Refuting Creationism - The 'Smoking Gun' of Life On Early Mars

Daybreak at the Gale Crater on Mars where organic material was found.

Photo: NASA/JPL-Caltech/MSSS

Mount Sharp in the centre of Gale Crater where organic material was found by Curiosity Rover

Photo: NASA/JPL-Caltech/MSSS

Organic material from Mars reveals the likely origin of life’s building blocks – University of Copenhagen

Those creationists who understand the implication for their superstition will be dreading the discovery of evidence of life elsewhere in the Universe, so to have it discovered on our neighbouring planet in the solar system will be doubly worrying for them.

The reason for this fear is that they have invested so much of their argument for a magic creator in a proclaimed vast unlikelihood to the point of impossibility, of inorganic elements forming themselves into organic molecules - the basic building blocks of living systems. Combine that with their false dichotomy fallacy which says the only possibility is that their locally popular god did it, and you have the basis of the creationist argument from 'impossible' abiogenesis.

So, discovering that it happened on Mars shows that not only is it not impossible, nor even highly unlikely, but it happens when the conditions are right as easily as mixing hydrochloric acid and sodium hydroxide gives table salt (\(\small \text{HCl} + \text{NaOH} \rightarrow \text{NaCl} + \text{H}_2\text{O}\)). No magic is needed, and it can all be accounted for with the basic laws of chemistry and physics.

Of course, those creationists who have been preparing for this eventuality will simply declare that their unproven magic creator did it there too. Sadly for them this just leaves them to explain why a supposedly omniscient, super-intelligent creator would create the building blocks for organic life on a planet so singularly unsuitable for living systems as Mars?

What would be the consequences for creationism if the building blocks for living systems were found on Mars? The discovery of the building blocks for living systems on Mars would have significant implications for various perspectives on creationism, particularly in how they interpret the origin and distribution of life. Here are some potential consequences:

1. Young Earth Creationism (YEC):
   • Challenge to Beliefs: YEC proponents typically believe that Earth and life were created relatively recently (within the last 10,000 years) and uniquely by divine action. Finding the building blocks of life on Mars could challenge the view that Earth is the exclusive site of creation.
   • Reinterpretation of Evidence: YEC advocates might argue that these building blocks were either created by God on Mars or arrived there via panspermia from Earth, thus maintaining that life is still unique to God's creation on Earth.
2. Old Earth Creationism (OEC):
   • Expanded View of Creation: OEC proponents, who accept the scientific consensus on the age of the Earth but believe that life was created by God over billions of years, might see the discovery as evidence of a broader scope of divine creation. They might argue that God created life or its precursors not only on Earth but also elsewhere in the universe.
   • Integration with Science: OEC might integrate this discovery into their worldview, suggesting that the building blocks of life are a part of God's creative design and could be expected to be found throughout the universe.
3. Intelligent Design (ID):
   • Support for Design Hypothesis: Proponents of ID, who argue that life is too complex to have arisen without an intelligent cause, might interpret the discovery of life's building blocks on Mars as further evidence of a purposeful design by an intelligent entity. They could argue that life's building blocks being present on multiple planets supports the idea of a designed and purposeful universe.
   • New Arguments for Design: ID proponents might develop new arguments or refine existing ones to account for the distribution of life's building blocks, using this discovery to bolster their claims about the prevalence of design in the universe.
4. Progressive Creationism:
   • Alignment with Existing Beliefs: Progressive creationists, who believe that God intervened at various points to create new forms of life, might view the presence of life's building blocks on Mars as part of God's creative process. They could argue that these building blocks were placed there as part of a divine plan that includes multiple planets.
   • Divine Purpose and Planning: This perspective might emphasize the idea that God's creative work extends beyond Earth, highlighting a divine purpose that includes the entire cosmos.
5. Theistic Evolution:
   • Compatibility with Science: Theistic evolutionists, who believe that God works through the process of evolution, would likely see the discovery as consistent with their view that the natural processes observed by science are the means through which God creates life. They might argue that finding life's building blocks on Mars is evidence of the widespread potential for life in the universe, as part of God's natural order.
   • Reinforcement of Universal Creation: This perspective might interpret the discovery as reinforcing the idea that life is a fundamental aspect of God's creation and that the potential for life exists throughout the universe.

