A recent study about the weather on Mars has revealed an interesting fact that its atmosphere is well protected from the effects of the solar wind. At first, it might not sound odd. But the interesting facts is that Mars does not Magnetic dipole like Earth. Researchers till now have revealed that Mars is a cold and dry planet with less than one per of Earth's atmospheric pressure at the surface. But, certain geological features have indicated that the planet had an active hydrological cycle about 3-4 billion years ago.
If that theory is believed to be true then for an active hydrological cycle would have required a warmer climate in the planet's early history and therefore a thicker atmosphere which can cause a strong greenhouse effect. The common hypothesis that scientist believe is that the solar wind over time has eroded the early Martian atmosphere. It is believed to cause a strong the greenhouse effect resulting in the collapse of the hydrological cycle.
Mars also do not have magnetic dipole like Earth but solar wind instead induces currents in the ionized upper atmosphere, creating an induced magnetosphere. According to Robin Ramstad (Umea University, Sweden),” It has long been thought that this induced magnetosphere is insufficient to protect the Martian atmosphere. Our measurements show something different.” The researchers are using measurements from the Swedish particle instrument ASPERA-3 on the Mars Express spacecraft.
Mars Express Spacecraft has been measuring the ion escape from Mars since 2004. Researchers have combined and compared measurements of the ion escape under varying solar wind conditions and levels of ionizing solar radiation. The result surprised everyone! It showed that the solar wind has a comparatively small effect on the ion escape rate.
So, despite the stronger solar wind and extreme ultraviolet radiations under the sun, ion escape cannot explain more than 0.006 bar of atmospheric pressure lost over the course of 3.9 billion years.
The scientist believes that 0.01 bar of pressure is insignificant to maintain a sufficiently strong greenhouse effect. The results also showed that a stronger solar wind mainly accelerates particles already escaping the planet's gravity but much to the surprise it does not increase the ion escape rate. Also, the induced magnetosphere is also shown to protect the bulk of the Martian ionosphere from solar wind energy transfer.
Mystery still continues around Mars’s atmospheric condition. The scientist is trying hard to solve the unknown facts about Mars as they believe it is the only planet on Earth which is capable of supporting a healthy ecosystem. Now, we will have to wait until we can reach Mars so that we can actually confirm these hypotheses.
Image Source: Solar wind