A new University of Colorado Boulder study asserts that the comets and asteroids the size of West Virginia made life on Mars temporarily habitable for a few million years. The impact from these enormous celestial objects emitted enough heat to melt the Red Planet’s icy subsurface, creating regional hydrothermal systems that could have sheltered chemically-powered microbes like the ones found in Yellowstone National Park.

The study published in Earth and Planetary Science Letters explains that this event is also known as the Late Heavy Bombardment that occurred when the solar system was still developing, firing asteroids, planets, comets and moons into space 3.9 billion years ago. Moreover, the impact most likely increased the planet’s atmospheric pressure that heated it occasionally which also revived a dormant water cycle.

“This study shows the ancient bombardment of Mars by comets and asteroids would have been greatly beneficial to life there, if life was present,” adds CU-Boulder geological sciences department Professor Stephen Mojzsis. “But up to now we have no convincing evidence life ever existed there, so we don’t know if early Mars was a crucible of life or a haven for life.”


Ancient impacts on Mars likely enhanced climate conditions for life. Photo from NASA

The researchers created a 3-D model using the Janus supercomputer cluster at the university. Based on their simulations, they concluded that the planet was heated by the bombardment of asteroids and comets that lasted for a time before Mars became the cold and uninhabitable planet we now know of today.

Additionally, the researchers claim that this Late Heavy Bombardment boosted life on Earth. Mojzsis pointed out in 2009 that the asteroid and comet impact theorised to have wiped out Earth’s early life actually did not cause any extinction.

The researchers plan to study how the bombardment affected Mercury and Venus. This could lead to further understanding of how the inner solar system evolved, which could help scientists study other solar systems.