Astrobiology

Category: Astrobiology (page 1 of 9)

Our Ever-Growing Menagerie of Exoplanets

While we have never seen an exoplanet with anything near this kind of detail, scientists and artists now do know enough to represent them with characteristics that are plausible, given what is known about them.. (NASA)

With so many exoplanets already detected, with the pace of discovery continuing to be so fast, and with efforts to find more distant worlds so constant and global, it’s easy to become somewhat blase´ about new discoveries. After so many “firsts,” and so many different kinds of planets found in very different ways, it certainly seems that some of the thrill may be gone.

Surely the detection of a clearly “Earth-like planet” would cause new excitement — one that is not only orbiting in the habitable zone of its host star but also has signs of a potentially nurturing atmosphere in a generally supportive cosmic neighborhood.

But while many an exoplanet has been described as somewhat “Earth-like” and potentially habitable, further observation has consistently reduced the possibility of the planets actually hosting some form of biology. The technology and knowledge base needed to find distant life is surely advancing, but it may well still have a long way to go.

In just the last few days, however, a slew of discoveries have been reported that highlight the allure and science of our new Exoplanet Era. They may not be blockbusters by themselves, but they are together part of an immense scientific exploration under way, one that is re-shaping our understanding of the cosmos and preparing us for bigger discoveries and insights to come.

Already 3,940 exoplanets have been identified (as of April 17) with an additional 3,504 candidates waiting to be confirmed or discarded. this is but the start since it is widely held now that virtually every star out there has a planet, or planets, orbiting it. That’s billions of billions of planets. This image is a collection of NASA exoplanet renderings.

What I have in mind are these discoveries:

The first Earth-sized planet detected by NASA’s year-old orbiting telescope TESS (Transiting Exoplanet Survey Satellite.) TESS is designed to find planets orbiting massive stars in our near neighborhood, and it has already made 10 confirmed discoveries. But finding a small exoplanet — 85 percent the size of Earth — is a promising result for a mission designed to not only locate as many as 20,000 new exoplanets, but to find 500 to 1,000 the rough size of Earth or SuperEarth.

A Significant Advance: Primitive Earth Life Survives an 18-Month Exposure to Mars-Like Conditions in Space

April 4, 2019 / Marc Kaufman / 0 Comments

The European Space Agency’s BIOMEX array, outside the Russian Zvezda module of the ISS. (ESA)

The question of whether simple life can survive in space is hardly new, but it has lately taken on a new urgency.

It is not only a pressing scientific question — might life from Mars or another body have seeded life on Earth? Might organisms similar to extreme Earth life survive Mars-like conditions? — but it is also has some very practical implications. If humans are going to some day land and live on the moon or on Mars, they will need to grow food to survive.

So the question is pretty basic: can Earth seeds or dormant life survive a long journey to deep space and can they then grow in the protected but still extreme radiation, temperature, and vacuum of deep space?

It was with these questions in mind that the European Space Agency funded a proposal from the German Institute of Planetary Research to send samples of a broad range of simple to more complex life to the International Space Station in 2014, and to expose the samples to extreme conditions outside the station.

Some of the findings have been reported earlier, but last month the full results of the Biomex tests (Biology on Mars Experiment) were unveiled in the journal Astrobiology.

And the answer is that many, though certainly not all, of the the samples of snow and permafrost algae, cyanobacteria, archaea, fungi, biofilms, moss and lichens in the did survive their 533 days of living dangerous in their dormant states. When brought back to Earth and returned to normal conditions, they returned to active life.

“For the majority of the chosen organisms, it was the first and the longest time they ever were exposed to space and Mars-like conditions,” Jean-Pierre Paul de Vera, principal investigator of the effort, wrote to me. And the results were promising.

For the BIOMEX experiment, on 18 August 2014, Russian cosmonauts Alexander Skvortsov and Oleg Artemyev placed several hundred samples in an experiment container on the exterior of the Zvezda’Russian ISS module. The containers, open to the surrounding space environment, held primitive terrestrial organisms such as mosses, lichens, fungi, bacteria, archaea and algae, as well as cell membranes and pigments.

A microbiologist and planetary researcher at the German Space Agency’s Institute of Planetary Research in Berlin, de Vera and his team went from Antarctica to the parched Atacama desert in Chile, from the high Alps to the steppe highlands of central Spain to find terrestrial life surviving in extreme conditions (extremophiles.)

