A Stunning Revelation: How One Martian Storm Resulted in Dramatic Water Loss
Mars, the enigmatic red planet, has long puzzled scientists with the mystery of its vanishing water. For years, researchers have debated the whereabouts of this precious resource. Thanks to data gathered from various rovers such as Perseverance and Curiosity, alongside orbiting satellites like the Mars Reconnaissance Orbiter and ExoMars, we know that Mars once boasted a vibrant hydrodynamic cycle, teeming with water. Yet today, it stands arid and lifeless. So, what happened to all that water? A recent study synthesizing information from six distinct instruments across three different spacecraft sheds new light on this question, revealing that dust storms play a crucial role in pushing water into the Martian atmosphere, where it is actively broken down throughout the year.
Scientists estimate that, at some point in its history, Mars had sufficient surface water to cover most of its terrain to depths of several hundred meters. This estimation relies on a method known as the deuterium/hydrogen (D/H) ratio. Deuterium, an isotopic variant of hydrogen that is heavier, occurs in a small fraction of water molecules. This slightly denser form of water, often referred to as "heavy water," has a lower likelihood of being elevated high into the atmosphere, where harmful ultraviolet (UV) radiation can break it apart, allowing the resulting hydrogen atoms to be swept away by solar winds.
Over time, as the lighter hydrogen is lost, the D/H ratio in Martian water increases. Scientists have detected this ratio on Mars to be 5 to 8 times greater than that found on Earth. By extrapolating these findings, researchers suggest that sufficient water once existed on Mars to cover much of its surface, even if it may not have been in liquid form at that time.
In a recent discussion, Fraser explores potential reservoirs of liquid water on Mars with Dr. Aditya Khuller.
To unravel the mystery of where this water has gone, one must consider the seasonal dynamics of Mars. Like Earth, Mars has an axial tilt which gives rise to seasons. However, its orbit is significantly more elliptical, resulting in extreme temperature variations; one season, particularly when Mars is closest to the Sun (perihelion), can be markedly warmer than another when it is farthest away (aphelion).
This means that summers in the southern hemisphere are considerably hotter than those in the northern hemisphere. Until now, scientists largely believed that the loss of water to the atmosphere primarily occurred during the warmer southern summer months. However, the latest paper challenges this notion by documenting a specific kind of intense dust storm, termed a "rocket storm," that occurred in the northern hemisphere a few years ago.
These warmer summers influence the mechanism by which water is introduced into the upper atmosphere, contrasting sharply with lower atmospheric levels where water is somewhat shielded from the UV radiation that can break it down. During the southern summer, dust storms propel particles into the mid-atmosphere, raising temperatures by roughly 15 degrees Celsius. Typically, ice clouds would form at this altitude, effectively trapping water vapor within the lower atmosphere by freezing the molecules together.
A NASA video illustrating the evolution of Mars. Credit - NASA Goddard YouTube Channel
However, with the added warmth from the dust, these ice clouds fail to form, allowing water to rise higher into the atmosphere, where it can be destroyed by radiation. Previously, it was assumed that this atmospheric water loss was confined to the southern summer; nevertheless, data collected from ExoMars, the Emirates Mars Mission (EMM), and the Mars Reconnaissance Orbiter revealed an unprecedented strong storm during the northern summer of Mars year 37 (corresponding to 2022-2023 on Earth). This event demonstrated that the same destructive processes observed during southern summers can occur year-round, not just during specific historical periods.
While this particular "rocket storm" was exceptionally powerful, researchers speculate that Mars may have experienced even more intense axial tilts in the past, potentially fostering the formation of such storms during much warmer northern summers. This additional route for water to escape could help clarify the discrepancies between the current amount of water on Mars, the estimated historical levels, and the mechanisms that might have led to its depletion.
Discover More:
- Royal Belgian Institute for Space Aeronomy - An unusual dust storm on Mars reveals how the Red Planet lost some of its water (https://www.aeronomie.be/en/news/2026/unusual-dust-storm-mars-reveals-how-red-planet-lost-some-its-water)
- A. Brines et al - Out-of-season water escape during Mars' northern summer triggered by a strong localized dust storm (https://www.nature.com/articles/s43247-025-03157-5)
- UT - Earth has a Water Cycle. Mars has a Dust Cycle (https://www.universetoday.com/articles/earth-has-a-water-cycle-mars-has-a-dust-cycle)
- uT - Mars Might Have Lost its Water Quickly (https://www.universetoday.com/articles/mars-might-have-lost-its-water-quickly)
