Mars Chronicles Ep 21: The Forensic Search for Water on Mars
From dried ancient river deltas to subsurface radar reflections: how orbital spectrometers and robotic rovers uncovered vast reservoirs of hidden water ice on Mars.
"Follow the water." For four decades, this four-word mantra guided NASA’s entire Mars Exploration Program.
Water is the universal solvent of biology. On Earth, wherever you find liquid water—whether in boiling hydrothermal vents, acidic mine runoff, or trapped deep inside Antarctic ice cores—you find microbial life.
If Mars was once wet, could it have harbored life? And if water remains today, where is it hiding?
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| THE MARTIAN WATER TIMELINE |
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| 1. NOACHIAN EPOCH (4.1 - 3.7 Billion Years Ago): |
| - Dense CO2 atmosphere, liquid surface oceans, river networks. |
| - Clay minerals & phyllosilicates formed in standing water. |
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| 2. HESPERIAN & AMAZONIAN EPOCHS (3.7 Ga - Present): |
| - Core dynamo shuts down; solar wind strips atmosphere. |
| - Atmospheric pressure drops below the triple point of water |
| (611 Pa): Liquid water can no longer exist stably on the surface! |
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| 3. MODERN WATER RESERVOIRS (Where it sits today): |
| - Polar Ice Caps: Vast layered sheets of water ice & CO2 frost. |
| - Subsurface Glaciers: Buried sheets 1-2m under dust in Arcadia. |
| - Hydrated Minerals: Chemically bound water in surface clays. |
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1. The Triple Point Problem: Why Surface Water Boils Away
On modern Mars, surface atmospheric pressure hovers around 600 Pascals (0.006 atmospheres).
In thermodynamics, the triple point of water is at .
- Because Martian atmospheric pressure sits below or right at the triple point, pure liquid water cannot remain in an open container.
- If you were to pour liquid water onto the ground at Gale Crater, it would simultaneously freeze and boil away violently into water vapor through sublimation!
2. Orbital Radar: Finding Glaciers Under the Dust
If liquid water cannot sit on the surface, where did the ancient oceans go?
Using the SHARAD (Shallow Radar) instrument aboard NASA’s Mars Reconnaissance Orbiter (MRO) and MARSIS on ESA’s Mars Express:
- Radar pulses penetrate deep into the Martian crust, reflecting off dielectric boundary layers.
- In mid-latitude regions like Arcadia Planitia and Deuteronilus Mensae, radar detected massive subterranean glaciers covered by just 1 to 2 meters of insulating regolith dust.
- These buried ice sheets contain millions of cubic kilometers of high-purity water ice—enough to flood the entire planet tens of meters deep if melted!
3. Ground Truth: Phoenix and Curiosity
In 2008, NASA’s Phoenix lander scooped up soil in the Martian Arctic:
- Within days, white chunks in the robotic trench sublimated into the atmosphere, confirming pure water ice just centimeters below the surface.
- In 2021, the Curiosity rover discovered evidence of ancient mud cracks in Gale Crater, proving that ancient Mars experienced wet-dry cyclic seasons identical to terrestrial lakes.
Mars was not born a frozen desert. It is a planet in cryogenic storage—waiting for human technology to unlock its hidden hydrological riches.