Mars was once a warm, wet world with a thick atmosphere and flowing water. Today, its atmosphere is barely one percent as dense as Earth's, and its surface is a cold, dry desert. Scientists have long known that the solar wind — a stream of charged particles flowing from the Sun — has been gradually stripping the Martian atmosphere over billions of years. But the exact mechanism has remained unclear.
A new study published in August 2026, using joint observations from NASA's MAVEN orbiter and China's Tianwen-1 spacecraft, has identified a previously underestimated process. The solar wind generates giant rolling waves — known as Kelvin-Helmholtz waves — at the boundary where the solar wind meets the planet's upper atmosphere. These waves create large plasma clouds that detach from the atmosphere and are carried away into space.
The dual-spacecraft observations allowed researchers to link upstream solar-wind conditions directly to the ion-loss rate. When the solar wind is particularly strong, the waves grow larger, and more atmospheric ions are swept away. The data show that this wave-driven escape process is a significant contributor to the total atmospheric loss, possibly more important than previously thought.
This finding helps explain why Mars lost its once-thick atmosphere despite having a weak induced magnetosphere. The Kelvin-Helmholtz instability operates continuously, unlike sporadic events such as solar storms. Understanding the rate of atmospheric loss is crucial for reconstructing Mars' climate history and for planning future human missions.
Knowledge takeaway: the solar wind generates Kelvin-Helmholtz waves at Mars' upper-atmosphere boundary, creating plasma clouds that carry atmospheric particles into space; this wave-driven escape process is a major, continuous contributor to Mars' atmospheric loss over billions of years.