In summary, while the discovery of the building blocks for living systems on Mars would challenge some specific creationist views, it would also offer an opportunity for reinterpretation and integration within other creationist frameworks. The response would vary depending on the particular beliefs and theological interpretations of each creationist perspective.

Is it the act of an intelligent creator to create the building blocks of life on a planet such as Mars which is singularly unsuitable for life as we know it to exist on?

The question of whether it is the act of an intelligent creator to create the building blocks of life on a planet such as Mars, which is currently unsuitable for life as we know it, can be approached from various perspectives, each influenced by different theological, philosophical, and scientific viewpoints. Here are several possible interpretations:

1. Testing Grounds for Life:
   • Perspective: Some might argue that an intelligent creator could place the building blocks of life on Mars as a kind of experiment or preparation for life that might develop under different conditions.
   • Rationale: This could be seen as a way for the creator to ensure that the building blocks of life are universally distributed, giving life the potential to arise in diverse environments, possibly under conditions that we do not yet fully understand or recognize.
2. Part of a Larger Plan:
   • Perspective: From a theological standpoint, the presence of life's building blocks on Mars might be interpreted as part of a grander divine plan that extends beyond our current understanding of habitability.
   • Rationale: Proponents of this view might suggest that Mars could have been more suitable for life in the past or could become suitable again in the future, or that these building blocks serve a purpose in ways that are not immediately apparent to us.
3. Evidence of Universal Design:
   • Perspective: Some advocates of intelligent design or creationism might see the widespread distribution of life's building blocks as evidence of a purposeful design by an intelligent creator.
   • Rationale: This perspective might hold that the creator designed the universe with the potential for life in various forms, and that the presence of these building blocks on Mars reflects the creator's intention for life to potentially arise or be studied in different environments.
4. Scientific Explanation with Theistic Interpretation:
   • Perspective: Theistic evolutionists or those who integrate science and faith might view the presence of life's building blocks on Mars as a natural consequence of the laws and processes set in motion by a creator.
   • Rationale: They might argue that life's building blocks are naturally distributed by processes such as asteroid impacts, comets, or interplanetary dust, which are part of the universe's design. This distribution could be seen as evidence of a universe finely tuned to produce and support life.
5. Philosophical and Existential Considerations:
   • Perspective: From a philosophical standpoint, the discovery might provoke questions about the nature of life and the conditions necessary for it, expanding our understanding of what it means for a planet to be "suitable" for life.
   • Rationale: This could lead to a broader consideration of life as a phenomenon that might not be confined to Earth-like conditions, suggesting that the creator's intentions might encompass a wider variety of life forms and habitats than we currently imagine.

In conclusion, the interpretation of an intelligent creator placing the building blocks of life on Mars depends heavily on one's worldview. Some may see it as a sign of a larger, incomprehensible plan or an evidence of a designed and purposeful universe, while others may integrate it into a scientific framework that does not necessarily require direct divine intervention. The suitability of Mars for life as we know it might be less relevant in these discussions than the broader implications of finding life's precursors beyond Earth.

In other words, it must be intelligently designed because it was designed by an intelligent designer? Is that a rational argument?

The argument that "it must be intelligently designed because it was designed by an intelligent designer" is an example of a circular argument. In logic, a circular argument is one in which the conclusion is assumed in one of the premises. Here's a breakdown of why this is considered circular and why it may not be rational:

Structure of the Argument

1. Premise: The building blocks of life on Mars are intelligently designed.
2. Conclusion: Therefore, they were designed by an intelligent designer.

In this structure, the premise assumes what it is trying to prove (i.e., that the building blocks are intelligently designed).

Rational Evaluation

1. Begging the Question: This argument begs the question because it assumes the conclusion within the premise. For an argument to be rational and persuasive, it should provide independent support for its conclusion rather than assume it from the outset.
2. Lack of Independent Evidence: For the argument to be rational, it would need to provide independent evidence or reasoning to support the claim that the building blocks of life on Mars were designed by an intelligent designer. This might include evidence of complexity that cannot be explained by natural processes, specific patterns that indicate design, or other empirical data that suggest intelligent intervention.
3. Alternative Explanations: A rational argument should also consider and address alternative explanations. In this case, it should examine naturalistic explanations for the presence of life's building blocks on Mars, such as abiogenesis, panspermia, or chemical processes that could occur without intelligent intervention.

