Scientists studying the Red Planet have developed a few possible explanations for the presence of methane in Mars' atmosphere. Methane on Mars is being constantly depleted by a chemical reaction triggered by sunlight, meaning that the methane is also replenished at a significant rate. One theory, that methane was being carried into the atmosphere by extramartian bodies such as meteorites, has been taken off the table thanks to a new study by researchers at Imperial College London. The study found that the volume of methane released by meteorites upon entering the atmosphere is far too low to supply Mars' current methane levels. Other studies have ruled out another possibility, that volcanic activity has been producing the methane.

This leaves two frontrunner solutions to Mars' methane mystery. One possibility is that the methane is produced as a byproduct of a chemical reaction between volcanic rock and water. The other is that microorganisms are living on the planet's surface and that their metabolic process produces methane.

It's far, far away from indicating life on Mars, but it does narrow down the hunt for the methane's source. A joint NASA/ESA mission is scheduled to head to Mars in 2018 to look for the source of the methane.

Life on Mars theory boosted by new methane study [PhysOrg]

Spaceflight Now is reporting that, within the next few days, NASA plans to publicly discuss new research concerning ALH 84001, the Martian meteorite found in Allan Hills, Antarctica. The research is said to strengthen the findings of the team that studied the meteorite over a decade ago and announced in 1996 that the meteorite might contain evidence of bacterial life.

The new research, detailed in a 46-page peer reviewed paper, looks at magnetic bacteria found on Earth. The researchers have closely studied magnetic bacteria and the formations they create in rocks. The bacteria leave distinctive remnants in the rock, uniquely-shaped magnetite crystals that test with a chemical purity that reflects biological, rather than geological, origins. That these remnants are unique to magnetic bacteria on Earth and are also found in the Allan Hills meteorite strongly suggests that the crystals indicate ancient bacterial life on Mars.

Critics of the original NASA report have doubted these features as reliable fossils, claiming that the shape and chemical purity could be achieved by the same thermal shock that separated the material from Mars in the first place. But new research reported in the paper disproves the thermal shock theory.

Spaceflight says that the new research isn't quite a "smoking gun," but it greatly strengthens the case for life on Mars, and could change the conversation about future NASA missions.

Martian meteorite surrenders new secrets of possible life [Spaceflight via Universe Today]

Richard Greenberg of the University of Arizona will be presenting his findings on Europa today at American Astronomical Society's Division for Planetary Sciences. Europa's ability to support macrofauna — more complex organisms like animals — hinges on how much oxygen is contained in the suspected ocean beneath the moon's icy surface.

Greenberg believes that energetic particles from the sun are able to reach Europa's subterranean ocean despite that layer of ice. Because the surface of Europa is relatively impact-free, the ice is believed to be relatively new, about 50 million years. Based on this, Greenberg sets forth the idea that Europa is being constantly resurfaced, possibly with fresh materials, thanks to oxidizers at the planet's surface. He also estimates that, if there were, say, fish on Europa, and those fish used the same amount of oxygen as Earth fish, the moon's ocean has enough oxygen to support 6.6 billion pounds of such macrofauna.

Of course, just because Europa might be able to sustain life doesn't mean we'll find life there. But this does present the possibility that other bodies produce enough oxygen to support complex biological processes.

Europa, Jupiter's Moon, Could Support Complex Life [Discovery]

A paper published in this week's Public Library of Science ONE examined the obstacles to mammalian reproduction in space. While frogs, salamanders, and sea urchins all have proven records of extraplanetary fertility, mammals sent to space have not fared so well in the breeding department.

The team of Japanese biologists decided to investigate the impact of low gravity on mammalian embryonic development. They stored mouse eggs and sperm inside a three-dimensional clinostat, a device that mimics the effects of weightlessness, and then fertilized the eggs, allowing some to develop inside the clinostat and others to develop in normal gravity.

They found that, while fertilization occurred normally in the simulated microgravity, embryos that continued to develop in the clinostat had more difficulty dividing and maturing than those developing in normal gravity. Some of the embryos did survive and were implanted in mice, but they survived in much lower numbers than the embryos that were fertilized in the clinostat but developed outside it (no word on the relative health of the mice that were ultimately born). And the experiment suggests that mammalian embryos are especially sensitive to changes in gravity, and that it might be difficult for humans to reproduce in places where the gravity does not resemble Earth's.

