About 4 billion years ago, the young planet Mars was bombarded by massive comets and asteroids.
While such an event appears destructive, findings of a new study suggest that the bombardment of extraterrestrial rocks may have improved the climate conditions of the Red Planet, making it more conducive to life, at least for a time in its history.
One of the things that make Mars different from Earth is that it is believed to have spent most of its history in a cold state. Earth, on the other hand, was likely habitable for most of its existence.
Study researcher Stephen Mojzsis, from the University of Colorado Boulder, said that if early Mars was as cold and barren as it is today, the impact of massive asteroids and comets at the time would have generated enough heat to cause the melting of subsurface ice.
The event occurred during the Late Heavy Bombardment some 3.9 billion years ago when the developing solar system was marked by a shooting gallery of asteroids, comets, planets and moons.
To find out how the Late Heavy Bombardment impacted the Red Planet, the researchers used 3D computer modeling. They found that when comets and asteroids had impacted the planet, huge amounts of hot materials ejected from the craters had covered nearby areas.
The impact would have generated regional hydrothermal systems comparable to those seen on Earth's Yellowstone National Park, which now support microbes that can survive extreme environments such as boiling hot springs and waters that are too acidic they can dissolve nails.
Besides creating hydrothermal regions on Martian crust, the impact may have also temporarily improved the atmospheric pressure of the planet. This periodically warmed the Red Planet enough to set off a dormant water cycle.
Researchers have long been aware that Mars once harbored running water as evidenced by the existence of river valleys and lake beds.
"If early Mars was generally arid and cold, impact-induced heating punctuated this surface state by intermittently destabilizing the near-subsurface cryosphere to generate regional-scale hydrothermal systems," the researchers wrote.
A few million years after the bombardment, however, Mars has cooled to its current desert-like state.
"Ancient bombardment of Mars by comets and asteroids would have been greatly beneficial to life there, if life was present," said Mojzsis.
The study was published in the Earth and Planetary Science Letters.