How to Make a Rational Argument for Intelligent Design

To construct a more rational argument for the intelligent design of the building blocks of life on Mars, one could:

1. Present Empirical Evidence: Provide specific examples of features or characteristics of the building blocks that strongly suggest design over natural processes. This might include irreducible complexity or specified complexity that natural processes cannot easily account for.
2. Demonstrate the Inadequacy of Natural Explanations: Show why natural processes (e.g., chemical evolution, random molecular interactions) are insufficient to account for the building blocks' presence and complexity.
3. Use Inference to the Best Explanation: Argue that intelligent design is the best explanation among competing hypotheses based on the evidence available. This involves comparing the explanatory power and scope of intelligent design versus naturalistic explanations.

Example of a Rational Argument

An example of a more rational argument might look like this:

1. Premise 1: The building blocks of life exhibit patterns and complexities (e.g., molecular structures, chirality) that are highly unlikely to arise through known natural processes.
2. Premise 2: Such patterns and complexities are best explained by the action of an intelligent cause, as they resemble known products of intelligence (e.g., human-engineered molecules).
3. Conclusion: Therefore, it is reasonable to infer that the building blocks of life on Mars were designed by an intelligent cause.

This argument provides premises that can be independently evaluated and supports the conclusion with evidence rather than assuming it.

In summary, the assertion that "it must be intelligently designed because it was designed by an intelligent designer" is circular and not rational by itself. A rational argument would need to provide independent evidence and reasoning to support the conclusion of intelligent design.

Wouldn't one need to provide empirical evidence a priori that an entity capable of designing anything actually exists, otherwise is should be pared away using Occam's Razor.

Yes, according to principles of logical reasoning and empirical investigation, providing empirical evidence that an entity capable of designing anything exists is essential for the argument of intelligent design to be robust. Additionally, Occam's Razor, which favors simpler explanations with fewer assumptions, would suggest that without such evidence, the hypothesis of an intelligent designer should be set aside in favor of naturalistic explanations that do not require the introduction of additional, unproven entities. Here’s a more detailed examination:

Empirical Evidence of an Intelligent Designer

To argue convincingly for intelligent design, one must:

1. Demonstrate the Existence of the Designer: Present empirical evidence or a logically coherent argument that an intelligent designer exists. This might include evidence from cosmology, biology, or other fields that point to the presence of a designing intelligence.
2. Show Capability and Action: Provide evidence that this designer has the capability to create life and has acted to do so. This would involve showing that the designer has the necessary attributes (such as intelligence, power, and intention) and has indeed performed acts of creation or design.

Application of Occam's Razor

Occam's Razor is a heuristic tool that helps to eliminate unnecessary assumptions:

1. Naturalistic Explanations: If naturalistic explanations (such as abiogenesis, chemical evolution, or panspermia) can account for the presence of life’s building blocks without invoking an intelligent designer, then these explanations are generally preferred. They do not require assuming the existence of an additional entity.
2. Parsimony: The principle of parsimony suggests that we should not multiply entities beyond necessity. Therefore, if the existence of an intelligent designer is not empirically demonstrated and is not necessary to explain the phenomenon, it should be excluded from the explanation.

Example of Applying Occam's Razor

Consider two hypotheses to explain the presence of life’s building blocks on Mars:

1. Naturalistic Hypothesis: The building blocks of life are the result of chemical processes that occur naturally in the universe, possibly delivered via meteorites or formed through planetary processes.
2. Intelligent Design Hypothesis: An intelligent designer placed the building blocks of life on Mars.

Evaluation:

• Naturalistic Hypothesis: This requires the assumption that natural chemical processes can produce life’s building blocks, which is supported by scientific evidence and does not require additional assumptions about the existence of an intelligent entity.
• Intelligent Design Hypothesis: This requires the assumption of an intelligent designer, whose existence and capabilities must be independently verified. Without empirical evidence of such a designer, this hypothesis adds an unnecessary layer of complexity.