Making Babies in Space May Be Harder Than It Sounds [Wired]

At this year's meeting of the General Assembly of the International Astronomical Union, at a panel titled "Solar and Stellar Variability ― impact on Earth and Planets," a multidisciplinary group of experts discussed the evolving research into the types of suns and planets that would be hospitable to the development of life.

Edward Guinan, a professor of astronomy at Villanova University, claims that our sun provided better conditions for the formation of life in its youth. Over four billion years ago, the sun rotated ten times faster than it does today, causing the sun to generate a stronger magnetic field and considerably more radiation than it does today. These conditions have aided the formation of life, but other stars exist that maintain such a rapid rotation for a much longer duration:

The Sun does not seem like the perfect star for a system where life might arise. Although it is hard to argue with the Sun's ‘success' as it so far is the only star known to host a planet with life, our studies indicate that the ideal stars to support planets suitable for life for tens of billions of years may be a smaller slower burning ‘orange dwarf' with a longer lifetime than the Sun ― about 20-40 billion years. These stars, also called K stars, are stable stars with a habitable zone that remains in the same place for tens of billions of years. They are 10 times more numerous than the Sun, and may provide the best potential habitat for life in the long run.

Jean-Mathias Grießmeier of ASTRON's research similarly suggests that the Earth may not be an ideal planet for the formation and development of life. Grießmeier examined planetary magnetic fields, finding that a planet with a stronger magnetic field is less likely to have its atmosphere blown away by cosmic debris and is also better able to shield its surface from cosmic radiation. Guinan suggests that planets larger than Earth might be better able to protect any burgeoning life forms:

On the more speculative side we have also found indications that planets like Earth are also not necessarily the best suited for life to thrive. Planets two to three times more massive than the Earth, with a higher gravity, can retain the atmosphere better. They may have a larger liquid iron core giving a stronger magnetic field that protects against the early onslaught of cosmic rays. Furthermore, a larger planet cools more slowly and maintains its magnetic protection. This kind of planet may be more likely to harbour life.

That K stars are relatively common may offer new hope for the possibility of extraterrestrial life, although astronomers are quick to note they don't fully understand how common or fragile life in the universe may be. But their findings do suggest that, on a cosmological scale, Earth can't support life much longer. Says Guinan:

The Earth's period of habitability is nearly over ― on a cosmological timescale. In a half to one billion years the Sun will start to be too luminous and warm for water to exist in liquid form on Earth, leading to a runaway greenhouse effect in less than 2 billion years.

[Science Daily]

In a paper published in the International Journal of Astrobiology, Chandra Wickramasinghe of the Cardiff Centre for Astrobiology — one of the earliest proponents of the theory of panspermia, that the seeds of life exist throughout the universe — revealed his team's calculation, which indicate that large reserves of water likely existed inside comets in our solar system, that happened to form around the same time as the Earth:

The Cardiff team has calculated the thermal history of comets after they formed from interstellar and interplanetary dust approximately 4.5 billion years ago. The formation of the solar system itself is thought to have been triggered by shock waves that emanated from the explosion of a nearby supernova. The supernova injected radioactive material such as Aluminium-26 into the primordial solar system and some became incorporated in the comets. Professor Chandra Wickramasinghe together with Drs Janaki Wickramasinghe and Max Wallis claim that the heat emitted from radioactivity warms initially frozen material of comets to produce subsurface oceans that persist in a liquid condition for a million years.

Wickramasinghe claims that a "large fraction" of the 100 billion comets in our solar system probably contained liquid interiors, with ideal conditions for the growth of bacteria, which perhaps lends greater credence to Wickramsinghe's theories on the extraterrestrial origins of life.

[Universe Today]

Extremophiles are organisms that thrive in the most extreme environments on Earth. From the sulphuric hot springs in Yellowstone National Park to the icy Antarctic, these creatures push the limits of what we know about biology, and force us to reevaluate the possibility of extraterrestrial life forms. Scientists are finding an ever-increasing number of these tough little organisms living quite happily in places where we previously believed no life could possibly exist. Extremophiles have even been found nestled in the heart of a nuclear reactor.

