NASA's MAVEN spacecraft has observed a previously unknown plasma squeezing effect at Mars, where the solar wind compresses the planet's induced magnetosphere in a manner not seen before. This discovery, announced by the mission team, reveals a dynamic interaction between the solar wind and Mars' tenuous atmosphere.
MAVEN, which stands for Mars Atmosphere and Volatile EvolutioN, has been studying the Martian upper atmosphere since it entered orbit in September 2014. The spacecraft's instruments detected periods when the solar wind, a stream of charged particles from the Sun, causes the plasma surrounding Mars to contract or "squeeze" into a smaller region. This occurs even when Mars lacks a global magnetic field to deflect the solar wind.
The findings stem from data collected during MAVEN's extended mission, highlighting how the solar wind can intermittently compress the induced magnetosphere—a protective bubble formed by the planet's ionosphere interacting with the solar wind. The squeezing effect was observed during specific solar wind conditions, offering new insights into the dynamics of Martian space weather.
This phenomenon is significant because it alters how Mars' atmosphere interacts with the solar wind, potentially affecting atmospheric escape over geological timescales. Understanding these plasma dynamics helps scientists refine models of Martian climate evolution, as the solar wind has been gradually stripping away Mars' atmosphere for billions of years.
While the MAVEN team is confident in the detection, ongoing observations are needed to determine how frequently this squeezing occurs and its broader implications. The finding underscores the complexity of space weather interactions at unmagnetized planets like Mars.