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What Early Earth Teaches Us About Finding Life

By Jonathan Bala May 8, 2024

What Early Earth Teaches Us About Finding Life

Key Takeaway:

The study of early Earth provides a fascinating glimpse into the conditions that existed billions of years ago, offering valuable insights into the origins of life on our planet. By examining the harsh environments in which life thrived and the chemical processes that gave rise to living organisms, scientists can draw parallels to the search for life beyond Earth.

Summary:

Earth’s atmosphere has changed significantly over its 4.5 billion years of existence.
Research on early Earth’s biogeochemistry helps in evaluating exoplanetary potential for life.
Earth’s microbial biosphere thrived under different atmospheric conditions, providing insights into remote detection of life.
Plate tectonics and atmospheric processes have influenced Earth’s atmosphere over time.
Lessons from Earth include the presence of multiple atmospheric stages, altered rock records, delayed detection of oxygen, and the impact of plate tectonics on chemistry.
Remote detection of exoplanetary biospheres relies on telescopic observations of atmospheric composition.
Advanced telescopes like the JWST are enhancing our ability to detect chemicals in exoplanet atmospheres.
Future tools may enable the recognition of surface features indicative of life.
Earth serves as a model for understanding and accelerating the search for life beyond our solar system.

What Early Earth Teaches Us About Finding Life — The JWST has been in the news for its work on exoplanet atmospheres and the detection of chemicals. On July 10, 2022, the telescope’s Near-Infrared Spectrograph (NIRSpec) recorded a transmission spectrum from the hot gas giant exoplanet WASP-39 b. This data showed the first clear evidence of carbon dioxide in the atmosphere of a planet beyond our Solar System. The image credits go to NASA, ESA, CSA, and L. Hustak from STScI. The responsible scientific team is the JWST Transiting Exoplanet Community Early Release Science Team.

Exploring Early Earth: Lessons for the Search for Life

Earth stands as a unique oasis of life in the vast expanse of the cosmos. Its evolution over billions of years offers a window into the potential for life on other planets. By Decoding the mysteries of Earth’s past, scientists gain valuable insights into how to search for life beyond our solar system.

Earth’s atmosphere has experienced significant changes since it first formed 4.5 billion years ago. Initially, it lacked oxygen and was described as anoxic. Over time, a series of geological and biological processes reshaped the atmosphere. One crucial event, known as the Great Oxygenation Event, occurred approximately 2.4 billion years ago. During this event, oxygen began to accumulate in the atmosphere, primarily due to the emergence of photosynthetic organisms.

“Earth’s atmospheric composition is very strongly controlled by life.” – Research findings

Lessons from Earth’s Biogeochemical Evolution

Multiple Atmospheric Stages: Earth has experienced three distinct atmospheres, each influenced by different factors such as outgassing and biological activity. Understanding these stages provides a framework for evaluating exoplanetary atmospheres.
Altered Rock Records: Geological evidence of early life on Earth is scarce due to the alteration and destruction of rock records over time. This challenges our ability to reconstruct the early biosphere accurately.
Delayed Oxygen Detection: Oxygenic photosynthesis appeared long before atmospheric oxygen became detectable. This suggests that exoplanets may host oxygen-producing life forms without immediately exhibiting atmospheric oxygen.
Impact of Plate Tectonics: Changes in Earth’s tectonic activity influenced atmospheric chemistry, affecting the detectability of biosignatures such as methane. Horizontal plate tectonics played a crucial role in shaping Earth’s atmospheric evolution.

While Earth offers tangible evidence through geological records, the search for life beyond our solar system relies on remote observation. Telescopes like the James Webb Space Telescope (JWST) enable scientists to analyze exoplanet atmospheres for chemical signatures indicative of life.

“We must remotely recognize the presence of alien biospheres and characterize their biogeochemical cycles in planetary spectra obtained with large telescopes.” – Research conclusions

Advancements in Exoplanet Exploration

Atmospheric Chemistry Analysis: The JWST has revolutionized exoplanet exploration by identifying chemicals in distant atmospheres. Detection of carbon dioxide in exoplanet atmospheres represents a significant milestone in our quest to understand extraterrestrial environments.
Surface Feature Recognition: Future telescopes may enable the identification of surface features indicative of life, such as light interaction with photosynthetic pigments and glint from liquid oceans.

Earth’s rich history serves as a blueprint for the exploration of life beyond our solar system. By deciphering Earth’s complex biogeochemical evolution, scientists can refine their search strategies and accelerate the quest for extraterrestrial life.

As humanity ventures into the unknown regions of space, Earth remains our guiding beacon. Through thorough study and technological innovation, we inch closer to unlocking the secrets of the cosmos. Each discovery brings us closer to answering one of the most profound questions: Are we alone in the universe?

