Category: The Origin of Life (page 3 of 4)

Messy Chemistry: A New Way to Approach the Origins of Life

Astrobiologist and chemist Irena Mamajanov and prebiotic chemist Kuhan Chandru in their messy chemistry garb at the Earth-Life Science Institute (ELSI) in Tokyo. Mamajanov leads an effort at the institute to study a new “messy” path to understanding how some prebiotic chemical systems led to building blocks of life on early Earth. (Nerissa Escanlar)

More than a half century ago, Stanley Miller and Harold Urey famously put water and gases believed to make up the atmosphere of early Earth into a flask with water, sparked the mix with an electric charge, and produced amino acids and other chemical building blocks of life.

The experiment was hailed as a ground-breaking reproduction of how the essential components of life may have been formed, or at least a proof of concept that important building blocks of life could be formed from more simple components.

Little discussed by anyone outside the origins of life scientific community was that the experiment also produced a lot of a dark, sticky substance, a gooey tar that covered the beaker’s insides. It was dismissed as largely unimportant and regrettable then, and in the thousands of parallel origins of life experiments that followed.

Today, however, some intrepid researchers are looking at the tarry residue in a different light.

Tarry residue from an experiment — a common result when organic compounds are heated.

Just maybe, they argue, the tar was equally if not more important as those prized amino acids (which, after all, were hidden away in the tar until they were extracted out.) Maybe the messy tar – produced by the interaction of organic compounds and an energy source — offers a pathway forward in a field that has produced many advances but ultimately no breakthrough.

Those now studying the tar call their research “messy chemistry,” as opposed to the “clean” chemistry that focused on the acclaimed organic compounds.

There are other centers where different versions of “messy chemistry” research are under way — including George Cody’s lab at the Carnegie Institution for Sciences and Nicholas Hud’s at the Georgia Institute of Technology — but it is probably most concentrated at the Earth-Life Science Institute in Tokyo (ELSI.)

There, messy chemistry is viewed as an ignored but promising way forward, and almost a call to arms.

“In classical origin-of-life synthetic chemistry and biology you’re looking at one reaction and analyzing its maximum result. It’s A+B = C+D,” said Irena Mamajanov, an astrobiologist with a background in chemistry who is now a principal investigator ELSI and head of the overall messy chemistry project.… Read more

Certain Big, Charged Molecules Are Universal to Life on Earth. Can They Help Detect It In The Far Solar System?

 

This article of mine, slightly tweaked for Many Worlds, first appeared today (July 6)  in Astrobiology Magazine,  http://www.astrobio.net

NASA’s Cassini spacecraft completed its deepest-ever dive through the icy plume of Enceladus on Oct. 28, 2015. The spacecraft did not have instruments that could detect life, but missions competing for NASA New Frontiers funding will — raising the thorny question of how life might be detected. (NASA/JPL-Caltech)

As NASA inches closer to launching new missions to the Solar System’s outer moons in search of life, scientists are renewing their focus on developing a set of universal characteristics of life that can be measured.

There is much debate about what might be considered a clear sign of life, in part, because there are so many definitions separating the animate from the inanimate.

NASA’s prospective missions to promising spots on Europa, Enceladus and Titan have their individual approaches to detecting life, but one respected voice in the field says there is a better way that’s far less prone to false positives.

Noted chemist and astrobiologist Steven Benner says life’s signature is not necessarily found in the presence of particular elements and compounds, nor in its effects on the surrounding environment, and is certainly not something visible to the naked eye (or even a sophisticated camera).

Rather, life can be viewed as a structure, a molecular backbone that Benner and his group, Foundation for Applied Molecular Evolution (FfAME), have identified as the common inheritance of all living things. Its central function is to enable what origin-of-life scientists generally see as an essential dynamic in the onset of life and its increased complexity and spread: Darwinian evolution via transfer of information, mutation and the transfer of those mutations.

“What we’re looking for is a universal molecular bio-signature, and it does exist in water,” says Benner. “You want a genetic molecule that can change physical conditions without changing physical properties — like DNA and RNA can do.”

