The Great London:
Astrobiology

New research has revealed that fewer than predicted planets may be capable of harboring life because their atmospheres keep them too hot.

When looking for planets that could harbor life, scientists look for planets in the 'habitable zones' around their stars - at the right distance from the stars to allow water to exist in liquid form. Traditionally, this search has focused on looking for planets orbiting stars like our Sun, in a similar way to Earth.

However, recent research has turned to small planets orbiting very close to stars called M dwarfs, or red dwarfs, which are much smaller and dimmer than the Sun. M dwarfs make up around 75 per cent of all the stars in our galaxy, and recent discoveries have suggested that many of them host planets, pushing the number of potentially habitable planets into the billions.

This month, both the TRAPPIST and Kepler planet-hunting telescopes have announced the discovery of multiple near-Earth-sized planets orbiting M dwarf stars, some within the habitable zones.

New research from Imperial College London and the Institute for Advanced Studies in Princeton, published in the >Monthly Notices of the Royal Astronomical Society, has revealed that although they orbit smaller and dimmer stars, many of these planets might still be too hot to be habitable.

The scientists suggest that some of the planets might still be habitable, but only those with a smaller mass than Earth, comparable to Venus or Mars.

Dr James Owen, Hubble Fellow and lead author of the study from the Institute for Advanced Studies in Princeton, said: "It was previously assumed that planets with masses similar to Earth would be habitable simply because they were in the 'habitable zone'. However, when you consider how these planets evolve over billions of years this assumption turns out not to be true."

It was known previously that many of these planets are born with thick atmospheres of hydrogen and helium, making up roughly one percent of the total planetary mass. In comparison, the Earth's atmosphere makes up only a millionth of its mass. The greenhouse effect of such a thick atmosphere would make the surface far too hot for liquid water, rendering the planets initially uninhabitable.

However, it was thought that over time, the strong X-ray and ultraviolet radiation from the parent M dwarf star would evaporate away most of this atmosphere, eventually making the planets potentially habitable.

The new analysis reveals that this is not the case. Instead, detailed computer simulations show that these thick hydrogen and helium envelopes cannot escape the gravity of planets that are similar to or larger in mass than the Earth, meaning that many of them are likely to retain their stifling atmospheres.

However, all is not lost, according to the researchers. While most of the M dwarf planets that are Earth-mass or heavier would retain thick atmospheres, smaller planets, comparable to Venus or Mars, could still lose them to evaporation.

Dr Subhanjoy Mohanty, the other study author from the Department of Physics at Imperial College London, said: "There are hints from recent exoplanet discoveries that relatively puny planets may be even more common around red dwarfs than Earth mass or larger ones, in which case there may indeed be a bonanza of potentially habitable planets whirling around these cool red stars."

Ongoing ground- and space-based searches, and new space missions to be launched in the near future, should provide a definitive answer to this question as well as other questions about the potential suitability of these planets for life.

Author: Hayley Dunning | Source: Imperial College London [May 26, 2016]

The world's attention is now on Proxima Centauri b, a possibly Earth-like planet orbiting the closest star, 4.22 light-years away. The planet's orbit is just right to allow liquid water on its surface, needed for life. But could it in fact be habitable?

If life is possible there, the planet evolved very different than Earth, say researchers at the University of Washington-based Virtual Planetary Laboratory (VPL) where astronomers, geophysicists, climatologists, evolutionary biologists and others team to study how distant planets might host life.

Astronomers at Queen Mary University in London have announced discovery of Proxima Centauri b, a planet orbiting close to a star 4.22 light-years away. The find has been called "the biggest exoplanet discovery since the discovery of exoplanets."

Rory Barnes, UW research assistant professor of astronomy, published a discussion about the discovery at palereddot.org, a website dedicated to the search for life around Proxima Centauri. His essay describes research underway through the UW planetary lab -- part of the NASA Astrobiology Institute -- to answer the question, is life possible on this world?

"The short answer is, it's complicated," Barnes writes. "Our observations are few, and what we do know allows for a dizzying array of possibilities" -- and almost as many questions.