Hashtags:

#Exoplanets, #Astrobiology, #Biogeochemistry, #SpaceExploration

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Space-Based Navigation

Webb’s Report of Life on an Exoplanet Deserves a Closer Look

By Jonathan Bala May 4, 2024

Webb’s Report of Life on an Exoplanet Deserves a Closer Look

Key Takeaway

The James Webb Space Telescope (JWST) has doubtfully detected dimethyl sulphide (DMS) in the atmosphere of the exoplanet K2-18b. DMS is a potential biosignature. However, this detection has not been conclusively confirmed. Further observations in the mid-infrared range are required to definitively determine if DMS is present or absent.

Summary

The JWST’s observations of K2-18b, a sub-Neptune exoplanet orbiting a red dwarf star, revealed hints of dimethyl sulphide (DMS) in its atmosphere, which caught attention as DMS is produced by living organisms on Earth.
However, the DMS signal was weak and overlapped with methane, making it challenging to confirm its presence using the JWST’s near-infrared instruments.
Researchers performed modeling studies and found that the data is unlikely to show the presence of DMS in K2-18b’s atmosphere.
For DMS to be detectable, the biological production would need to be about 20 times higher than on Earth.
The researchers suggest that it is more plausible to detect DMS in the mid-infrared range between 9 and 13 micrometers, where it does not overlap with methane.
The JWST will observe K2-18b again next year using its mid-infrared instrument (MIRI), which could definitively confirm or rule out the presence of DMS.
The study highlights that biosignatures on exoplanets may differ significantly from those on Earth, and a holistic understanding of atmospheric chemistry and potential biosignatures is essential.
While the initial detection of DMS was not confirmed, the study suggests that the search for biogenic sulphur gases as potential biosignatures on Hycean worlds (temperate, ocean-covered planets with hydrogen-rich atmospheres) is plausible.

Webb's Report of Life on an Exoplanet Deserves a Closer Look (1) — This figure displays the wavelength ranges of various instruments and the modes they can operate in. Image Credit: NASA/STScI

Mystery of Potential Biosignatures on K2-18b: A Journey with the James Webb Space Telescope

The quest for signs of life beyond Earth has captivated the imaginations of scientists and fanatics alike. Recently, the James Webb Space Telescope (JWST) trained its powerful gaze on K2-18b, a captivating sub-Neptune exoplanet orbiting a red dwarf star, igniting hopes of detecting potential biosignatures.

In September 2023, the JWST’s observations of K2-18b’s atmospheric spectrum revealed intriguing hints of dimethyl sulphide (DMS), a compound closely associated with life on Earth. DMS is predominantly produced by marine microbes, making its potential presence on an ocean-covered exoplanet like K2-18b particularly intriguing.

The detection of DMS, even in tentative form, sent ripples of excitement through the scientific community. Could this be the first glimpse of life on an alien world? However, as is often the case in the pursuit of scientific truth, the path forward was shrouded in uncertainty and the need for further investigation.

While the initial detection of DMS was undoubtedly captivating, subsequent analyses revealed significant challenges in confirming its presence. The signal was weak and overlapped with methane, making it difficult to isolate and identify with certainty using the JWST’s near-infrared instruments.

To shed light on this enigma, a team of researchers from the USA, Germany, and the UK researched into atmospheric modeling and simulation studies. Their findings, published in the Astrophysical Journal Letters, presented a sobering reality: the data obtained by the JWST is unlikely to definitively confirm the presence of DMS in K2-18b’s atmosphere.

However, not all hope is lost. The researchers suggest that the detection of DMS may be more plausible in the mid-infrared range between 9 and 13 micrometers, where it does not overlap with methane’s spectral signature. Fortunately, the JWST is equipped with a powerful mid-infrared instrument (MIRI) capable of probing this wavelength range.

In a captivating twist, the JWST is scheduled to observe K2-18b again next year, this time utilizing MIRI’s capabilities. This highly anticipated observation could potentially provide the definitive evidence needed to confirm or rule out the presence of DMS, unlocking a crucial piece of the puzzle in the search for extraterrestrial life.

One of the most profound lessons emerging from this investigation is the recognition that biosignatures on exoplanets may differ significantly from those we observe on Earth. As astrobiologist Eddie Schwieterman from the University of California, Riverside, rightly stated,

“The best biosignatures on an exoplanet may differ significantly from those we find most abundant on Earth today.”

This paradigm shift challenges our Earth-centric perspective and encourages a more comprehensive understanding of atmospheric chemistry and potential biosignatures across a diverse range of exoplanetary environments.

