NASA’s MAVEN (Mars Atmosphere and Volatile Evolution) probe, which has been orbiting the red planet since September 2014, has uncovered more evidence pertaining to the disappearance of the red planet’s atmosphere. A team of scientists from NASA, the University of Colorado’s Laboratory for Atmospheric and Space Physics (LASP), and the University of Iowa, announced their findings in a live broadcast on November 5.
Scientists have long suspected that Mars had once been a habitable planet like ours. Recent missions have thus focused on finding evidence of water – the prime ingredient needed for life. Their findings have included visual and mineral evidence of water, meaning that, in ancient times, Mars likely had enough of it to support microbial life, and would have had a warmer and thicker atmosphere. Geological studies have estimated that water may have been abundant even 3.7 million years ago. Nowadays, the planet is cold and dry, with an atmosphere so thin that liquid water cannot be sustained; it either evaporates or freezes.
So, what happened then? A number of theories have been presented over the years, but essentially, the atmosphere either went up or went down. It may have dissipated into space over time, or otherwise gases such as carbon dioxide may have crystalized into carbonates that could potentially now be found in the soil. However, not enough carbonates have been found to account for the amount of atmosphere that has been lost. With new research, it now seems that the verdict is in: ions in the atmosphere were stripped from the planet by solar winds, travelling at 1,000,000 miles/hour from our central star. These winds, made of electrically charged particles following magnetic fields from the sun, have contributed the most to the depletion of the atmosphere.
The MAVEN probe, which monitors the top of the atmosphere where this takes place, has estimated an escape rate of about 100 grams of matter (mostly oxygen and carbon dioxide) per second, as a lower limit. This rate can increase ten or twenty-fold during solar storms, as documented during a flare event in March 2015, in which 3 flares in a row created more intense atmospheric stripping. The findings also imply that some additional challenges may be encountered in the mission to send humans to Mars, a goal that NASA hopes to achieve in the 2030s. Terraforming the planet by taking carbon dioxide from the crust may be less feasible, as the majority of the gas is no longer on the planet.
The next big topic of discussion is what the findings mean for Earth, and whether or not our own planet is headed for the same fate. NASA scientists say that, while the Earth does experience some degree of atmospheric loss, we won’t be experiencing a phenomenon quite as dramatic as Mars’ for a number of reasons. For one, solar storms used to be much more intense, and are tamer in recent times. The Earth is also protected from the effects by its own, much stronger magnetic field in comparison with Mars. As the red planet grew older, its internal core temperature decreased and as a result its magnetic field was greatly weakened, leaving its gaseous particles more susceptible to solar winds. While Earth does experience more particle escape from the poles and is particularly vulnerable during geomagnetic reversals (in which the position of the north and south magnetic poles exchange positions), it will not become like Mars unless our planet also cools and loses is magnetic field.
These findings unlock more information about our solar system, and the effect of the sun on the planets. It also gives us something to think about when it comes to our own planet, and what may become of it in the future. Perhaps someday it, too, might look like Mars.
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