According to a study released Sunday, a potentially life-giving sea covered over a third of Mars about 3.5 billion years ago.
Scientists have argued for decades over whether Mars once harbored bodies of water big enough to help nourish a hydrological cycle marked by evaporation and rainfall.
Gaetano Di Achille and Brian Hynek of the University of Colorado in Boulder went through huge stores of images that NASA’s Mars Orbiter Laser Altimeter (MOLA) in the late 1990s and other more recent European and US satellite-based monitoring systems.
The researchers were the first to link up all available information on Mars’ terrain into a single computer-driven model.
The study found 52 river-delta deposits scattered across the planet.
Over half occurred at about the same elevation, which marks the boundary of the once-massive sea.
The scientists calculated that the ancient sea covered 36 percent of the planet’s surface and contained about 30 million cubic miles of water.
The scientists wrote that Mars probably had an Earth-like water cycle 3.5 billion years ago, including precipitation, runoff, cloud formation, ice formation and ground water accumulation.
Hynek and colleagues wrote in a parallel study that about 40,000 river valleys existed, four times the number previously suspected.
“The abundance of these river valleys required a significant amount of precipitation,” Hynek wrote in the Journal of Geophysical Research (Planets).
“This effectively puts the nail in the coffin regarding the presence of past rainfall on Mars.”
However, many puzzles still remain.
“One of the main questions we would like to answer is where all of the water on Mars went,” said Di Achille.
The new studies provide critical leads on where to look for signs of early Martian life.
“On Earth, deltas and lakes are excellent collectors and preservers of signs of past life,” Di Achille told AFP news.
“If life ever arose on Mars, deltas may be the key to unlocking Mars’ biological past.”
Hynek wrote that long-lived oceans may have provided an environment for microbial life to take hold on Mars.
The European Space Agency (ESA) and NASA have separately planned a manned flight to Mars in about 30 years.
Mars is between 34 million and 248 million miles from Earth.
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Image Caption: This is an illustration of what Mars might have looked like some 3.5 billion years ago when an ocean likely covered one-third of the planet’s surface, according to a new University of Colorado at Boulder study. (Illustration by University of Colorado)
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