With ongoing man-made and natural calamities hitting our home, Earth, scientists are working on several projects that aim to find other planets suitable for life. Mars, for example, probably had liquid water on its surface and could one day become our new home!
Two Researchers, Giacomo Certini and his colleague Riccardo Scalenghe, at the Department of Plant, Soil, and Environmental Science, University of Palermo, Italy, recently published a study in the Planetary and Space Science journal, claiming that the surfaces of Venus, Mars, and the Moon appear to be suitable for agriculture.
On Earth, five factors work together to form soil: the parent rock, climate, topography, time, and biota—the organisms in a region such as its flora and fauna. This last factor is still subject to debate among scientists: “Most scientists think that biota is necessary to produce soil,” Certini said, “Other scientists, me included, believe that important parts of our own planet, such as the Dry Valleys of Antarctica or the Atacama Desert of Chile, have virtually life-free soils. They demonstrate that soil formation does not require biota”.
The researchers claim that classifying a material as soil depends on weathering. According to them, a soil is any weathered veneer of a planetary surface that retains information about its climatic and geochemical history. On Venus, Mars and the Moon, weathering occurs in different ways.
Venus has a dense atmosphere at a pressure that is 91 times the pressure found at sea level on Earth; it is mainly composed of carbon dioxide and sulphuric acid droplets, in addition to small amounts of water and oxygen. Researchers predict that weathering on Venus could be caused by a thermal process or corrosion carried out by the atmosphere, volcanic eruptions, impacts of large meteorites, and wind erosion.
As for Mars, it is currently dominated by physical weathering caused by meteorite impacts and thermal variations rather than chemical processes. According to Certini, there is no active volcanism that affects the Martian surface; however, the temperature difference between the two hemispheres causes strong winds. Certini also said that the reddish hue of the planet’s landscape, which is a result of rusting iron minerals, is indicative of chemical weathering in the past.
On the Moon, on the other hand, a layer of solid rock is covered by a layer of loose debris. The weathering processes seen on the Moon include changes created by meteorite impacts, deposition, and chemical interactions caused by solar wind, which interacts with the surface directly.
Nevertheless, some scientists feel that weathering alone is not enough and that the presence of life is an intrinsic part of any soil. “Studying soils on our celestial neighbors means to individuate the sequence of environmental conditions that imposed the present characteristics to soils; thus, helping reconstruct the general history of those bodies,” Certini said.
In 2008, NASA’s Phoenix Mars Lander performed the first wet chemistry experiment using Martian soil. Scientists who analyzed the data said that the Red Planet appears to have environments more appropriate for sustaining life than was expected; environments that could one day allow human visitors to grow crops.
“There is more evidence for water because salts are there,” said Phoenix co-investigator Sam Kounaves of Tufts University in a press release issued after the experiment. “We also found a reasonable number of nutrients, or chemicals needed by life as we know it”.
One of the primary uses of soil on another planet would be to use it for agriculture; to grow food and sustain any populations that may one day live on that planet. Some scientists, however, are questioning whether soil is really a necessary condition for space farming.
Researchers found traces of magnesium, sodium, potassium and chloride. The data also revealed that the soil was alkaline, a finding that challenged a popular belief that the Martian surface was acidic.
This information, obtained through soil analyses, becomes important in looking toward the future to determine which planet would be the best candidate for sustaining human colonies.
References
astrobio.net
space.com
news.nationalgeographic.com
sciencedaily.com
*Published in SCIplanet Printed Magazine, Autumn 2015 Issue "Food and Agriculture"