We know Mars to be a dry red surfaced planet today, however, billions of years ago, the neighbouring planet may have had large water bodies due to the presence of a thick atmosphere.
Space scientists are using a key tracer, isotopes of oxygen, to analyse how much atmosphere Mars has lost. According to researchers at NASA, the previous measurements have disagreed significantly. New observations by the space agency have found that the isotopes of oxygen can differ depending on the time of day and the surface temperature of the neighbouring planet.
Isotopes of oxygen are important as they help in estimating how much atmosphere Mars might have had once upon a time and if the red-coloured planet could have once been habitable or not. The tracer also provides scientists an indication of what the conditions of the surface of Mars may have been in its earlier life, NASA explained in a statement.
Scientists know that Mars is a cold, inhospitable desert today, however, features such as dry riverbeds and minerals that only form with liquid water indicate that once upon a time, it had an atmosphere that was thick enough to retain the heat required for water. Scientists want to analyse how habitable was Mars earlier.
It seems that the red planet lost much of its atmosphere over billions of year that transformed its climate from one that may have supported life into th frozen one today, according to results from NASA’s MAVEN, Curiosity and Viking missions.
According to NASA scientists, isotopes of oxygen are an important indicator of the atmosphere in the past because they carry different weights. The isotopes which are lighter tend to escape to space faster than the isotopes which are heavier. This means that the atmosphere that remains on the planet gets gradually enriched in the heavier isotope.
NASA scientists are measuring 18O and 16O. The team is measuring the heavier 18O against the lighter 16O to check how much atmosphere was there on ancient Mars and estimate how quickly the lighter 16O escapes. They are assuming that the relative amount of each isotope on Earth and Mars was once similar.
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Measurements of these isotopes have not been consistent as different missions measured different ratios which resulted in the different understanding of the ancient atmosphere. The scientists found that measurements using a single method vary in a single day. Variance in isotope ratio is around 9 per cent depleted in heavy isotopes at noon on Mars to being about 8 per cent enriched in heavy isotopes by about 1:30 pm compared to normal isotope ratios for Earth’s oxygen.