The Chernobyl fungus was discovered several years ago, when scientists were using an R.O.V. to inspect the Chernobyl site. To their surprise, they found a dark slime on the walls, living within the reactor and actually feeding on the radiation. The melanin-rich fungus increases rapidly in size when exposed to a high level of gamma rays (and no, you wouldn't like it when it's angry). Other fungi and bacteria have been discovered with the same ability to thrive within radioactive environments. Deinococcus radiodurans, an amazing polyextremophile with the distinction of being considered the world's most durable bacterium, is capable of withstanding 5,000 Grays of radiation (500,000 rads). The discovery of such fungi and bacteria have provided scientists with a dramatic breakthrough in finding organic ways in which to detoxify radioactive waste.

Extremophiles are not just microbes; more highly evolved creatures have also proved to be as durable, and as strange and wonderful, as the Deinococcus radiodurans bacteria.

The Pompeii Worm

This extremophile keeps a cool head even in extreme temperatures. The Pompeii Worm finds a habitat on or near Black Smokers, hydrothermal vents on the sea floor, which give the worm its volcanic name. Nestled within its cozy tube, its body stays at a very toasty 175º F, while its plume-like head protrudes from the tube into water that is a much more temperate 72º F. Weirder still, its fleecy coat is actually a colony of bacteria that lives in a symbiotic relationship with the worm, fed by mucus secretions produced by the worm. Truly an oddity, the Pompeii worm (and its living coat) obviously has a lot to teach us about living in an extreme range of temperatures.

The Tardigrade
The Tardigrade is considered the king of the extremophiles. These microscopic organisms look like clear gummi bears come to life (hence their more common name, "Water Bears") and have proven to be more durable than Twinkies. Tardigrades have been discovered all over the world, and in the most amazing places, from the peaks of the Himalayas to the sea floor, from temperatures approaching absolute zero to temperatures over 303° F.

Like the Chernobyl fungus, these wonderful Water Bears can withstand doses of gamma rays lethal to humans without flinching. Tardigrades can also withstand the extreme pressure of a vacuum, and research is being conducted to test Tardigrades' durability in space. The Tardigrade Space program has been geekily nicknamed... yes, you guessed it... TARDIS.

NASA astrobiologist Richard Hoover is leading the hunt for more extremophiles, hoping to prove that some of these little fellas are not of our world, but interstellar hitch-hikers that came here millions of years ago on meteors. The existence of organisms like Deinococcus radiodurans and the Tardigrades gives weight to the argument that some of these extremophile lifeforms are actually aliens among us. If these creatures can exist in the vacuum of space and withstand such high levels of radiation, then it is just possible that these abilities are evolutionary traits that enabled them to arrive here, on Earth, from somewhere else in the galaxy.

The Extremophile Hunter:

The molecule is glycolaldehyde, the simplest monosaccharide sugar, which can react with propenal to form ribose, which is, in turn, the central component of RNA. Researchers believe that glycolaldehyde may be a key ingredient in the origin of life, but it has previously been detected only toward the center of our galaxy, where conditions make the formation of life unlikely.

The discovery of glycolaldehyde in a star-forming region of our galaxy, roughly 26,000 light years from Earth, suggests that the molecule could prove to be wide spread throughout the galaxy, and could offer clues as to where we should focus our search for extraplanetary life.

Image from NASA via Universe Today.

[Physorg via Universe Today]

Astronomers have long referred to regions of space where conditions are favorable for life as the “Goldilocks Zone.” Conventional wisdom is that Earth is a rarity, a world where conditions happen to be “just right” for sustaining life. But as they discover new worlds and run simulations on virtual planets, many astronomers are expanding their definition of habitability.