The samples were then placed in regolith (soil, dust and other rocky materials) simulated to be as close as possible to what is found on Mars.… Read more

Ancient Mars Water. Ever More of It, and Flowing Ever Longer on the Surface

March 28, 2019 / Marc Kaufman / 0 Comments

A photo of a preserved river channel on Mars with color overlaid to show different elevations (blue is low, yellow is high).
(Courtesy of NASA/JPL/Univ. Arizona/Univ. Chicago)

Rather like a swollen river overflowing its banks, the story of water on Mars keeps on rising and spreading in quite unpredictable ways.

While the planet is now inarguable parched — though with lots of polar and subsurface ice and, perhaps, some seasonal surface trickles — data from the Curiosity rover, the Mars Reconnaissance Orbiter and other missions have proven quite reliably that the planet was once much wetter and warmer. But how much wetter, and for how long, remains of subject of hot debate.

On one side, Mars climate modelers have struggled to find mechanisms to keep the planet wetter and warmer for more than it’s earliest period — perhaps 500 million years. Their projections flow from the seemingly established conclusion that Mars lost much of its atmosphere by 3.5 billion years ago, and without that protection warmer and wetter appear to be impossible.

But the morphology of the planet, the gorges, the fossil lakes, the riverbeds and deltas that are visible because of 21st century technology and missions, appears to tell a different and more wide-ranging story of Mars water.

Mudstone at the “Kimberley” formation on Mars taken by NASA’s Curiosity rover. The strata in the foreground dip towards the base of Mount Sharp, indicating the ancient depression that existed before the larger bulk of the mountain formed.
Credit:NASA/JPL-Caltech/MSSS

And now, in one of the most expansive interpretations of the Martian water story, University of Chicago planetary scientist and Mars expert Edwin Kite and colleagues report in a Science Advances paper that the planet not only once had many, many lakes and rivers, but that they were filled as part of a water cycle involving precipitation, rather than primarily through the sporadic melting of primordial ice as a result of incoming meteorites or other astrophysical events.

What’s more, they write, the rivers continued to sporadically flow well past the time when the Martian surface has been assumed to be dead dry.

The era when Mars has been most often described as going from wet-to-dry is around 3.5 billion years ago, but their interpretation of when precipitation-filled rivers stopped running is about 3 billion years ago. In other words, Kite’s team now says the rivers ran — often quite actively — for more than one billion years.… Read more

A New and Revelatory Window Into Evolution on Earth

March 22, 2019 / Marc Kaufman / 0 Comments

A Leanchoilia fossil from at the Qingjiang site in China. A very early arthropod found with sharply defined appendages is an arthropod and one of the prime examples of early Cambrian life (D Fu et al., Science 363:1338 (2019)

Virtually every definition of the word “life” includes the capability to undergo Darwinian evolution as a necessary characteristic. This is true of life on Earth and of thinking about what would constitute life beyond Earth. If it can’t change, the thinking goes, then it cannot be truly alive.

In addition, evolutionary selection and change occurs within the context of broad planetary systems — the chemical makeup of the atmosphere, the climactic conditions, the geochemistry and more. If an environment is changing, then the lifeforms that can best adapt to the new conditions are the ones that will survive and prosper.

So evolution is very much part of the landscape that Many Worlds explores — the search for life beyond Earth and effort to understand how life emerged on Earth. Evolution happens in the context of broad conditions on Earth (and perhaps elsewhere), and finding potential life elsewhere involves understanding the conditions on distant planets and determining if they are compatible with life.

This all came to mind as I read about the discovery of a remarkable collection of fossils alongside a river in China, fossils of soft-bodied creatures that lived a half billion years ago in the later phase of what is termed the the Cambrian explosion. They are of being compared already with the iconic “Burgess Shale” fossil find in Canada of decades ago, and may well shed equally revelatory light on a crucial time in the evolution of life on Earth.

Artist rendering of Qingjiang life showing characteristics of different early Cambrian taxonomical groups. More than 50 percent had never been identified before. (ZH Yao and DJ Fu)

The new discovery is reported in the journal Science in a paper authored by Dongjing Fu and a team largely from the Northwest University in Xi’an. The paper reports on a zoo of Cambrian-era creatures, with more than half of them never identified before in the rock record.

