In a groundbreaking discovery, a collaborative team of scientists from institutions in the United States and France has made the first direct observation of atmospheric sputtering on Mars. This significant finding, detailed in the journal Science Advances, was achieved through extensive analysis of data collected by NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) probe. The researchers examined nine years of satellite data and identified fluctuations in argon gas densities in Mars’ upper atmosphere that vary based on solar wind activity, direct evidence of atmospheric sputtering.
Atmospheric sputtering on Mars occurs when high-energy ions in the solar wind collide with a planet’s atmosphere, knocking atoms and molecules into space. While scientists have long theorized that this process contributed heavily to Mars’ transformation into a cold, arid world, the new findings mark the first time this phenomenon has been directly observed on the Red Planet.
How the Discovery Was Made
The MAVEN probe, which has been orbiting Mars for over a decade, provided critical data for the research. By comparing argon gas levels at 350 kilometers above the planet’s surface with those found at lower altitudes, researchers found that upper-atmosphere argon concentrations fluctuate depending on the direction of the incoming solar wind and its electric field. In contrast, the argon levels closer to the surface remained consistent, indicating that the variations were linked to external forces acting at high altitudes.
These changes in argon density revealed another crucial detail: lighter argon isotopes were more likely to be lost to space, leaving behind heavier ones. This isotopic imbalance is a telltale sign of atmospheric sputtering on Mars, where solar wind selectively strips away lighter elements from a planet’s atmosphere over time. The team also noted that during solar storms, the differences in argon density became more pronounced, offering further confirmation of the process.
Implications for Mars’ Climate History
The confirmation of ongoing atmospheric sputtering on Mars has far-reaching implications for our understanding of Mars’ climatic evolution. Scientists believe that this mechanism has played a pivotal role in the gradual thinning of the Martian atmosphere and the disappearance of surface water. Without a global magnetic field to deflect solar particles, Mars is particularly vulnerable to atmospheric loss.
The researchers also highlighted that in the early days of the solar system, the sun emitted stronger ultraviolet radiation, which would have intensified atmospheric sputtering on Mars. This historical perspective reinforces the theory that Mars may once have had a much thicker, wetter atmosphere, one capable of supporting liquid water on the surface.
Overall, the study provides vital insights into the ongoing processes shaping Mars today, while also helping scientists better understand the planet’s past and its potential to support life in ancient times. The findings could also inform future missions focused on Mars’ climate, evolution and the role atmospheric sputtering on Mars plays in shaping planetary atmospheres more broadly.