For one thing, says David Spiegel of Princeton University, planets that experience harsh conditions may still have habitable zones or habitable seasons, which may be sufficient for life to survive at certain times:

Spiegel argues that this kind of simulation shows that astronomers should not think of habitability as an all-or-nothing thing. It makes more sense to think in terms of "fractional habitability", he says, as in what fraction of a planet's surface is habitable, for what fraction of the year, or for what fraction of its history. "Even the Earth is not 100 per cent habitable, at least by the standard liquid-water definition," Spiegel points out. "Parts of the planet are frozen part of the time. Parts of the planet are frozen all of the time."

Additionally, while Earth’s life-sustaining heat comes from its particular distance from the sun, other planets may reach an optimal temperature in other ways:

This year, a team led by Brian Jackson of the University of Arizona in Tucson explored the extent to which some planets have internal heat sources. Planets orbiting close to a star or with non-circular, eccentric orbits move towards and away from their star in the course of an orbit. As a result, they are stretched and squeezed by variations in the gravitational pull from their star, and this causes enough friction in their interiors to generate heat.

And all this assumes that life on other planets has similar climate requirements to those of life on Earth. Jonathan Lunine at the University of Arizona notes that we don’t yet fully understand why life has flourished on Earth and it would be presumptuous to assume all life requires the same conditions:

There is always the chance that the search for liquid water on the surface may be missing the point. What if exotic forms of life could thrive where there is no liquid water at all - swimming around in lakes of liquid methane on Saturn's frigid moon, Titan, for example? "One should not rule out the notion that a kind of life or organised chemistry could exist in that kind of liquid," says Lunine. "Let's cast the net broadly."

[New Scientist]

Researchers studying data from the European Space Agency’s Huygens probe have reported that Titan’s atmosphere contains a faint electrical field, opening the door to the possibility of lightening strikes on the planet’s surface:

"As of now, lightning activity has not been observed in Titan's atmosphere," said lead author Juan Antonio Morente of the University of Granada in Spain.

But, he said, the signals that have been detected "are an irrefutable proof for the existence of electric activity."

The discovery is a significant one since many biochemists theorize that lightning triggered the reactions necessary for the creation of life on Earth. Since Titan’s atmosphere contains chemicals similar to those in Earth’s prebiotic astmosphere, it increases the possibility that life could form on Titan or in other parts of the universe:

"I look at Titan as a big, frozen, prebiotic casserole," [Jeffrey] Bada [of the Scripps Institution of Oceanography] said, referring to the state before the emergence of life.

"The idea that life could be widespread in the universe, I think, is very credible."

Electricity Found on Saturn Moon—Could It Spark Life? [National Geographic]

Bebo sponsored a competition to collect 501 photos, drawings, and text messages from its users and had those message transmitted from the RT-70 radar telescope in Evpatoria, Ukraine. But, despite shelling out $40,000 for the transmission, Bebo’s primary interest is not in making first contact:

Bebo's intent was to raise awareness for the concerns that young people have for the future of Earth, and to generate interest in space exploration. Bebo spokesman Mark Charkin said, "A 'Message From Earth' presents an opportunity for the digital natives of today… to reconnect with science and the wider universe in a simple, fun and immersive way."

On the other hand, Dr. Alexander Zaitsev of the Russian Academy of Science, who acted as Bebo’s consultant on the project, believes that these proactive attempts at contact, may be the only way we’ll find other life in the universe:

In his paper "Making the Case for METI [Messaging Extra Terrestrial Intelligence]," Zaitsev and two colleagues wrote, "It is possible we live in a galaxy where everyone is listening and no one is speaking. In order to learn of each others' existence - and science - someone has to make the first move."

Gliese 581c is approximately 20 light years away from Earth, meaning it will be over 40 years before we find out if any lifeforms there want to be Bebo’s friend.

Messages From Earth Beamed to Alien World [Universe Today]

Professor John Learned suggested that a civilization could attempt to initiate communication with other advanced civilizations by making unnatural alterations to Cepheids, relatively rare stars that other civilizations are likely to study:

Cepheids dim and brighten regularly, in a pattern that depends on their brightness. This lets astronomers measure the distance to the stars, helping to resolve mysteries such as the Universe's age and how fast it is expanding. As such, any sufficiently advanced civilization would want to monitor such stars, the scientists reasoned.