The animals are soft-bodied — making it all the more remarkable that they were preserved — and some bear little resemblance to anything that followed. Like the Burgess Shale fossils, the Qingjiang discovery is of an entire ecosystem that largely disappeared as more fit (and predatory) animals emerged.… Read more

Japan’s Hayabusa2 Asteroid Mission Reveals a Remarkable New World

March 13, 2019 / Elizabeth Tasker / 0 Comments

The Hayabusa2 touchdown movie, taken on February 22, 2019 (JST) when Hayabusa2 first touched down on asteroid Ryugu to collect a sample from the surface. It was captured using the onboard small monitor camera (CAM-H). The video playback speed is five times faster than actual time (JAXA).

On March 5 the Japan Aerospace Exploration Agency (JAXA) released the extraordinary video shown above. The sequence of 233 images shows a spacecraft descending to collect material from the surface of an asteroid, before rising amidst fragments of ejected debris. It is an event that has never been captured on camera before.

The images were taken by a camera onboard the Hayabusa2 spacecraft, a mission to explore a C-type asteroid known as “Ryugu” and bring a sample back to Earth.

C-type asteroids are a class of space rock that is thought to contain carbonaceous material and undergone little evolution since the early days of the Solar System. These asteroids may have rained down on the early Earth and delivered our oceans and possibly our first organics. Examination of the structure of Ryugu and its composition compared to Earth will help us understand how planets can become habitable.

Asteroid Ryugu from an altitude of 6km. Image was captured with the Optical Navigation Camera – Telescopic (ONC-T) on July 20, 2018 at around 16:00 JST. (JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, University of Aizu, AIST.)

Hayabusa2 arrived at asteroid Ryugu on June 27, 2018. The spacecraft spent the summer examining the asteroid with a suite of onboard instruments. Despite being a tiny world at only 1km across, Hayabusa2 spotted different seasons on Ryugu. Like the Earth, the asteroid’s rotation axis is inclined so that different levels of sunlight reach the northern and southern hemispheres.

It also rotated upside down, spinning in the opposite sense to the Earth and its own path around the Sun. This is likely indicative of a violent past, a view supported by the heavily bouldered and cratered surface. This rugged terrain presented the Hayabusa2 team with a problem: where could they land?

After a summer of observations, Hayabusa2 had been planning three different operations on the asteroid surface. The first was the deployment of two little rovers known as the MINERVA-II1. The second was the release of a shoebox-sized laboratory known as MASCOT, designed by the German and French space agencies.… Read more

How Creatures End Up Miles Below the Surface of Earth, and Maybe Mars Too

March 4, 2019 / Marc Kaufman / 0 Comments

Poikilolaimus oxycercus is a microscopic nematode, or roundworm, found alive and well more than a mile below the surface in South Africa, where its ancestors had lived for hundreds or thousands of years. (Gaetan Borgonie)

When scientists speculate about possible life on Mars, they generally speak of microbial or other simple creatures living deep below the irradiated and desiccated surface. While Mars long ago had a substantial period that was wetter and warmer when it also had a far more protective atmosphere, the surface now is considered to be lethal.

But the suggestion that some potential early Martian life could have migrated into the more protected depths is often discussed as a plausible, if at this point untestable possibility. In this scenario, some of that primitive subsurface life might even have survived the eons in their buried, and protected, environments.

This thinking has gotten some support in the past decade with the discovery of bacteria and nematodes (roundworms) found as far down as three miles below the surface of South Africa, in water dated as being many thousands or millions years old. The lifeforms have been discovered by a team that has regularly gone down into the nation’s super-hot gold and platinum mines to search for life coming out of boreholes in the rock face of deep mine tunnels.

Borgonie setting up a water collector for a borehole at the Driefontein mine in the Witwatersrand Basin of South Africa. He said he stopped counting his journeys into the deep mines at 50, but that the number now is much higher. (Courtesy of Borgonie)

Now a new paper describes not only the discovery of additional deep subsurface life, but also tries to explain how the distant ancestors of the worms and bacteria and algae might have gotten there.

Their conclusion: many were pulled down when fractures opened in the aftermath of earthquakes and other seismic events. While many lifeforms were swept down, only a small percentage were able to adapt, evolve and thus survive.

