Mars’ Missing Water: Dust Storms Now Suspected of Year-Round Loss
New research suggests that dust storms, not just warmer seasons, are actively stripping water from Mars’ atmosphere, offering a crucial piece in the puzzle of the planet’s dramatic climate shift. For years, scientists have debated the fate of the vast quantities of water that once flowed on the Red Planet, and data from multiple spacecraft is now pointing to a surprisingly consistent mechanism of loss.
The question of where all the water went on Mars has long captivated researchers. Data gathered by rovers like Perseverance and Curiosity, alongside orbiting satellites including the Mars Reconnaissance Orbiter and ExoMars, confirms that Mars was once a “wet world” with a robust hydrodynamic cycle. However, that is no longer the case. A new study, synthesizing data from at least six instruments across three spacecraft, reveals that dust storms are consistently driving water vapor into the Martian atmosphere, where it is broken down and lost to space.
Scientists estimate that ancient Mars may have held enough water to cover most of its surface to a depth of hundreds of meters. This estimation relies on analyzing the deuterium/hydrogen (D/H) ratio in the Martian atmosphere. Deuterium, a heavier isotope of hydrogen, is less susceptible to being lost to space. As lighter hydrogen escapes, the D/H ratio increases over time. Current measurements show Mars’ D/H ratio is 5-8 times higher than Earth’s, suggesting a significant loss of water over billions of years.
Understanding Mars’ seasons is key to unraveling this mystery. Like Earth, Mars experiences seasons due to its axial tilt. However, its highly elliptical orbit creates a significant difference in temperature between its summers. Southern summers, when Mars is closest to the sun (at perihelion), are much warmer than northern summers, occurring when the planet is farthest from the sun (at aphelion). Traditionally, scientists believed water loss was primarily driven by atmospheric processes during these warmer southern summers.
However, this new research challenges that assumption. The study highlights a particularly powerful “rocket storm” that occurred in the northern hemisphere during Mars year 37 (2022-2023 on Earth). This storm, unprecedented in its intensity, demonstrated that water loss isn’t limited to the southern summer.
Warmer temperatures, driven by dust, inject water into the upper atmosphere, where it is vulnerable to breakdown by ultraviolet (UV) radiation. During southern summer dust storms, dust is propelled into the middle atmosphere, warming the air by approximately 15°C. Normally, water ice clouds would form at this altitude, trapping water molecules. But the increased warmth prevents cloud formation, allowing water to rise higher and be destroyed by radiation.
Data from ExoMars, the Emirates Mars Mission (EMM), and the Mars Reconnaissance Orbiter all confirmed that the northern summer storm triggered the same water destruction process observed during southern summers. This finding indicates that dust storm cycles contribute to water loss year-round.
“This suggests the destruction of water wasn’t limited to specific periods of Mars’ history,” one analyst noted.
While the observed northern storm was exceptionally strong, researchers theorize that a more pronounced axial tilt in Mars’ past could have created conditions for similar, frequent storms in warmer northern summers. This additional pathway for water loss could reconcile discrepancies between the estimated amount of water Mars once held and the current amount, as well as the known destruction processes.
This article was originally published by Universe Today. Read the original article.
