In 2014, NASA’s MAVEN (Mars Atmosphere and Volatile Evolution mission) spacecraft measured the speed and direction of ions escaping from Mars. The data collected as it orbited the Red Planet is visualized in this NASA Goddard video, a possible explanation for why Mars might have gone from a warm, wet climate (previous to 3.8 billion years ago) to a cold, dry one. From PopSci:
“We know younger stars are more active,” David Brain, a space physicist on the MAVEN team, tells Popular Science. “Younger stars have more solar storms, and more intense storms. Mars was probably being bombarded by these storms early in its history.”
Lucky for us, Earth’s magnetic field repelled the brunt of those particles. Mars wasn’t so lucky. Although the planet once had a protective magnetic field, it disintegrated at some point. As a result, the charged particles from the CMEs crashed into Mars’ atmosphere like a tsunami wave.
Scientists have long suspected those crashing waves of CME particles might have played a role in degrading Mars’ atmosphere. Now, thanks to MAVEN, they can finally estimate how large that role was.
And from at Smithsonian.com:
“What’s exciting to me is the idea of Mars as a laboratory,” says Brain. “Once our models are really trustworthy, we can apply them in new situations.”
For instance, such improved models could lead to new insights about Venus, which has a similarly weak magnetic field. They could also offer clues to how Earth interacts during the sun during flips in its magnetic field. And instead of only looking at how the sun affects Mars, scientists plan to ask what their observations in turn reveal about the sun.
Update: All Things Considered sums it up well. Listen here.