Research led by Muhammad Alyan

Syed Saim Ali, Ansa Ismail, Saman Shahid

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‍Finding Extraterrestrial life using Chemistry

Introduction

Extraterrestrial life also referred as Alien life is a life which is not originated from earth. Till now no extraterrestrial life has yet been scientifically concluded to be discovered. Such life may Range from species such prokaryotes to intelligent beings possible bring forth civilizations that may be far more advanced than us human being. Study of such species life is called Astrobiology. Considering the size of the universe there are at least 100 billion stars in our galaxy along and there are about 100 billion galaxies of about the same size scattered throughout space.

The study for Extraterrestrial life has captivated human imagination for many years. Recent advances in astrobiology and astrochemistry have shifted the spotlight from speculative searches to scientifically driven investigations. Chemistry plays a crucial role in the pursuit as it offers unique methods to detect and categorize life beyond our planet. One of which is Chemical biosignatures which are chemical or biological signs of life which astrologist discover in interstellar space, comets, asteroids and planetary atmospheres. It is further categorized into chiral biosignatures, isotopic bio signatures and organic molecules. The detection methods include mass spectrometry, chromatography, as well as In-Situ Measurements.

 Hypothesis

Water is essential for life

Water-Based Life Hypothesis stands out for its focus on one of the most essential elements to life as we understand it. The Water-Based Life Hypothesis has played a crucial role in shaping research in astrobiology and planetary science, directing efforts toward exploring celestial bodies where liquid water is present or once existed. This approach has led to significant discoveries and sparked exciting missions, but it also has limitations due to its Earth-centered perspective. As our knowledge of possible forms of life and their habitats expands, this hypothesis may need to be revised or supported by new theories. However, the Water-Based Life Hypothesis will likely remain an essential framework in the ongoing search for life beyond Earth. The importance of water in the search for extraterrestrial life has led to a number of space missions that aim to identify celestial bodies with evidence of liquid water. Such as Mars Missions: designed to explore ancient river beds and lake beds, looking for signs of past or present water .NASA's upcoming Europa Clipper mission is set to explore Jupiter's moon Europa, focusing on its hidden ocean beneath the icy surface. This moon is thought to have a liquid ocean under its frozen crust, which may provide conditions suitable for life.

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Detection of biosignatures

Most approaches aimed at detecting life rely on searching for biosignatures. We define biosignatures as chemical species, features or processes that provide evidence for the presence of life. Such examples are Chemical compounds or groups of compounds that are typically associated with living organisms, like pigments; distinctive traits of biologically produced compounds, such as chirality; and biological patterns that show complexity.  finding different biosignatures may give us a different degree of confidence that they have been produced biologically. Evaluation is necessary for both further development of life detection science and planning future missions and remote observations aimed at searching for signs of life.

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Extremophiles hypothesis

The extremophiles hypothesis in the search for extraterrestrial life suggests that life could exist in extreme environments similar to where extremophiles thrive on Earth. Extremophiles are organisms that live in conditions once thought to be uninhabitable, such as extreme heat, cold, acidity, radiation, or high-pressure environments.

This hypothesis proposes that if life on Earth can survive in such extreme conditions, then it’s possible that life on other planets or moons with harsh environments, such as Mars, Europa, or Titan, might also exist. The hypothesis expands the potential habitats where scientists might find extraterrestrial life, even in places without conditions traditionally considered "Earth-like."

Extremophiles that thrive in conditions resembling outer space are especially intriguing because they expand our understanding of the potential for life beyond Earth and how we might detect it on-site. Additionally, many extremophiles are used as model organisms in astrobiology to study the potential existence of alien life or the detection of life-produced substances outside of Earth.

 Methods used to discover

One chemist proposes a simple approach to searching for life on other planets, focusing on identifying complex molecular structures, regardless of their chemical composition. This strategy offers a potential method for upcoming space missions to broaden their search.

Up to this point, efforts to detect signs of life, or biosignatures, on other planets have mainly centered on molecules familiar to life on Earth. For example, Mars missions aim to find organic compounds, while future missions to Europa may search for amino acids, imbalances in mirror-image molecules, and unusual carbon isotope ratios, all of which are indicators of life as we know it on Earth.

Radio telescopes

Projects aimed at detecting signals from extraterrestrial civilizations are known as the Search for Extraterrestrial Intelligence (SETI). The first modern SETI experiment, conducted in 1960 by American astronomer Frank Drake, was called Project Ozma. Using a radio telescope, Drake attempted to detect signals from nearby Sun-like stars. In 1961, he introduced the Drake equation, which estimates the number of civilizations in the Milky Way that might be transmitting signals. The equation factors in the frequency of habitable planets, the likelihood of intelligent life developing on those planets, and the duration such societies would transmit signals. However, because many of these factors are unknown, the equation is more valuable for framing the challenges of detecting extraterrestrial intelligence rather than predicting when or if it will be discovered.

