Astrobotany
Astrobotany
The Soil of Mars, Venus, and Earth
By Hajrah Khalid Kushtiwala
Astrobotany refers to the study of either plant interactions and plant life in space environments. Earth, the planet we live in, is home to infinite living organisms, whether it be humans’ plants or animals, but lately Venus and Mars both have captured the attention of scientist as the possible place for the survival of living organisms. Specially after it was discovered that Mars has liquid water on its surface, and that Venus has phosphine in its atmosphere. Catering to the possibility of harboring life in the two other planets. (1)[i].
The Composition of Soil on Earth
Mineral matter, organic matter, air and water are the four major components of the Earths soil. Mineral matter consists of small particles, that come from the breakdown of the rocks; on the Earth’s surface, organic matter is something that has carbon, derived from a living thing. And air is the mixture of gasses that together make up the Earth’s atmosphere. The temperature at Earth is optimum for the growth of plants, neither too low neither too high. Therefore, the Earth’s soil and atmosphere support the life of humans or plants.
The Composition of Soil on Mars
The soil of Mars though not entirely similar to that of the earth, is made up of mainly mineral matter with a limited amount of water present, which makes Mars extremely dry. There is no air in the Martian atmosphere, 96% of it being carbon-dioxide. The soil of Mars is red, due to the presence of iron oxides, which is similar to the volcanic soil on Earth. The conclusion that is derived is that plants can in fact grow on the Martian soil, as the essential nutrients may be present in its soil, although the levels may be low, with the help of fertilisers it is possible. “On Earth, a Mars soil stimulant has been used to grow several different food crops. Scientists in the Netherlands have grown ten crop plants, including tomato, peas and rye.” (2)[ii] proving that plants may have a chance to grow on Mars. But there still may be a few things that may hinder this, first being the harsh condition of Mars which may pose challenges to plant growth there. The soil in Mars has too much chlorine, which is harmful for plants. A Martian Garden may need more water, more sunlight, and protection from the low temperature of the planet. Therefore, it is important to recreate similar conditions like that of the Earth to promote healthy growth of plants at Mars.
Figure 3: Martian soil. This collage (from NASA) shows typical, reddish soil from three different sites on Mars. The soils tested by the Spirit rover (A and B), the Viking lander (C) and the Curiosity rover (D) were all similar. The white material revealed by Spirit’s wheels (A and B) are mineral deposits.
Source:https://www.nasa.gov/mission_pages/msl/multimedia/pia16571.html
In the movie The Martian we saw that, by artificially creating such an environment through usage of oxygen, human waste, water, potatoes, Mark Watney was able to grow potatoes in Mars. Many thought this part to be non-scientific and over exaggerated but turns out that as hinted on before too, “Mars soil simulants have been found to hold water better than Earth soil and produce better growth of plant species.” (3)[iii] on one hand no one would want to eat vegetables that grow from human waste as they may have pathogens but, in The Martians case the waste was freeze dried, and the extreme low temperature at Mars help kill those pathogens. Potatoes also need a good amount of sunlight to grow, but Mars has 44% less sun in comparison to Earth, but Watney uses lights most probably grow lights as he was conducting botany experiments from before which helped in the healthy growth of the patatoes. (4)[iv]
Figure 4 : Still from 'The Martian': Mark Watney growing potatoes
Source : https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.kold.com%2Fstory%2F30172643%2Fthe-martian-movie-not-all-that-far-fetched%2F&psig=AOvVaw0ISSauv0mR3J9tdB_CvYOi&ust=1638277950523000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCMj215DTvfQCFQAAAAAdAAAAABAJ
The Composition of Soil on Venus
Venus is a planet which is considered the twin of the Earth as it has a similar size, mass, density and the presence of atmosphere, but its environment is very different than that of the Earth.
Venus is reviewed to be another planet which has the possibility to cater to life. The atmosphere there is very dense, consisting of 96.5% of carbon-dioxide, 3.5% of nitrogen and sulphureous gas. Liquid water was also found to be present there, which now has completely evaporated, enhancing the greenhouse effect and raising the temperatures too much. The pressure is considered 92 times higher than that of Earth, which made life on Venus look impossible. But recently the scientists have found high amounts of phosphine gas, which is only produced through either, as a by-product of metabolic process of living organisms, or by human industrial activities, hinting towards the possible presence of living organism on the planet. Still much investigation is awaited.
Moreover, “In a study conducted by Otroshchenko and Surkov (1974), a model of Venus’s atmosphere was found to possess methane and formaldehyde, both organic molecules, as well as the amino acids glycine and alanine.” (5)[v] which means that there is a possibility that life can exist in certain layers of Venus’s atmosphere.
Conclusion
In conclusion it is fair to say that all three may have the ability too cater to life, specially Earth, but Mars and Venus still require more research to be sure, there is a need to recreate earthy conditions on the other two planets to make growing plants a possibility. And although all the information initially gathered was not promising enough but new discoveries have given hope to growth of plants in the two planets.
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