Tag Archives: #life

Life Could Exist in the Clouds of Jupiter But Not Venus (Planetary Science)

Jupiter’s clouds have water conditions that would allow Earth-like life to exist, but this isn’t possible in Venus’ clouds, according to the groundbreaking finding of new research led by a Queen’s University Belfast scientist with participation of the University of Bonn. The study has been published in the journal Nature Astronomy.

For some decades, space exploration missions have looked for evidence of life beyond Earth where we know that large bodies of water, such as lakes or oceans, exist or have previously existed. However, the new research shows that it isn’t the quantity of water that matters for making life viable, but the effective concentration of water molecules – known as ‘water activity’.

The new study also found that research published by an independent team of scientists last year, claiming that the phosphine gas in Venus’ atmosphere indicates possible life in the sulphuric acid clouds of Venus, is not plausible.

Through this innovative research project, Dr John E. Hallsworth from the School of Biological Sciences at Queen’s and his team of international collaborators devised a method to determine the water activity of atmospheres of a planet. Using their approach to study the sulphuric acid clouds of Venus, the researchers found that the water activity was more than a hundred times below the lower limit at which life can exist on Earth.

Dr Hallsworth comments: “Our research shows that the sulphuric acid clouds in Venus have too little water for active life to exist, based on what we know of life on Earth. We have also found that the conditions of water and temperature within Jupiter’s clouds could allow microbial-type life to subsist, assuming that other requirements such as nutrients are present.”

Co-author of the report, an expert on physics and chemical biology of water, Dr Philip Ball, says: “The search for extraterrestrial life has sometimes been a bit simplistic in its attitude to water. As our work shows, it’s not enough to say that liquid water equates with habitability. We’ve got to think too about how Earth-like organisms actually use it – which shows us that we then have to ask how much of the water is actually available for those biological uses.” 

A plant scientist in extraterrestrial spheres

Dr Jürgen Burkhardt of the Institute of Crop Science and Resource Conservation (INRES), a member of the Phenorob Cluster of Excellence and the Transdisciplinary Research Area “Innovation and Technology for Sustainable Futures” at the University of Bonn, contributed to this study primarily by making calculations of water activity and sulphuric acid concentration in the cloud droplets of the Venusian atmosphere. The fact that a scientist researching plant nutrition is contributing to Life in the Venus Atmosphere is due to Dr Burkhardt’s earlier work. He had previously used the aerosol model used in the study to characterize the state of deposited hygroscopic aerosols on leaf surfaces.

Dr. Jürgen Burkhardt – from the Institute of Crop Science and Resource Conservation (INRES) at the University of Bonn.© Photo: Maximilian Meyer

“These aerosols allow microorganisms to survive under certain conditions,” Burkhardt says. A shared interest in this habitat and its very specific physicochemical conditions, such as high acid concentrations and minimal amounts of water, led to contact years ago with the study’s first author, John Hallsworth. Experimental electron microscopy studies by Hallsworth and Burkhardt on this topic had already resulted in two earlier joint publications that also addressed the question of extraterrestrial life.

Participating institutions and funding:

Co-authors of this paper include planetary scientist Christopher P. McKay (NASA Ames Research Center, CA, USA); atmosphere chemistry expert Thomas Koop (Bielefeld University, Germany); expert on physics and chemical biology of water Philip Ball (London, UK); biomolecular scientist Tiffany D. Dallas (Queen’s University Belfast); biophysics-of-lipid-membrane expert Marcus K. Dymond (University of Brighton, UK); theoretical physicist María-Paz Zorzano (Centro de Astrobiologia [CSIC-INTA], Spain); micrometeorology and aerosol expert Juergen Burkhardt (University of Bonn, Germany); expert on acid-tolerant microorganisms Olga V. Golyshina (Bangor University, UK); and atmospheric physicist and planetary scientist Javier Martín-Torres (University of Aberdeen, UK).

The research was funded by Research Councils UK (RCUK) | Biotechnology and Biological Sciences Research Council (BBSRC) and Ministry of Science and Innovation.

Featured image: Thunderclouds on Jupiter – based on images from the Juno mission’s Stellar Reference Unit camera (NASA).© NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstädt/Heidi N. Becker/Koji Kuramura


Publication: John E. Hallsworth et al.: Water activity in Venus’s uninhabitable clouds and other planetary atmospheres, Nature Astronomy, DOI: 10.1038/s41550-021-01391-3


Provided by University of Bonn

NASA’s Search for Life: Astrobiology in the Solar System and Beyond (Planetary Science)

Are we alone in the universe? So far, the only life we know of is right here on Earth. But here at NASA, we’re looking.    

NASA is exploring the solar system and beyond to help us answer fundamental questions about life beyond our home planet. From studying the habitability of Mars, probing promising “oceans worlds,” such as Titan and Europa, to identifying Earth-size planets around distant stars, our science missions are working together with a goal to find unmistakable signs of life beyond Earth (a field of science called astrobiology).  

Through the study of astrobiology, NASA invests in understanding the origins, evolution, and limits of life on Earth. This work has been important in shaping ideas about where to focus search for life efforts. As NASA explores the solar system, our understanding of life on Earth and the potential for life on other worlds has changed alongside the many discoveries. The study of organisms in extreme environments on Earth, from the polar plateau of Antarctica to the depths of the ocean, have highlighted that life as we know it is highly adaptable, but not always easy to find. The search for life requires great care, and is based in the knowledge we gain by studying life on Earth through the lens of astrobiology. If there’s something out there, we may not yet know how to recognize it. 