While the initial detection of DMS on K2-18b remains unconfirmed, the study provides a glimmer of hope for the search for biogenic sulphur gases as potential biosignatures on Hycean worlds – temperate, ocean-covered planets with hydrogen-rich atmospheres.

HASHTAGS:

#JamesWebbSpaceTelescope, #Exoplanets, #K2-18b, #Biosignatures, #DimethylSulphide, #Astrobiology, #ExoplanetAtmospheres, #HyceanWorlds, #MidInfraredObservations, #ScienceJourney, #JWST #Report of Life on an Exoplanet

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Satellite Technology

Beyond Earth: Purple Bacteria’s Link to Finding Life Elsewhere

By Jonathan Bala April 24, 2024

Beyond Earth: Purple Bacteria’s Link to Finding Life Elsewhere

Key Takeaway

Astrobiologists propose that purple bacteria might be better biosignatures than green plants for detecting life on exoplanets, offering a new perspective in the search for extraterrestrial life.

Purple bacteria that use simpler forms of photosynthesis and don’t produce oxygen might be more prevalent on a wider range of exoplanets than green plants, and could serve as a stronger biosignature for detecting potential life on other worlds.

Summary

Astrobiologists are searching for signs of life on exoplanets. They are looking beyond green plants and chlorophyll for these signs. They focus on alternative biosignatures to detect possible life.
A recent study shows that purple bacteria are unique. They have simpler systems for photosynthesis. They also use different pigments, known as bacteriochlorophyll. These bacteria can grow in a wider variety of conditions compared to green plants.
Purple bacteria live in many places on Earth. They are found in shallow waters, marshes, and deep-sea hydrothermal vents. They might have been common on early Earth. This was before plants started doing photosynthesis.
Purple bacteria thrive on planets that circle cooler red dwarf stars. Red dwarf stars are the most abundant type in our galaxy.
On exoplanets dominated by purple bacteria, their clear pigments would produce a unique “light fingerprint” detectable by future telescopes.
The researchers modeled Earth-like planets where purple bacteria dominate the surface and showed the impact on the reflectance spectra of these exoplanets.
Studying the signatures of purple bacteria could improve the chances of detecting life on exoplanets with upcoming telescopes, complementing the traditional search for green plant-like biosignatures.
The research provides a new resource to guide the detection of purple bacteria, expanding the database of potential signs of life for future exoplanet observations.

The Cosmic Hunt for Purple Life: Bacteria Could Outshine Plants as Biosignatures

Astrobiologists always search for signs of life in space. They often look for green plants’ signs on distant planets. But, a new study shows we might have missed something important. It suggests purple bacteria could be a more common sign of life in the universe.

Before plant photosynthesis evolved, Earth looked very different. It was full of purple bacteria instead of green plants. These purple bacteria are tough. They live in many places, from shallow marshes to deep hydrothermal vents. They use a basic form of photosynthesis that doesn’t make oxygen.

Purple bacteria are different from green ones. They use special pigments, like bacteriochlorophyll. These pigments absorb infrared and low-energy red light. This lets them thrive in harsh conditions that plants can’t handle. This ability makes them likely to survive on many exoplanets.

According to Lígia Fonseca Coelho, a postdoctoral associate at the Carl Sagan Institute and lead author of the study,

“Purple bacteria can thrive under a wide range of conditions, making it one of the primary contenders for life that could dominate a variety of worlds.”

The research team characterized the reflectance spectra of various purple sulfur and non-sulfur bacteria found on Earth, involving a vibrant palette of colors, including yellow, orange, brown, and red. These distinct hues result from the unique pigments that enable the bacteria to harness energy from different wavelengths of light.

On a hypothetical exoplanet dominated by purple bacteria, the surface would emit a distinctive “light fingerprint” detectable by next-generation telescopes. By modeling Earth-like planets where these bacteria reign supreme, the researchers demonstrated the impact of their signatures on the reflectance spectra of terrestrial exoplanets.

Lisa Kaltenegger, director of the Carl Sagan Institute and co-author of the study, emphasized the importance of expanding our understanding of potential biosignatures:

“We need to create a database for signs of life to make sure our telescopes don’t miss life if it happens not to look exactly like what we encounter around us every day.”

The study shows important results for finding life on exoplanets. These planets orbit red dwarf stars, the most common stars in our galaxy. By looking beyond signs of green plant life, we boost our chances of finding different kinds of life.

As we eagerly await the launch of next-generation telescopes, such as the James Webb Space Telescope and the Extremely Large Telescopes, the study provides a valuable resource to guide the detection of purple bacteria, potentially Revealing a new chapter in the cosmic tale of life’s diversity.

