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Curiosity finds organic molecules in Mars rocks and methane content variations in the thin Martian atmosphere when the seasons change.
Mars. For centuries, humans have placed their hopes of finding alien life on the red planet. Over the last 50 years, various missions have been sent to Mars to investigate the possibility of life on neighboring planets on the outer edge of the habitable zone.
Is Mars lonely? Is there ever life on the red planet? This is what the answer is trying to find.
Stepping on the Environment Lifestyle on Mars
Mars became the main target because this one planet has a resemblance to Earth when young. The cold climate, the absence of tectonic plates and continental drift indicate not much change has occurred on Mars since the Hesperian period. The period when Mars changed from the wet and warm periods to the planet is dry, cold and dusty as it is now.
Mars conditions that do not change much to give its own advantages. If there was ever life on Mars, of course, the trail is still stored to be found.
The trace is water.
This one element is vital to the carbon-based life we know on Earth. Without water, there is no life. Mars is currently dry, barren, and its surface is experiencing high solar radiation due to the thin atmosphere. But, in the past, it was possible that the surface of this red planet was once flooded with water, even though the water that once existed eventually evaporated. Even predicted, Mars once had an ocean covering 19% of its surface and a wet period on the planet much longer than previously thought.
This water trail is what astronomers are looking for. It could be that Mars still has water on the surface or even underground. Water in the form of ice can be found in ice caps at the poles of Mars. Nevertheless, the evidence of the existence of liquid water can still be found when NASA's Mars Global Surveyor succeeds in discovering a ditch that was originally thought to have been formed from the flow of water. Further research results show the possibility that the trench is formed from dry ice.
Reports of the presence of water were also successfully provided by Spirit, a landed robot on Mars. Spirit detects goethite, an iron oxide compound that can only form in liquid water.
Hunting Organic Molecules
The presence of robotic landers on Mars opens the opportunity to be able to find traces of life on Mars. Water footprints in the past and organic molecules become a priority search.
The hunt for organic molecules on Mars began in 1976 when the Viking twin landers arrived on Mars at different locations. The purpose of this lander to find traces of life on the red planet. Despite reporting the existence of two chlorine compounds namely chloromethane and dichloromethane, ultimately astronomers suspect that Mars is only a dead planet. Both of these chemical compounds are thought to be brought from Earth and contaminate Mars.
In 2008, the idea then faded after the Phoenix lander found another chlorine compound that is perchlorate in the land of Mars.
The presence of Curiosity on Mars becomes a new chapter in the search for traces of organic molecules on the planet. This one lander successfully confirmed the existence of Gale Crater as a potentially lethal lake billions of years ago. The lake is filled with water, the main ingredient of life that we know and the water is on the surface of Mars. It is in this area that all life-forming agents can be found, including chlorinated hydrocarbon organic compounds such as chlorobenzene and dichlorobutane. Both compounds were found in the sedimentary rock drilling powder at Yellowknife Bay not far from the landing area.
If life appeared in Yellowknife Bay, then at least lifelike microbes would find a suitable location to evolve.
Organic Molecules on Mars
Still, from the Crater of Gale, Curiosity again reported its success in finding other evidence that could support the existence of primordial life on Mars. The evidence is found in sedimentary stones and in the atmosphere.
What is found are organic molecules containing carbon and hydrogen, with oxygen, nitrogen and other elements. Curiosity discovered this organic molecule after heating the mudstone taken from Gale Crater at 500ºC. The goal is to remove organic molecules from the mudstone powder.
The result as already known. Curiosity finds a non-volatile organic molecule and contains sulfur, thiophene, benzene, toluene, propane, and butane. In the present invention, carbon is found to contain 10 bpj (parts per million). Almost the same amount of carbon found in meteorites from Mars and 100 times more than previously detected organic carbon on the surface of Mars.
The organic molecules found can be an indication of life on Mars as it is formed from a biological process. However, they may be composed of non-biological processes and are not an indication of the existence of life on Mars.
There are two possible origins of the organic molecule.
Firstly, this organic molecule is a trace of life left behind when Mars is still habitable. Or in other words, the result of a biological process or a second possibility, the organic molecules appear without any life on Mars.
However, the organic molecule found is a chemical trace that can answer Mars's past history and what processes are happening on the red planet.
It is not easy to find traces of organic molecules on the surface of Mars, given the planet is exposed by radiation from outer space that can easily destroy organic matter on the surface.
Colorized shaded relief map of Gale crater. The general landing area for Curiosity on the northwestern crater floor, named Aeolis Palus, is circled. (HRSC data).wikipedia
For this reason, Curiosity in his research carried out sedimentary rock excavations in four different areas in the Gale crater. As a result, organic molecules are found at a depth of 5 cm of ancient sedimentary stone that was 3.5 billion years old.
If Curiosity can find organic molecules that survive on a 5 cm deep layer, then if digging deeper, there will be another possibility to find larger organic compounds. Or even to be found other signs of life on Mars.
Especially if under the surface of Mars there are oceans. Submarine water can protect the life formed from cosmic radiation on the surface of Mars.
Methane on Mars
Another discovery is the change in methane content in the thin atmosphere of Mars. Methane formed from the water reacts with rocks and minerals was first discovered in the atmosphere of Mars in 2004. At that time found a considerable methane content of 45 parts per million.
In his observations for nearly 3 years of Mars or nearly 6 years on Earth, Curiosity found evidence of changes in methane content in Mars during the summer. High methane content can be found in late summer and early autumn in the northern hemisphere, and its content will drop in winter and spring.
Methane-structure.wikimedia
During summer, the methane content in the atmosphere reaches 0.65 parts per billion and drops to 0.24 parts per billion in winter. In addition, the methane content experienced a spike of 7 parts per billion at random times.
The presence of methane in the atmosphere of Mars is not stable. Ultraviolet radiation The sun that hit the red planet will destroy methane. Therefore, there must be an active source on the surface that can maintain a considerable amount of methane in the atmosphere of Mars. On Earth, methane is made up of biological processes. That's why the presence of methane could be an indication of Mars supporting life.
Slow seepage from underground reservoirs could explain the occurrence of seasonal variations and a surge of methane in the atmosphere. Mars's rocky surface on Mars becomes a means of storing methane in the winter and releases it when the surface gets warm in summer. Occasionally, when the rocks on the surface are broken or destroyed, large quantities of methane will be released and cause a surge of methane in the atmosphere.
The discovery of organic molecules and methane in the atmosphere is not yet a valid proof of life on Mars. Whether the chemical compounds that come from biological processes or not have found the answer. Surely with Mars missions in the future such as the Rover Mars 2020 to be launched by NASA and ESA's EXOMars rover, we will be able to trace the past life of Mars even further.
Reference :
https://www.nasa.gov/press-release/nasa-finds-ancient-organic-material-mysterious-methane-on-mars
https://www.space.com/40819-mars-methane-organics-curiosity-rover.html
https://www.sciencealert.com/nasa-confirms-seasonal-variation-mars-methane-emissions
https://www.geekwire.com/2018/nasas-curiosity-rover-organic-methane-mars/
http://exploration.esa.int/mars/46038-methane-on-mars/