Dive into the past, present, and future of NASA’s search for life in the universe.  

Past Missions   

Viking 1 and 2  

Over 45 years ago, the Viking Project found a place in history when it became the first U.S. mission to land a spacecraft safely on the surface of Mars.   

Viking 1 and 2, each consisting of an orbiter and a lander, were NASA’s first attempt to search for life on another planet and thus the first mission dedicated to astrobiology. The mission’s biology experiments revealed unexpected chemical activity in the Martian soil, but provided no clear evidence for the presence of living microorganisms near the landing sites.   

Galileo  

NASA’s Galileo mission orbited Jupiter for almost eight years, and made close passes by all its major moons. Galileo returned data that continues to shape astrobiology science –– particularly the discovery that Jupiter’s icy moon Europa has evidence of a subsurface ocean with more water than the total amount of liquid water found on Earth. These findings also expanded the search for habitable environments outside of the traditional “habitable zone” of a system, the distance from a star at which liquid water can persist on the surface of a planet. 

Cassini  

For more than a decade, the Cassini spacecraft shared the wonders of Saturn and its family of icy moons –– taking us to astonishing worlds and expanding our understanding of the kinds of worlds where life might exist. 

For the first time, astrobiologists were able to see through the thick atmosphere of Titan and study the moon’s surface, where they found lakes and seas filled with liquid hydrocarbons. Astrobiologists are studying what these liquid hydrocarbons could mean for life’s potential on Titan. Cassini also witnessed icy plumes erupting from Saturn’s small moon Enceladus. When flying through the plumes, the spacecraft found evidence of saltwater and organic chemicals. This raised questions about whether habitable environments could exist beneath the surface of Enceladus.   

Spirit and Opportunity Mars Exploration Rovers  

NASA’s twin Mars Exploration Rovers, Spirit and Opportunity, launched towards Mars in 2003 in search of answers about the history of water on Mars. Originally a three-month prime mission, both robotic explorers far outlasted their original missions and spent years collecting data at the surface of Mars.     

Spirit and Opportunity were the first mission to prove liquid water, a key ingredient for life, had once flowed across the surface of Mars. Their findings shaped our understanding of Mars’ geology and past environments, and importantly suggested Mars’ ancient environments may once have been suitable for life.  

Kepler and K2  

NASA’s first planet-hunting mission, the Kepler Space Telescope, paved the way for our search for life in the solar system and beyond. An important part of Kepler’s work was the identification of Earth-size planets around distant stars.  

After nine years in deep space, collecting data that indicate our sky to be filled with billions of hidden planets – more planets even than stars – the space telescope retired in 2018. Kepler left a legacy of more than 2,600 exoplanet discoveries, many of which could be promising places for life.  

Spitzer  

Over its sixteen years in space, the Spitzer Space Telescope evolved into a premier tool for studying exoplanets, using its infrared view of the universe. Spitzer marked a new age in planetary science as one of the first telescopes to directly detect light from the atmospheres of planets outside the solar system, or exoplanets. This enabled scientists to study the composition of those atmospheres and even learn about the weather on these distant worlds.  

Spitzer’s infrared instruments allowed scientists to peer into cosmic regions that are hidden from optical telescopes, including dusty stellar nurseries, the centers of galaxies, and newly forming planetary systems. Spitzer’s infrared eyes also enabled astronomers to see cooler objects in space, like failed stars (brown dwarfs), extrasolar planets, giant molecular clouds, and organic molecules that may hold the secret to life on other planets.  

Current Missions  

Hubble  

Since it launched in 1990, the Hubble Space Telescope has made immense contributions to astrobiology. Astronomers used Hubble to make the first measurements of the atmospheric composition of extrasolar planets, and Hubble is now vigorously characterizing exoplanet atmospheres with constituents such as sodium, hydrogen, and water vapor. Hubble observations are also providing clues about how planets form, through studies of dust and debris disks around young stars.  

Not all of Hubble’s contributions involve distant targets. Hubble has also been used to study bodies within the solar system, including asteroids, comets, planets, and moons, such as the intriguing ocean-bearing icy moons Europa and Ganymede. Hubble has provided invaluable insight into life’s potential in the solar system and beyond.  

MAVEN  

NASA’s atmosphere-sniffing Mars Atmosphere and Volatile Evolution (MAVEN) mission launched in November 2013 and began orbiting Mars roughly a year later. Since that time, the mission has made fundamental contributions to understanding the history of the Martian atmosphere and climate.     

Astrobiologists are working with this atmospheric data to better understand how and when Mars lost its water and identifying periods in Mars’ history when habitable environments were most likely to exist at the planet’s surface.  

Mars Odyssey  

For two decades, NASA’s Mars Odyssey – the longest-lived spacecraft at the Red Planet – has helped locate ice, assess landing sites, and study the planet’s mysterious moons.    

Odyssey has provided global maps of chemical elements and minerals that make up the surface of Mars. These detailed maps are used by astrobiologists to determine the evolution of the Martian environment and its potential for life.  

Mars Reconnaissance Orbiter  

NASA’s Mars Reconnaissance Orbiter (MRO) is on a search for evidence that water persisted on the surface of Mars for a long period of time. While other Mars missions have shown that water flowed across the surface in Mars’ history, it remains a mystery whether water was ever around long enough to provide a habitat for life.  

