Mars was once wet, but what happened to its water?
NASA’s Hubble and MAVEN missions are helping solve the mystery.
Scientists combine the missions’ data to measure how atoms escape into space.
This helps estimate past escape rates and understand the planet's water loss over time.
Sunlight breaks Martian water molecules into hydrogen and oxygen.
The team measured hydrogen and deuterium, a heavier form of hydrogen.
Due to its higher mass, deuterium escapes into space more slowly than regular hydrogen.
As Mars loses water, the deuterium-to-hydrogen ratio rises.
The ratio reveals past water levels…
…and helps scientists understand what regulates the escape of these atoms into space today.
Mars has a more dynamic annual cycle than astronomers previously thought.
The atmosphere expands (heats) and contracts (cools) rapidly…
…as the Sun's brightness annually varies by 40%.
Hydrogen and deuterium escape faster when Mars is near the Sun.
Studying Mars' water history is key to understanding our solar system…
…as well as Earth-sized planets around other stars.
Mars, Earth, and Venus share the same habitable zone but have vastly different conditions…
…making Mars a valuable proxy for exploring distant worlds.
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