In addition to radio signals, SETI searches for light pulses are being conducted at various institutions, including the University of California at Berkeley, Lick Observatory, and Harvard University. These efforts focus on nearby star systems or scan the sky for brief flashes of light that may be caused by extraterrestrial civilizations using high-powered pulsed lasers to signal other worlds. These lasers, if concentrated into a brief pulse, could momentarily outshine the light of their star, making them detectable.

Despite numerous efforts, no confirmed extraterrestrial signals have been found by SETI experiments. Early searches often detected candidate signals, the most famous being the "Wow" signal recorded at Ohio State University in 1977, but subsequent observations failed to detect the signal again. Thus, these detections are not considered solid evidence of extraterrestrial life.

Most SETI projects do not transmit signals themselves, as the vast distances between stars would make two-way communication difficult and time-consuming. Instead, they focus on detecting signals that could be intentionally sent by extraterrestrial civilizations or could result from unintended emissions.

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 Planetary mass spectrometry

Mass spectrometry plays a crucial role in gathering concrete evidence of extraterrestrial life. Instruments like Super Cam, the pyrolysis-gas chromatography-mass spectrometer (Pyrolysis-GC-MS), and laser-based mass spectrometers highlight advancements in space exploration. These tools target biomolecules and biogenic isotope ratios, which can be found in rocks, soil, or icy material. For instance, Super Cam, mounted on the Mars 2020 Perseverance Rover, uses laser-induced breakdown spectroscopy to remotely analyze specimens up to 2-3 meters away.

 The process involves using a high-powered laser to excite atoms in a sample. As these atoms return to their ground state, they emit light, which is captured in a spectral graph to identify the sample's composition. This method works on both biological and non-living materials.

However, despite its strengths, Super Cam has limitations. Its primary goal is to detect small biological signatures, but its spatial accuracy is limited. The laser used is 100 μm thick, which means the analysis of microorganisms (typically 1-2 μm thick) can be hindered by surrounding materials. Additionally, the sensitivity is reduced since only a fraction of the light emitted by the excited sample is captured, as the light disperses in all directions.

When searching for Martian life, two key readings are examined: visual signatures and chemical indicators. Visual signatures, such as mineralogical records, can provide evidence of past biological activity, like coral reefs do on Earth. While no such analog has been found on Mars yet, ongoing missions continue to search. Chemical indicators, such as specific isotope ratios and preserved biological waste, also offer clues about potential past life on the planet.

Scope and Progress

Most evidence available to fuel debates in favor of the existence of extraterrestrial life is a result of chemical analysis; for example, the Curiosity rover used its Chemistry and Mineralogy (CheMin) device to scan and measure the mineral composition of soil and rock samples on Mars finding relatively high concentrations of water, Carbon dioxide and other amorphous materials which are not formed in high temperature environments. Further analysis showed that sediments were deposited in water with low salinity and acidity providing an environment capable of developing life. In 2009, NASA also launched the Kepler space telescope assigned to finding earth-shaped planets with water, an essential compound necessary for life's survival.

The future of finding extraterrestrial life through chemistry is bright, driven by advancements in technology. The James Webb Space Telescope, launched in December 2021, is set to revolutionize our understanding of exoplanet atmospheres. Its sensitive instruments allow for the detection of complex organic molecules, providing vital information behind the search for extraterrestrial life. Furthermore, upcoming missions to icy moons such as Europa aim to explore oceans that may be home to extraterrestrial life proven by chemical analysis of the composition of these oceans.

Conclusion

Extraterrestrial life, or alien life, refers to life forms that originate outside Earth, ranging from simple prokaryotes to advanced civilizations. The study of such life is known as astrobiology, which has gained momentum due to recent advances in astrochemistry and the search for biosignatures—chemical indicators of life found in various celestial environments. The Water-Based Life Hypothesis emphasizes the importance of liquid water in the search for extraterrestrial life, directing missions to Mars and Jupiter's moon Europa, where conditions may be suitable for life.

The extremophiles hypothesis suggests that life could exist in extreme environments, expanding the potential habitats for extraterrestrial life. Detection methods include mass spectrometry, radio telescopes, and chemical analysis, focusing on identifying complex molecular structures and biosignatures associated with life. The Search for Extraterrestrial Intelligence (SETI) employs radio telescopes and light pulse detection to find signals from advanced civilizations, though no confirmed extraterrestrial signals have been found yet.

Future missions, like the James Webb Space Telescope and Mars explorations, aim to enhance our understanding of potential life-supporting environments through chemical analysis. Overall, the quest for extraterrestrial life continues to evolve, driven by technological advancements and a broader understanding of life's possibilities beyond Earth.

In conclusion extraterrestrial life using chemistry has revolutionised our understanding of the universe potential by life. By identifying bio signatures and analysing chemical composition, scientists have made significant progress in detecting life beyond Earth. Search for extraterrestrial life using chemistry has transformed from speculations to data driven endeavour as we continue to push the boundaries of our knowledge VH closer. You answering humanities profound question Are we alone in the universe?

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