The Virtual Planetary Laboratory is directed by Victoria Meadows, UW professor of astronomy. UW-affiliated researchers include Giada Arney, Edward Schwieterman and Rodrigo Luger. Using computer models, the researchers studied clues from the orbits of the planet, its system, its host star and apparent companion stars Alpha Centauri A and B -- plus what is known of stellar evolution to begin evaluating Proxima b's chances.

Relatively little is known about Proxima:

• It's at least as massive as Earth and may be several times more massive, and its "year" -- the time it takes to orbit its star -- is only 11 days

• Its star is only 12 percent as massive as our sun and much dimmer (so its habitable zone, allowing liquid water on the surface, is much closer in) and the planet is 25 times closer in than Earth is to our sun

• The star may form a third part of the Alpha Centauri binary star system, separated by a distance of 15,000 "astronomical units," which could affect the planet's orbit and history

• The new data hint at the existence of a second planet in the system with an orbital period near 200 days, but this has not been proven

Perhaps the biggest obstacle to life on the planet, Barnes writes, is the brightness of its host star. Proxima Centauri, a red dwarf star, is comparatively dim, but wasn't always so.

"Proxima's brightness evolution has been slow and complicated," Barnes writes. "Stellar evolution models all predict that for the first one billion years Proxima slowly dimmed to its current brightness, which implies that for about the first quarter of a billion years, planet b's surface would have been too hot for Earth-like conditions."

Barnes notes that he and UW graduate student Rodrigo Luger recently showed that had modern Earth been in such a situation, "it would have become a Venus-like world, in a runaway greenhouse state that can destroy all of the planet's primordial water," thus extinguishing any chance for life.

Next come a host of questions about the planet's makeup, location and history, and the team's work toward discerning answers.

• Is the planet "rocky" like Earth? Most orbits simulated by the planetary lab suggest it could be -- and thus can host water in liquid form, a prerequisite for life

• Where did it form, and was there water? Whether it formed in place or farther from its star, where ice is more likely, VPL researchers believe it is "entirely possible" Proxima b could be water-rich, though they are not certain.

• Did it start out as a hydrogen-enveloped Neptune-like planet and then lose its hydrogen to become Earth-like? VPL research shows this is indeed possible, and could be a viable pathway to habitability

• Proxima Centauri flares more often than our sun; might such flares have long-since burned away atmospheric ozone that might protect the surface and any life? This is possible, though a strong magnetic field, as Earth has, could protect the surface.

Also, any life under even a few meters of liquid water would be protected from radiation.

Another concern is that the planet might be tidally locked, meaning one side permanently faces its star, as the moon does Earth. Astronomers long thought this to mean a world could not support life, but now believe planetwide atmospheric winds would transport heat around the planet.

"These questions are central to unlocking Proxima's potential habitability and determining if our nearest galactic neighbor is an inhospitable wasteland, an inhabited planet, or a future home for humanity," Barnes writes.

Planetary laboratory researchers also are developing techniques to determine whether Proxima b's atmosphere is amenable to life.

"Nearly all the components of an atmosphere imprint their presence in a spectrum (of light)," Barnes writes. "So with our knowledge of the possible histories of this planet, we can begin to develop instruments and plan observations that pinpoint the critical differences."

At high enough pressures, he notes, oxygen molecules can momentarily bind to each other to produce an observable feature in the light spectrum.

"Crucially, the pressures required to be detectable are large enough to discriminate between a planet with too much oxygen, and one with just the right amount for life.

As we learn more about the planet and the system, we can build a library of possible spectra from which to quantitatively determine how likely it is that life exists on planet b."

Our own sun is expected to burn out in about 4 billion years, but Proxima Centauri has a much better forecast, perhaps burning for 4 trillion years longer.

"If Proxima b is habitable, then it might be an ideal place to move. Perhaps we have just discovered a future home for humanity. But in order to know for sure, we must make more observations, run many more computer simulations and, hopefully, send probes to perform the first direct reconnaissance of an exoplanet," Barnes writes. "The challenges are huge, but Proxima b offers a bounty of possibilities that fills me with wonder."