Data from MRO is essential to astrobiologists studying the potential for habitable environments on past and present Mars. Additionally, these studies are important in building climate models for Mars, and for use in comparative planetology studies for the potential habitability of exoplanets that orbit distant stars.     

Curiosity Mars Rover  

The Curiosity Mars rover is studying whether Mars ever had environments capable of supporting microbial life. In other words, its mission is to determine whether the planet had all of the ingredients life needs – such as water, carbon, and a source of energy – by studying its climate and geology.   

It’s been nearly nine years since Curiosity touched down on Mars in 2012, and the robot geologist keeps making new discoveries. Curiosity provided evidence that freshwater lakes filled Gale Grater billions of years ago. Lakes and groundwater persisted for millions of years and contained all the key elements necessary for life, demonstrating Mars was once habitable. 

TESS Mission  

The Transiting Exoplanet Survey Satellite (TESS) is the next step in the search for planets outside of our solar system, including those that could support life. Launched in 2018, TESS is on a mission to survey the entire sky and is expected to discover and catalogue thousands of exoplanets around nearby bright stars.  

To date, TESS has discovered more than 120 confirmed exoplanets and more than 2,600 planet candidates. The planet-hunter will continue to find exoplanets targets that NASA’s upcoming James Webb Space Telescope will study in further detail.  

Perseverance Mars Rover  

NASA’s newest robot astrobiologist, the Perseverance Mars rover, touched down safely on Mars on February 18, 2021, and is kicking off a new era of exploration on the Red Planet. Perseverance will search for signs of ancient microbial life, which will advance the agency’s quest to explore the past habitability of Mars.    

What really sets this mission apart is that the rover has a drill to collect core samples of Martian rock and soil, and will store them in sealed tubes for pickup by a future Mars Sample Return mission that would ferry them back to Earth for detailed analysis.   

Upcoming Missions  

James Webb Space Telescope  

The James Webb Space Telescope (Webb), slated to launch in 2021, will be the premier space-based observatory of the next decade. Webb is a large infrared telescope with a 6.5-meter primary mirror.   

Webb observations will be used to study every phase in the history of the universe, including planets and moons in our solar system, and the formation of distant solar systems potentially capable of supporting life on Earth-like exoplanets. The Webb telescope will also be capable of making detailed observations of the atmospheres of planets orbiting other stars, to search for the building blocks of life on Earth-like planets beyond our solar system.  

Europa Clipper Mission  

Jupiter’s moon Europa may have the potential to harbor life. The Europa Clipper mission will conduct detailed reconnaissance of Europa and investigate whether the icy moon could harbor conditions suitable for life. Targeting a 2024 launch, the mission will place a spacecraft in orbit around Jupiter in order to perform a detailed investigation of Europa –– a world that shows strong evidence for an ocean of liquid water beneath its icy crust.    

Europa Clipper is not a life-detection mission, though it will investigate whether the icy moon, with its subsurface ocean, has the capability to support life. Understanding Europa’s habitability will help scientists better understand how life developed on Earth and the potential for finding life beyond our planet.  

Dragonfly Mission to Titan  

The Dragonfly mission will deliver a rotorcraft to visit Saturn’s largest and richly organic moon, Titan. Slated for launch in 2027 and arrival in 2034, Dragonfly will sample and examine dozens of promising sites around Saturn’s icy moon and advance our search for the building blocks of life.     

This revolutionary mission will explore diverse locations to look for prebiotic chemical processes common on both Titan and Earth. Titan is an analog to the very early Earth, and can provide clues to how prebiotic chemistry under these conditions may have progressed.  

Nancy Grace Roman Telescope  

Slated to launch in the mid-2020s, the Roman Space Telescope will have a field of view that is 200 times greater than the Hubble infrared instrument, capturing more of the sky with less observing time. In addition to ground-breaking astrophysics and cosmology, the primary instrument on Roman, the Wide Field Instrument, has a rich menu of exoplanet science. It will perform a microlensing survey of the inner Milky Way that will reveal thousands of worlds orbiting within the habitable zone of their star and farther out, while providing an additional bounty of more than 100,000 transiting exoplanets

The mission will also be fitted with “starglasses,” a coronagraph instrument that can block out the glare from a star and allow astronomers to directly image giant planets in orbit around it. The coronagraph will provide the first in-space demonstration of technologies needed for future missions to image and characterize smaller, rocky planets in the habitable zones of nearby stars. Roman coronagraph will make observations that could contribute to the discovery of new worlds beyond our solar system and advance the study of extrasolar planets that could be suitable for life.    

Learn more about the NASA Astrobiology Program: 

https://astrobiology.nasa.gov/  

Featured image credit: NASA


Provided by NASA

Robot Chemist Offers Insight Into The Origins Of Life (Biology)

A robotic ‘evolution machine’ capable of exploring the generational development of chemical mixtures over long periods of time could help cast new light on the origins of life, scientists say.

A team of chemists from the University of Glasgow developed the robot, which uses a machine-learning algorithm to make decisions about which chemicals from a selection of 18 to combine in a reactor, and how to set conditions under which the reaction occurs. The robot is capable of running the experiments on its own, with minimal human supervision.

The process aims to provide new insight into how Earth’s complex organic life developed from its simple, non-living chemical origins by allowing the machine to run experiments over the course of several weeks.

