Contact CU Independent News Staff Writer Taryn Parsons at taryn.parsons@colorado.edu.
On Nov. 5, NASA revealed new findings about Mars’ atmosphere. With the help of the MAVEN mission, which is being led by the University of Colorado, it has discovered that a major source of atmospheric depletion comes from solar winds.
When solar winds from the sun reach Mars, the ions in the atmosphere reach escape velocity (the speed required for the ions to leave the atmosphere), and the atmosphere is stripped away. Today, about 100 grams (roughly 1/4 pound) of atmospheric gas is stripped away by solar winds every second, which becomes significant over time, MAVEN principal investigator at CU’s Laboratory for Atmospheric and Space Physics (LASP), Bruce Jakosky, said.
Data from MAVEN suggests that this process turned Mars from a warm and wet climate to a cold, dry climate when the solar system was young.
“We’ve seen that the atmospheric erosion increases significantly during solar storms, so we think the loss rate was much higher billions of years ago when the sun was young and more active,” Jakosky said.
LASP scientist and MAVEN investigator Dave Brain said that scientists can infer how our sun behaved during the early history of the solar system by observing young stars, which are very active and stormy.
In March 2015, a series of large solar storms hit Mars’ atmosphere, and MAVEN found that they accelerated the loss rate. This suggests that the sun’s higher frequency of storms in its early history had a dramatic influence in the change of Mars’ climate, including the decrease in the amount of water on the planet’s surface.
“We have found that a long time ago, there was a thick atmosphere and very likely liquid water on Mars, and from the missions like MAVEN that measure the atmosphere and the ion escape, we understand the loss process from the atmosphere, and by putting all of this information together we can conclude that Mars was like Earth a long time ago,” Brain said.
Earth endures the same solar wind, but there is a magnetic field surrounding Earth that shields the planet from the same atmospheric damage. Mars had a similar magnetic field that shut off in the early history of the solar system, so the atmosphere was vulnerable to more damage from solar flares and solar storms.
Yaxue Dong, LASP scientist and MAVEN investigator, explained that Earth might face the same fate as Mars, but not for a very long time.
“When the magnetic field shuts off, Earth will have a very similar situation to Mars, and the solar wind will be able to take more of the atmosphere, but there is another factor: Earth’s gravity is able to hold onto more atmospheric particles than Mars.”
Even though Earth might end up like Mars, there is another potential end for the planet. When a star like the sun nears the end of its life and its core shrinks under its own gravity, it turns into a red giant: an enormous, very luminous star with a low surface temperature. When the sun turns into a red giant, it will emit a much higher amount of energy that it does now.
Brain explains that if the sun enters the red giant phase before the Earth loses its magnetic field, the sun will most likely engulf Earth. No need to worry, though, because this won’t happen for another few billion years.
So what’s next for the exploration of Mars?
“If we want to understand the loss process more precisely or in more detail, we need to know how it acts under different conditions, which requires way more data than we have now, and one thing we plan to do is an extended MAVEN mission,” Dong said.
Brain added, “Maybe [MAVEN] will focus on auroral observing campaigns now that we know where and under what conditions they occur, and there are things we can do with the dust that was recorded as well.”
For now, MAVEN will continue exploring Mars’ climate and atmosphere and continue gathering information for scientists to analyze. There are about 30 LASP scientists, undergraduates and graduate students analyzing MAVEN’s results. CU-Boulder provided two science instruments and leads science operations for MAVEN. CU also provides education and public outreach for the mission.
