Scientists have long suspected the solar wind of stripping the Martian upper atmosphere into space, turning Mars from a blue world to a red one. Now, NASA's MAVEN orbiter is observing this process in action, providing significant data on solar wind erosion at Mars.
Today, Mars is a global desert with an atmosphere far too thin to support bodies of flowing water, but evidence shows that Mars was considerably wetter in the ancient past. Scientists think that climate change on Mars was caused by the loss of an early, thick atmosphere, and NASA’s MAVEN mission is investigating whether it was driven into space.
One of the prime suspects is the solar wind, a stream of electrically charged particles continuously blowing outward from the Sun. Unlike Earth, Mars lacks a global magnetic field to deflect the incoming solar wind. Instead, charged particles from the Sun crash into the Mars upper atmosphere, and can accelerate Martian ions into space. Now, MAVEN has observed this process in action – by measuring the velocity of ions escaping from Mars.
The movies on this page compare simulations of ion escape with MAVEN’s observations of oxygen ion flux. The results closely fit the expected pattern, with the most energetic ions (in red) accelerated in a plume above Mars, while the majority of escaping ions (green) are lost along the “tail” region in the wake of the solar wind. MAVEN’s observations confirm that the solar wind is a significant contributor to atmosphere loss on Mars, and they bring scientists closer to solving the mystery of the ancient Martian climate. Read the full press release about this finding.
GCMD keywords can be found on the Internet with the following citation:
Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 220.127.116.11.0