For the first time, scientists are piecing together the complete story of Martian climate across billions of years.
Imagine standing on the surface of Mars, watching as dust devils dance across rusty plains and water vapor rises through the thin, cold air. Today, this scene exists only in simulations, but scientists are working to recreate it with unprecedented accuracy in a race to understand Mars' past. At the forefront of this effort, researchers are developing the first comprehensive surface-to-exosphere model of the Martian atmosphere—a virtual time machine that could finally reveal whether the Red Planet was once habitable.
Mars presents us with a profound mystery. Geological evidence clearly shows that liquid water once flowed across its surface, carving river valleys and filling lakes. Yet today, Mars is a frozen desert with an atmosphere just 1% as thick as Earth's. What catastrophic climate shift transformed this potentially habitable world into the barren planet we see today? 1
Liquid water flowed on surface, carving river valleys and filling lakes.
Frozen desert with atmosphere just 1% as thick as Earth's.
The answer lies in understanding Mars as a complete system, from its surface to the uppermost reaches of its atmosphere. Unlike Earth, Mars lacks a protective magnetic field, leaving its atmosphere vulnerable to being stripped away by solar radiation. To piece together this planetary puzzle, an international team of researchers led by François Forget at the Pierre Simon Laplace Institute has embarked on an ambitious project called "Mars through time." Their goal: build a virtual model that simulates Mars' climatic evolution over millions of years. 1
"We are trying to invent a new model, to build a virtual planet that evolves through time," says Forget. "It's a super ambitious project." Unlike current models that provide only climate snapshots, this new tool will simulate the evolution of glaciers, lakes, and atmosphere across geological timescales. 1
The exosphere—the outermost atmospheric layer where gases can escape into space—holds crucial clues about Mars' climate history. This tenuous region is dominated by atomic hydrogen and represents the critical boundary between atmosphere and space. Here, gases interact directly with solar radiation and wind, gradually escaping Mars' gravitational pull.
Knowledge of exospheric composition provides significant insight into temporal atmospheric evolution. Throughout solar system history, this slow but persistent atmospheric escape has fundamentally shaped planetary environments. For Mars, understanding these escape rates across different seasons and solar activity levels is essential to reconstructing how its thicker ancient atmosphere gradually dissipated.
Mars' thin atmosphere presents unique modeling challenges, particularly in the upper atmospheric regions. At these altitudes, the air becomes so sparse that it's considered "rarefied gas," behaving differently than the thick air we experience at Earth's surface. Specialized computational methods are required to accurately simulate fluid dynamics under these conditions. 8
Researchers have developed sophisticated simulation environment boxes that replicate Martian atmospheric conditions. By combining computational fluid dynamics with experimental validation, scientists can create more accurate representations of how gases and heat circulate in Mars' upper atmosphere—a crucial step toward building comprehensive climate models. 8
While modeling the upper atmosphere requires sophisticated computations, understanding processes at the surface demands careful laboratory experimentation. One crucial study conducted at the SpaceQ facility has provided remarkable insights into the elusive Martian water cycle—particularly how liquid water might temporarily exist on modern Mars.
Researchers designed three elegant experiments to investigate water behavior under Martian conditions: 5
Scientists first created an environment nearing saturation at temperatures around water's triple point (0°C), observing how water interchange occurs between atmosphere and surface materials.
In the second experiment, researchers blended deliquescent salts with Mojave Martian Simulant (MMS) to quantify the regolith's water absorption capacity and observe texture changes caused by hydrate and brine formation.
The final experiment studied pure water evaporation when both air and ground reached equal temperatures near saturation, but away from the triple point.
Throughout these tests, scientists meticulously monitored relative humidity and water vapor pressure changes in real-time, replicating the dramatic temperature swings observed by rovers like Curiosity, where ground temperatures can plummet 20°C below air temperatures just 1.6 meters above the surface. 5
The experiments yielded fascinating discoveries with profound implications for Martian habitability:
Researchers observed that frost can form spontaneously when saturation occurs, then transform into liquid water when temperatures rise above 0°C. This liquid water can persist for 3.5 to 4.5 hours under Martian surface conditions. 5
Deliquescent salts similar to those found on Mars increased their mass by 32-85% through atmospheric water absorption within hours. When mixed with regolith simulant in 10% concentration, these salts produced aggregated granular structures with water gains of 18-50% by weight. 5
The simulated Martian ground captured up to 53% of available atmospheric water as pure liquid water, hydrate, or brine. 5
These findings demonstrate that liquid water may be more common on modern Mars than previously assumed, with significant implications for both potential habitability and future human exploration.