Proxima Centauri b may be the first exoplanet to be directly characterized by powerful ground- and space-based telescopes planned for the future, and its atmosphere spectroscopically probed for active biology. The research was funded by the NASA Astrobiology Institute. "Whether habitable or not," Barnes concludes, "Proxima Centauri b offers a new glimpse into how the planets and life fit into our universe."

Author: Peter Kelley | Source: University of Washington [August 30, 2016]

Astronomers using ESO telescopes and other facilities have found clear evidence of a planet orbiting the closest star to Earth, Proxima Centauri. The long-sought world, designated Proxima b, orbits its cool red parent star every 11 days and has a temperature suitable for liquid water to exist on its surface. This rocky world is a little more massive than the Earth and is the closest exoplanet to us -- and it may also be the closest possible abode for life outside the Solar System. A paper describing this milestone finding will be published in the journal Nature on 25 August 2016.

Just over four light-years from the Solar System lies a red dwarf star that has been named Proxima Centauri as it is the closest star to Earth apart from the Sun. This cool star in the constellation of Centaurus is too faint to be seen with the unaided eye and lies near to the much brighter pair of stars known as Alpha Centauri AB.

During the first half of 2016 Proxima Centauri was regularly observed with the HARPS spectrograph on the ESO 3.6-metre telescope at La Silla in Chile and simultaneously monitored by other telescopes around the world >[1]. This was the Pale Red Dot campaign, in which a team of astronomers led by Guillem Anglada-Escudé, from Queen Mary University of London, was looking for the tiny back and forth wobble of the star that would be caused by the gravitational pull of a possible orbiting planet >[2].

As this was a topic with very wide public interest, the progress of the campaign between mid-January and April 2016 was shared publicly as it happened on the Pale Red Dot website and via social media. The reports were accompanied by numerous outreach articles written by specialists around the world.

Guillem Anglada-Escudé explains the background to this unique search: "The first hints of a possible planet were spotted back in 2013, but the detection was not convincing. Since then we have worked hard to get further observations off the ground with help from ESO and others. The recent Pale Red Dot campaign has been about two years in the planning."

The Pale Red Dot data, when combined with earlier observations made at ESO observatories and elsewhere, revealed the clear signal of a truly exciting result. At times Proxima Centauri is approaching Earth at about 5 kilometres per hour -- normal human walking pace -- and at times receding at the same speed. This regular pattern of changing radial velocities repeats with a period of 11.2 days. Careful analysis of the resulting tiny Doppler shifts showed that they indicated the presence of a planet with a mass at least 1.3 times that of the Earth, orbiting about 7 million kilometres from Proxima Centauri -- only 5% of the Earth-Sun distance >[3].

Guillem Anglada-Escudé comments on the excitement of the last few months: "I kept checking the consistency of the signal every single day during the 60 nights of the Pale Red Dot campaign. The first 10 were promising, the first 20 were consistent with expectations, and at 30 days the result was pretty much definitive, so we started drafting the paper!"

Red dwarfs like Proxima Centauri are active stars and can vary in ways that would mimic the presence of a planet. To exclude this possibility the team also monitored the changing brightness of the star very carefully during the campaign using the ASH2 telescope at the San Pedro de Atacama Celestial Explorations Observatory in Chile and the Las Cumbres Observatory telescope network. Radial velocity data taken when the star was flaring were excluded from the final analysis.

Although Proxima b orbits much closer to its star than Mercury does to the Sun in the Solar System, the star itself is far fainter than the Sun. As a result Proxima b lies well within the habitable zone around the star and has an estimated surface temperature that would allow the presence of liquid water. Despite the temperate orbit of Proxima b, the conditions on the surface may be strongly affected by the ultraviolet and X-ray flares from the star -- far more intense than the Earth experiences from the Sun >[4].

Two separate papers discuss the habitability of Proxima b and its climate. They find that the existence of liquid water on the planet today cannot be ruled out and, in such case, it may be present over the surface of the planet only in the sunniest regions, either in an area in the hemisphere of the planet facing the star (synchronous rotation) or in a tropical belt (3:2 resonance rotation). Proxima b's rotation, the strong radiation from its star and the formation history of the planet makes its climate quite different from that of the Earth, and it is unlikely that Proxima b has seasons.

