According to a newspaper report published on October 23, 2020, Mars is losing its atmosphere to outer space at a faster rate than Earth. This study was confirmed by data and images sent by ISRO’s Mars Orbiter Mission (MOM) and NASA’s Mars Orbiter Mars Atmosphere and Volatile EvolutioN (MAVEN).
All terrestrial planets in the solar system—Mercury, Venus, Earth, and Mars— constantly lose their atmosphere to outer space, and this loss rate is determined by the size of the planet. As Mars is smaller than Earth, it is losing its atmosphere to the outer space at a faster rate.
On October 21, 2020, the Indian Space Research Organisation (ISRO) posted these findings on its website sent by MOM and MAVEN. The scientists studied about a global dust storm, a dynamical meteorological phenomena on Mars, in June–July 2018.
Such a storm significantly heated and expanded the Martian upper atmosphere, which led to a part of Mars atmosphere quickly reaching the exobase altitude (lying at 220 km). Any hot gases above the exobase altitude are more likely to move to further higher altitudes and subsequently escape to outer space. Hence, it can be inferred that the 2018 global dust storm resulted in enhanced escape of the Martian atmosphere.
MOM observed the evening side of Mars by diving down to altitude as low as 155 km. The Mars Exospheric Neutral Composition Analyser (MENCA) instrument, a mass spectrometer onboard the ISRO orbiter, measured the neutral densities of the Mars’ thermosphere (which lies between 100 and 200 km).
By analysing these measurements, scientists at the National Atmospheric Research Laboratory (NARL), Andhra Pradesh, found that the upper atmosphere of Mars was undergoing warming and expansion. Also, MAVEN, which was simultaneously measuring the Martian thermosphere on the morning side, confirmed such an increase.
ISRO’s MOM
ISRO had launched MOM on November 5, 2013, which was placed in the Martian orbit on September 24, 2014. Though meant to last only six months, the mission is still alive and sending images from time to time nearly seven years after its launch.
The ISRO and NASA spacecraft both observed a significant increase in neutral densities in the Martian upper thermosphere (150–220 km) associated with the development of a global dust storm in the lower atmosphere.
The results of the study have been published in the Journal of Geophysical Research (JGR) and show the scientific potential of ISRO’s MOM and the advantages of multi-spacecraft measurements in exploring planetary atmosphere.
Courtesy: India Today, The Times of India