Measuring the mass index of the product of each experiment teaches the robot something new about the complexity of molecule produced by each reaction. That information helps it learn how to vary the experiment to create a more complex molecule in subsequent reactions – a digital version, the team hopes, of the natural selection for complexity which gave rise to organic life.

In a new paper published today in the journal Nature Communications, the research team describe how the robot carried out hundreds of experiments across six batches of tests carried out over four-week periods.

Over this time, the team found not only that complex molecules were created, but they also found that some of these new molecules were persisting over many cycles despite dilution. This indicates that other processes, like catalysis and replication, may be occurring.

The system builds on previous research led by the University’s Regius Professor of Chemistry, Lee Cronin. Researchers from his Cronin Group developed the chemical robot capable of autonomously carrying out chemical reactions, and launched a ‘Spotify for chemistry’ to allow researchers to download chemical formulas to use in their own chemical robots.

They have also recently published a paper on Assembly Theory, a formula they have developed which quantifies the complexity of molecules and could be used to identify the telltale signs of the chemical building blocks of life. 

A photograph of the Cronin Group's chemical robot system

Professor Cronin said: “The work we’ve been doing over the last decade or so has in many ways been leading up to this. Our chemical robot has really expanded the horizons of what is possible in the lab by automating basic tasks and allowing them to be done over and over again across long periods of time.

“Very few chemical experiments last longer than a few days, but the natural development of chemical biological systems took place over millions of years. Allowing the robot to carry out dozens of recursive experiments over the span of weeks, and then eventually to months and even years. opens up new opportunities to learn how chemical complexity began at the dawn of life.

“As robot chemists become more common in labs around the world, and the digital democratisation of chemistry becomes more widespread, we’re hoping that other researchers will get on board and use the platform we’ve developed to make their own contributions.”

The team’s paper, titled ‘A robotic prebiotic chemist probes long term reactions of complexifying mixtures’, is published in Nature Communications. The research was supported by funding from the John Templeton Foundation, the Engineering and Physical Sciences Research Council (ESPRC), the Breakthrough Prize Foundation and NASA, and the European Research Council (ERC).


Reference: Asche, S., Cooper, G.J.T., Keenan, G. et al. A robotic prebiotic chemist probes long term reactions of complexifying mixtures. Nat Commun 12, 3547 (2021). https://doi.org/10.1038/s41467-021-23828-z


Provided by University of Glasgow

Did Earth’s Early Rise in Oxygen Help Multicellular Life Evolve? (Earth Science)

A new study is taking the air out of a hypothesis linking early Earth’s oxygenation to larger, more complex organisms. Georgia Tech researchers report a more complex effect

Scientists have long thought that there was a direct connection between the rise in atmospheric oxygen, which started with the Great Oxygenation Event 2.5 billion years ago, and the rise of large, complex multicellular organisms.

That theory, the “Oxygen Control Hypothesis,” suggests that the size of these early multicellular organisms was limited by the depth to which oxygen could diffuse into their bodies. The hypothesis makes a simple prediction that has been highly influential within both evolutionary biology and geosciences: Greater atmospheric oxygen should always increase the size to which multicellular organisms can grow.

It’s a hypothesis that’s proven difficult to test in a lab. Yet a team of Georgia Tech researchers found a way — using directed evolution, synthetic biology, and mathematical modeling — all brought to bear on a simple multicellular lifeform called a ‘snowflake yeast’. The results? Significant new information on the correlations between oxygenation of the early Earth and the rise of large multicellular organisms — and it’s all about exactly how much O2 was available to some of our earliest multicellular ancestors.

“The positive effect of oxygen on the evolution of multicellularity is entirely dose-dependent — our planet’s first oxygenation would have strongly constrained, not promoted, the evolution of multicellular life,” explains G. Ozan Bozdag, research scientist in the School of Biological Sciences and the study’s lead author. “The positive effect of oxygen on multicellular size may only be realized when it reaches high levels.”

“Oxygen suppression of macroscopic multicellularity” is published in the May 14, 2021 edition of the journal Nature Communications. Bozdag’s co-authors on the paper include Georgia Tech researchers Will Ratcliff, associate professor in the School of Biological Sciences; Chris Reinhard, associate professor in the School of Earth and Atmospheric Sciences; Rozenn Pineau, Ph.D. student in the School of Biological Sciences and the Interdisciplinary Graduate Program in Quantitative Biosciences (QBioS); along with Eric Libby, assistant professor at Umea University in Sweden and the Santa Fe Institute in New Mexico.

Directing yeast to evolve in record time

“We show that the effect of oxygen is more complex than previously imagined. The early rise in global oxygen should in fact strongly constrain the evolution of macroscopic multicellularity, rather than selecting for larger and more complex organisms,” notes Ratcliff.

“People have long believed that the oxygenation of Earth’s surface was helpful — some going so far as to say it is a precondition — for the evolution of large, complex multicellular organisms,” he adds. “But nobody has ever tested this directly, because we haven’t had a model system that is both able to undergo lots of generations of evolution quickly, and able to grow over the full range of oxygen conditions,” from anaerobic conditions up to modern levels.

The researchers were able to do that, however, with snowflake yeast, simple multicellular organisms capable of rapid evolutionary change. By varying their growth environment, they evolved snowflake yeast for over 800 generations in the lab with selection for larger size.

The results surprised Bozdag. “I was astonished to see that multicellular yeast doubled their size very rapidly when they could not use oxygen, while populations that evolved in the moderately oxygenated environment showed no size increase at all,” he says. “This effect is robust — even over much longer timescales.”

