When it comes to the search of ancient microbial life beyond Earth, Mars has been the closest to having traces of gases and conditions that might support the activity. However, one such gas has puzzled scientists for years. The question of whether methane, the main constituent of natural gas on Earth, is present on Mars has baffled scientists.
While the gas has been observed by the Curiosity rover, which is trundling on the surface of the Gale crater on Mars, the European Space Agency's orbiter hovering above has not been able to detect it in the Martian atmosphere.
Now, a new study suggests that methane concentrations rise and fall throughout the day at the surface of Gale crater, which could in turn be causing the discrepancy in detecting the gas.
The study published in the Astronomy & Astrophysics journal states that the quantity, distribution, and behaviour of methane in the atmosphere of Mars are of great interest since the gas is recognised as a potential biosignature for microbes to flourish.
WHY HAS METHANE BAFFLED SCIENTISTS?
On Earth, a significant amount of methane is produced by microbes that help most livestock digest plants. Therefore, its potential presence on a planet 300 million kilometres away has created excitement. The presence of methane on Mars could imply that microbes were, or are, living on the Red Planet. However, there are chances that methane on Mars could have nothing to do with microbes or any other biology and could have been produced by geological processes that involve the interaction of rocks, water, and heat.
While its presence is exciting, its detection by one instrument while no trace on the other has been a cause of concern.
The Tunable Laser Spectrometer (TLS) instrument onboard Curiosity had measured less than one-half part per billion in volume of methane on average in Gale crater. "That’s equivalent to about a pinch of salt diluted in an Olympic-size swimming pool," Nasa said in a statement.
However, the ExoMars Trace Gas Orbiter hasn’t detected any methane higher in the Martian atmosphere.
Some scientists had suggested that the rover might itself be releasing the gas as it moved ahead crushing rocks and due to the degradation of its wheels. However, a deep analysis of the machine showed no such chemical reaction happening as Curiosity moved about.
DIFFERENCES IN METHANE CONCENTRATION DURING DAY AND NIGHT
Now scientists have studied the discrepancy between methane measurements by analysing the time at which the readings are taken. The rover's TLS operates mostly at night when no other Curiosity instruments are working. The Martian atmosphere is calm at night and so methane seeping from the ground builds up near the surface where Curiosity can detect it, scientists observed.
However, the orbiter requires sunlight to pinpoint methane about 5 kilometres above the surface.
The heat from the Sun churns the atmosphere as warm air rises and cool air sinks. Therefore, the methane that is confined near the surface at night is mixed into the broader atmosphere during the day, which dilutes it to undetectable levels. This leads to no reading on the orbiter.
Scientists are now looking at solving why methane is not present in the Martian atmosphere which is 95 per cent carbon dioxide. "Experiments are underway to test whether very low-level electric discharges induced by dust in the Martian atmosphere could destroy methane, or whether abundant oxygen at the Martian surface quickly destroys methane before it can reach the upper atmosphere," Nasa said in a statement.
https://news.google.com/__i/rss/rd/articles/CBMiaGh0dHBzOi8vd3d3LmluZGlhdG9kYXkuaW4vc2NpZW5jZS9zdG9yeS9tYXJzLW1ldGhhbmUtbXlzdGVyeS1jdXJpb3NpdHktcm92ZXItbmFzYS1qcGwtMTgyMTIxMS0yMDIxLTA2LTMw0gFsaHR0cHM6Ly93d3cuaW5kaWF0b2RheS5pbi9hbXAvc2NpZW5jZS9zdG9yeS9tYXJzLW1ldGhhbmUtbXlzdGVyeS1jdXJpb3NpdHktcm92ZXItbmFzYS1qcGwtMTgyMTIxMS0yMDIxLTA2LTMw?oc=5
2021-06-30 10:46:41Z
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