How the Sun Stripped Mars of Its Atmosphere

NASA's MAVEN spacecraft, which ended its 11-year mission in June 2026, measured how solar wind—charged particles streaming from the Sun—gradually stripped away Mars's upper atmosphere. By tracking escape rates against solar activity cycles, MAVEN showed directly that Mars once had a thicker, denser atmosphere capable of supporting a warmer climate. The data reshape how we understand why Mars became the cold, thin-aired world we see today.