Steven Benner, director of the Foundation for Applied Molecular Evolution or FfAME. (SETI)

Looking for DNA or RNA on an icy moon, or elsewhere would presuppose life like our own — and life that has already done quite a bit of evolving.

A more general approach is to find a linear polymer (a large molecule, or macromolecule, composed of many repeated subunits, of which DNA and RNA are types) with an electrical charge. That, he said, is a structure that is universal to life, and it can be detected.… Read more

Nobel Laureate Jack Szostak: Exoplanets Gave The Origin of Life Field a Huge Boost

Jack Szostak, Nobel laureate and pioneering researcher in the origin-of-life field, was the featured speaker at a workshop this week at the Earth-Life Science Institute (ELSI) in Tokyo.  One goal of his Harvard lab is to answer this once seemingly impossible question:  was the origin of life on Earth essentially straight-forward and “easy,” or was it enormously “hard” and consequently rare in the universe. (Nerissa Escanlar)

Sometimes tectonic shifts in scientific disciplines occur because of discoveries and advances in the field.  But sometimes they occur for reasons entirely outside the field itself.  Such appears to be case with origins-of-life studies.

Nobel laureate Jack Szostak was recently in Tokyo to participate in a workshop at the Earth-Life Science Institute (ELSI) at the Tokyo Institute of Technology on “Reconstructing the Phenomenon of Life To Retrace the Emergence of Life.”

The talks were technical and often cutting-edge, but the backstory that Szostak tells of why he and so many other top scientists are now in the origins of life field was especially intriguing and illuminating in terms of how science progresses.

Those ground-shifting discoveries did not involve traditional origin-of-life questions of chemical transformations and pathways.  They involved exoplanets.

“Because of the discovery of all those exoplanets, astronomy has been transformed along with many other fields,” Szostak said after the workshop.

“We now know there’s a large range of planetary environments out there, and that has stimulated a huge amount of interest in where else in the universe might there be life.  Is it just here?  We know for sure that lots of environments could support life and we also would like to know:  do they?

“This has stimulated much more laboratory-based work to try to address the origins question.  What’s really important is for us to know whether the transition from chemistry to biology is easy and can happen frequently and anywhere, or are there one or many difficult steps that make life potentially very rare?”

In other words, the explosion in exoplanet science has led directly to an invigorated scientific effort to better understand that road from a pre-biotic Earth to a biological Earth — with chemistry that allows compounds to replicate, to change, to surround themselves in cell walls, and to grow ever more complex.

With today’s increased pace of research, Szostak said, the chances of finding some solid answers have been growing.  In fact, he’s quite optimistic that an answer will ultimately be forthcoming to the question of how life began on Earth.… Read more

The Magma Ocean and Us

A vast magma ocean covered the very early Earth in its late period of formation, the likely result of heat from impacts as materials large and small fell to Earth.  The magma ocean climbed to temperatures of 2000˚F and well above and reached depths of hundreds of miles.  Magma breaks the surface now only rarely in volcanic eruption, when it is called lava. This lava lake sits in Mount Nyiragongo, Democratic Republic of Congo. (National Geographic.)

In the late stages of the formation of Earth, the planet was a brutally hot, rough place.  But perhaps not precisely in the way you might imagine.

Most renderings of that time show red-hot lava flowing around craggy rocks, with meteorites falling and volcanoes erupting.  But according to those who study the time, the reality was rather different.

There was most likely no land much of the time, the medium to large meteorites arrived every few thousand years , and the surface was the consistency of a kind of room-temperature oil.  Of course it was not oil, since this was a pre-organic time.  Rather, it was mostly molten silicates and iron that covered the Earth in a “magma ocean.”

At its most extreme, the magma ocean may have been as deep in places as the radius of Mars.  And it would have created thick atmospheres of carbon dioxide, silica dust, other toxic gases and later water vapor.