This discovery will be the beginning of extensive further observations, both with current instruments >[5] and with the next generation of giant telescopes such as the European Extremely Large Telescope (E-ELT). Proxima b will be a prime target for the hunt for evidence of life elsewhere in the Universe. Indeed, the Alpha Centauri system is also the target of humankind's first attempt to travel to another star system, the StarShot project.

Guillem Anglada-Escudé concludes: "Many exoplanets have been found and many more will be found, but searching for the closest potential Earth-analogue and succeeding has been the experience of a lifetime for all of us. Many people's stories and efforts have converged on this discovery. The result is also a tribute to all of them. The search for life on Proxima b comes next..."

>Notes

>[1] Besides data from the recent Pale Red Dot campaign, the paper incorporates contributions from scientists who have been observing Proxima Centauri for many years. These include members of the original UVES/ESO M-dwarf programme (Martin Kürster and Michael Endl), and exoplanet search pioneers such as R. Paul Butler. Public observations from the HARPS/Geneva team obtained over many years were also included.

>[2] The name Pale Red Dot reflects Carl Sagan's famous reference to the Earth as a pale blue dot. As Proxima Centauri is a red dwarf star it will bathe its orbiting planet in a pale red glow.

>[3] The detection reported today has been technically possible for the last 10 years. In fact, signals with smaller amplitudes have been detected previously. However, stars are not smooth balls of gas and Proxima Centauri is an active star. The robust detection of Proxima b has only been possible after reaching a detailed understanding of how the star changes on timescales from minutes to a decade, and monitoring its brightness with photometric telescopes.

>[4] The actual suitability of this kind of planet to support water and Earth-like life is a matter of intense but mostly theoretical debate. Major concerns that count against the presence of life are related to the closeness of the star. For example gravitational forces probably lock the same side of the planet in perpetual daylight, while the other side is in perpetual night. The planet's atmosphere might also slowly be evaporating or have more complex chemistry than Earth's due to stronger ultraviolet and X-ray radiation, especially during the first billion years of the star's life. However, none of the arguments has been proven conclusively and they are unlikely to be settled without direct observational evidence and characterisation of the planet's atmosphere. Similar factors apply to the planets recently found around TRAPPIST-1.

>[5] Some methods to study a planet's atmosphere depend on it passing in front of its star and the starlight passing through the atmosphere on its way to Earth. Currently there is no evidence that Proxima b transits across the disc of its parent star, and the chances of this happening seem small, but further observations to check this possibility are in progress.

This research is >published in the journal Nature.

Source: European Southern Observatory (ESO) [August 25, 2016]

Extensive systems of fossilised riverbeds have been discovered on an ancient region of the Martian surface, supporting the idea that the now cold and dry Red Planet had a warm and wet climate about 4 billion years ago, according to UCL-led research>.

The study, >published in Geology and funded by the Science & Technology Facilities Council and the UK Space Agency, identified over 17,000km of former river channels on a northern plain called Arabia Terra, providing further evidence of water once flowing on Mars.

"Climate models of early Mars predict rain in Arabia Terra and until now there was little geological evidence on the surface to support this theory. This led some to believe that Mars was never warm and wet but was a largely frozen planet, covered in ice-sheets and glaciers. We've now found evidence of extensive river systems in the area which supports the idea that Mars was warm and wet, providing a more favourable environment for life than a cold, dry planet," explained lead author, Joel Davis (UCL Earth Sciences).

Since the 1970s, scientists have identified valleys and channels on Mars which they think were carved out and eroded by rain and surface runoff, just like on Earth. Similar structures had not been seen on Arabia Terra until the team analysed high resolution imagery from NASA's Mars Reconnaissance Orbiter (MRO) spacecraft.

The new study examined images covering an area roughly the size of Brazil at a much higher resolution than was previously possible -- 6 metres per pixel compared to 100 metres per pixel. While a few valleys were identified, the team revealed the existence of many systems of fossilised riverbeds which are visible as inverted channels spread across the Arabia Terra plain.

