Connect with us

Earth is the only life-supporting planet we know of, so it’s tempting to use it as a standard in the search for life elsewhere. But the modern Earth can’t serve as a basis for evaluating exoplanets and their potential to support life. Earth’s atmosphere has changed radically over its 4.5 billion years.

A better way is to determine what biomarkers were present in Earth’s atmosphere at different stages in its evolution and judge other planets on that basis.

That’s what a group of researchers from the UK and the USA did. Their research is titled “The early Earth as an analogue for exoplanetary biogeochemistry,” and it appears in Reviews in Mineralogy. The lead author is Eva E. Stüeken, a PhD student at the School of Earth & Environmental Sciences, University of St Andrews, UK.

When Earth formed about 4.5 billion years ago, its atmosphere was nothing like it is today. At that time, the atmosphere and oceans were anoxic. About 2.4 billion years ago, free oxygen began to accumulate in the atmosphere during the Great Oxygenation Event, one of the defining periods in Earth’s history. But the oxygen came from life itself, meaning life was present when the Earth’s atmosphere was much different.

This isn’t the only example of how Earth’s atmosphere has changed over geological time. But it’s an instructive one and shows why searching for life means more than just searching for an atmosphere like modern Earth’s. If that’s the way we conducted the search, we’d miss worlds where photosynthesis hadn’t yet appeared.

In their research, the authors point out how Earth hosted a rich and evolving population of microbes under different atmospheric conditions for billions of years.

“For most of this time, Earth has been inhabited by a purely microbial biosphere albeit with seemingly increasing complexity over time,” the authors write. “A rich record of this geobiological evolution over most of Earth’s history thus provides insights into the remote detectability of microbial life under a variety of planetary conditions.”

It’s not just life that’s changed over time. Plate tectonics have changed and may have been ‘stagnant lid’ tectonics for a long time. In stagnant lid tectonics, plates don’t move horizontally. That can have consequences for atmospheric chemistry.

The main point is that Earth’s atmosphere does not reflect the solar nebula the planet formed in. Multiple intertwined processes have changed the atmosphere over time. The search for life involves not only a better understanding of these processes, but how to identify what stage exoplanets might be in.

This figure from the research shows how the abundance of major gases in Earth's atmosphere has changed over time due to various factors. Image Credit: Stüeken et al. 2024.
This figure from the research shows how the abundance of major gases in Earth’s atmosphere has changed over time due to various factors. Image Credit: Stüeken et al. 2024.

It’s axiomatic that biological processes can have a dramatic effect on planetary atmospheres. “On the modern Earth, the atmospheric composition is very strongly controlled by life,” the researchers write. “However, any potential atmospheric biosignature must be disentangled from a backdrop of abiotic (geological and astrophysical) processes that also contribute to planetary atmospheres and would be dominating on lifeless worlds and on planets with a very small biosphere.”

The authors outline what they say are the most important lessons that the early Earth can teach us about the search for life.

The first is that the Earth has actually had three different atmospheres throughout its long history. The first one came from the solar nebula and was lost soon after the planet formed. That’s the primary atmosphere. The second one formed from outgassing from the planet’s interior. The third one, Earth’s modern atmosphere, is complex. It’s a balancing act involving life, plate tectonics, volcanism, and even atmospheric escape. A better understanding of how Earth’s atmosphere has changed over time gives researchers a better understanding of what they see in exoplanet atmospheres.

https://mansbrand.com/dinkineshs-moonlet-is-only-2-3-million-years-old/

Continue Reading

Frontier Adventure

Galaxies Regulate their Own Growth so they Don’t Run Out of Star Forming Gas

Picture1 copy

Look at most spiral or barred spiral galaxies and you will see multiple regions where stars are forming. These star forming regions are comprised of mostly hydrogen gas with a few other elements for good measure. The first galaxies in the Universe had huge supplies of this star forming gas. Left unchecked they could have burned through the gas quickly, generating enormous amounts of star formation. Life fast though and die young for such an energetic burst of star formation would soon fizzle out leaving behind dead and dying stars. In some way it seems, galaxies seem to regulate their star formation thanks to supermassive black holes at their centre. 

The first galaxies formed about 400 to 700 million years after the Big Bang, during the Epoch known as Reionization. These early galaxies were small and faint, mostly composed of hydrogen and helium, and contained dense clusters of massive, short-lived Population III stars (the first generation of stars.) The intense radiation from these stars ionised the surrounding gas, clearing the fog that permeated space making the universe transparent for the first time. These primordial galaxies began merging and interacting, laying the foundation for the galaxy types seen today.