To send messages using a Cepheid, Learned and his colleagues suggest that extraterrestrials might change the star's cycle. A Cepheid becomes dimmer as ionized helium builds up in its atmosphere. Eventually, the atmosphere expands and deionizes, restarting the cycle.

Firing a high-energy neutrino beam into a Cepheid could heat its core and brighten the star early - "just as an electric pulse to the heart can make it skip a beat," Learned says.

Thus, the Cepheids might provide an intergalactic network of relays, which distant societies could use to broadcast messages to one another. But don't go warming up those neutrinos yet:

[T]he galactic internet would be slow - a Cepheid with a roughly one-day period could transmit about 180 bits per year. Such a transmission would require roughly a millionth of the star's energy, the researchers estimate.

For the time being, it makes more sense to comb through the 100 years' worth of data researchers have collected on the Cephids, searching for irregularities in the pulsing power. Learned estimates:

"Analyzing that data would take a graduate student a couple of months, and just think if it turned out to be correct."

At least the university's indentured academics know how they'll be spending their school year.

'Galactic internet' proposed [Nature]

According to New Scientist:

Kathleen Benison, a geologist at Central Michigan University, Mount Pleasant, led a team that studied the sediments formed by acidic and very salty lakes in modern day Western Australia, and those deposited around 250 million years ago in North Dakota. It is very difficult to survive in such a tough environments and few signs of life have ever been found in these sorts of lakes.

Inside the halite and gypsum "evaporate" minerals, which form as the lake waters dry up, Benison and colleagues found previously unknown fossilised blobs at both the modern and ancient sites, ranging in size from 0.05 to 1.5 millimetres. They were made up of a mix of inorganic crystals and "hairs" stuck together in a mass (pictured). They named them hairy blobs.

The team argues that each hair was in fact a separate microorganism because the hair fossils are made of disordered graphite which, unlike inorganic graphite, has irregular layers that suggest it was once a live organism..

Many of the hairs are coated with crystals of gypsum, a calcium sulphate mineral. This link with gypsum suggests that the microorganisms were fuelled by chemical interactions with sulphur in the acidic water - which helped the gypsum to form.

Scientists are still divided on whether these crystal-hair creatures actually count as "life." As they run further tests on the fossils, the mere existence of such creatures fuels hope among astrobiologists that life could indeed have evolved on Mars and we might get a chance to meet it — or at least, to find its fossilized remains. Images from Benison's published paper in Astrobiology.

Hairy Blobs Found in Acidic Hell [via Eurekalert and New Scientist]

See full text of Benison's article here (just scroll down).

Lineweaver's idea kind of rocks SETI scientists' mission statement to the core. Ever since Carl Sagan's famously framed the ET question "are we alone?" as "Are there functionally equivalent humans elsewhere in the universe?" SETI folks have been trying to answer it. It's a gargantuan task, and one that that Lineweaver argues we're making worse by assuming that there is something about humans that is unique or special, or that life on Earth "wants" to be human.

If there is any tendency for life to evolve to get as functionally human-like as possible, then Lineweaver asks why haven't isolated part of Earth evolved human-like intelligence? Madagascar has been separated from Africa for millions of years, and should therefore be full of high-level primates instead of lemurs — apes' distant cousins. New Zealand (which because of its isolation Jared Diamond said was "the best opportunity we'll ever have to study life on another planet") should be filled with super-intelligent giant birds.

Lineweaver thinks that big brains aren't the be-all and end all of evolution. In fact, he argues that the answer to Sagan's question is "no" — functionally equivalent humans don't exist elsewhere in the universe. Instead, life elsewhere might be so weird as to be unrecognizable. "Intelligence" could easily take the form of some kind of system at profound disequilibrium with its environment — something like a hurricane or a star could be intelligent.

It's sounds like he's begging to get the SETI Institute's funding pulled, and to declare the entire SETI operation utterly useless, and in a sense he is. But he also thinks it's worth continuing the search because there's a lot of unexplored universe still out there to look at. And he admits he could be wrong — there could be a Planet of the Apes out there, too.

Lineweaver presented his theories at the Astrobiology Science Conference 2008.

