Solar wind and Mars. Visualization of ion flux data from MAVEN (Mars Atmosphere and Volatile Evolution Mission) showing a predicted bow shock pattern as the solar wind encounters Mars. Unlike Earth, Mars lacks a magnetic field to deflect the stream of high-speed charged particles flowing from the sun. The magnetic field carried by the solar wind as it flows past Mars accelerates ions in Mars' upper atmosphere and shoots them into space. During solar storms, the bow shock pushes even deeper into the atmosphere and is accompanied by increased rates of ion escape. The data supports the theory that over time, solar winds have eroded the Martian atmosphere. As a result it has become a cold, arid world unable to sustain bodies of water as it did in its ancient past.