This question has been puzzling the world’s greatest thinkers for decades now, and as of recently, there has not been hard empirical evidence as to exactly what caused Mars’ climate to change. Perhaps this new research article published by Bruce Jakosky, a geologist from the University of Colorado, and his colleagues on November 6th is the answer.
Jakosky and his colleagues are the team behind the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, which was designed to study the atmosphere of Mars while orbiting the planet. According to their article, data suggests that the Martian atmosphere was likely destroyed by particles emitted by the sun.
It was back in March 2015 when a giant blast of plasma and magnetism, also known as a Coronal Mass Ejection (CME), from the sun suddenly came in contact with the atmosphere in Mars. It is a common thing for charged particles from the sun to find their way across the solar system and they can prove to be quite harmful. Fortunately for us, the Earth’s magnetic field has the capacity to deflect these solar winds to prevent them from causing damage to the atmosphere. In the case of Mars, the same cannot be said.
Mars has a weaker magnetic field than planet Earth. What this means is that when a CME comes close to Mars, nothing can stop it from penetrating the atmosphere. At least not the planet’s magnetic field. And that is exactly what happened, according to the data recorded by MAVEN. The CME caused the atmospheric particles to become charged and its magnetism also redirected some of the planet’s magnetic field far into space. This resulted in the charged particles being dragged into space as well, never to return home.
Over time, more and more atmospheric pressure is lost in Mars due to these CMEs. Right now, Mars has less than 1% of Earth’s atmospheric pressure.
The simulation of ions escaping from the atmosphere
“So what happened to Mars? I’ll quote Bob Dylan: ‘The answer my friend is blowing in the wind,’”said Michael Meyer, who is the lead scientist for the Mars Exploration Program at NASA, during a press conference on Thursday.
It is important to note that the loss of atmosphere recorded by MAVEN as reported by NASA is just a quarter of a pound per second. This is clearly insignificant compared to the overall atmospheric mass. However, considering the fact that the sun regularly emits CMEs and the fact that it emitted CMEs more frequently billions of years ago than it currently does, it is reasonable to deduce that most of the atmosphere in Mars would have been removed by CMEs over this time period.
“The loss rate is relatively low, but still enough to remove the entire Mars atmosphere in a couple of billion years,” Jakosky told Tech Insider.
There is also another interesting finding by this research paper. According to the paper, there is good evidence that Mars also lost its water in the same fashion. You might probably be aware of NASA’s recent discovery of water on Mars by now. The researchers found out that among all the gases in the atmosphere, hydrogen and oxygen escape more easily than others. Based on this finding, Steve Bougher provided an intuitive explanation that since water is composed of hydrogen and oxygen, it makes sense that water also escaped Martian atmosphere over time.