While meteor impacts did play a major role in those earliest days, the dynamics of the magma ocean were more determined by the convection currents of the super-hot magma (2000 degrees F and more), the high winds blowing above the surface, the steam atmosphere it often created and ultimately by the cooling that over hundreds of million of years led to the formation of a solid crust.

There is a burgeoning scientific interest in the magma ocean, which is expected to be part of the formation of any terrestrial planet and some lunar formations.  The research focuses on the gaining an understanding of the characteristics and diversity of magma oceans, and increasingly on the potentially significant role it plays in the origin of life on Earth, and perhaps elsewhere.

The reason why is pretty simple:  life (i.e., biochemistry) emerged on Earth from geochemistry (i.e., rocks and sediment.)  Some of the earliest geochemistry occurred in the magma ocean, and so it makes sense to learn as much as possible about the very earliest conditions that ultimately led to the advent of biology.… Read more

Curiosity Has Found The Element Boron On Mars. That’s More Important Than You Might Think

ChemCam target Catabola is a raised resistant calcium sulfate vein with the highest abundance of boron observed so far. The red outline shows the location of the ChemCam target remote micro images (inset). The remote micro images show the location of each individual ChemCam laser point (red crosshairs) and the B chemistry associated with each point (colored bars). The scale bar is 9.2 mm or about 0.36 inches. Credit JPL-Caltech/MSSS/LANL/CNES-IRAP/William Rapin

Using its laser technology, the Curiosity ChemCam instrument located the highest abundance of boron observed so far on this raised calcium sulfate vein. The red outline shows the location of the ChemCam target remote micro images (inset). The remote micro images show the location of each individual ChemCam laser point (red crosshairs) and the additional chemistry associated with each point (colored bars).  JPL-Caltech/MSSS/LANL/CNES-IRAP/William Rapin

For years, noted chemist and synthetic life researcher Steven Benner has talked about the necessary role of the element boron in the origin of life.

Without boron, he has found, many of the building blocks needed to form the earliest self-replicating ribonucleic acid (RNA) fall apart when they come into contact with water, which is nonetheless needed for the chemistry to succeed. Only in the presence of boron, Benner found and has long argued, can the formation of RNA and later DNA proceed.

Now, to the delight of Benner and many other scientists, the Curiosity team has found boron on Mars.  In fact, as Curiosity climbs the mountain at the center of Gale Crater, the presence of boron has become increasingly pronounced.

And to make the discovery all the more meaningful to Benner, the boron is being found in rock veins.  So it clearly was carried by water into the fractures, and was deposited there some 3.5 billion years ago.

Combined with earlier detections of phosphates, magnesium, peridots, carbon and other essential elements in Gale Crater, Benner told me, “we have found on Mars an environment entirely consistent with a what we consider conducive for the origin of life.

“Is it likely that life arose?  I’d say yes…perhaps even, hell yes.  But it’s also true that an environment conducive to the formation of life isn’t necessarily one conducive to the long-term survival of life.”

The foreground of this scene from the Mastcam on NASA's Curiosity Mars rover shows purple-hued rocks near the rover's late-2016 location. The middle distance includes future destinations for the rover. Variations in color of the rocks hint at the diversity of their composition on lower Mount Sharp. Credits: NASA/JPL-Caltech/MSSS

The foreground of this scene from the Mastcam on NASA’s Curiosity Mars rover shows purplish rocks near the rover’s late-2016 location. The middle distance includes future destinations for the rover. Variations in color of the rocks hint at the diversity of their composition on lower Mount Sharp. NASA/JPL-Caltech/MSSS

Another factor in the Mars-as-habitable story from Benner’s view is that there has never been the kind of water world there that many believe existed on early Earth.

While satellites orbiting Mars and now Curiosity have made it abundantly clear that early Mars also had substantial water in the form of lakes, rivers, streams and perhaps an localized ocean, it was clearly never covered in water.… Read more

The Stellar Side of The Exoplanet Story

K2-33b, shown in this illustration, is one of the youngest exoplanets detected to date. It makes a complete orbit around its star in about five days. Credits: NASA/JPL-Caltech

K2-33b, shown in this illustration, is one of the youngest exoplanets detected to date. It makes a complete orbit around its star in about five days, and as a result its characteristics are very much determined by its host. (NASA/JPL-Caltech)

 

When it comes to the study of exoplanets, it’s common knowledge that the host stars don’t get much respect.