A new study published in the Monthly Notices of the Royal Astronomical Society explores why galaxies are not as large as astronomers would expect. The research suggests that galaxies, even those that formed first, avoid an early death because they have mechanisms similar to “heart and lungs,” which regulate their “breathing”. Without these regulatory processes our bodies, and galaxies would have aged much faster, resulting in massive galaxies filled with dead and dying stars and devoid of new star formation.

Observations show that galaxies are not so big and full of dying stars having outgrown themselves. It seems something limits their ability to allow gas to form into stars. Astrophysicists at the University of Kent believe they may have the answer: galaxies could be controlling their growth rate through a process not too dissimilar to “breathing.” They compare the supermassive black hole at the centre of a galaxy to a heart and the supersonic jets emerging from the poles with the radiation and gas they emit to airways feeding a pair of lungs.

The supermassive black holes seem to pulse just like a heart. These pulses cause a shock front to oscillate along the jets like a diaphragm inflating and deflating the lungs. This process transmits energy along the jet slowly counteracting the pull of gravity and slowing gas accretion and star formation. The idea was developed by PhD student Carl Richards and his simulations showed a black hole pulsing like a heart. 

Picture1 copy 1
Assisted by magnetic fields, a spiraling wind helps the supermassive black hole in galaxy ESO320-G030 grow. In this illustration, the core of the galaxy is dominated by a rotating wind of dense gas leading outwards from the (hidden) supermassive black hole at the galaxy’s center. The motions of the gas, traced by light from molecules of hydrogen cyanide, have been measured with the Atacama Large Millimeter/submillimeter Array. Image credit: M. D. Gorski/Aaron M. Geller, Northwestern University, CIERA, the Center for Interdisciplinary Exploration and Research in Astrophysics.

Richards explains “We realised that there would have to be some means for the jets to support the body – the galaxy’s surrounding ambient gas – and that is what we discovered in our computer simulations,” He continued “The unexpected behaviour was revealed when we analysed the computer simulations of high pressure and allowed the heart to pulse.”

Evidence of ripples just like those in Richards’ simulations, in extra-galactic media have been found in galaxy clusters like the Perseus cluster. These ripples are thought to sustain a galaxy’s environment, though their generation mechanism was unclear. Conventional simulations fail to explain gas flows into galaxies, but the work of the team from the University of Kent may well have answered the question.

Source : How the ‘heart and lungs’ of a galaxy extend its life.

The post Galaxies Regulate their Own Growth so they Don’t Run Out of Star Forming Gas appeared first on Universe Today.

Did you miss our previous article…
https://mansbrand.com/bear-essentials-how-to-store-food-when-backcountry-camping-3/

Continue Reading

Frontier Adventure

Bear Essentials: How to Store Food When Backcountry Camping

Tet19 047 Me on Teton Crest Trail copy cropped 28

By Michael Lanza

On our first night in the backcountry of Yosemite National Park on one of my earliest backpacking trips, two friends and I—all complete novices—hung our food from a tree branch near our camp. Unfortunately, the conifer trees around us all had short branches: Our food stuff sacks hung close to the trunk.

During the night, the predictable happened: We awoke to the sound of a black bear clawing up the tree after our food.

Despite our nervousness and incompetence, we somehow managed to shoo that black bear off, though not before he (or she) departed with a respectable haul from our food supply. But by virtue of having started out with way more food than we needed—another rookie mistake that, ironically, compensated for this more-serious rookie mistake (read my tips on not overpacking)—we made it through that hike without going hungry and ultimately had a wonderful adventure.

And we went home with a valuable lesson learned.

Tet19 047 Me on Teton Crest Trail copy cropped 29
Hi, I’m Michael Lanza, creator of The Big Outside. Click here to sign up for my FREE email newsletter. Join The Big Outside to get full access to all of my blog’s stories. Click here for my e-books to classic backpacking trips. Click here to learn how I can help you plan your next trip.