The inverted channels are similar to those found elsewhere on Mars and Earth. They are made of sand and gravel deposited by a river and when the river becomes dry, the channels are left upstanding as the surrounding material erodes. On Earth, inverted channels often occur in dry, desert environments like Oman, Egypt, or Utah, where erosion rates are low -- in most other environments, the channels are worn away before they can become inverted.

"The networks of inverted channels in Arabia Terra are about 30m high and up to 1-2km wide, so we think they are probably the remains of giant rivers that flowed billions of years ago. Arabia Terra was essentially one massive flood plain bordering the highlands and lowlands of Mars. We think the rivers were active 3.9-3.7 billion years ago, but gradually dried up before being rapidly buried and protected for billions of years, potentially preserving any ancient biological material that might have been present," added Joel Davis.

"These ancient Martian flood plains would be great places to explore to search for evidence of past life. In fact, one of these inverted channels called Aram Dorsum is a candidate landing site for the European Space Agency's ExoMars Rover mission, which will launch in 2020," said Dr Matthew Balme, Senior Lecturer at The Open University and co-author of the study.

The researchers now plan on studying the inverted channels in greater detail, using higher-resolution data from MRO's HiRISE camera.

Source: University College London [August 23, 2016]

The National Science Foundation's Green Bank Telescope (GBT) will join in the most powerful, comprehensive, and intensive scientific search ever for signs of intelligent life in the Universe. The international endeavor, known as the Breakthrough Listen, will scan the nearest million stars in our own Galaxy and stars in 100 other galaxies for the telltale radio signature of an advanced civilization.

In a contract signed with the Breakthrough Prize Foundation, significant funding -- approximately $2 million per year for 10 years -- will go to the GBT to participate in this exhilarating journey of discovery.

"Beginning early next year, approximately 20 percent of the annual observing time on the GBT will be dedicated to searching a staggering number of stars and galaxies for signs of intelligent life via radio signals," said Tony Beasley, director of the National Radio Astronomy Observatory, which operates the GBT and other world-class radio astronomy facilities. "We are delighted to play such a vital role in hopefully answering one of the most compelling questions in all of science and philosophy: are we alone in the Universe?"

In addition to the GBT, the Parkes Telescope in Australia will also be involved in this endeavor.

Breakthrough Listen will be the biggest scientific search ever undertaken for signs of intelligent life beyond Earth. It will be 50 times more sensitive and cover 10 times more of the sky than previous searches. In tandem with this radio search, the Automated Planet Finder Telescope at Lick Observatory in California will undertake the world's deepest and broadest search for optical laser transmissions, a tantalizing complementary approach to searching the cosmos for extraterrestrial intelligence.

The $100 million Breakthrough Listen initiative was announced today at the Royal Society in London.

The program will include a survey of the one million closest stars to Earth. It will scan the center of our Galaxy and the entire galactic plane. Beyond the Milky Way, it will search for messages from the 100 closest galaxies. If a civilization based around one of the 1,000 nearest stars transmits to us with the power of common aircraft radar, the GBT and the Parkes Telescope could detect it.

The program will generate vast amounts of data; all of which will be open to the public. This will likely constitute the largest amount of scientific data ever made publicly available. The Breakthrough Listen team will use and develop the most powerful software for sifting and searching this flood of data. All software will be open source. Both the software and the hardware used in the Breakthrough Listen project will be compatible with other telescopes around the world, so that they could join the search for intelligent life. As well as using the Breakthrough Listen software, scientists and members of the public will be able to add to it, developing their own applications to analyze the data.

Breakthrough Listen will also be joining and supporting SETI@home, the University of California, Berkeley ground-breaking distributed computing platform, with 9 million volunteers around the world donating their spare computing power to search astronomical data for signs of life. Collectively, they constitute one of the largest supercomputers in the world.

The 100-meter Green Bank Telescope is the world's largest fully steerable radio telescope. Its location in the National Radio Quiet Zone and the West Virginia Radio Astronomy Zone protects the incredibly sensitive telescope from unwanted radio interference, enabling it to perform unique observations.