Yes, everyone knows that there wouldn’t be exoplanets without stars, and that they serve as the essential background for exoplanet transit observations and as the wobbling object that allows for radial velocity measurements that lead to new exoplanets discoveries.

But stars in general have been seen and studied for ever, while the first exoplanet was identified only 20-plus years ago.  So it’s inevitable that host stars have generally take a back seat to the compelling newly-found exoplanets that orbit them.

As the field of exoplanet studies moves forward, however, and tries to answer questions about the characteristics of the planets and their odds of being habitable, the perceived importance of the host stars is on the rise.

The logic:  Stars control space weather, and those conditions produce a space climate that is conducive or not so conducive to habitability and life.

Space weather consists of a variety of enormously energetic events ranging from solar wind to solar flares and coronal mass ejections, and their characteristics are defined by the size, variety and age of the star.  It is often said that an exoplanet lies in a “habitable zone” if it can support some liquid water on its surface, but absent some protection from space weather it will surely be habitable in name only.

A recognition of this missing (or at least less well explored) side of the exoplanet story led to the convening of a workshop this week in New Orleans on “The Impact of Exoplanetary Space Weather On Climate and Habitability.”

“We’re really just starting to detect and understand the secret lives of stars,”  said Vladimir Airapetian, a senior scientist at the Goddard Space Flight Center.  He organized the highly interdisciplinary workshop for the Nexus for Exoplanet Space Studies (NExSS,) a NASA initiative.

“What has become clear is that a star affects and actually defines the character of a planet orbiting around it,” he said.  “And now we want to look at that from the point of view of astrophysicists, heliophysicists, planetary scientists and astrobiologists.”

William Moore, principal investigator for a NASA-funded team also studying how host stars affect their exoplanets, said the field was changing fast and that “trying to understand those (space weather) impacts has become an essential task in the search for habitable planets.”… Read more

One Planet, But Many Different Earths

Artist conception of early Earth. (NASA/JPL-Caltech)

Artist conception of early Earth. (NASA/JPL-Caltech)

We all know that life has not been found so far on any planet beyond Earth — at least not yet.  This lack of discovery of extraterrestrial life has long been used as a knock on the field of astrobiology and has sometimes been put forward as a measure of Earth’s uniqueness.

But the more recent explosion in exoplanet discoveries and the next-stage efforts to characterize their atmospheres and determine their habitability has led to rethinking about how to understand the lessons of life of Earth.

Because when seen from the perspective of scientists working to understand what might constitute an exoplanet that can sustain life,  Earth is a frequent model but hardly a stationary or singular one.  Rather, our 4.5 billion year history — and especially the almost four billion years when life is believed to have been present  — tells many different stories.

For example, our atmosphere is now oxygen-rich, but for billions of years had very little of that compound most associated with complex life.  And yet life existed.

The same with temperature.  Earth went through snowball or slushball periods when most of the planet’s surface was frozen over.  Hardly a good candidate for life, and yet the planet remained habitable and inhabited.

And in its early days, Earth had a very weak magnetic field and was receiving only 70 to 80 percent as much energy from the sun as it does today.  Yet it supported life.

“It’s often said that there’s an N of one in terms of life detected in the universe,” that there is but one example, said Timothy Lyons, a biogeochemist and distinguished professor at University of California, Riverside.

“But when you look at the conditions on Earth over billion of years, it’s pretty clear that the planet had very different kinds of atmospheres and oceans, very different climate regimes, very different luminosity coming from the sun.  Yet we know there was life under all those very different conditions.

“It’s one planet, but it’s silly to think of it as one planetary regime. Each of our past chapters is a potential exoplanet.”

