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

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

Many Worlds, Subterranean Edition

Scanning electron microscope blue-tinted image of nematode on biofilm, collected from Kopanang mine almost one mile below surface. (Borgonie, ELi)

Scanning electron microscope blue-tinted image of a nematode on bio-film, collected from Kopanang mine almost one mile below surface. (Borgonie, ELi)

One of the richest lines of research for those thinking about life beyond Earth has been the world of microscopic creatures that live in especially extreme and hostile environments here.  The realm of extremophiles has exploded in roughly the period that exoplanet discoveries have exploded, and both serve to significantly change our view of what’s possible in nature writ large.

I was reminded of this with the publication today of a paper on extreme life in the deep mines of South Africa.  This is not a brand new story, but rather significant step forward in a story that has implications galore for the search for life beyond Earth.

The extremophile chronology in South Africa goes like this:

First there was the microbe D. Audaxviator, “the Bold Traveler,” found living in light-less solitude more than two miles down a South African gold mine. Nothing alive had ever been found in rock fractures at that depth before.

Then there was H. Mephisto, the “Worm From Hell,” the first complex, multi-cellular creature (a type of worm) found living at almost equal depths in the same group of mines.

SEM of critters

Scanning electron microscope images of species of worms and a crustacean from Driefontein and Kopanang mines (Borgonie, ELi)

Now the researchers who made both of those discoveries have discovered a “veritable zoo” of multicellular creatures living in the wet rock fissures of the gold and diamond mines of the Witwaterstrand Basin of South Africa, roughly
a mile below the surface.

The earlier discoveries (reports about them were published in 2006 and 2011) had already changed scientists’ understanding of life in the rocky underworld. They had also given encouragement to those convinced that microbes and maybe multi-celled creatures can survive in fissures deep below the surface  of Mars and other moons and planets. The latest jackpot carries this shift in thinking further.

“It is very crowded in some places down under,” said Gaetan Borgonie of ELi, a Belgian nonprofit that studies extreme life, and of South Africa’s University of the Free State in Bloemfontein.

Borgonie, lead author of a paper about the “veritable zoo,” said that his discovery in 2011 of a new species of nematode at great depth had been dismissed by some as a “freak find.” But now, he said, “the fact that we have found in two mines, in different water, two ecosystems featuring several types of invertebrates hopefully puts that notion to rest as wrong.”… Read more

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