Mars may have been cold, icy billions of years ago

A new study has revealed that Mars may have been cold and icy billions of years ago, which also suggests that aliens may not have existed ever on the planet.

The high seas of Mars may never have existed, according to a new study that looks at two opposite climate scenarios of early Mars and suggests that a cold and icy planet billions of years ago better explains water drainage and erosion features seen on the planet today.

For decades, researchers have debated the climate history of Mars and how the planet's early climate led to the many water-carved channels seen today. The idea that 3 to 4 billion years ago Mars was once warm, wet and Earth-like with a northern sea, conditions that could have led to life, was generally more popular than that of a frigid, icy planet where water was locked in ice most of the time and life would be hard put to evolve.

The study's authors found that the cold scenario was more likely to have occurred than the warm scenario, based on what was known about the history of the Sun and the tilt of Mars's axis 3 to 4 billion years ago.

The colder scenario was more straightforward to model, Robin Wordsworth of the Harvard Paulson School of Engineering and Applied Sciences explained, because Mars only gets 43 percent of the solar energy of Earth, and early Mars was lit by a younger Sun believed to have been 25 percent dimmer than it is today. That makes it very likely early Mars was cold and icy, he said.

Wordsworth further added that the cold/icy scenario isn't perfect but it's a better fit to the observations in general. While this scenario accumulates frozen water closer to the drainage features observed today on Mars, something had to have melted the ice which carved the valleys and in this scenario, the climate is cool most of the time, and short-lived events like meteor impacts and volcanic eruptions likely caused the necessary melting.

Bethany Ehlmann, a planetary scientist at California Institute of Technology and NASA's Jet Propulsion Laboratory in Pasadena, California, said that the 3-D climate modeling used in the new study begins to address these questions with a new level of sophistication by investigating how specific locations might have accumulated rain or snow.

The study is published in the AGU's Journal of Geophysical Research: Planets.