Source: National Radio Astronomy Observatory [July 20, 2015]

Scientists analysing samples from Mars' surface have so far not conclusively detected organic compounds that are indigenous to Mars, which would be indicators of past or present life. The inconclusive results mean that researchers are now suggesting that a good place to find these organic compounds would be deep underground – from rocks that have been blasted to the surface by meteor impacts. This is because such rocks have been sheltered from the Sun's harmful radiation and from chemical processes on the surface that would degrade organic remains.

Now, a team of scientists from Imperial College London and the University of Edinburgh has replicated meteorite blasts in the lab. The aim of the study was to see if organic compounds encased in rock could survive the extreme conditions associated with them being blasted to the surface of Mars by meteorites.  The study, >published in Scientific Reports, suggests that rocks excavated through meteorite impacts may incorrectly suggest a lifeless early Mars, even if indicators of life were originally present.

In the study the team replicated blast impacts of meteorites of around 10 metres in size. The researchers found that the types of organic compounds found in microbial and algal life - long chain hydrocarbon-dominated matter- were destroyed by the pressures of impact. However, the types of organic compounds found in plant matter – dominated by aromatic hydrocarbons - underwent some chemical changes, but remained relatively resistant to impact pressures. Meteorites often contain organic matter not created by life, which have some similarities in their organic chemistry to land plants. The team infer that they also should also be resistant to blast impacts.

Their study could help future missions to Mars determine the best locations and types of blast excavated rocks to examine to find signs of life. For example, it may be that meteorite impacts of a certain size may not destroy organic compounds or scientists may need to concentrate on rocks excavated from a certain depth.

Professor Mark Sephton, co-author of the research from the Department of Earth Science and Engineering at Imperial College London, said: "We've literally only scratched the surface of Mars in our search for life, but so far the results have been inconclusive. Rocks excavated through meteorite impacts provide scientists with another unique opportunity to explore for signs of life, without having to resort to complicated drilling missions. Our study is showing us is that we may need to be nuanced in our approach to the rocks we choose to analyse."

Dr Wren Montgomery, co-author of the study from the Department of Earth Science and Engineering, added: "The study is helping us to see that when organic matter is observed on Mars, no matter where, it must be considered whether the sample could have been affected by the pressures associated with blast impacts. We still need to do more work to understand what factors may play an important role in protecting organic compounds from these blast impacts. However, we think some of the factors may include the depths at which the rock records are buried and the angles at which meteorites hit the Martian surface."

Previous in situ analyses of the Martian terrain have found inconclusive evidence for the existence organic compounds – so far only finding chlorinated organic matter. The issue for scientists has been that it is not easy to look at simple chlorine-containing organic molecules and determine the origin of the organic compound components.

NASA's Viking landers in 1976 detected chlorine-containing organic compounds, but they were thought to be chemical left-overs from cleaning procedures of Viking's equipment before it left Earth. Later, the Phoenix Mission in 2008 discovered chlorine-containing minerals on the Martian surface, but no organic compounds. In 2012 the Mars Science Laboratory Mission detected chlorinated organic matter, but they thought that the analysis process, which involved heating chlorine containing minerals and carbonaceous material together, was producing chlorine-containing organic compounds. Working out whether the source of the carbon found on Mars was carried once again from Earth or was indigenous to Mars remains frustratingly difficult for scientists.

The team carried out their research by subjecting the different types of organic matter to extreme pressure and temperature in a piston cylinder device. They then did a chemical analysis using pyrolysis-gas chromatography mass spectrometry.

The next steps will see the team investigating a broader range of pressures and temperatures, which would help them understand the likely effects of a greater range of meteorite impacts. This would enable them to identify the specific conditions under which organic material may escape the destructive effects of blasts – even when excavated from deep underground by violent events. This could help future Mars missions further refine the types and locations of rocks that they can analyse for signs of past or present life.

Author: Colin Smith | Source: Imperial College London [August 08, 2016]

Early Earth was an inhospitable place where the planet was often bombarded by comets and other large astrophysical bodies.

Some of those comets contained complex prebiotic materials, such as amino acids and peptides (chains of amino acids), which are some of the most basic building blocks of life on Earth.