SETI scientists have been looking for alien lasers for years now — part of the Optical SETI programs several universities and observatories across the country.

Those projects are still going full-bore, but scientists are hoping to increase their chances of success by building a detector that will look for near-infrared lasers, too. Just on the lower edge of the optical range of electromagnetic wavelengths, Andrew Howard and colleagues from UC Berkeley figure there's no good reason aliens wouldn't build a near-IR laser. And if they did, they'd obviously use it to broadcast complex signals to Earth containing detailed plans on how to build a device for interstellar travel.

Maybe that's getting a bit ahead of ourselves, but just in case, we'd better look for intelligent signals broadcast through gravity waves, too. These still-theoretical ripples in space-time are being tested for by the LiGO (Laser interferometry Gravitational wave Observatory) detector, mostly as a way to test astronomical theories. At least one researcher, Peter Hahn believes we should start analyzing the data for signs of ET, too.

In his simulations, Rasio assumed that the Earth-like planet was orbiting at the same distance we orbit our Sun (1Astronomical Unit, or AU, or around 93 million miles), and he calculated orbital eccentricities in cases where the second star was orbiting at distances of 250, 500, and 1000 AU.

Left by itself the lonely Earth-twin would probably oscillate between a highly elliptical orbit, and a fairly circular one. If it's too oval (an eccentricity greater around 0.7 say) the planet's climate goes haywire and turns into a runaway greenhouse, superheating the surface. At around an eccentricity of 0.4, most of the water would evaporate, but would hover in the atmosphere...and Vaporators would sell like hotcakes.

Things got a little better when Kita added a Jupiter-mass planet to the system. When placed just a few AU from the Earth-like planet, the eccentric orbit stabilized. In that case, the rocky planet's climate would be much like ours.

So far there are two systems that are our best bets for finding the real Mos Eisley — 55 Cancri and Epsilon Andromeda. Both have multiple planets, though Kita says we're not sure yet whether any are rocky or if they're all gas giants.

The Earthrise photo (and check out the video if you really want to feel tiny) taken from Apollo 8 is one of the most famous space pics ever taken. Along with a few other nearly identical images, the shots are the only space-borne perspective that feature our pale blue dot from anything like a wide-angle view. This sort of thing is exactly what we need more of, Wolfe said. Imaging all of the phases of Earth (crescent, half, gibbous, full, etc.) from at least one lunar distance away would give us tons of info for what a world with continents, a dynamic atmosphere and water looks like.

The grand prize would be taking an image of the Sun's reflection on our oceans in polarized light. "That would give us a measurement of what the glint of sunlight on water looks like," Wolfe said, which could be used to determine whether planets are other stars have liquid water on their surfaces too.

Image: NASA

Lineweaver's four main preconditions for a piece of galactic real estate being hospitable to intelligent life are:

- Distance from galactic center. Our sun is about 8.5 kiloparsecs from the center of the Milky Way which is about right. The further you go out from the center of a galaxy, the fewer stars there are. The further you go in, the more likely a nearby star will go supernova, and wipe out life in your start system. LIneweaver figures between 7 and 9 kpc is about right.

- Age. Life takes time to evolve into something resembling intelligent. This takes a few billion years.

- Metallicity. This is Lineweaver's way of measuring how much of the supernova leftovers are accumulated in a given region of space. If there's less than 1% of the metals found in our solar system, there's probably not enough to build a rocky planet (in astronomers' parlance, 'metals' includes everything that's not hydrogen and helium, so stuff, like water, too).

- The likelihood of forming a gas giant. Like supernovas, Jupiters, Saturns and other giant planets make bad neighbors for harboring life. During the early stages of star system formation, they have a tendency to come crashing through planetary habitable zones, annihilating rocky planets that may one day harbor life.

In short, it's a galactic jungle out there, and in 2004 Lineweaver's beginning to get his head around narrowing down the best places we may find our interstellar neighbors, whether in this galaxy or the next. All that said, though, he's careful to point out that we don't even really know what a good definition of life is, so instead of "habitable zone" maybe the name should be changed to the more sensible (and way less-exciting) "pre-habitable zone."

Image: NASA

Chart: Science