Using Occam’s Razor, the naturalistic hypothesis is preferred because it is simpler and relies on fewer assumptions.

Conclusion

For the intelligent design hypothesis to be considered rational and preferable:

1. Empirical Evidence Required: There must be empirical evidence for the existence of an intelligent designer capable of creating life’s building blocks.
2. Simplicity and Parsimony: In the absence of such evidence, the hypothesis should be set aside in favor of simpler, naturalistic explanations that do not require additional, unproven entities.

Therefore, without prior empirical evidence of an intelligent designer, the hypothesis of intelligent design is less favored by Occam's Razor compared to naturalistic explanations.

But find it they have, or at least the 'smoking gun' that shows the basic building blocks for organic molecules existed on the early Mars. How the team of scientists from the University of Copenhagen did so is the subject of an open access research aper in Nature Geoscience and a detailed news release from Copenhagen University.

Before continuing, any creationists preparing to dismiss this with their traditional 'God did it! parrot squawk would be well advided to read the panel on the right, especially the final section on a priori evidence and the use of Occam's Razor.

Organic material from Mars reveals the likely origin of life’s building blocks

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Mars Two samples from Mars together deliver the "smoking gun" in a new study showing the origin of Martian organic material. The study presents solid evidence for a prediction made over a decade ago by University of Copenhagen researchers that could be key to understanding how organic molecules, the foundation of life, were first formed here on Earth.

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In a meteor crater on the red planet, a solitary robot is moving about. Right now it is probably collecting soil samples with a drill and a robotic arm, as it has quite a habit of doing. NASA's Curiosity rover has been active on Mars as the extended arm of science for nearly 12 years, and it continues to make discoveries that surprise and challenge scientists' understanding of both Mars and our own world here on Earth.

Facts: Organic material

The sample found on Mars contains deposits of so-called organic material.

To laymen this may sound more exciting than it is. Organic material in a chemical context does not necessarily mean something living, as one might normally think. The term covers molecules that contain carbon and at least one other element and can easily exist without life. These molecules are rather the building blocks of life.

Most recently, the discovery of sedimentary organic material with particular properties has had many researchers scratching their heads. The properties of these carbon-based materials, in particular the ratio of its carbon isotopes, surprised researchers.

Organic materials with such properties, if found on Earth, would typically be a sign of microorganisms, but they can also be the result of non-biological, chemical processes. The find obviously had researchers scrambling for a clear answer, but nothing seemed to fit.

However, for the research collaboration behind a study published in Nature Geoscience, there has been little hair scratching and much enthusiasm.

In fact, the discovery on Mars provided the missing piece that made everything fall into place for this group of researchers from the University of Copenhagen and the Tokyo Institute of Technology.

As co-author and chemistry professor Matthew Johnson puts it, it is "the smoking gun" needed to confirm a decade old theory of his about so-called photolysis in Mars' atmosphere.

With the Curiosity sample, the new research is able to prove with reasonable certainty that the Sun broke down \(\small\ce{CO2}\) in the Martian atmosphere billions of years ago - as the old theory predicted. And that the resulting carbon monoxide gradually reacted with other chemicals in the atmosphere synthesizing complex molecules – and thus providing Mars with organic materials.

Facts: What is Photolysis

Photolysis means that the Sun's UV rays provide molecules with energy to perform a chemical transformation. According to the research this happened in the Martian atmosphere, where 20% of \(\small\ce{CO2}\) molecules there were split into oxygen and carbon monoxide.

In earlier research, Johnson and colleagues showed that carbon dioxide containing the carbon-12 isotope is photolysed more quickly than the heavier isotope carbon-13. Over time, \(\small\ce{CO}\) is produced that is depleted in \(\small\ce{^13C}\), and \(\small\ce{^13C}\) builds up in the remaining \(\small\ce{CO2}\). This results in so-called isotopic enrichment in \(\small\ce{CO2}\) and depletion in \(\small\ce{CO}\), like mirror images or each other or the two halves of a broken plate.

It is the fractionation ratio in carbon, which serves as evidence of photolysis in the two samples from Mars.

