitzer

Posted on by Nancy Atkinson

Where Could Humans Survive in our Solar System?

Habitability in our solar system. Credit: UPR Arecibo, NASA PhotoJournal

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If humans were forced to vacate Earth, where is the next best place in our solar system for us to live? A study by the University of Puerto Rico at Arecibo has provided a quantitative evaluation of habitability to identify the potential habitats in our solar system. Professor Abel Mendez, who produced the study also looked at how the habitability of Earth has changed in the past, finding that some periods were even better than today.

Mendez developed a Quantitative Habitability Theory to assess the current state of terrestrial habitability and to establish a baseline for relevant comparisons with past or future climate scenarios and other planetary bodies including extrasolar planets.

“It is surprising that there is no agreement on a quantitative definition of habitability,” said Mendez, a biophysicist. “There are well-established measures of habitability in ecology since the 1970s, but only a few recent studies have proposed better alternatives for the astrobiology field, which is more oriented to microbial life. However, none of the existing alternatives from the fields of ecology to astrobiology has demonstrated a practical approach at planetary scales.”

His theory is based on two biophysical parameters: the habitability (H), as a relative measure of the potential for life of an environment, or habitat quality, and the habitation (M), as a relative measure of biodensity, or occupancy. Within the parameters are physiological and environmental variables which can be used to make predictions about the distribution, and abundance of potential food (both plant and microbial life), environment and weather.

The image above shows a comparison of the potential habitable space available on Earth, Mars, Europa, Titan, and Enceladus. The green spheres represent the global volume with the right physical environment for most terrestrial microorganisms. On Earth, the biosphere includes parts of the atmosphere, oceans, and subsurface (here’s a biosphere definition). The potential global habitats of the other planetary bodies are deep below their surface.

Enceladus has the smallest volume but the highest habitat-planet size ratio followed by Europa. Surprisingly, Enceladus also has the highest mean habitability in the Solar System, even though it is farther from the sun, and Earth, making it harder to get to. Mendez said Mars and Europa would be the best compromise between potential for life and accessibility.

n Oct. 5, 2008. Image credit: NASA/JPL/Space Science Institute Cassini came within 25 kilometers (15.6 miles) of the surface of Enceladus o
n Oct. 5, 2008. Image credit: NASA/JPL/Space Science Institute Cassini came within 25 kilometers (15.6 miles) of the surface of Enceladus o

“Various planetary models were used to calculate and compare the habitability of Mars, Venus, Europa, Titan, and Enceladus,” Mendez said. “Interestingly, Enceladus resulted as the object with the highest subsurface habitability in the solar system, but too deep for direct exploration. Mars and Europa resulted as the best compromise between habitability and accessibility. In addition, it is also possible to evaluate the global habitability of any detected terrestrial-sized extrasolar planet in the future. Further studies will expand the habitability definition to include other environmental variables such as light, carbon dioxide, oxygen, and nutrients concentrations. This will help expand the models, especially at local scales, and thus improve its application in assessing habitable zones on Earth and beyond.”

Studies about the effects of climate change on life are interesting when applied to Earth itself. “The biophysical quantity Standard Primary Habitability (SPH) was defined as a base for comparison of the global surface habitability for primary producers,” Mendez said. “The SPH is always an upper limit for the habitability of a planet but other factors can contribute to lower its value. The current SPH of our planet is close to 0.7, but it has been up to 0.9 during various paleoclimates, such as during the late Cretaceous period when the dinosaurs went extinct. I’m now working on how the SPH could change under global warming.”

The search for habitable environments in the universe is one of the priorities of the NASA Astrobiology Institute and other international organizations. Mendez’s studies also focus on the search for life in the solar system, as well as extrasolar planets.

“This work is important because it provides a quantitative measure for comparing habitability,” said NASA planetary scientists Chris McKay. “It provides an objective way to compare different climate and planetary systems.”

“I was pleased to see Enceladus come out the winner,” McKay said. “I’ve thought for some time that it was the most interesting world for astrobiology in the solar system.”

Mendez presented his results at the Division for Planetary Sciences of the American Astronomical Society meeting earlier this month.

Source: AAS DPS

Posted on by Nancy Atkinson

Searching for Life As We Don’t Know It

Artist's impression of exoplanets around other stars. Credits: ESA/AOES Medialab

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When discussing the possibility of finding life on other worlds, we usually add the phrase “life – as we know it.” But we’ve been surprised at exotic forms of life even on our own world and we need figure out how life might evolve elsewhere with foreign biochemistry in alien environments. Scientists at a new interdisciplinary research institute in Austria are working to understand exotic life and how we might find it.

Traditionally, planets that might sustain life are looked for in the ‘habitable zone’, the region around a star in which Earth-like planets with carbon dioxide, water vapor and nitrogen atmospheres could maintain liquid water on their surfaces. Consequently, scientists have been looking for biomarkers produced by extraterrestrial life with metabolisms resembling the terrestrial ones, where water is used as a solvent and the building blocks of life, amino acids, are based on carbon and oxygen. However, these may not be the only conditions under which life could evolve.

The University of Vienna established a research group for Alternative Solvents as a Basis for Life Supporting Zones in (Exo-)Planetary Systems in May 2009, under the leadership of Maria Firneis.

“It is time to make a radical change in our present geocentric mindset for life as we know it on Earth,” said Dr. Johannes Leitner, from the research group. “Even though this is the only kind of life we know, it cannot be ruled out that life forms have evolved somewhere that neither rely on water nor on a carbon and oxygen based metabolism.”

One requirement for a life-supporting solvent is that it remains liquid over a large temperature range. Water is liquid between 0°C and 100°C, but other solvents exist which are liquid over more than 200 °C. Such a solvent would allow an ocean on a planet closer to the central star. The reverse scenario is also possible. A liquid ocean of ammonia could exist much further from a star. Furthermore, sulphuric acid can be found within the cloud layers of Venus and we now know that lakes of methane/ethane cover parts of the surface of the Saturnian satellite Titan.

Consequently, the discussion on potential life and the best strategies for its detection is ongoing and not only limited to exoplanets and habitable zones. The newly established research group at the University of Vienna, together with international collaborators, will investigate the properties of a range of solvents other than water, including their abundance in space, thermal and biochemical characteristics as well as their ability to support the origin and evolution of life supporting metabolisms.

“Even though most exoplanets we have discovered so far around stars are probably gas planets, it is a matter of time until smaller, Earth-size exoplanets are discovered,” said Leitner.

The research group discussed their initial investigations at the European Planetary Science Conference in Potsdam, Germany.

Source: Europlanet