NASA's Mars Atmosphere and Volatile Evolution spacecraft reached the orbit of Mars in September 2014 and is now delivering its first data about the atmosphere of the red planet.
This new data reveals clues about how the solar wind penetrates deeper into Mars' atmosphere than previously thought, causing the loss of atmosphere to space over time. The new information also shows the composition of the planet's upper atmosphere, as well as its ionosphere.
Maven orbits around Mars at the top of its upper atmosphere, but in each orbit, it dips down into the planet's ionosphere, that area of ions and electrons that should shield the planet from the extreme heat and high energy of the solar wind.
Except Maven discovered that Mars' ionosphere isn't exactly protecting the planet as it should. Maven discovered streams of particles from the solar wind that actually traveled into the upper atmosphere and into Mars' ionosphere. This happens when some sort of interaction happens at the top of the upper atmosphere that converts the ions of the solar wind into something that can travel farther. When it gets to the ionosphere, it becomes ions again.
Scientists believe this process is what has caused, and is still causing, Mars to lose its atmosphere.
"We are beginning to see the links in a chain that begins with solar-driven processes acting on gas in the upper atmosphere and leads to atmospheric loss," says Bruce Jakosky, Maven principal investigator with the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder. "Over the course of the full mission, we'll be able to fill in this picture and really understand the processes by which the atmosphere changed over time."
Maven will continue its mission by studying gases escaping from Mars' upper atmosphere to try to figure out exactly what is causing the solar wind to penetrate through the ionosphere and cause this loss. Also, measuring the variations of gases in the planet's upper and lower atmospheres will offer insight into the overall atmosphere's composition and weather.
Maven's main mission is to study Mars' upper atmosphere to figure out where the atmosphere went, along with the water that may have once been present on the planet. Answers to such questions could lead us to knowing more about Mars' past, and future, potential for its sustaining habitable life.
"As the first orbiter dedicated to studying Mars' upper atmosphere, Maven will greatly improve our understanding of the history of the Martian atmosphere, how the climate has changed over time, and how that has influenced the evolution of the surface and the potential habitability of the planet," says NASA Administrator Charles Bolden. "It also will better inform a future mission to send humans to the Red Planet in the 2030s."
[Photo Credit: NASA's Goddard Space Flight Center]