Such carbon-based complex molecules are the prerequisite of life, the building blocks of life one might say. So, this it is a bit like the old debate about which came first, the chicken or the egg. We show that the organic material found on Mars has been formed through atmospheric photochemical reactions - without life that is. This is the 'egg', a prerequisite of life. It still remains to be shown whether or not this organic material resulted in life on the Red Planet. Additionally because Earth, Mars and Venus had very similar \(\small\ce{CO2}\) rich atmospheres long ago when this photolysis took place, it can also prove important for our understanding of how life began on Earth.

Professor Matthew Johnson, co-author
Department of Chemistry
University of Copenhagen, Copenhagen, Denmark.

Two pieces separated by 50 Million Kilometers – one puzzle solved

12 years ago Johnson and two colleagues used simulations based on quantum mechanics to determine what happens when a \(\small\ce{CO2}\) rich atmosphere is exposed to the UV-light of the Sun, in a process known as photolysis.

Facts: Isotopes Have Different Weights

Isotopes are variants of the same element that have different weights because the nucleus contains more or fewer neutrons.

Carbon has two stable isotopes - Normally, about 99% of carbon has 6 protons and 6 neutrons in its nucleus (\(\small\ce{^12C}\)). About 1% has 6 protons and 7 neutrons instead (\(\small\ce{^13C}\)). The ratio can serve as a chemical fingerprint revealing what reactions the carbon has undergone.

Photolysis favors carbon-12, and a high concentration of the isotope can therefore indicate this process.

Basically, on Mars around 20% of the \(\small\ce{CO2}\) is split into oxygen and carbon monoxide. But carbon has two stable isotopes: carbon-12 and carbon-13. Usually they are present in a ratio of one carbon-13 for every 99 carbon-12. However, photolysis works faster for the lighter carbon-12, so the carbon monoxide produced by photolysis has less carbon-13 (is depleted), and the left over \(\small\ce{CO2}\) has more (is enriched). Because of this, Johnson and his colleagues were able to make very precise predictions of the ratio of carbon isotopes after photolysis. And this gave them two distinctive fingerprints to look for. One of these was identified in a different Martian sample, years ago.

We actually have a piece of Mars here on Earth, which was knocked off that planet by a meteorite, and then became one itself, when it landed here on Earth. This meteorite, called Allan Hills 84001 for the place in Antarctica where it was found, contains carbonate minerals that form from \(\small\ce{CO2}\) in the atmosphere. The smoking gun here is that the ratio of carbon isotopes in it exactly matches our predictions in the quantum chemical simulations, but there was a missing piece in the puzzle. We were missing the other product of this chemical process to confirm the theory, and that's what we've now obtained.

Professor Matthew Johnson.

Extra Info: The Famous Mars Meteorite

The discovery of organic sediments on Mars with a low ratio of carbon-13 completes the puzzle of empirical evidence for the photolysis theory, since researchers already found the other part of that puzzle years ago in the famous meteorite, Allan Hills 84001. The meteorite contains carbonate with a heightened concentration of heavy carbon 13 isotopes.

Discovered in Antarctica 40 years ago by Roberta Score, the meteorite is believed to originate from the Red Planet and became particularly well known because it contains some deposits that led NASA researchers to announce in 1996 that they believed they had found traces of microscopic fossils of bacteria from Mars.

Today, the consensus is that these deposits are abiotic - that is, stemming from non-biological processes.

The carbon in the Allan Hills meteorite is enriched in carbon-13, which makes it the mirror image of the depletion in carbon-13 that has now been measured in the organic material found by Curiousity on Mars.

The new study has thus linked data from two samples, which researchers believe have the same origin in Mars' childhood but were found more than 50 million kilometers apart.

There is no other way to explain both the carbon-13 depletion in the organic material and the enrichment in the Martian meteorite, both relative to the composition of volcanic \(\small\ce{CO2}\) emitted on Mars, which has a constant composition, similar as for Earth’s volcanos, and serves as a baseline.

Professor Matthew Johnson.

Hope to find the same evidence on Earth

Because the organic material contains this isotopic “fingerprint” of where it came from, researchers are able to trace the source of the carbon in the organic material to the carbon monoxide formed by photolysis in the atmosphere. But this also reveals a lot about what happened to it in between.