 

A rendering of the theorized "Snowball Earth" period when, for millions of years, the Earth was entirely or largely covered by ice, stretching from the poles to the tropics. This freezing happened over 650 million years ago in the Pre-Cambrian, though it's now thought that there may have been more than one of these global glaciations. They varied in duration and extent but during a full-on snowball event, life could only cling on in ice-free refuges, or where sunlight managed to penetrate through the ice to allow photosynthesis.

A particularly extreme phase of our planet’s history is called  the “Snowball Earth” period.  During these episodes, the Earth’s surface was entirely or largely covered by ice for millions of years, stretching from the poles to the tropics. One such freezing happened over 700 to 800 million years ago in the Pre-Cambrian, around the time that animals appeared.

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More Evidence of Water Plumes On Europa Increases Confidence That They’re For Real

 Figure 2: This composite image shows suspected plumes of water vapor erupting at the 7 o’clock position off the limb of Jupiter’s moon Europa. The Hubble data were taken on January 26, 2014. The image of Europa, superimposed on the Hubble data, is assembled from data from the Galileo and Voyager missions. Credits: NASA/ESA/W. Sparks (STScI)/USGS Astrogeology Science Center Image comparison of 2014 transit and 2012 Europa aurora observations


This composite image shows suspected plumes of water vapor erupting at the 7 o’clock position off the limb of Jupiter’s moon Europa. The Hubble data were taken on January 2014, and appear to show plumes that spit out as much as 125 miles.  The image of Europa, superimposed on the Hubble data, is assembled from data from the Galileo and Voyager missions. (NASA/ESA/W. Sparks (STScI)/USGS Astrogeology Science Center)

Europa is a moon no bigger than our own and is covered by deep layers of ice, but it brings with it a world of promise.  Science fiction master and sometimes space visionary Arthur C. Clarke, after all,  named it as the most likely spot in our solar system to harbor life, and wrote a “2001: A Space Odyssey”  follow-up based in part on that premise.

Many in the planetary science and astrobiology communities are similarly inclined and have supported a specifically Europa mission geared to learning more about what is generally considered to be a large ocean beneath that ice.

Along the way, Europa became the only object deemed by Congress to be an obligatory NASA destination, and formal plans for such a voyage have been under way — however slowly — for several years.  Formal development of the “Europa Clipper” flyby project began last year, after a half decade of conceptual work.

The logic for the flyby got a major boost on Monday when a team using the Hubble Space Telescope reported that they had most likely detected plumes of water erupting out of Europa on three separate occasions.

Because of the difficulty of the observation — and the fact that plumes were found on 3 out of 10 passes — nobody was willing to claim that the finding was definitive.  But coupled with an earlier identification of a Europa plume by a different team using a different technique, the probability that the plumes are real is getting pretty high.

And if there really are plumes of water vapor or ice crystals being pushed through Europa’s thick surface of ice, then the implications for the search for signs of habitability and of life on Europa are enormous.

“Europa is surely one of the most compelling astrobiological targets in solar system with its apparent saline oceans,” said William Sparks, an astronomer with Space Telescope Science Institute in Baltimore and lead author of the Europa paper, to be published in The Astrophysical Journal.… Read more

Earth: A Prematurely Inhabited Planet?

A schematic of the history of the cosmos since the Big Bang identifies the period when planets began to form, but there's indication of when life might have started. Harvard's Avi Loeb wants to put life into this cosmological map, and foresees much more of it in the future, given certain conditions. ( NASA)

A schematic of the history of the cosmos since the Big Bang identifies the period when planets began to form, but there’s no indication of when life might have started. Harvard’s Avi Loeb wants to add life into this cosmological map, and foresees much more of it in the future, given certain conditions. ( NASA)

The study of the formation and logic of the universe (cosmology) and the study of exoplanets and their conduciveness to life do not seem to intersect much.  Scientists in one field focus on the deep physics of the cosmos while the others search for the billions upon billions of planets out there and seek to unlock their secrets.