“The survivability of these compounds under impact conditions is mostly unknown,” said Lawrence Livermore’s Nir Goldman, who recently received a NASA grant to continue his astrobiology research. “Our research hopes to answer these questions and give an indication for what types of potentially life-building compounds would be produced under these conditions.”

Basically, Goldman is trying to figure out if life on Earth really did come from out of this world.

Goldman’s early research found that the impact of icy comets crashing into Earth billions of years ago could have produced a variety of small prebiotic or life-building compounds. His work using quantum simulations predicted that the simple molecules found in comets (such as water, ammonia, methanol and carbon dioxide) could have supplied the raw materials, and the impact with early Earth would have yielded an abundant supply of energy to drive the synthesis of compounds like protein forming amino acids. In later work, researchers from Imperial College in London and University of Kent conducted a series of experiments very similar to Goldman’s simulations in which a projectile was fired using a light gas gun into a typical cometary ice mixture. The result: Several different types of amino acids formed.

“Impact events could have not only delivered prebiotic precursors to the primitive planet, but the sudden increase in pressure and temperature from the impact itself was likely a driving factor in synthesizing their assembly into these primary structures,” Goldman said.

Specifically, this new $500,000 grant will fund quantum simulation studies to understand aqueous mixtures of pre-formed amino acids under impact conditions. Goldman’s current efforts will extend his previous work by looking at one step higher in complexity, where extreme pressures and temperatures from impact could induce the formation of more intricate chemical structures like peptide chains or simple proteins.

“Large astrophysical bodies such as comets likely already contain more complex prebiotic materials, like amino acids. It’s possible that pre-existing amino acids would have experienced additional impacts during periods of heavy bombardment on early Earth,” Goldman said. “Our quantum simulations hope to help answer these questions, and to give an indication as to what set of thermodynamic conditions promotes their assembly into larger structures.”

How and when prebiotic organic material appeared on early Earth has been debated for close to 60 years, starting with the seminal Miller-Urey experiments, which showed that amino acids could be produced in aqueous mixtures subjected to electrical discharges, simulating lightning on early Earth.

Large bodies from space are carriers of prebiotic materials. Previous analysis of dust samples from comet Wild 2 has shown the presence of the amino acid glycine in the captured material. In addition, dipeptides (i.e., an amino acid dimer) likely exist in interstellar ices. Assuming survival upon delivery to Earth, these could have acted as catalysts in the formation of a number of prebiotic compounds, including sugars and enzymes.

“Our predictions will help spur future collaboration with experimental groups to characterize the synthesis of primary biomaterials due to exposure to extreme pressures and temperatures,” Goldman said.

Source: Lawrence Livermore National Laboratory [July 07, 2015]

Extra-terrestrials that resemble humans should have evolved on other, Earth-like planets, making it increasingly paradoxical that we still appear to be alone in the universe, the author of a new study on convergent evolution has claimed.

The argument is one of several that emerge from The Runes Of Evolution, a new book in which the leading evolutionary biologist, Professor Simon Conway Morris, makes the case for a ubiquitous "map of life" that governs the way in which all living things develop.

It builds on the established principle of convergent evolution, a widely-supported theory -- although one still disputed by some biologists -- that different species will independently evolve similar features.

Conway Morris argues that convergence is not just common, but everywhere, and that it has governed every aspect of life's development on Earth. Proteins, eyes, limbs, intelligence, tool-making -- even our capacity to experience orgasms -- are, he argues, inevitable once life emerges.

The book claims that evolution is therefore far from random, but a predictable process that operates according to a fairly rigid set of rules.

If that is the case, then it follows that life similar to that on Earth would also develop in the right conditions on other, equivalent planets. Given the growing number of Earth-like planets of which astronomers are now aware, it is increasingly extraordinary that aliens that look and behave something like us have not been found, he suggests.

"Convergence is one of the best arguments for Darwinian adaptation, but its sheer ubiquity has not been appreciated," Professor Conway Morris, who is a Fellow at St John's College, University of Cambridge, said.

"Often, research into convergence is accompanied by exclamations of surprise, describing it as uncanny, remarkable and astonishing. In fact it is everywhere, and that is a remarkable indication that evolution is far from a random process. And if the outcomes of evolution are at least broadly predictable, then what applies on Earth will apply across the Milky Way, and beyond."

