What happened to Mars? Finding after finding indicates regions of Mars had substantial amounts of water in its ancient past. That means Mars must have had a denser, warmer atmosphere at some point in its past. New data suggests the Sun may have played a big part in turning Mars from a warm, wet environment into the cold, arid planet we see today.
Last September, NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) probe entered orbit around Mars. It’s designed to figure out how solar wind is affecting Mars’ atmosphere today.
Armed with new data, researchers were able to figure out how much gas the Martian atmosphere is losing due to solar wind. Solar winds strip about 100 grams of gas every second.
In March, a series of strong solar storms hit Mars’ atmosphere. And MAVEN was in perfect position to see how the increase in solar activity affected how much atmosphere was lost. The amount of gas lost every second spiked according to Jakosky.
What about Mars’ ancient past? MAVEN shows atmospheric loss spikes during solar storms. And our Sun was much more active billions of years ago. According to NASA, the combination of the two suggests that solar winds and the subsequent loss of atmosphere “was likely a major process in changing the Martian climate.”
What did the atmosphere loss look like? The new data points to atmospheric loss in three different regions around Mars. Below is a data visualization video NASA put together showing the atmospheric loss. You can see Mars’ atmosphere leaking down the ‘tail,’ above Mars’ poles and in a cloud surrounding the planet. Nearly 75% of the escaping ions come from the tail according to the MAVEN science team. Another 25% comes from the polar regions and a tiny bit from the cloud.
As for Earth? Thanks to our magnetic field, we don’t have to worry about losing our atmosphere due to solar winds anytime soon. Mars also used to have a magnetic field protecting it. Scientists still aren’t sure exactly what happened to it. Theories range from asteroid bombardments to a weak magnetic field that just dissipated over time.
While MAVEN points to solar winds, a new Mars mission may help explain what happened to Mars’ magnetic field. The InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) lander will focus on the red planet’s interior, including its core. Understanding what Mars’ core is made of could shed more light on what happened to its magnetic field.