But astrophysicist and cosmologist Avi Loeb — a prolific writer about the early universe from his position at the Harvard-Smithsonian Center for Astrophysics– sees the two fields of study as inherently connected, and has set out to be a bridge between them.  The result was a recent theoretical paper that sought to place the rise of life on Earth (and perhaps elsewhere) in cosmological terms.

His conclusion:  The Earth may well be a very early example of a living biosphere, having blossomed well before life might be expected on most planets.   And in theoretical and cosmological terms, there are good reasons to predict that life will be increasingly common in the universe as the eons pass.

By eons here, Loeb is thinking in terms that don’t generally get discussed in geological or even astronomical terms.  The universe may be an ancient 13.7 billion years old, but Loeb sees a potentially brighter future for life not billions but trillions of years from now.  Peak life in the universe, he says, may arrive several trillion years hence.

“We used the most conservative approaches to understanding the appearance of life in the universe, and our conclusion is that we are very early in the process and that it is likely to ramp up substantially in the future,” said Loeb, whose paper was published in the Journal of Cosmology and Astroparticle Physics.

“Given the factors we took into account, you could say that life on Earth is on the premature side.”

 

The Earth was formed some 4.5 billions years ago, and life that existed as long ago as 3.5 to 3.8 billion years ago has been discovered. Harvard astrophysicist Avi Loeb argues that life on Earth may well be "premature" in cosmological terms, and that many more planets will have biospheres in the far future. (xxx)

The Earth was formed some 4.5 billion years ago, and signs of life have been discovered that are 3.5 to 3.8 billion years old. Harvard astrophysicist Avi Loeb, with co-authors Rafael Batista and David Sloan of the University of Oxford, argue that life on Earth may well be “premature” in cosmological terms, and that many more planets will have biospheres in the far future. 

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Forget the "Habitable Zone," Think the "Biogenic Zone"

An eruption on April 16, 2012 was captured here by NASA's Solar Dynamics Observatory in the 304 Angstrom wavelength, which is typically colored in red. Credit: NASA/SDO/AIA

A highly-energetic coronal mass ejection coming off the sun in 2012 was captured here by NASA’s Solar Dynamics Observatory.  Increasingly, the study of exoplanets and their potential habitability is focusing on the nature and dynamics of host stars.  (NASA/SDO/AIA)

 

It is hardly surprising that in this burgeoning exoplanet era of ours, those hitherto unknown planets get most of the attention when it comes to exo-solar systems.  What are the planet masses?  Their orbits?  The chemical makeup of their atmospheres? Their potential capacity to hold liquid surface water and thereby become “habitable.”

Less frequently highlighted in this exoplanet scenario are the host stars around which the planets orbit.  We’ve known for a long time, after all, that there are billions and billions of stars out there, and have only known for sure that there are planets for 20 years.  So the stars hosting exoplanets have largely played a background role focused on detection:  Does the light curve of a star show the tiny dips that tell of a transiting planet?  Does a star “wobble” every so slightly due to the gravitational forces or orbiting planets.

Gradually, however, that backseat role for stars in the exoplanet story is starting to change, especially as the key question moves from whether new exoplanets have been found to whether they hold the potential to support life.

And a growing number of scientists — and especially those specializing in stars — argue that central to that latter question are understanding the make-up and dynamics of the host stars.

Vladimir Airapetian, a research heliophysicist and astrophysicist at NASA’s Goddard Space Flight Center, has been a leader in this emphasis on the stellar side of the exoplanet story.  And now, he has proposed a re-conceiving  and re-naming of that area around stars where planets could potentially host liquid water and support life — the so-called “Goldilocks” or habitable zone.

His alternative:  the “biogenic zone.”

“Liquid water is undeniably important for possible life on a planet, but it is not sufficient,” he told me.  “I believe that equally important is the amount of  energy coming from the host star.

“The last twenty years has seen a huge increase in knowledge about our own sun, and the lessons learned are now being used on exoplanet-host star systems.  This is essential because without an understanding of the energy arriving at a planet from a star, it’s really impossible to assess its potential to support life.”… Read more

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