Life on Mars an ‘unsolved puzzle’

The question of how research should be directed to definitively prove whether life once existed on Mars or if traces of life still exist beneath the planet's surface remains an unsolved mystery. This is especially intriguing as scientific studies have now confirmed the presence of water on Mars.

However, this water exists not in liquid form but as ice beneath the surface. This ice is referred to as permafrost, meaning water mixed with sediment has remained frozen for an extended period.

This discovery has made Mars a challenging and fascinating subject for scientists over the past several decades. The truth is that wherever there is water, the possibility of life becomes inevitable. However, no concrete evidence has yet been found on Mars to confirm whether life once existed there or still does.

Years of research have established that rivers likely flowed on Mars in the past, as images captured by satellites orbiting the planet show surface features resembling river channels. Studies suggest that these structures were formed when rivers dried up around 3.5 billion years ago. Therefore, it would be incorrect to dismiss the possibility of life ever existing on Mars.

This evidence suggests that Mars likely had a life-supporting environment on its surface during past 500 million years. To gain deeper insights into this, numerous missions have been deployed to the Martian surface over the past few decades. In the early years, between 1975 and 2008, missions to Mars included the Viking landers and the Phoenix Lander. Later, the Curiosity Rover was launched in 2011, followed by the Perseverance Rover in 2020. These missions have detected organic matter in the analysis of rock and soil samples from the Martian surface. This discovery has significantly strengthened the possibility that life may have existed on Mars in ancient times.

Dr. Arif Hussain Ansari, a scientist at the Birbal Sahni Institute of Palaeosciences (BSIP), Lucknow, has offered fresh insights into this intriguing subject. In his review, he has proposed specific directions for studies related to Mars, aiming to accelerate the search for life on the planet. He explained that when scientists embark on the search for life on any planet, they typically focus on two key objectives. First, they investigate the presence of water. If water is found, the next step is to search for organic matter, as it serves as a critical indicator of the potential presence or absence of life. This raises the question: does the presence of organic matter definitively indicate the existence of life? To some extent, this is true. However, studies suggest that the presence of organic matter alone does not provide conclusive evidence of life.

Dr. Ansari explained that complex organic compounds, such as amino acids, polysaccharides, and phospholipids, play a crucial role in the formation of biological structures and are primarily produced through biological processes. However, some simple (light) organic compounds and even certain complex organic matters can also be formed through abiotic processes. In this context, it becomes challenging to determine whether the organic matter discovered on Mars was formed by biotic or abiotic processes.

Organic matter is found throughout the universe, and it continues to reach the surfaces of various planets through cosmic dust and meteorites. Additionally, in geochemical processes occurring at high temperatures within planets, carbon dioxide and hydrogen combine to form organic compounds. Therefore, it becomes crucial to determine the processes by which the organic substances found in Martian samples were formed—an ongoing challenge for scientists. Investigations conducted during various missions to Mars have also revealed that the organic substances discovered on the planet may have another potential source.

This potential source could be traces of organic solvents carried by the instruments sent to Mars as part of the missions. These solvents were used in analyzing Martian samples through the gas chromatography method. In 2020, the Perseverance rover used Deep Ultraviolet Spectroscopy to investigate organic compounds on Mars. This method suggests that the possibility of contamination from organic substances related to the instruments is minimal. The analysis revealed the presence of organic compounds in Martian samples, such as benzene and naphthalene.

These studies confirm the presence of some complex organic compounds on Mars. To better understand the source of these organic substances, another mission, called the ExoMars mission, will soon be sent to Mars. As part of this mission, an instrument will be deployed to collect samples by drilling up to a depth of 2 meters beneath the surface, where it will be analyzed.

Dr. Ansari believes that a targeted method of investigation should be developed to yield accurate results. Since the lifespan of Mars missions and the capacity to analyze Martian soil samples are very limited, it is crucial to first identify samples on Mars that are likely to have preserved organic substances for an extended period. Additionally, it is essential to have a prior understanding of the types of organic substances that might be found in such samples. For example, hydrothermal regions on Mars, where large deposits of silica are found, are considered promising targets for the search for organic matter related to life. However, very little research has been conducted on this subject so far.

Dr. Ansari believes that the study of organic compounds in samples of various minerals, soil, sediments, and stones found in cold desert regions on Earth, similar to Mars, and the hydrothermal deposits they contain, along with understanding their biological and inorganic sources, could be instrumental in developing such a method. The knowledge gained from such studies will be crucial for developing strategies and tools to investigate the potential for life on Mars, as well as on other similar planets, moons, and meteorites in the future.

by,

P.D.Saxena

credit:

frontiers| Frontiers in Astronomy and Space Sciences

TYPE Review PUBLISHED 10 February 2023 001 10.3389/fspas 2023.1075052

Detection of organic matter on Mars, results from various Mars missions, challenges, and future strategy: A review

Arif H. Ansari

Birbal Sahni Institute of Palaeosciences Lucknow, India