HASHTAGS:

#astrobiology, #exoplanets, #purplebacteria, #biosignatures, #redwdwarfstars, #alienhunting, #astronomy, #spaceexploration, #extremelife, #scienceinsights #Purple Bacteria

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Technology

Could We Determine if TRAPPIST-1e Supports Life?

By Jonathan Bala April 23, 2024

Could We Determine if TRAPPIST-1e Supports Life?

Key Takeaway:

Studying the potential for life on distant exoplanets involves studying how life evolved on Earth and using clues from different geological eras. A recent study suggests looking for signs of ancient life similar to that of the Archean era on TRAPPIST-1e, which could help us identify signs of life beyond our solar system.

Summary:

Exoplanet Characterization: Scientists are transitioning from discovering exoplanets to characterizing them, focusing on biosignatures.
TRAPPIST-1 System: This system, with its seven rocky planets orbiting a red dwarf star, offers opportunities to search for extraterrestrial life.
Evolution of Earth’s Atmosphere: Earth’s early atmosphere during the Archean Eon serves as a model for potential biosignatures on other planets.
Archean-like Biosignatures: Researchers have identified methane, carbon dioxide, and water vapor as key indicators of pre-oxygen photosynthesizing life.
Modeling Archean Conditions: By considering how early life forms interacted with their environment, scientists predict potential biosignatures.
Impact of Host Star: The type of host star influences atmospheric chemistry and the presence of certain gases, affecting biosignature detection.

TRAPPIST-1e

Life on other planets has long been a subject of fascination and scientific inquiry. The discovery of exoplanets has brought us closer to answering the age-old question: are we alone in the universe? The TRAPPIST-1 system, with its seven rocky planets orbiting a red dwarf star, has emerged as a promising candidate in the search for extraterrestrial life. But how will we know if a planet like TRAPPIST-1e harbors life?

In recent years, scientists have shifted their focus from simply discovering exoplanets to characterizing them in more detail. One crucial aspect of this characterization is the search for biosignatures—chemical signatures that could indicate the presence of life. However, there is ongoing debate about which biosignatures are most indicative of life, particularly when considering the evolution of Earth’s atmosphere over billions of years.

Dr. Jake Eager-Nash, a postdoctoral research fellow at the University of Victoria and lead author of a recent study on biosignatures, emphasizes the importance of understanding Earth’s history when searching for life on other planets:

“I think the Earth’s history provides many examples of what inhabited exoplanets may look like, and it’s important to understand biosignatures in the context of Earth’s history as we have no other examples of what life on other planets would look like.”

The study, titled “Biosignatures from pre-oxygen photosynthesizing life on TRAPPIST-1e,” explores the possibility of detecting life on TRAPPIST-1e based on conditions similar to Earth’s early Archean Eon. During this time, Earth’s atmosphere was vastly different from what it is today, composed primarily of carbon dioxide, methane, and volcanic gases. Simple microbial life forms existed in this oxygen-poor environment, providing a potential model for life on other rocky planets.

To simulate Archean-like conditions, researchers developed a model that takes into account interactions between early life forms and their environment. This model predicts that certain gases, such as methane, carbon dioxide, and water vapor, would be key biosignatures for detecting pre-oxygen photosynthesizing life on rocky planets.

According to Dr. Eager-Nash,

“Archean-like biosignatures are thought to require the presence of methane, carbon dioxide, and water vapor… the absence of carbon monoxide is important as it is thought that life would quickly evolve a way to consume this energy source.”

One of the challenges in detecting biosignatures is understanding how the type of host star influences atmospheric chemistry. Red dwarf stars, like the one in the TRAPPIST-1 system, are known for their variability and propensity for flare activity. Despite these challenges, scientists are optimistic that upcoming telescopes, such as the James Webb Space Telescope, will provide valuable insights into the atmospheres of exoplanets.

While the search for life on other planets remains a complex and challenging endeavor, studying Earth’s history provides valuable clues and insights. By modeling Archean-like conditions and identifying key biosignatures, scientists are paving the way for future discoveries in the field of astrobiology.

Hashtags:

#Exoplanets #Astrobiology #TRAPPIST1e #Biosignatures #SpaceExploration #ScientificResearch

Sources:

arXiv: https://arxiv.org/pdf/2404.11611.pdf
Universe Today: https://www.universetoday.com/140293/to-find-evidence-of-life-on-exoplanets-scientists-should-search-for-purple-earths/
Universe Today: https://www.universetoday.com/138447/finding-alien-life-bad-great-filter/
ESO: https://elt.eso.org/
NASA Science: https://science.nasa.gov/missions/hubble/promising-worlds-found-around-nearby-ultra-cool-dwarf-star

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