Size — and oxygen levels — matter for multicellular growth

In the team’s research, “large size easily evolved either when our yeast had no oxygen or plenty of it, but not when oxygen was present at low levels,” Ratcliff says. “We did a lot more work to show that this is actually a totally predictable and understandable outcome of the fact that oxygen, when limiting, acts as a resource — if cells can access it, they get a big metabolic benefit. When oxygen is scarce, it can’t diffuse very far into organisms, so there is an evolutionary incentive for multicellular organisms to be small — allowing most of their cells access to oxygen — a constraint that is not there when oxygen simply isn’t present, or when there’s enough of it around to diffuse more deeply into tissues.”

Ratcliff says not only does his group’s work challenge the Oxygen Control Hypothesis, it also helps science understand why so little apparent evolutionary innovation was happening in the world of multicellular organisms in the billion years after the Great Oxygenation Event. Ratcliff explains that geologists call this period the “Boring Billion” in Earth’s history — also known as the Dullest Time in Earth’s History, and Earth’s Middle Ages — a period when oxygen was present in the atmosphere, but at low levels, and multicellular organisms stayed relatively small and simple.

Bozdag adds another insight into the unique nature of the study. “Previous work examined the interplay between oxygen and multicellular size mainly through the physical principles of gas diffusion,” he says. “While that reasoning is essential, we also need an inclusive consideration of principles of Darwinian evolution when studying the origin of complex multicellular life on our planet.” Finally being able to advance organisms through many generations of evolution helped the researchers accomplish just that, Bozdag adds.

This work was supported by National Science Foundation grant no. DEB-1845363 to W.C.R, NSF grant no. IOS-1656549 to W.C.R., NSF grant no. IOS-1656849 to E.L., and a Packard Foundation Fellowship for Science and Engineering to W.C.R. C.T.R. and W.C.R. acknowledge funding from the NASA Astrobiology Institute.

Featured image: Artist rendering of early Earth © NASA


Reference: Bozdag, G.O., Libby, E., Pineau, R. et al., “Oxygen suppression of macroscopic multicellularity.” (Nat Commun 12, 2838 2021). https://doi.org/10.1038/s41467-021-23104-0


Provided by Georgia Institute of technology

Rooting the Bacterial Tree Of Life (Biology)

Scientists now better understand early bacterial evolution, thanks to new research featuring University of Queensland researchers.

Bacteria comprise a very diverse domain of single-celled organisms that are thought to have evolved from a common ancestor that lived more than three billion years ago.

Professor Phil Hugenholtz, from the Australian Centre for Ecogenomics in UQ’s School of Chemistry and Molecular Biosciences, said the root of the bacterial tree, which would reveal the nature of the last common ancestor, is not agreed upon.

“There’s great debate about the root of this bacterial tree of life and indeed whether bacterial evolution should even be described as a tree has been contested,” Professor Hugenholtz said.

“This is in large part because genes are not just shared ‘vertically’ from parents to offspring, but also ‘horizontally’ between distant family members.

“We’ve all inherited certain traits from our parents, but imagine going to a family BBQ and suddenly inheriting your third cousin’s red hair.

“As baffling as it sounds, that’s exactly what happens in the bacterial world, as bacteria can frequently transfer and reconfigure genes horizontally across populations quite easily.

“This might be useful for bacteria but makes it challenging to reconstruct bacterial evolution.”

For the bacterial world, many researchers have suggested throwing the ‘tree of life’ concept out the window and replacing it with a network that reflects horizontal movement of genes.

“However, by integrating vertical and horizontal gene transmission, we found that bacterial genes travel vertically most of the time – on average two-thirds of the time – suggesting that a tree is still an apt representation of bacterial evolution,” Professor Hugenholtz said.

“The analysis also revealed that the root of the tree lies between two supergroups of bacteria, those with one cell membrane and those with two.

“Their common ancestor was already complex, predicted to have two membranes, the ability to swim, sense its environment, and defend itself against viruses.”

The University of Bristol’s Dr Tom Williams said this fact led to another big question.

“Given the common ancestor of all living bacteria already had two membranes, we now need to understand how did single-membrane cells evolve from double-membraned cells, and whether this occurred once or on multiple occasions,” Dr Williams said.

“We believe that our approach to integrating vertical and horizontal gene transmission will answer these and many other open questions in evolutionary biology.”

The research was a collaboration between UQ, the University of Bristol in the UK, Eötvös Loránd University in Hungary, and NIOZ in the Netherlands, and has been published in Science (DOI: 10.1126/science.abe5011).

Featured image: Fusobacteria, Gracilicutes and Bacteroidota all branched off from a last bacterial common ancestor. © University of Queensland


Provided by University of Queensland Australia

Astronomers Find “Hope Of Life” On Saturn (Planetary Science / Chemistry)

The hydrogen cyanide (HCN) molecule in the planetary atmosphere is key to the formation of building blocks of life. The HCN present in photochemical reactions, create lipids, amino acids and nucleosides, the 3 basic building blocks of life. Earlier in 2016, we detected hydrogen cyanide (HCN) in the atmosphere of Saturn moon “Titan”. The discovery of an HCN emission line in the atmosphere of Saturn may be crucial in the formation of certain complex bio substances, as well as prebiotic molecules. Without the existence of HCN, CO, and H2O, the development and evolution of prebiotic molecules with carbon-based metabolism is difficult in the atmosphere of Saturn.