Professor Conway Morris has previously raised the prospect that alien life, if out there, would resemble earthlings -- with limbs, heads, and bodies -- notably at a Royal Society Conference in London in 2010. His new book goes even further, however, adding that any Earth-like planet should also evolve thunniform predators (like sharks), pitcher plants, mangroves, and mushrooms, among many other things.

Limbs, brains and intelligence would, similarly, be "almost guaranteed." The traits of human-like intelligence have evolved in other species -- the octopus and some birds, for example, both exhibit social playfulness -- and this, the book suggests, indicates that intelligence is an inevitable consequence of evolution that would characterise extraterrestrials as well.

Underpinning this is Conway Morris' claim that convergence is demonstrable at every major stepping stone in evolutionary history, from early cells, through to the emergence of tissues, sensory systems, limbs, and the ability to make and use tools.

The theory, in essence, is that different species will evolve similar solutions to problems via different paths. A commonly-cited example is the octopus, which has evolved a camera eye that is closely similar to that of humans, although distinctive in important ways that reflect its own history. Although octopi and humans have a common ancestor, possibly a slug-like creature, this lived 550 million years ago and lacked numerous complex features that the two now share. The camera eye of each must therefore have evolved independently.

Conway Morris argues that this process provides an underlying evolutionary framework that defines all life, and leads to innumerable surprises in the natural world. The book cites examples such as collagen, the protein found in connective tissue, which has emerged independently in both fungi and bacteria; or the fact that fruit flies seem to get drunk in the same manner as humans. So too the capacity for disgust in humans -- a hard-wired instinct helping us avoid infection and disease -- is also exhibited by leaf-cutter ants.

The study also identifies many less obvious evolutionary "analogues," where species have evolved certain properties and characteristics that do not appear to be alike, but are actually very similar. For example, "woodpeckerlike habits" are seen in lemurs and extinct marsupials, while the mechanics of an octopus' tentacles are far closer to those of a human arm than we might expect, and even their suckers can operate rather like hands.

Conway Morris contends that all life navigates across this evolutionary map, the basis of what he describes as a "predictive biology." "Biology travels through history," he writes, "but ends up at much the same destination."

This, however, raises fascinating and problematic questions about the possibility of life occurring on other planets. "The number of Earth-like planets seems to be far greater than was thought possible even a few years ago," Conway Morris said. "That doesn't necessarily mean that they have life, because we don't necessarily understand how life originates. The consensus offered by convergence, however, is that life is going to evolve wherever it can."

"I would argue that in any habitable zone that doesn't boil or freeze, intelligent life is going to emerge, because intelligence is convergent. One can say with reasonable confidence that the likelihood of something analogous to a human evolving is really pretty high. And given the number of potential planets that we now have good reason to think exist, even if the dice only come up the right way every one in 100 throws, that still leads to a very large number of intelligences scattered around, that are likely to be similar to us."

If this is so, as the book suggests in its introduction, then it makes Enrico Fermi's famous paradox -- why, if aliens exist, we have not yet been contacted -- even more perplexing. "The almost-certainty of ET being out there means that something does not add up, and badly," Conway Morris said. "We should not be alone, but we are."

The Runes Of Evolution was six years in the making and draws on thousands of academic sources, and throws up numerous other, surprising findings as well. Sabre-teeth, for example, turn out to be convergent, and Conway Morris explains why it is that the clouded leopard of Asia, Neofelis nebulosa, has developed features that could, as it evolves "presage the emergence of a new sabre-tooth," although sadly it looks set to become extinct before this happens. Elsewhere, the study suggests that certain prehistoric creatures other than bats and birds may have attempted to evolve flight.

"It makes people slightly uneasy that evolution can end up reaching the same solutions to questions about how to catch something, how to digest something, and how to work," Conway Morris added. "But while the number of possibilities in evolution in principle is more than astronomical, the number that actually work is an infinitesimally smaller fraction."

The Runes Of Evolution, by Simon Conway Morris, is published by Templeton Press

Source: University of Cambridge [July 02, 2015]