More than nine years of satellite observations have led to a revolutionary discovery. For the first time, an international team of scientists led by Shannon Curry from the University of Colorado has unequivocally observed the main mechanism that continues to blow Mars’ atmosphere into the cosmic void. This phenomenon, known as atmospheric sputtering, is considered key to the process that billions of years ago transformed Mars from a potentially habitable planet filled with rivers and seas into the cold, dry desert we see today.
Atmospheric fountain
Sputtering is one of the key factors in the loss of the Red Planet’s atmosphere. A powerful stream of charged particles from the Sun constantly collides with the upper layers of the Martian atmosphere. Since the Red Planet does not have a global magnetic field to protect in the same way as Earth, solar wind reaches the atmosphere unimpeded. Charged ions from the solar wind generate strong electric fields in the upper atmosphere. These fields accelerate local atmospheric ions to enormous speeds.
This is a photo of the surface of Mars taken by the Viking 1 orbiter in 1976.
It looks like something out of a sci-fi film you'd see today.
(And yes, that *is* a smiley face in that crater…)
Credit: NASA/JPL-Caltech, processing by Andrea Luck (@andrealuck.bsky.social)
— Paul Byrne (@theplanetaryguy.bsky.social) 17 березня 2025 р. о 04:21
This is where “cosmic billiards” begins: accelerated ions strike the neutral atoms and molecules of the gases surrounding them with tremendous force. As a result of these collisions, some of the neutral atoms receive such a powerful push that they acquire enough speed to overcome Mars’ gravity. They literally “shoot” into space, leaving the planet forever. Like a fountain spouting jets of water, only this time it is streams of atmospheric gases rushing on an irreversible journey through interstellar space.
Hunting for an ethereal phenomenon
Directly observing the sputtering on Mars was an extremely difficult task. In addition, observations had to cover both the day and night sides of the planet at a significant depth in the atmosphere.
The only spacecraft capable of doing this is NASA’s MAVEN (Mars Atmosphere and Volatile EvolutioN), which has been studying Mars from orbit since September 2014. Shannon Curry’s team carefully analyzed the data sets collected by MAVEN over many years. The key to success was finding simultaneous traces of two phenomena: solar electric field activity and a sharp increase in the number of argon atoms in the upper layers of the atmosphere. Argon, a heavy, inert gas, proved to be an ideal sputtering indicator. And scientists have finally found these undeniable coincidences in the data.
Real evidence
This discovery is direct evidence that sputtering is not a theoretical model, but a real and powerful mechanism that is still occurring on Mars today. Its role in the past, when the Sun was much more active, was probably even more significant. Sputtering could have been the dominant process that led to the massive loss of Mars’ atmosphere.
The loss of the atmospheric “blanket” caused a catastrophic drop in pressure and temperature, which ultimately made it impossible for liquid water to exist on the surface, sending the planet on a path to its current inhospitable state.
Earlier, we discussed how long the Red Planet supported life.
According to sciencealert.com