Now, Manna and Pal presented the spectroscopic detection of the rotational molecular line of nitrile species hydrogen cyanide (HCN) in the atmosphere of Saturn using the archival data of the Atacama Large Millimeter/Submillimeter Array (ALMA) in band 7 observation. Their observations given us a “hope of life” on saturn.

They detected strong rotational emission line of HCN at frequency ν = 354.505 GHz (>4σ statistical significance). They also detected the rotational emission line of carbon monoxide (CO) at frequency ν = 345.795 GHz. The statistical column density of hydrogen cyanide and carbon monoxide emission line is N(HCN)∼2.42×1016 cm¯2 and N(CO)∼5.82×1017 cm¯2. The abundance of HCN and CO in the atmosphere of Saturn relative to the H2 is estimated to be f(HCN)∼1.02×10¯9 and f(CO)∼2.42×10¯8.

Article continues below images

Figure 1: Molecular rotational emission spectrum of HCN in the atmosphere of Saturn at the frequency of ν = 354.505 GHz with transition J=4–3 using ALMA band 7 observation. The spectrum was made by integrating the reduced ALMA data cubes from the center of Saturn with 1.1″ circular region. The spectral coverage in the figure is 200 MHz with a total integration time of 476.402 second. In the spectrum, the solid red line corresponds to the best fit model of column density 2.42×1016 cm¯2 © Manna and Pal
Figure 2: Molecular rotational emission spectrum of CO in the atmosphere of Saturn at the frequency of ν = 345.795 GHz with transition J=3–2 using ALMA band 7 observation. The spectrum was made by integrating the reduced ALMA data cubes from the center of Saturn with 1.1″ circular region. The spectral coverage in the figure is 250 MHz with a total integration time of 476.402 second. In the spectrum, the solid red line corresponds to the best fit model of column density 5.82×1017 cm¯2 © Manna and Pal

They also discussed possible chemical pathways to the formation of the detected nitrile gas HCN in the atmosphere of Saturn.

“In the atmosphere of Saturn, HCN is produced due to the photochemical reaction of CO2, and CH4.”

They explained that atmosphere of Saturn primarily consists of H2, CO2, CO, and CH4 which are very essential for the production of HCN. The formation of HCN in the nitrogen-based atmospheres requires the N≡N bond and it needs to find a carbon atom. First, the nitrogen bond is split from NH3, and second, carbon molecules need to win over oxygen for the competition of getting free nitrogen. The first condition is very easy because NH3 molecules are present in the atmosphere of Saturn, which has a large absorption cross-section over N2. The hot temperature is necessary to split the hydrogen atom from NH3.

Figure 3: Suggested chemical pathways to the formation of HCN in the atmosphere of Saturn. The rate constant for this chemical reaction to formation of HCN is found in the STAND2019 chemical network which is a modification version of the STAND2016 network © Manna and Pal

After the split of the nitrogen bond, it reacts with nearby molecules as well as other stable molecules. The single nitrogen atom finds another single nitrogen atom to create N2. We already know a big amount of H2 exists in the atmosphere of Saturn. So the nitrogen is rapidly reacted with hydrogen to create NH2 and then will continue to react with abundant hydrogen to the formation of NH4. Similarly, the nitrogen atom reacts with the oxygen atom to produce NO2. According to authors, the trace species HCN are producing in the atmosphere of Saturn if the nitrogen bonds are reacted with carbon and hydrogen. In the atmosphere of Saturn, the carbon to oxygen balance is a key to understand nitrile chemistry. Fig. 3 above provides the possible reaction of the chemical network to the formation of HCN from CO2, CO, CH4 in the atmosphere of Saturn via photochemical pathways.

In addition, they mentioned that the formation mechanism of HCN in the atmosphere of Saturn is varied with temperature, molecular composition, impact rate, surface process, and rate of lighting. In the atmosphere of Saturn, the HCN can be produced by the photochemical pathways and atmospheric lightning.

“In our predicted chemical reaction, some reactions are photochemical which denoted as hν and it requires photon for the production of HCN. We used the STAND2019 chemical network for chemical modeling which is a modification of the STAND2016 network which includes H/C/N/O chemistry with 3 carbons, 2 nitrogens, 3 oxygens, and 8 hydrogens and valid up to 30000 K temperature and also include some gas-phase reactions involving Na, K, Mg, Fe, Ti, Si, and Cl. The STAND2019 chemical network included 5000 reactions involving over 350 amount of chemical species. In the planetary atmosphere, CO2 and CH4 are very important species for the formation of other molecular gas due to photochemical reaction.”

Finally, they concluded that, in the atmosphere of Saturn, further spectroscopic observations of the complex molecular gas will aid in confirming the origin and formation mechanism of the observed trace gases.


Reference: Arijit Manna, Sabyasachi Pal, “ALMA detection of hydrogen cyanide and carbon monoxide in the atmosphere of Saturn”, Arxiv, pp. 1-6, 2021. https://arxiv.org/abs/2104.10474


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Music Improves Older Adults’ Sleep Quality (Medicine)

Listening to music before going to be can improve sleep quality among older adults, according to an analysis of all relevant published clinical trials.

In the analysis, which is published in the Journal of the American Geriatrics Society, five randomized trials met the investigators’ criteria. Older adults who listened to music experienced significantly better sleep quality than those who did not listen to music. Also, older adults who listened to sedative music experienced a greater improvement in sleep quality than those who listened to more rhythmic music. Furthermore, listening to music for longer than four weeks was especially effective at improving sleep quality. 