A black bear along the Sol Duc River Trail in Olympic National Park.
” data-image-caption=”A black bear along the Sol Duc River Trail in Olympic National Park.
” data-medium-file=”https://i0.wp.com/tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2019/03/06232206/Olym6-070-Black-bear-Sol-Duc-River-Trail-Olympic-NP-WA-2.jpg?fit=300%2C201&ssl=1″ data-large-file=”https://i0.wp.com/tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2019/03/06232206/Olym6-070-Black-bear-Sol-Duc-River-Trail-Olympic-NP-WA-2.jpg?fit=900%2C602&ssl=1″ tabindex=”0″ role=”button” src=”https://i0.wp.com/tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2019/03/06232206/Olym6-070-Black-bear-Sol-Duc-River-Trail-Olympic-NP-WA-2-1024×685.jpg?resize=900%2C602&ssl=1″ alt=”A black bear along the Sol Duc River Trail in Olympic National Park.” class=”wp-image-34782″ srcset=”https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2019/03/06232206/Olym6-070-Black-bear-Sol-Duc-River-Trail-Olympic-NP-WA-2.jpg 1024w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2019/03/06232206/Olym6-070-Black-bear-Sol-Duc-River-Trail-Olympic-NP-WA-2.jpg 300w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2019/03/06232206/Olym6-070-Black-bear-Sol-Duc-River-Trail-Olympic-NP-WA-2.jpg 768w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2019/03/06232206/Olym6-070-Black-bear-Sol-Duc-River-Trail-Olympic-NP-WA-2.jpg 1080w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2019/03/06232206/Olym6-070-Black-bear-Sol-Duc-River-Trail-Olympic-NP-WA-2.jpg 1200w” sizes=”(max-width: 900px) 100vw, 900px” data-recalc-dims=”1″ />A black bear along the Sol Duc River Trail in Olympic National Park.

I’ve learned much more about storing food properly in the backcountry over the more than three decades since that early trip, including the 10 years I spent as the Northwest Editor of Backpacker magazine and even longer running this blog. This article shares what I’ve learned about protecting food from critters like bears and, more commonly, mice and other small animals and some birds like ravens.

Follow the tips below and you’ll not only save yourself and your party or family from going hungry, you might save a bear from developing a habit of seeing humans as sources of food, which too often leads to a bad outcome for that animal.

If you have any questions or tips of your own to share, please do so in the comments section at the bottom of this
Did you miss our previous article…
https://mansbrand.com/the-rugged-desert-moss-best-equipped-to-survive-on-mars/

Continue Reading

Frontier Adventure

The Rugged Desert Moss Best Equipped to Survive on Mars

Mars

For decades, we have seen Mars as a desolate landscape devoid of any signs of life. Attempt to identify ways of growing plants and food on the red planet have focussed on greenhouse like structures to enable plants to survive, that is, until now! A desert moss called ‘Syntrichia caninervis’ has been identified and it can grown in extreme environments like Antarctica and the Mojave Desert. A new study revealed the moss can survive Mars-like environments too including low temperatures, high levels of radiation and drought. 

Mars has often be referred to as the “Red Planet” for its distinct red hue. It is the fourth planet from the Sun and to some extent resembles the Earth. Polar ice caps, seasonal weather patterns, extinct volcanoes, ancient riverbeds and flood plains are among the many surface features and. This cold world has fascinated us for centuries and its thin atmosphere, mostly made up of carbon dioxide, has been subjected to lots of studies. It has been thought for many years that it experiences some of the harshest weather conditions, including planet-wide dust storms but the recent study suggests there may just be a plant on Earth capable of surviving these conditions. 

Mars 1
Mars, Credit NASA

Exploring and colonising planets like Mars can enhance human sustainability. Since no life forms have been found on Mars, introducing Earth organisms might be necessary for creating suitable conditions for human life in a process known as terraforming. This will involve selecting or engineering plants that can thrive in the harsh environments of an alien world. Few studies have tested organisms’ ability to withstand extreme environments of space or Mars, focusing mainly on microorganisms, algae, and lichens. However until recently, studies including mosses and whole plants have been lacking.

There have been many long term plans and even whimsical ideas to establish settlements on Mars. Pivotal to the success is the establishment of adapted crops that can grow in controlled, synthetic environments. However, to develop such a plant requires significant progress and development before plants are capable of growing in the soils and harsh conditions. In the report by lead author Xiaoshuang Li and team the incredible resilience of a moss called Syntrichia caninervis (S. caninervis) to survive a Mars-like environment even after having lost more than 98% of its water content.

Studies into the resilience of the plants have shown they can withstand extremely low temperatures and regenerate even after being stored in a freezer at -80°C for five years or in liquid nitrogen for one month. S. caninervis also demonstrates high resistance to gamma radiation and can survive in simulated Martian conditions.

The study concluded that S. caninervis is among the most stress-tolerant organisms known. It shows how it is a real potential species for the colonisation of alien worlds like Mars. The resilience to extreme conditions such as desiccation, low temperatures, and high radiation makes it an ideal for future terraforming efforts. It helps to understand the unique properties of this moss (in particular) and how it can form a foundational layer for biologically sustainable human habitats in space.

Source : The extremotolerant desert moss Syntrichia caninervis is a promising pioneer plant for colonizing extraterrestrial environments

The post The Rugged Desert Moss Best Equipped to Survive on Mars appeared first on Universe Today.

Did you miss our previous article…
https://mansbrand.com/do-planets-have-the-raw-ingredients-for-life-the-answer-is-in-their-stars/

Continue Reading

Trending