Mars has always captivated our imagination with its enigmatic past and present. We’ve seen images of its dry riverbeds and expansive ancient ocean basins, hinting at a time when liquid water flowed freely across the Red Planet. But where did all this water go? In recent years, scientists have been piecing together clues to answer this question. New research has shed light on the fate of Mars’s water, suggesting a dual process of water loss: sublimation into space and retention in the Martian subsurface.
The Enigma of Mars’s Water
Mars’s transformation from a wet world to a parched desert has puzzled scientists for decades. Two main theories have emerged to explain the disappearance of its water:
- Water Retained Underground: Some of Mars’s water may have seeped into the planet’s subsurface.
- Sublimation into Space: Water could have been lost to space as hydrogen and oxygen atoms.
Recent studies have bolstered both theories, painting a more nuanced picture of Mars’s hydrological history.
Recent Findings: Mars’s Hidden Water
InSight’s Discoveries
The Mars InSight mission, which landed on Mars in 2018 and operated until 2022, has been crucial in our understanding of Mars’s water. InSight’s seismometer detected multiple marsquakes and vibrations that suggested the presence of a “soggy” subsurface. This finding implies that Mars once had enough water beneath its surface to cover the entire planet in an ocean approximately a mile deep.
- Key Insight: Mars’s subsurface might still hold significant quantities of water, challenging the idea that all Martian water has vanished.
The Role of Atmosphere and Hydrogen Escape
New research published in Science Advances offers a fresh perspective on Mars’s water loss. This study used data from two NASA spacecraft: the Hubble Space Telescope and the MAVEN orbiter.
- Hubble Space Telescope: Observed Mars’s atmospheric changes over 33 years.
- MAVEN Orbiter: Provided insights into Martian atmospheric conditions since 2014.
These observations focused on the escape of hydrogen, which is a key indicator of how Mars’s water was lost to space.
How Hydrogen Escape Reveals Mars’s Water Loss
Water on Mars is broken down into hydrogen and oxygen by ultraviolet light from the sun. Here’s what happens:
- Ordinary Hydrogen: Escapes more easily due to its lower mass.
- Deuterium: A heavier form of hydrogen, escapes more slowly.
On Mars, lighter hydrogen atoms have been escaping into space over billions of years, altering the ratio of deuterium to hydrogen in the Martian atmosphere. This ratio now differs significantly from that on Earth, which retains its water due to its thicker atmosphere.
- Significant Finding: Mars’s atmosphere has up to eight times more deuterium relative to hydrogen compared to Earth, indicating substantial water loss.
Mars’s Elliptical Orbit’s Impact
Mars’s orbit around the sun is highly elliptical, varying between 128 and 155 million miles from the sun. This eccentricity affects Mars’s atmospheric conditions:
- At Aphelion (Furthest from the Sun): Water vapour concentration is extremely low, less than one part per million.
- At Perihelion (Closest to the Sun): Water vapour concentration increases to over 50 parts per million.
This fluctuation results in variable water and hydrogen loss throughout the Martian year.
- Implication: Mars experiences intense atmospheric changes, leading to increased water and hydrogen loss during its closest approach to the sun.
What Does This Mean for Mars’s Hydrology?
Based on recent studies, we now have a clearer picture of Mars’s water loss:
- Underground Reservoirs: Mars likely retains a significant amount of water beneath its surface or in polar ice caps.
- Space Escape: A considerable portion of Mars’s water has escaped into space, mainly in the form of hydrogen atoms.
These findings confirm that both mechanisms—subsurface retention and atmospheric escape—have contributed to the drying of Mars.
Final Thoughts
The mystery of Mars’s water is unraveling, revealing a complex history of loss and retention. As we continue to explore Mars, new missions and studies will provide further insights into this fascinating planet’s past and present.
By understanding where Mars’s water went, we gain valuable clues about the planet’s potential for past life and its suitability for future exploration.
Related Links for Further Reading
- Mars InSight
- Hubble Space Telescope
- MAVEN Orbiter
- Martian Atmosphere
- Deuterium to Hydrogen Ratio