“Music intervention is an effective strategy and is easy to administer by a caregiver or healthcare worker,” the authors wrote. “Music therapy might be the first line of therapy to recommend in older adults with sleep disturbances, which would reduce the need for dependence on sedatives and sleeping medication.”

Read the American Geriatrics Society’s Health in Aging blog summary of this article here.

Additional Information

Link to Studyhttps://onlinelibrary.wiley.com/doi/10.1111/jgs.17149


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Looking For Life? Don’t Trust Oxygen (Planetary Science)

According to a recent study, conducted by a team of researchers using evolutionary computational models, rocky planets found in the habitable zones of Sun-like stars can contain oxygen of non-biological origin in their atmospheres, making its spectral detection a biological signature. not very reliable and certainly not sufficient to affirm the presence of life forms. All the details on Agu advances

The presence of oxygen in the atmosphere of an exoplanet could be an unreliable biological signature : this is what emerges from a new study conducted by teams of researchers led by the University of California at Santa Cruz (Ucsc).

The researchers based their discovery on a thermo-geochemical-climatic computational model that made it possible to study the evolution of the atmosphere of terrestrial planets by varying the initial inventory of the volatile chemical compounds present in it. The results obtained, published yesterday in the journal Agu Advances, show three different scenarios in which a rocky planet around a star similar to the Sun – after 4.5 billion years of evolution, corresponding to the age established for the Earth – can develop atmospheres rich in oxygen of abiotic origin, i.e. coming from non-biological activity, which would make any detection of the molecule’s spectral signature – if interpreted as a biosignature – a false positive.

The research, explains Joshua Krissansen-Totton , researcher at the University of Santa Cruz and first author of the publication, “shows that there are several ways to produce oxygen in the atmosphere without this indicating the presence of life, but there are other observations that they can do to help distinguish these false positives from the true signal ».

In the coming decades, perhaps as early as the late 1930s, astronomers will have telescopes capable of acquiring images and absorption spectra of molecules in potentially Earth-like planets around Sun-like stars. researchers, is to point telescopes towards these worlds where life may have emerged and characterize their atmospheres. But the false positive detections are, in fact, a problem.

“There has been a lot of discussion about considering the detection of ‘sufficient’ oxygen as a sign of life,” notes Jonathan Fortney , also from the University of Santa Cruz and co-author of the study. «This work highlights the need to know the context of the surveys. What molecules are found besides oxygen and what does this tell us about the evolution of the planet? ».

Oxygen can be produced in a planet’s upper atmosphere by high-energy ultraviolet light that splits water molecules into its components: hydrogen and, indeed, oxygen, the researchers say. The lighter hydrogen is lost in space, leaving behind oxygen, which thus accumulates. But there are also processes that can remove oxygen from the atmosphere: carbon monoxide and hydrogen released by outgassing from molten rock, for example, react with oxygen reducing its quantities. And the atmospheric agents that erode the rock also absorb the molecule. These are some of the processes the researchers incorporated into their model to study the evolution of a rocky planet.

The scenarios that these evolutionary models have returned, in which the atmospheres contained oxygen of abiotic origin, are three, we said. A fourth scenario, in which the soup of volatile gases inserted is what is thought to be the early Earth, has never produced oxygen of such an origin.

“If you run the model for the Earth, by inserting what we think is the initial inventory of volatile compounds, you get the same result every time: without life, no oxygen is produced in the atmosphere,” says Krissansen-Totton. “But we also found several scenarios in which it is possible to obtain oxygen without the presence of life.”

The first scenario that the authors describe in the publication is that in which the initial conditions of planetary formation are similar to those of the Earth but with a quantity of carbon dioxide greater than water (CO2 / H2O ratio greater than 1). This results in a constant and high greenhouse effect which, by making the planet very hot, prevents water vapor from condensing on the planet’s surface. The result is the constant atmospheric presence of water in the gaseous state available to the action of UV light which, as mentioned, splits it into hydrogen and oxygen.

“In this scenario, similar to that of Venus, all volatile molecules are in the atmosphere,” says Krissansen-Totton. “Few remain in the mantle to be degassed and prevent the formation of oxygen.”

The second and third scenarios also start from conditions similar to those of the Earth, but while in the first case the input is a quantity of water from 10 to 230 times greater than that present on our planet, in the second it is 0.3 times the quantity of water on Earth.

For water-rich worlds, the researchers explain, deep oceans exert tremendous pressure on the planetary crust. This effectively disrupts geological activity, including some processes such as melting or erosion of rocks that would remove oxygen from the atmosphere.

In the case of desert worlds, however, the surface magma of the initially molten planet can freeze rapidly, while water, albeit little, remains in the atmosphere, allowing, as it is split, the accumulation of oxygen and the escape of hydrogen. .

“The typical sequence is that the solidification of surface magma occurs simultaneously with the condensation of water in the surface oceans,” adds Krissansen-Totton. “On Earth, once the water condensed on the surface, the escape rates were low. But if water vapor still remains in the atmosphere after the molten surface has solidified, there is a window of about a million years in which oxygen can accumulate, because no molten surface can consume the oxygen produced by the leak. of hydrogen “.

The scenarios outlined in this study emphasize that no single observation, including the detection of oxygen on planets in habitable areas around Sun-like stars, can be an unambiguous sign of the presence of life, the researchers conclude. The evaluation of biosignatures should be a systemic approach, in which the biological origin of a molecule is judged by the presence of multiple lines of evidence.