The is how Gaetan Borgonie, lead author of the paper in Scientific Reports, explained it to me via email:

“After the discovery of multicellular animals in the deep subsurface up to 3.8 km (2.5 miles) in South Africa everyone was baffled and asked the question how did they get that deep? This question more or less haunted us for more than a decade as we were unable to get our head around it.… Read more

All About Emergence

February 14, 2019 / Marc Kaufman / 0 Comments

A swarm of birds act as an emergent whole as opposed to a collection of individual birds. The workings of swarms have been fruitfully studied by artificial life scientists, who look for abstracted insights into life via computers and other techniques. (Walerian Walawski)

If there was a simple meaning of the often-used scientific term “emergence,” then 100-plus scientists wouldn’t have spent four days presenting, debating and not infrequently disagreeing about what it was.

But as last month’s organizers of the Earth-Life Science Institute’s “Comparative Emergence” symposium in Tokyo frequently reminded the participants, those debates and disputes are perfectly fine and to be expected given the very long history and fungibility of the concept.

At the same time, ELSI leaders also clearly thought that the term can have resonance and importance in many domains of science, and that’s why they wanted practitioners to be exposed more deeply to its meanings and powers.

Emergence is a concept commonly used in origins of life research, in complexity and artificial life science; less commonly in chemistry, biology, social and planetary sciences; and — originally – in philosophy. And in the 21^st century, it is making a significant comeback as a way to think about many phenomena and processes in the world.

So what is “emergence?” Most simply, it describes the ubiquitous and hugely varied mechanisms by which simple components in nature (or in the virtual or philosophical world) achieve more complexity, and in the process become greater than the sum of all those original parts.

The result is generally novel, often surprising, and sometimes most puzzling – especially since emergent phenomena involve self-organization by the more complex whole.

Think of a collection of ants or bees and how they join leaderless by the many thousands to make something – a beehive, an ant colony – that is entirely different from the individual creatures.

The Eagle nebula is an intense region of star formation, an emergent phenomenon
that clearly creates something novel out of simpler parts. (European Space Observatory.)

Think of the combination of hydrogen and oxygen gases which make liquid water. Think of the folding of proteins that makes genetic information transfer possible. Think of the processes by which bits of cosmic dust clump and clump and clump millions of times over and in time become a planetesimal or perhaps a planet. Think of how the firing of the billions of neurons in your brain results in consciousness.… Read more

The Moon-Forming Impact And Its Gifts

January 28, 2019 / Marc Kaufman / 0 Comments

Rice University petrologists have found Earth most likely received the bulk of its carbon, nitrogen and other life-essential volatile elements from the planetary collision that created the moon more than 4.4 billion years ago. (Rice University)

The question of how life-essential elements such as carbon, nitrogen and sulfur came to our planet has been long debated and is a clearly important and slippery scientific subject.

Did these volatile elements accrete onto the proto-Earth from the sun’s planetary disk as the planet was being formed? Did they arrive substantially later via meteorite or comet? Or was it the cataclysmic moon-forming impact of the proto-Earth and another Mars-sized planet that brought in those essential elements?

Piecing this story together is definitely challenging, but now there is vigorous support for one hypothesis — that the giant impact brought us the elements would later be used to enable life.

Based on high pressure-temperature experiments, modeling and simulations, a team at Rice University’s Department of Earth, Environmental and Planetary Sciences makes that case in Science Advances for the central role of the proto-planet called Theia.

“From the study of primitive meteorites, scientists have long known that Earth and other rocky planets in the inner solar system are volatile-depleted,” said study co-author Rajdeep Dasgupta. “But the timing and mechanism of volatile delivery has been hotly debated. Ours is the first scenario that can explain the timing and delivery in a way that is consistent with all of the geochemical evidence.”

“What we are saying is that the impactor definitely brought the majority supply of life-essential elements that we see at the mantle and surface today,” Dasgupta wrote in an email.

A schematic depicting the formation of a Mars-sized planet (left) and its differentiation into a body with a metallic core and an overlying silicate reservoir. The sulfur-rich core expels carbon, producing silicate with a high carbon to nitrogen ratio. The moon-forming collision of such a planet with the growing Earth (right) can explain Earth’s abundance of both water and major life-essential elements like carbon, nitrogen and sulfur, as well as the geochemical similarity between Earth and the moon. (Rajdeep Dasgupta; background photo of the Milky Way galaxy is by Deepayan Mukhopadhyay)

Some of their conclusions are based on the finding of a similarity between the isotopic compositions of nitrogen and hydrogen in lunar glasses and in the bulk silicate portions of the Earth. … Read more

Artifacts In Space

December 13, 2018 / Marc Kaufman / 0 Comments

Voyager 2 entered interstellar space last month, becoming a space “artifact” of our civilization. (NASA)

All of a sudden, we have spacecraft and objects both coming into our solar system and leaving for interstellar space. This is highly unusual, and very intriguing.

