The FORGOTTEN History of Mars Before Its Water Vanished - SPACE DOCUMENTARY

Billions of years ago, Mars was not the barren desert world we see through our telescopes today. Instead, it was a dynamic planet with rivers, lakes, and perhaps even vast oceans spreading across its surface. Traces of ancient valleys carved by flowing water, delta formations, and mineral deposits tell us that liquid water once shaped the Martian landscape. The forgotten history of Mars before its water vanished is a story of transformation from a potentially habitable world to the cold, dry, and dusty planet we know now. Scientists studying this past are piecing together evidence from orbiters, landers, rovers, and meteorites that reveal Mars once resembled Earth far more closely than we imagined. Understanding this history is not just about reconstructing Mars’s past but also about asking whether life could have emerged there and whether traces of it may still remain hidden beneath the surface. Mars formed around the same time as Earth, about 4.5 billion years ago, within the swirling disk of dust and gas that surrounded the young Sun. At first, both planets followed similar paths: molten surfaces, intense bombardment from asteroids, and heavy volcanic activity. But while Earth grew into a larger, warmer, and wetter planet, Mars remained smaller and more fragile. Despite its limitations, Mars developed thick volcanic plains, a protective magnetic field, and a denser atmosphere that supported surface water. Around 3.5 to 4 billion years ago, water flowed abundantly across the Martian surface, creating valleys that rival the largest river systems on Earth. Massive basins such as Hellas and northern lowlands may have hosted seas or oceans. Sedimentary layers observed by NASA’s Curiosity rover in Gale Crater show ancient lakes that lasted for millions of years. Minerals like clays and sulfates, which only form in the presence of water, are widespread across the planet, leaving little doubt that Mars once had a wetter, more Earth-like climate. The great mystery is why Mars changed so drastically. One of the leading explanations is the loss of its magnetic field. Earth’s magnetic field shields our atmosphere from the solar wind, a constant stream of charged particles from the Sun. Mars, however, lost its global magnetic field relatively early in its history, perhaps around 4 billion years ago. Without this protection, the solar wind gradually stripped away the atmosphere, thinning it until surface water could no longer remain stable. As the air thinned, temperatures plummeted and liquid water either froze underground or evaporated into space. The once-blue Mars faded into the red desert we see today, its rivers cut short and its oceans dried into memory. This transformation was not instantaneous. Evidence suggests that water persisted in some places for hundreds of millions of years after the atmosphere began to thin. Valleys and outflow channels hint at catastrophic floods, possibly triggered by volcanic or tectonic activity releasing underground reservoirs. Mars may have gone through cycles of wet and dry periods, with temporary climates that allowed water to resurface before vanishing again. Even in its late stages, glaciers carved valleys and left deposits that testify to a complex hydrological history. But eventually, the planet crossed a threshold where surface water could no longer exist for long durations. Ice retreated into the polar caps and subsurface layers, and the era of flowing Martian rivers came to a permanent end. For scientists, reconstructing this forgotten history is like solving a puzzle with scattered clues. Orbiters map valleys and mineral deposits from above, while rovers explore sedimentary layers on the ground. Martian meteorites that landed on Earth carry isotopic signatures showing how much atmosphere and water were lost to space. The MAVEN mission has directly measured atmospheric escape, confirming that solar wind erosion continues even today. Piece by piece, these findings show how Mars went from being a world of lakes and possible oceans to the dry desert it is now. The implications go far beyond geology. If Mars once had stable liquid water for millions of years, then the conditions for life may have been present. Microbial life could have evolved in those lakes and rivers, leaving behind fossils or chemical traces still hidden in the rocks. Even after surface water disappeared, underground aquifers may have provided refuges for microbial communities. Modern missions are searching for these biosignatures, drilling into rocks and analyzing ancient sediments to see whether Mars’s watery past left evidence of biology.