Featured image: Artistic illustration showing the paths through which the atmospheres of planets orbiting stars similar to the Sun can be enriched with oxygen of non-biological origin. Credits: J. Krissansen-Totton.


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Researchers Identify Five Double Star Systems Potentially Suitable For Life (Planetary Science)

New mathematical framework predicts that systems Kepler-34, -35, -38, -64 and -413 with circumbinary giant planets have stable Habitable Zones

Almost half a century ago, the creators of Star Wars imagined a life-sustaining planet, Tatooine, orbiting a pair of stars. Now, scientists have found new evidence that five known systems with multiple stars, Kepler-34, -35, -38, -64 and -413, are possible candidates for supporting life. A newly developed mathematical framework allowed researchers at New York University Abu Dhabi and the University of Washington to show that those systems – between 2764 and 5933 light years from Earth, in the constellations Lyra and Cygnus – support a permanent “Habitable Zone”, a region around stars in which liquid water could persist on the surface of any as yet undiscovered Earth-like planets. Of these systems, Kepler-64 is known to have at least four stars orbiting one another at its center, while the others have two stars. All are known to have at least one giant planet the size of Neptune or greater. This study, published in Frontiers in Astronomy and Space Sciences, is proof-of-principle that the presence of giant planets in binary systems does not preclude the existence of potentially life-supporting worlds.

“Life is far most likely to evolve on planets located within their system’s Habitable Zone, just like Earth. Here we investigate whether a Habitable Zone exists within nine known systems with two or more stars orbited by giant planets. We show for the first time that Kepler-34, -35, -64, -413 and especially Kepler-38 are suitable for hosting Earth-like worlds with oceans,” says corresponding author Dr Nikolaos Georgakarakos, a research associate from the Division of Science at New York University Abu Dhabi.

The scientific consensus is that the majority of stars host planets. Ever since 1992, exoplanets have been discovered at an accelerating pace: 4375 have been confirmed so far, of which 2662 were first detected by NASA’s Kepler space telescope during its 2009-2018 mission to survey the Milky Way. Further exoplanets have been found by NASA’s TESS telescope and missions from other agencies, while the European Space Agency is due to launch its PLATO space craft to search for exoplanets by 2026.

Twin stars and giant planets pose special conditions on life

Twelve of the exoplanets discovered by Kepler are “circumbinary”, that is, orbiting a close pair of stars. Binary systems are common, estimated to represent between half and three quarters of all star systems. So far, only giant exoplanets have been discovered in binary systems, but it is likely that smaller Earth-like planets and moons have simply escaped detection. Gravitational interactions within multi-star systems, especially if they contain other large bodies such as giant planets, are expected to make conditions more hostile to the origin and survival of life: for example, planets might crash into the stars or escape from orbit, while those Earth-like exoplanets that survive will develop elliptical orbits, experiencing strong cyclical changes in the intensity and spectrum of radiation.

“We’ve known for a while that binary star systems without giant planets have the potential to harbor habitable worlds. What we have shown here is that in a large fraction of those systems Earth-like planets can remain habitable even in the presence of giant planets,“ says coauthor Prof Ian Dobbs-Dixon, likewise at New York University Abu Dhabi.

Georgakarakos et al. here build on previous research to predict the existence, location, and extent of the permanent Habitable Zone in binary systems with giant planets. They first derive equations that take into account the class, mass, luminosity, and spectral energy distribution of the stars; the added gravitational effect of the giant planet; the eccentricity (i.e. degree of ellipticity of the orbit), semi-major axis, and period of the hypothetical Earth-like planet’s orbit; the dynamics of the intensity and spectrum of the stellar radiation that falls upon its atmosphere; and its “climate inertia”, that is, the speed at which the atmosphere responds to changes in irradiation. They then look at nine known binary star systems with giant planets, all discovered by the Kepler telescope, to determine whether Habitable Zones exist in them and are “quiet enough” to harbor potentially life sustaining worlds.

The authors show for the first time that permanent Habitable Zones exist in Kepler-34, -35, -38, -64, and -413. Those zones are between 0.4-1.5 Astronomical Units (au) wide beginning at distances between 0.6-2 au from the center of mass of the binary stars.

Not all systems with circumbinary giant planets are suitable

“In contrast the extent of the Habitable Zones in two further binary systems, Kepler-453 and -1661, is roughly half the expected size, because the giant planets in those systems would destabilize the orbits of additional habitable worlds. For the same reason Kepler-16 and -1647 cannot host additional habitable planets at all. Of course, there is the possibility that life exists outside the habitable zone or on moons orbiting the giant planets themselves, but that may be less desirable real-estate for us,” says coauthor Dr Siegfried Eggl at the University of Washington.

“Our best candidate for hosting a world that is potentially habitable is the binary system Kepler-38, approximately 3970 light years from Earth, and known to contain a Neptune-sized planet,” says Georgakarakos.

“Our study confirms that even binary star systems with giant planets are hot targets in the search for Earth 2.0. Watch out Tatooine, we are coming!”

Featured image credit: 213688585 / Shutterstock


Reference: Nikolaos Georgakarakos et al., “Circumbinary Habitable Zones in the Presence of a Giant Planet”, Front. Astron. Space Sci., 15 April 2021 | https://doi.org/10.3389/fspas.2021.640830


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