| Material | Water Gain (%) | Form of Water Retained | Time Scale |
|---|---|---|---|
| Deliquescent Salts (pure) | 32-85% | Brines, Hydrates | Few hours |
| Salts + Regolith Simulant (10%) | 18-50% | Brines, Hydrates | Few hours |
| Simulated Ground | Up to 53% of atmospheric water | Pure liquid water, Hydrates, Brines | Night-Morning cycle |
| Material/Solution | Function in Research | Relevance to Mars |
|---|---|---|
| Mojave Martian Simulant (MMS) | Recreates chemical and physical properties of Martian soil in experiments | Provides realistic substrate for water cycle and atmosphere-regolith interaction studies |
| Deliquescent Salts (perchlorates, chlorides) | Study brine formation and water absorption processes | Explain potential water activity on modern Mars and soil aggregation |
| Ceramic Alumina Membranes | Enable photophoretic levitation studies | Model upper atmospheric dynamics and potential exploration technology |
| Carbon Dioxide Formulations | Recreate Martian atmospheric composition | Allow accurate simulation of greenhouse effects and climate evolution |
| Hydrogen-Injected Atmospheric Mixes | Test early Mars climate hypotheses | Investigate mechanisms for warm climate periods in Martian history |
At Stony Brook University, researchers are tackling a different challenge: creating physically accurate 3D models of Martian terrain. Using NASA rover imagery, they've developed the M3arsSynth data engine that reconstructs detailed digital landscapes reflecting the planet's actual structure. 3
"Mars data is messy," admits Professor Chenyu You. "The lighting is harsh, textures repeat, and rover images are often noisy. We had to clean and align every frame to make sure the geometry was accurate." Their resulting MarsGen AI model can generate new, controllable videos of Mars from single frames—an invaluable tool for mission planning and scientific analysis. 3
At Caltech and MIT, researchers have developed a breakthrough method called IT-π that identifies the most critical variables for predicting physical phenomena. When applied to heat flux calculations for spacecraft entering Mars' atmosphere, their method reduced the required variables from seven to just two. 7
"The theorem we derived will tell you how to construct dimensionless inputs that contain the maximum amount of information about what you want to predict," explains lead researcher Adrián Lozano-Durán. This approach dramatically reduces the computational power needed for accurate modeling. 7
| Modeling Approach | Key Features | Applications |
|---|---|---|
| Mars Through Time (3D Planetary Climate Model) | Simulates evolution over millions of years, couples hydrology, glacial flows with climate model | Understanding long-term climate evolution, habitability periods |
| AI Terrain Reconstruction | Generates physically accurate 3D models from rover imagery | Mission planning, geological analysis, visualization |
| IT-π Dimensionless Learning | Identifies most critical variables using information theory | Efficient prediction of atmospheric entry heat flux and other phenomena |
| Whole Atmosphere Community Climate Model | Simulates entire atmosphere from surface to upper thermosphere | Studying impact of geomagnetic storms and solar activity |
As the "Mars through time" project approaches its November 2025 conclusion, researchers are already looking toward the next frontiers. The model continues to incorporate new data from active missions like Curiosity and Perseverance, refining its simulations of how atmospheric composition, orbital oscillations, and catastrophic events shaped Martian history. 1 9
The implications extend far beyond Mars. "The limit of habitability is a big topic," Forget notes. "We can explore what it takes for a planet like Earth to have liquid water on its surface. We want to define where water will stabilize." Understanding Mars' dramatic climate shifts provides crucial insights into planetary evolution everywhere. 1
Each discovery brings us closer to answering humanity's most profound questions: Was Mars ever habitable? Could life have emerged there? And what does Mars' climate history reveal about our own planet's future? As these comprehensive surface-to-exosphere models continue to evolve, they offer not just a window into Mars' past, but potentially a mirror for understanding Earth's place in the cosmos.
Initial development of Mars through time project begins
Breakthrough experiments on water absorption in Martian soil analogs
Development of AI terrain reconstruction tools
Integration of atmospheric escape models with surface climate simulations
Completion of first comprehensive surface-to-exosphere Mars atmosphere model
Just 1% of Earth's atmosphere
3.5 to 4.5 hours on modern Mars surface
Salts increase mass by 32-85% through water absorption
Completion expected November 2025