Facts: The oxygen painted Mars red

Photolysis of a \(\small\ce{CO2}\) molecule yields carbon monoxide (\(\small\ce{CO}\)) and an oxygen atom (\(\small\ce{O}\)). On Mars, only carbon monoxide remains, which is transformed into the organic material found by the Curiosity rover.

But where the oxygen has gone is also no secret. The oxygen combines into \(\small\ce{O2}\), which interacts with iron on Mars' surface. The Red Planet is rust red due to oxidized iron.

This shows that carbon monoxide is the starting point for the synthesis of organic molecules in these kinds of atmospheres. So we have an important conclusion about the origin of life’s building blocks. Although so far only on Mars.

Professor Matthew Johnson.

Researchers hope to find the same isotopic evidence on Earth, but this has yet to happen, and it could be a much bigger challenge because our geological development has changed the surface significantly compared to Mars, Johnson explains.

It is reasonable to assume that the photolysis of \(\small\ce{CO2}\) was also a prerequisite for the emergence of life here on Earth, in all its complexity. But we have not yet found this “smoking gun” material here on Earth to prove that the process took place. Perhaps because Earth's surface is much more alive, geologically and literally, and therefore constantly changing. But it is a big step that we have now found it on Mars, from a time when the two planets were very similar.

Professor Matthew Johnson.

Extra info: Mars, Earth, and Venus Had the Same Atmosphere

According to researchers, Earth had approximately the same atmosphere as our neighboring planets Mars and Venus billions of years ago.

When the early planets Venus, Earth, and Mars eventually formed solid surfaces, researchers believe they began to release large amounts of \(\small\ce{CO2}\) from extreme volcanic activity. That's how they formed their first atmospheres with large concentrations of the gas. Oxygen had not yet become part of the atmosphere; this happened later on Earth, after the emergence of life.

The photolysis theory states that UV rays from the sun then start a chain of chemical reactions. A chain that starts with the breakdown of \(\small\ce{CO2}\) into carbon monoxide, which is the building block for a multitude of other chemical compounds.

Thus, with the help of the Sun, the foundation for the many carbon compounds and complex molecules we have today was formed - in the case of Earth, the foundation for life.

Since then the fate of the three planets has been significantly different. Earth's carbon dioxide reacted with our large amount of surface water and much of it deposited over time as carbonate rocks like limestone, leaving the atmosphere dominated by nitrogen, as we have today. Life arose, and microorganisms produced oxygen, which, among other things, created our ozone layer, while Mars and Venus still have very \(\small\ce{CO2}\)-dominant atmospheres today.

Professor Matthew Johnson.

Today, Venus has a very dense and toxic atmosphere primarily of \(\small\ce{CO2}\) which gives it a surface temperature of around 450 degrees Celsius. On Mars, the atmosphere has become much thinner compared to Earth's, and has left a desert landscape.

About the new study:

The study is published in Nature Geoscience and has just appeared in the journal's June issue. The following researchers have contributed to the new study:

From the Department of Chemistry at the University of Copenhagen:

Matthew S. Johnson and Johan A. Schmidt

From the Tokyo Institute of Technology:

Yuichiro Ueno, Xiaofeng Zang, Alexis Gilbert, Hiroyuki Kurokawa and Tomohiro Usui

From the University of Tokyo and the Royal Belgian Institute of Space Aeronomy:

Shohei Aoki

Abstract
Organic matter found in early Martian sediment may yield clues to the planet’s environmental conditions, prebiotic chemistry and habitability, but its origin remains unclear. Strong (\(\small\ce{^13C}\)) depletion in sedimentary organic matter at Gale crater was recently detected by the Curiosity rover. Although this enigmatic depletion remains debated, if correct, a mechanism to cause such strong (\(\small\ce{^13C}\)) depletion is required. Here we show from \(\small\ce{CO2}\) photolysis experiments and theoretical considerations that solar ultraviolet photolysis of \(\small\ce{CO2}\) in a reducing atmosphere can yield strongly (\(\small\ce{^13C}\))-depleted \(\small\ce{CO}\). We suggest that atmospheric synthesis of organic compounds from photolysis-produced \(\small\ce{CO}\) is a plausible mechanism to explain the source of isotopically depleted organic matter in early Martian sediments. Furthermore, this mechanism could explain (\(\small\ce{^13C}\)) enrichment of early Martian \(\small\ce{CO2}\) without requiring long-term carbon escape into space. A mass balance model calculation using our estimated isotopic fractionation factor indicates the conversion of approximately 20% of volcanic \(\small\ce{CO2}\) emissions on early Mars into organics via \(\small\ce{CO}\), consistent with the available data for carbon isotopes of carbonate. Although alternative pathways for organic compound production have been proposed, our findings suggest that considerable amounts of organic matter may have been synthesized from \(\small\ce{CO}\) in a reducing early Martian atmosphere and deposited in sediments.

Main
Organic matter on Mars is important for understanding the habitability of the planet, prebiotic chemistry and the search for life in the universe. A series of analyses using the Sample Analysis at Mars (SAM) instrument on board the Curiosity rover discovered and confirmed that there is sedimentary organic matter preserved in circa 3.5-billion-year-old water-lain sediment at the Gale crater on Mars^1,2,3,4. Furthermore, recent analysis of SAM data revealed that this organic matter has an enigmatic stable carbon isotope composition \(\small\delta^{13}\text{C}_{\text{VPDB}}\) values [\(\small\equiv 1000 \left( \left( \frac{^{13}\text{C}}{^{12}\text{C}} \right)_{\text{sample}} \bigg/ \left( \frac{^{13}\text{C}}{^{12}\text{C}} \right)_{\text{VPDB}} - 1 \right)\)] from −137‰ to +22‰) (refs. ^5,6,7,8,9), some of which are strongly depleted in (\(\small\ce{^13C}\)) to an extent never found in Earth’s sedimentary rocks⁶. Although some in situ isotope analyses have been contaminated by a terrestrial material mixed into the SAM instrument^{3,4,5,6,7,8,9,10}, even taking this into account, it appears that several early Martian sediments contain organic carbon with \(\small\delta^{13}\text{C}_{\text{VPDB}}\) values at least less than −70‰ (ref. 10) and possibly down to −137 ± 8‰ (refs. ^6,8) (Supplementary Note provide details). The origin of this strong (\(\small\ce{^13C}\)) depletion remains uncertain but may arise from cosmic, biological or abiological processes^4,5,6. Interplanetary dust may include carbon particles with strong (\(\small\ce{^13C}\)) depletion¹¹ and might have accumulated in the sediment⁶, although the signal from outside the solar system would easily be diluted if indigenous carbon sources were available from biotic or abiotic processes on Mars. Some biological metabolic pathways, particularly methanotrophy, can induce large isotopic fractionation, but it is difficult to explain \(\small\delta^{13}\text{C}_{\text{VPDB}}\) < −100‰ in light of known biological fractionation factors⁶. In principle, the organic matter in early Martian sediment could be due to abiotic reactions such as Fischer–Tropsch-type reactions^2,6 or electro-chemical reduction of \(\small\ce{CO2}\)^5,6,12, but none of these mechanisms are known to produce the large carbon isotopic fractionations observed (ref. ⁶ and references therein). An alternative source of organic matter is atmospheric synthesis^{5,6,13,14,15,16}. Theoretically, atmospheric photochemistry under the appropriate conditions may produce a large carbon isotopic fractionation^14,15,17. Ab initio calculations using time-dependent wavepacket propagation of the absorption cross sections of \(\small\ce{CO2}\) isotopologues¹⁷ predicted that solar UV photolysis of \(\small\ce{CO2}\) yields strongly (\(\small\ce{^13C}\))-depleted \(\small\ce{CO}\), potentially lower than −100‰ (Fig. 1). However, the large isotope effect has not yet been verified by laboratory experiment^17,18.

Fig. 1: Wavelength-dependent isotopic fractionation of \(\small\ce{CO2}\) photolysis.