The departing spacecraft is Voyager 2, which launched in 1977 and has traveled spaceward some 11 billion miles. It has now officially left the heliosphere, the protective bubble of particles and magnetic fields created by the sun. In this it follows Voyager I – which left our solar system in 2012 — and managers of the two craft have reason to think they can travel until they cross the half-century mark.

This is taking place the same time that scientists are puzzling over the nature of a cigar-shaped object that flew into the solar system from interstellar space last year.

Nobody knows what the object – called Oumuamua, Hawaiian for “first messenger,” or “scout” – really is. The more likely possibilities of it being a comet or an solar system asteroid have been found to be inconsistent with some observed properties of the visitor, and this has led some senior scientists to even hypothesize that it just might be an alien probe.

The likelihood may be small, but it was substantial enough for Harvard University Astronomy Department Chairman Avi Loeb to co-author a paper presenting the possibility. In the Astrophysical Journal Letters, Loeb and postdoc Shmuel Bialy wrote that the object “may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization.”

They also say the object has some characteristics of a “lightsail of artificial origins,” rather like the one that Loeb is working on as chairman of the Breakthrough Starshot advisory committee. The well-funded private effort is hoping to develop ways to send a fleet of tiny lightsail probes to the star system nearest to us, Alpha Centauri.

This artist’s impression of the first detected interstellar visitor: Oumuamua. This object was discovered in October 2017 by the Pan-STARRS 1 telescope in Hawaii. Subsequent observations from ESO’s Very Large Telescope in Chile and other observatories around the world show that it was traveling through space for millions of years before its seemingly chance encounter with our star system. But some scientists wonder: might it be instead a probe sent into the cosmos by intelligent creatures?(NASA)

Put the two phenomenon together — the coming into our solar system and the going out — and you have a pathway into the world of alien “artifacts,” products of civilizations near and far. … Read more

Does Proxima Centauri Create an Environment Too Horrifying for Life?

November 29, 2018 / Elizabeth Tasker / 0 Comments

Artist’s impression of the exoplanet Proxima Centauri b. (ESO/M. Kornmesser)

In 2016, the La Silla Observatory in Chile spotted evidence of possibly the most eagerly anticipated exoplanet in the Galaxy. It was a world orbiting the nearest star to the sun, Proxima Centauri, making this our closest possible exoplanet neighbour. Moreover, the planet might even be rocky and temperate.

Proxima Centauri b had been discovered by discerning a periodic wobble in the motion of the star. This revealed a planet with a minimum mass 30% larger than the Earth and an orbital period of 11.2 days. Around our sun, this would be a baking hot world.

But Proxima Centauri is a dim red dwarf star and bathes its closely orbiting planet in a level of radiation similar to that received by the Earth. If the true mass of the planet was close to the measured minimum mass, this meant Proxima Centauri b would likely be a rocky world orbiting within the habitable zone.

Comparison of the orbit of Proxima Centauri b with the same region of the solar system. Proxima Centauri is smaller and cooler than the sun and the planet orbits much closer to its star than Mercury. As a result it lies well within the habitable zone. (ESO/M. Kornmesser/G. Coleman.)

Sitting 4.2 light years from our sun, a journey to Proxima Centauri b is still prohibitively long.

But as our nearest neighbor, the exoplanet is a prime target for the upcoming generation of telescopes that will attempt to directly image small worlds. Its existence was also inspiration for privately funded projects to develop faster space travel for interstellar distances.

Yet observations taken around the same time as the La Silla Observatory discovery were painting a very different picture of Proxima Centauri. It was a star with issues.

This set of observations were taken with Evryscope; an array of small telescopes that was watching stars in the southern hemisphere. What Evryscope spotted was a flare from Proxima Centauri that was so bright that the dim red dwarf star became briefly visible to the naked eye.

Flares are the sudden brightening in the atmosphere of a star that release a strong burst of energy. They are often accompanied by a large expulsion of plasma from the star known as a “coronal mass ejection”. Flares from the sun are typically between 10²⁷ – 10³² erg of energy, released in a few tens of minutes.… Read more

Many Worlds