Preferential dissociation of \(\small\ce{^12CO2}\) against \(\small\ce{^13CO2}\) is expected in a wavelength region from 170 nm to 200 nm, which is responsible for solar UV photolysis of \(\small\ce{CO2}\). a, Actinic UV spectra. Red: solar spectrum from ref. ⁴³. Blue: calculated spectrum at 30 km altitude (alt.) of model early Mars (10 mbar \(\small\ce{CO2}\) at surface) (Methods). Black: measured UV spectrum of the high pressure Xe lamp used in the laboratory experiment (Methods). b, Calculated absorption cross sections of \(\small\ce{^12CO2}\) (black) and \(\small\ce{^13CO2}\) (orange) at 295 K from ref. ¹⁷. c, Calculated isotope effect (1,000 ln α₁) as a function of wavelength for the 295 K absorption spectra. Results were averaged over a 1 nm (black) and 5 nm (red) windows. Oxygen isotopic fractionation and its implications for Mars atmosphere were given elsewhere¹⁷.

Explaining the origin of the strong (\(\small\ce{^13C}\)) depletion becomes even more problematic considering that the early carbonate precipitate in the approximately 4 billion years old (4 Ga) Martian meteorite ALH 84001 was rather enriched in (\(\small\ce{^13C}\)) (up to +55‰) (refs. ^19,20,21) relative to Mars mantle carbon (\(\small\delta^{13}\text{C}_{\text{VPDB}}\) = −25 ± 5‰) (ref. ²²) (Methods). For present-day Mars, the (\(\small\ce{^13C}\)) enrichment of atmospheric \(\small\ce{CO2}\) (\(\small\delta^{13}\text{C}_{\text{VPDB}}\) = +46 ± 4‰) (ref. ²³) has been thought to result from carbon escape into space^14,24,25 through the 4-billion-year history of Mars. However, even assuming the 4 Ga carbonate were in equilibrium with the atmospheric \(\small\ce{CO2}\), its \(\small\delta^{13}\text{C}_{\text{VPDB}}\) value should have already been enriched in (\(\small\ce{^13C}\)) ( + 20 ± 10‰) at that time (Methods provide details). It is problematic to understand whether several hundred million years after formation of Martian atmosphere, enough time has passed to create the (\(\small\ce{^13C}\)) enrichment of \(\small\ce{CO2}\) only via carbon escape into space^14,25. Furthermore, based on geomagnetic observations²⁶, early Mars probably had a geomagnetic field before 4 Ga. The geomagnetic field on early Mars could have prevented solar winds from interacting with ions in the upper atmosphere and shielded the neutral atmosphere from sputtering loss. Robust magnetic shielding of the atmosphere before 4 Ga is supported by observations of low-fractionated atmospheric argon (\(\small\ce{^38Ar}\)/\(\small\ce{^36Ar}\)) and nitrogen (\(\small\ce{^15N}\)/\(\small\ce{^14N}\)) recorded in ALH 84001^27,28. Therefore, (\(\small\ce{^13C}\)) enrichment of Mars’ early carbonate is still enigmatic and may have been caused by other fractionation processes^14,25,29. Here we present a new laboratory experiment and quantum theoretical and model calculations that demonstrate how solar UV photolysis of \(\small\ce{CO2}\) and subsequent organic synthesis from atmospheric \(\small\ce{CO}\) could explain both the strong (\(\small\ce{^13C}\)) depletion in the organic matter and the (\(\small\ce{^13C}\)) enrichment of \(\small\ce{CO2}\). A previous \(\small\ce{CO2}\) photolysis experiment¹⁸ was conducted using an ultraviolet light source with a confined wavelength at 184.9 nm, which does not simulate the actual fractionation that occurs in a planetary atmosphere where the expected isotope effect depends on the broad distribution of wavelengths of the actinic UV flux¹⁷ (Fig. 1). Therefore, we used a solar-like broadband UV source for \(\small\ce{CO2}\) photolysis (Fig. 1a) to confirm the large carbon isotope effect and quantify the actual fractionation factor associated with \(\small\ce{CO2}\) photolysis in the early Martian atmospheres.

It's going to be interesting watching creationists trying to ignore the evidence, that this finding establishes, that the natural creation of building blocks of life is not impossible nor even highly unlikely, but happens as readily as any other chemical reaction in the presense of inorganic molecules that were abundant on early Earth, as on early Mars. No god-magic required.

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